 As severe weather season ramps up, avid storm chasers will continue to flock to the Great Plains and adjacent regions in the hopes of observing tantalizing storm structure and captivating tornadoes. However, if you’re a photographer looking for a picturesque landscape featuring a stunning lightning bolt in the background, the Southwest United States may be your destination. The Southwest US Monsoon season begins June 15th, and lasts through September. Much of this geographic regions annual precipitation falls during this time in the form of heavy rains from convective storms. In addition to flooding rains, these storms usually produce strong winds, occasionally dense blowing dust, and the potential for prolific lightning photography (see below).  Two lightning bolts strike during the evening hours in the vicinity of El Paso, TX (Photo Credit: John Fausett). Like most weather/climate variables, the Southwest US Monsoon can have very active, and inactive seasons. This past year, 2021, was certainly very active for portions of southern Arizona, southwestern and south-central New Mexico, in addition to far west Texas. Several rounds of abundant moisture coupled with atmospheric energy produced very heavy rains and flash flooding. Check out the image below which shows rainfall as a percentage of normal for much of the the monsoon season across portions of the Southwest (focusing on southwest and south-central NM and far west Texas).  The image above shows the estimated rainfall as a percentage of normal for the time period June 15th through August 31st. Notice the greens, blues, and purples suggest above, to well above normal precipitation across much of the area (far west Texas and into southwestern portions of New Mexico). For reference, the map below shows a zoomed out version of the Southwest, with the blue circle on the location of the precipitation image above.  As a result of all this heavy rain, the desert transformed into an oasis. Look at the pictures below of the Franklin Mtns (located in El Paso) and how the greenery flourished with in the desert landscape.  An image of the Franklin Mountains up close and personal. Notice the copious amounts of green vegetation, thanks to heavy monsoonal rains during the 2021 season.  A similar picture of the Franklin mountains, but from afar. The greenish tint to the mountains remains evident, which to this level is quite uncommon (according to the locals). Whether you’re in the Great Plains with tornadoes and supercells, or the Desert Southwest with heavy rain, dust, and lightning, weather truly is a dangerous, and equally fascinating phenomena.
To learn more about North American Weather, click here! ©2022 Meteorologist Joe DeLizio
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 When you think of a desert landscape, what comes to mind? Perhaps flat, open land with sand dunes across the horizon. Maybe large Saguaro cacti native to the Sonoran Desert in Arizona. But how about fields of beautiful flowers as far as the eye can see? Several pictures of Mexican Golden Poppies on the east side of the Franklin mountains in El Paso, TX. These flowers pictured above are native to the Desert Southwest, termed Mexican Golden Poppies. Wet winters and early springs can enhance the coverage and length of the bloom. As far as El Paso is concerned (and much of southern New Mexico), it has been an extraordinarily wet March (3rd wettest on record in fact) and a relatively active February. Usually March begins the dry and windy season across New Mexico and far west Texas, which makes this wet March all the more spectacular. Lucky for El Pasoans, a brilliant bloom of wildflowers has livened up the Franklin Mountains. And who said deserts can’t be green/colorful?  It has been much drier, and a bit windier the last half/third of March in El Paso, as shown above in the F6 climate report from KELP (El Paso international airport). More of the same looks likely by the middle to later portions of next week as a large upper level trough barrels through the region. The track of this upper level system, through the Four Corners region, typically results in surface low pressure development in the vicinity of southeast Colorado/northeast New Mexico. The pressure gradient consequent of this low-pressure to the northeast results in windy conditions across New Mexico and far west Texas, including El Paso. This is common during March and April most years with dusty conditions possible as well. A diagram below gives a visual of this pattern.  Mother nature can deviate from the norm at will which is exactly what happened this March across portions of southern NM and far west TX. This helped to generate some stunning color in the desert this Spring.
To learn more about North American weather, click here! ©2020 Meteorologist Joe DeLizio  DISCUSSION: February is normally one of the wettest months for much of California. However, this February has been one of the driest in recent history for many regions of the state especially the San Francisco Bay Area. In most locations of the Bay Area, there has been no rain recorded including in San Jose, San Francisco, and the commonly wet locations of Napa and Sonoma. In addition, to the unusually dry conditions for much of the state, the Sierra Nevada range has received minimal new snow and is below normal of total snowfall for the rain year as the Sierra Nevada has reservoirs such as Hetch Hetchy which provides drinking water to areas including San Francisco.
One of the biggest reasons for the lack of rain has been due to many ridges over California. A ridge is an area of high pressure where there is a maximum in the curvature of the winds in an anticyclonic (clockwise) motion. In addition to the consistent ridges, the low pressure systems that tried to move through were either dry or most of the moisture went east towards the Great Basin and the Sierra Nevada mountain range while missing most of California. The moisture was driving to the east in the upper atmosphere due to the flow of the wind due to the pressure differences and the curvature of the Earth. However, on February 22, a small low pressure system brought some sprinkles to parts of California including the Central Coast and the Central Valley, however, it was not enough to relieve the dryness or even make a big impact. In addition, parts of Southern California and Arizona received moisture in this time period due to moisture being drawn from the warmer portion of the Pacific Ocean near Baja California. However, there is not all bad news due to the dry February. Many of the reservoirs especially closer to the Sierra Nevada such as Don Pedro and Lake Oroville are near or above average in how much is being stored at the moment compared to historical. In addition, a few locations such as San Diego and the northern coast cities such as Eureka and Crescent City have received above average monthly rains. Due to the dryness of January and February, much of the state has been placed in the abnormally dry category of the drought monitor with moderate drought levels for the Central Valley. A drought monitor is a way to show the cumulative lack of moisture in certain areas. However, counties such as San Bernardino, Riverside, San Diego, and Orange in Southern California are not in drought or dry conditions due to the amount of rain they received overall in the year. To learn more about other high-impact weather events occurring across North America, be sure to click here! ©2020 Meteorologist JP Kalb  A Look Back On the Decade: California Oaks and the Drought
Oak trees are one of the most prolific and common trees throughout California, finding home primarily throughout the northern valley and foothills, be it the endemic blue, canyon-live, or valley variety. With twisting, mighty limbs that extend to curled tendrils, and trunks like that of an ocean liner anchor, residents of the Golden State recognize these trees as a symbol of the state, unlike the palm trees that arise in nearly every media bit about the state. Hardy and enduring, California’s native oaks are no stranger to drought, and tolerate them well. With roots that can reach fifty plus feet deep into the soil, California oaks are able to access underground aquifers when water runs scarce. Though despite the brute-like strength and tolerance these trees possess, the record breaking drought experienced from 2011 until March 15th, 2019 saw a die-off of many oaks throughout the state. As water reservoir levels hit record lows in 2015 and 2016, underground water simultaneously disappeared. The sources of water that oaks could once depend on even in the worst of drought situations by reaching down their roots, sometimes as far as 80 feet, had essentially been depleted. As years accumulated with not enough rain to replenish these underground aquifers, the trees began to produce signs of stress, some of which were surprising. Blue oaks in some groves were found to have produced a physiological stress signal in response to the drought by dwarfing their leaves. Others became infested with bark beetles as the population of the pest exploded due to the dry weather, perfect for reproduction. Ring studies conducted on these trees indicated that the 2012-2015 portion of the drought was the most severe drought California had experienced in more than 600 hundred years. From atmospheric scientists to plant scientists to hydrologists, these endemic trees to California served as an important climate signal. They indicated to atmospheric scientists that drought such as the period of 2012-2015 was unprecedented and that the like had not been seen centuries before. Plant and environmental scientists warned that the lack of groundwater supply for the oaks and their subsequent die-off could signal a change in the California vegetation. If extended and record-breaking drought conditions were to continue and be the norm for the areas in which the trees grew, the vegetation would change drastically. The oaks that once signaled the mediterranean climate of the region would cease to exist, with drought-tolerant shrub and bush overtaking such as mesquite. The landscape would slowly turn to become more of a chaparral like that of Southern California as opposed to the temperate mediterranean climate of valley and foothills that Californians knew. In total, it was estimated that nearly 100 million trees died off in the nearly decade-long drought of California, the majority lying with the different species of oak throughout the state. From a complete dry-out of the underground aquifers to the infestation of bark beetles, oaks suffered from multiple angles and consequences of the drought. Moving forward, as the climate is expected to warm and these periods of extreme drought come to be more commonplace, mass die-offs of these stately organisms are feared, and expected. Climatologists warn that periods of extremes, from wet to dry, will be further and further apart, and more impactful as they do occur resulting from the imbalance. One may deduce that this may spell disaster for the stately trees. To read more about weather and atmospheric phenomena within North America, click here! https://www.globalweatherclimatecenter.com/north-america-weather-climate-topics © 2019 Weather Forecaster Alexis Clouser First widespread below 0°F in the Continental United States. (Photo Credit: NWS Grand Forks)12/16/2019  DISCUSSION: On the week of December 8, a trough moved over parts of North Dakota and Minnesota. The trough brought with it a dose of a very dry cold polar air from Canada into the U.S. leading to the first widespread below 0 degrees Fahrenheit temperatures across much of the Northern Plains of the 2019-20 Winter season. The trough also brought with it a strong wind which made the wind chill much more dangerously cold. However, some locations had below 0 temperatures in November but they were not as widespread. The wind was strong due to a tight pressure gradient in the upper atmosphere. A pressure gradient is a quantity that describes the change of pressure over a distance and is used to help determine wind speed at high levels of the atmosphere.
Wind chill is an apparent temperature developed to give a sense of how the temperature feels with how windy it is. It is used to help determine how long one should be outside before developing hypothermia and frostbite. However, wind chill is not always accurate as it does not factor in moisture especially if a person’s skin is wet or how many layers a person is wearing. In addition, wind chill is not consistent due to the minute time often varied in wind speed. The trough slowly moved out before another one moved in with a warm front bringing warmer temperatures and snow to the area including up to an inch at Minneapolis-St. Paul International Airport. In a normal year, places like Minneapolis-St. Paul and St. Cloud, Minnesota are not below 0 degrees until late December or early January as winter progresses. The coldest areas are usually the rural counties in North Dakota and Minnesota with International Falls, Minnesota being the most consistently, coldest metropolitan area during the winter. To learn more about other high-impact weather events occurring across North America, be sure to click here! ©2019 Meteorologist JP Kalb  A typical setup for strong westerly winds will develop across much of New Mexico (otherwise known as the Land of Enchantment) particularly for this Sunday. Strong westerly flow aloft is currently anchored over much of the Desert Southwest into portions of the central Rocky Mountains. This typically generates a lee side surface cyclone. Depending on how deep the surface cyclone is, breezy conditions can develop. Sunday will be particularly susceptible to windy conditions as an upper level trough swings through the Desert Southwest region and into northern NM. This shortwave will intensify the surface low pressure and increase the winds above the surface. During the daytime hours, when surface heating begins and the boundary layer becomes well mixed, these stronger winds from aloft will mix down to the surface resulting in the aforementioned windy conditions on Sunday.  Image above: 500mb heights from the GFS model. Circled in black is the trough that will enhance windy condition on Sunday. There are locations in southern New Mexico that are more susceptible to stronger winds in this type of setup. These include mountain ranges and more specifically on the eastern slopes of these mountain ranges.  Image: Map showing terrain features across New Mexico. Notice the Black Range and Sacramento Mountains labeled. These are typical high wind locations in southern NM, in addition to locations around the San Andres Mountains as well.
(https://www.nationsonline.org/oneworld/map/USA/new_mexico_map.htm) The Black Range and Sacramento Mountains in southern NM average about 8-9K feet in elevation with some peaks reaching around 10K ft. With a strong westerly wind, the mountains are higher in elevation and therefore will have higher winds. The east slopes of these mountains are susceptible to down-slope winds further enhancing these wind speeds. As a result, the NWS in Santa Teresa/El Paso and Albuquerque have issued a high-end wind advisory for these mountain ranges, the east slopes, and surrounding terrain. In addition, there is a lower end (meaning lower wind values) wind advisory for the rest of southern NM. To learn more about impactful wind events across North America, click here! ©2019 Meteorologist Joe DeLizio First snow of the season comes early to Yellowstone (Photo Credit: National Weather Service)10/10/2019  DISCUSSION: On Friday, September 20, the National Weather Service (NWS) offices in Riverton, WY, Great Falls, MT, Billings, MT, and Missoula, MT issued their first winter weather advisories and winter storm warnings of the 2019-2020 snow season. The advisories and warnings are the first of this season, as a trough of low pressure moved in from Canada bringing in a cold front to much of the northern Rockies including Yellowstone and Grand Teton National Parks. The warnings and advisories were mainly for the mountainous regions of Montana, Wyoming and parts of eastern Idaho.
One of the biggest factors for there to be snow with this front is that much of the air over the Yellowstone region was moist due to a southerly flow that was occurring in the higher levels of the atmosphere due to the wind flow of the trough over the past few days. The front edge of the trough was responsible for the southerly flow bringing moisture from the Gulf of Mexico to the colder area of the upper mountain west. However, the cold air that came from the north on the western side of the trough interacted with the moisture as air holds less water as it gets colder. Due to the amount of the moisture that was present in the atmosphere and the lower amount of vapor the colder air from the north could hold, the moisture condenses and forms larger droplets which in turn precipitate when large enough due to the effects of gravity. Normally, these droplets would dissipate as some of the lower levels of the atmosphere are warmer and not as saturated. In addition to the snow in the Tetons and Yellowstone area, the cold front continued to move south and east bringing severe thunderstorms to the Dakotas, northwestern Nebraska and eastern Wyoming as well as below freezing temperatures into Colorado. The front moved across the Mississippi River Valley over the weekend bringing more thunderstorms to the area which brought heavy rains to the area. The concern of heavy rains has resulted in many NWS offices along the northern portion of Mississippi River to issue flash flood watches and warnings along the river and the tributaries. This snow event was followed by another trough of low pressure on the very next weekend of September 28 through September 30 which brought even more snow to the upper Rockies and the Yellowstone area. This second trough also moved east bringing heavy rains to the Mississippi River Valley which led to the reissuance of flood warnings along the Mississippi River especially in Iowa, Minnesota, Illinois, and Missouri. To learn more about North American weather phenomena and events, please click here! ©2019 Meteorologist JP Kalb Dark clouds loom overhead above Isleta Amphitheater in Albuquerque during the July 2013 Luke Bryan concert (left), abandoned coolers and lawn chairs are left behind following a downpour at the ABQ Biopark concert series (right). No animals or humans were harmed in the storm. You may have heard about Hurricane Dorian in the weeks prior… what about Hurricane Green Chile? Monsoon thunderstorms may not be a result of a hurricane, but may produce as much wind and rain as a Category 1 hurricane. Monsoon season is usually referred to a contrast in land/ocean heating that bring torrential rain across Asia, Australia, and Africa, however, can also be used to describe an increase in summer precipitation across the southwestern United States. More than half of New Mexico’s precipitation amount occurs between the June and September months. A typical monsoon pattern usually shows an area of high pressure to the east of New Mexico. Since high’s are typically characterized by clockwise flow, this results in moisture being transported from south to north from the Gulf of Mexico and into New Mexico and Arizona.
The National Weather Service classifies the start of monsoon season through 3 consecutive days above a certain dew point threshold (47 degrees Fahrenheit or greater for Albuquerque, 55°F for Phoenix, 54°F for Tucson), reflecting the amount of surface moisture aloft that might fuel thunderstorms and produce a measurable amount of precipitation. Generally, warmer temperatures can enhance monsoon season precipitation by creating more instability in the atmosphere for thunderstorm growth, but this is not a straightforward forecast. If it gets too hot, less moisture is available and the ground dries out. But, a late start to monsoon season can mean as late as mid-July for northern and central New Mexico. With only about 2 weeks left in the monsoon season, the Albuquerque International Sunport has collected 2.56” through September 15th, 2019, making it one of the top 20 driest monsoons on record so far. The monsoon is not constant throughout the season and may consist of a pattern of moisture surges (“bursts”) and dry “break” periods. The 2013 monsoon season was in the top 10 wettest monsoons for Albuquerque with 7.16” between July and September. Above, a storm in July 2013 that caused 2 inches of rain accumulation in downtown Albuquerque, widespread power outages, and a peak wind gust of 89 mph recorded near the Albuquerque International Sunport from a wet downburst. To learn more about the monsoon and other North American weather phenomena, please click here! © 2019 Meteorologist Sharon Sullivan  What Makes the Sacramento Area a Mediterranean Climate?
Hot, blazing, pan-fried summers with little to no humidity and nothing in the way of rain. Mild and cool, occasionally cold, winters with about an average of no more than twenty inches of rain, the majority falling in January- these conditions are what define the Sacramento climate and make it so amicable to agriculture. Though, for anyone native to or having lived within the area long enough, they may have come across someone, perhaps the local news meteorologist describe the climate as that of “Mediterranean.” Yet, the mediterranean normally conjures up ideas of coastal areas such as that of Greece or perhaps southern Italy, Malta or southern Spain, not the valley-centric agricultural hub that is Sacramento. So, just how does Sacramento come to be named as a Mediterranean climate? The very definition of a Mediterranean Climate is a climate that produces relatively warm and wet winters followed by a long, hot and very dry summer with no precipitation. Winds in these types of climates are called “westerlies” as they find origin to the west. Any area with this sort of climate sits coastally, or relatively close to the coast and can be geographically pinpointed to about forty degrees latitude. Sitting just above the thirty degrees latitude line where the majority of the world’s deserts sit, and just below the sixty degree line where the subarctic region exists, one might easily see why the Mediterranean climate experiences extremely hot and dry summers and cool, wet winters. Vegetation throughout Mediterranean climates are often scrubby and small, and typically very drought tolerant. Flora all throughout the expanse of this climate zone must be able to endure the natural drought that summer brings, and to tolerate the deluge of rains in midwinter. Some deciduous trees such as oaks may be found, especially towards hills, though evergreens are found here as well such as that of Pine. Agricultural crops such as citrus, grapes, and olives flourish throughout the region and as a result, often define local cuisine. For those native to Sacramento, it may now be more easily recognizable that the capital does, in fact, exist within a Mediterranean climate. From the large crops of grapes produced and wine made, olives grown and their oil processed and sold all throughout the Sacramento region, to the Valley and Blue Oaks that dot the landscape, the land itself emanates the Mediterranean. With its ripping hot, frying-pan summers and mild, humid winters, the climate is a twin to that of Greece and the surrounding areas, the only difference being that of physical location. To read more about weather and atmospheric phenomena within North America, click here! https://www.globalweatherclimatecenter.com/north-america-weather-climate-topics © 2019 Weather Forecaster Alexis Clouser  Although the Sonoran Desert might seem like a barren wasteland, it’s actually a delicate ecosystem that relies on important food webs and a predictable climate. All the plants and animals native to this desert have specially adapted to their environment and each other, often making the existence of a particular species essential to the health of the ecosystem. These species are often called keystone species because of their critical value to the environment. One such species is the Saguaro cactus, located only in the western United States within the Sonoran Desert. These cacti provide shelter, shade, food, and water for small animals, as well as contribute to the natural beauty of the desert. These animals need the Saguaro because the harsh climate of the desert does not allow for many resources to exist.
Regrettably, people have been cutting down and taking cacti from the desert, usually in an effort to populate their front yard with succulents. This practice is not only bad for the environment, but it’s also illegal in the state of Arizona, which is where most Saguaro are found. Those found attempting to transplant, destroy, or otherwise uproot the cactus are subject to a felony charge. This doesn’t stop people from stealing the crucial desert flora, sadly. In fact, cacti heists have become so profuse in Arizona that park officials have started to install microchips in especially iconic cacti to deter succulent swindlers. The microchips have the ability to send out signals that notify park officials when a cactus has been wrangled. Directly moving cacti is not the only way people have been harming the Saguaro. Increasingly, wild fires have become a problem in the Sonoran Desert. Typically, wildfires don’t occur in the desert because of the lack of vegetation. If a fire were to start, it would burn out quickly before spreading because it would have nearly no fuel. With short grasses and shrubs added into desert by farmers, wild fires have become more of a problem in the southwest United States (although nowhere near as big of a scale as, say, the dry forests in California). Saguaro are especially vulnerable to wildfires because they have no defense against them as they have never experienced them before. Thankfully, the Saguaro is not currently endangered, with its conservation status listed as being of “least concern” by the International Union for Conservation of Nature (IUCN). That doesn’t mean people should be allowed to just meddle with them however they want, though. Regulation of the cactus exists because of how vital it is to the habitat of many plants and animals. Allowing them to be removed or destroyed could easily cause the cactus to plummet into endangered status, harming the rest of the desert with its decline. It should be well known at this point in ecological history that it’s not wise to wait until something is almost gone to protect it. To learn more about other global climate topics, be sure to click here! © 2019 Weather Forecaster Cole Bristow  For the millions of residents living within the Sacramento valley and surrounding areas, extreme summer heat with temperatures soaring above one hundred degrees is about as natural and native as the valley, interior live, and blue oaks that dot the foothills and the Sacramento valley floor. Though, something not so native or natural has managed to creep its way into the valley in the past century, growing and thriving in the heat just as the oaks do, but only proving harmful to residents. That unnatural thing is the haze that envelops Sacramento during those hot days: photochemical smog and ground-level ozone. Brown and grey, shrouding the valley in a toxic bubble, this invasive element has become so pervasive that Sacramento currently ranks within the top ten cities in the United States for the worst ozone pollution and within the top fifteen for short-term particle pollution. So what conditions in Sacramento are so prevalent as to cause this pollution?
As seen in a previous article regarding Sacramento’s pollution, the northern California topography plays a huge role in advancing Sacramento into the top ten cities for the worst air pollution. Though, what initiates the presence of this pollution in the first place is the abundance of nitrogen oxides within the atmosphere, churned out by the 1.3 million-plus cars registered in Sacramento county. With such a massive amount of cars concentrated in densely-populated, urban environment, thousands of tons of pollutants are dumped into the surrounding atmosphere each day, the primary being nitrogen oxide and dioxide which are produced as a result of the burning of fossil fuels. As ultraviolet sunlight reacts with these molecules, they are split apart, forming the constituents of photochemical smog such as ozone, aldehydes, and peroxyacetyl nitrates (PANS). Additionally, the dry, relatively arid climate of the Sacramento valley only further fuels this production as it provides a perfect breeding ground for ultraviolet light reactions with little water vapor to impede the pollution production. As Sacramento continues to grow in population, the number of vehicles within the county may be expected to increase as well, leading to further pollution from photochemical smog and ground-level ozone. With more fossil fuel run engines belching out nitrogen oxides, pollution will only continue and likely compound, thus producing unhealthy air for the millions that reside within the county. Although photochemical smog and ground-level ozone are the main culprits of this haze and unhealthy air quality, other factors and secondary pollutants contribute to this as well, such as dust particulates stirred into the air from the vast agricultural fields that span the entire valley. As farmers begin to plow and till soil in preparation for planting, billows of dust are seen whirling across the fields and highways before seemingly disappearing through the means of a dust devil, contributing to the haze. Additionally, ash and PM 2.5 from California’s nearly-annual wildfires also help contribute to this haze, smoking out and infiltrating the skies as vegetation dries out and temperatures soar. Although a common factor in the day to day life of Sacramentans, haze and pollution are not something that should at all be considered native and here to stay. Instead, it is a current, very serious problem, but one that the California Air Resources Board (CARB) and other agencies work diligently to battle. “Spare the Air” day warnings are a common tool used by this agency, encouraging residents to reduce their need for transportation or fossil fuel burning engines by taking public transit or ride-sharing. No-burn days are also issued, prohibiting citizens from burning any sort of fire in an effort to combat ash and PM 2.5 in the local atmosphere. Through these efforts and the cooperation and education of citizens, Sacramento haze may one day be a thing of the past, permitting unimpeded grand views of the oak-dotted foothills, the golden coastal mountains, and the snow-capped Sierra Nevadas once again. To read more about weather and atmospheric phenomena within North America, click here! https://www.globalweatherclimatecenter.com/north-america-weather-climate-topics © 2019 Weather Forecaster Alexis Clouser  DISCUSSION: On the week of July 15, A massive humid heatwave struck much of the Central United States from Kansas and Oklahoma to Ohio and West Virginia. The heatwave started after the remnants of Hurricane Barry was absorbed by a trough of low pressure that came from Canada. After the trough moved out towards New York and the East Coast, a strong ridge of high pressure built over the area which cleared the skies mostly. In addition, the ridge of high pressure brought a strong southerly flow of warm moist air from the Gulf of Mexico all the way up to Minnesota, Wisconsin and South Dakota.
The warm humid air led to Excessive Heat watches and warnings across the areas. The warnings were issued as the heat index values for much of the Central United States were in the triple digits. The heat index is an apparent temperature which factors in temperature and humidity and the higher the humidity, the higher the heat index feels like. However, the extreme heat and humidity led to afternoon thunderstorms across some of the region due to the large amount of Convective Available Potential Energy (CAPE) that was present for much of the region. CAPE is the buoyancy of a parcel of air and is related to the vertical motion of thunderstorms. CAPE is higher when there is more warmth and temperature in the atmosphere. The area of the extreme heat also happens to be where most of the corn is growing in the United States, click here to find out more about how corn plays a factor in the humidity. The hot and humid weather pattern expanded to New York and the East Coast by Friday and persisted for the weekend. However, the pattern shifted to be cooler as the new week began and the ridge of high shifted eastward. We at the Global Weather and Climate Center would like to remind you to stay hydrated and cool especially during the summer heat by drinking at least 8 cups of water a day especially during the warmest time of the day as well as staying in the shade as much as possible and to try to not do too much outside especially between the hours of 10 am and 5 pm as that is when the heat and sun is at the highest points. To learn more about North American weather click here! ©2019 Meteorologist JP Kalb
Evolution of the low-level jet over the sloped Great Plains terrain at f14 (7 pm CDT July 17), f19 (midnight), and f24 (5 am CDT on July 18th). A short case study is presented for July 17- July 18, 2010 to determine if there are characteristics present that define a classic summertime low-level jet. The nocturnal Great Plains Low-Level Jet (LLJ) is a fast-moving ribbon of air in the lowest level of the atmosphere (about half a mile above the surface). Wind speeds may increase to 40-60 miles per hour after midnight. The Great Plains Low-Level Jet is commonly found from Texas northward to Nebraska and centered geographically over the Oklahoma/Kansas border. Climatological analysis indicates that the low-level jet is most common in June and July, with a peak around mid-July.
There has been much debate over the past 50 years as to the mechanisms that initiate the low-level jet, but two main theories seem to emerge: Holton’s and Blackadar’s theory. Blackadar’s theory suggests that the low-level jet occurs as a result of the clockwise rotation of the nocturnal wind. Holton considered the diurnal variations of the heating and cooling of the sloping Kansas terrain to allow a pressure gradient to develop. During the daytime, a strong temperature gradient sets up from east to west along a constant height surface, where the strongest heating occurs above the highest slope of the terrain. At night, the pressure gradient reverses and the boundary layer begins to decouple from the surface layer. Both methods are acting in the LLJ, but the Blackadar method seems to dominate more. A cross-section completed using the Weather Research and Forecasting (WRF) model, a mesoscale numerical weather prediction system, shows a weak low-level jet with a weakly-defined jet core. The wind speeds increase significantly over the region in the early morning hours, as one would expect to see with the presence of an LLJ. The jet starts to appear at f14 (7 p.m.) and reaches its maximum at f21 with wind speeds in excess of 45 mph. The jet core appears over Tescott, Kansas in this case at a height of ~3000 feet above the surface. The jet became weaker at f24 (5 a.m.) and can be seen propagating to the east. A few scattered showers developed overnight due to enhancement by the low-level jet with the tendency for the storms to move south of the low-level jet axis with time. To learn more about the Great Plains Low-Level Jet and other North American phenomena, please click here! © 2019 Meteorologist Sharon Sullivan  Photo Credit: Glacier National Park Service Discussion: Although astronomical summer has started and meteorological summer is right around the corner, portions of the Northern Rockies are still experiencing snow. This should not come as a surprise as the western United States has seen quite active this spring ranging from snow to thunderstorms.  Notice on the satellite imagery above the large trough swinging through the Northern Rockies. This is the system that brought the lift and energy to the region and has triggered the snowfall. Scattered storms are shown across portions of the Southeast and Mid-Atlantic as well on this imagery. A potent trough dove into the Pacific Northwest late this past week and is now moving through the Northern Rockies (shown above). The cool air and energy from this trough along with a favorable location of the jet stream has produced several inches of snow across the higher elevations of Idaho, northwest Wyoming, and western Montana. South-central Montana is under a winter weather advisory until Sunday morning for this system with around half a foot of snow accumulation possible.  Beyond this system, conditions turn warmer and more convective in nature across portions of the Northern Rockies and Great Basin according to major global models. A bit of moisture and instability in addition to energy aloft will push into the region mid to late week which will trigger showers and thunderstorms. Rain, lightning, and perhaps some gusty winds will be possible hazards with this activity. An image above from Windy.com shows the ECMWF’s early depiction of the thunder activity across this region Thursday afternoon. Stay tuned to your local National Weather Service Office for more details in the coming days.
To learn more about North American weather click here! ©2019 Meteorologist Joe DeLizio A Closer Look at Deep Oklahoma Convection via GOES-East! (Imagery Credit: The Weather Channel)6/5/2019 
DISCUSSION: When it comes to severe weather, there is no debate that there several different hazards which come into play with a variety of different genres of severe weather events. Moreover, it is also very well known that some of the more common and more apparent severe weather hazards include (but are certainly not limited to) lightning, hail, and tornadoes. Having said that, one of the underlying threats from severe weather events which is often substantially more overlooked involves the threat tied to flooding and/or flash flooding threats which come into play under various circumstances. Moreover, a key method by which meteorologists identify evolving flooding and/or flash flooding threats is by considering various types of satellite-based indications of such events getting ready to occur.
More specifically, in looking back to May 21st of this year, the GOES-East satellite came in handy in a major way through providing real-time insights into the smaller-scale convective evolution of intense convective storms. That is, the convective storms which formed and evolved over the state of Oklahoma at the start of the final week of May. In looking back to May 21st, you can see (in the Tweet attached above) how there were persistent bursts of deeper convection which fired up over portions of northern as well as northeast Oklahoma as indicated by the areas of grey to white-colored cloud tops. It is worth noting that this satellite imagery being shown was longwave infrared satellite imagery which allows cloud-top temperatures to be readily interpreted even towards the evening and overnight hours in any given location. Thus, longwave infrared satellite imagery is most definitely a helpful tool when it comes to diagnosing the threat of flooding and/or flash flooding on a real-time basis. Just this one example of how flooding and/or flash flooding event anticipation as well as detection has become more effective and reliable is a perfect reason for why it is that much more important to always remain weather-ready. That way, you are never caught in a potentially dangerous situation without enough lead-time and so you can always have an opportunity to make relatively quick and critical decisions. To learn more about other high-impact weather events occurring across North America, be sure to click here! © 2019 Meteorologist Jordan Rabinowitz  As temperatures continue to increase globally, the ecosystem will ultimately adapt to this change. More specifically, deer ticks are adapting to increases in temperature. This may spread Lyme disease and increase the risk for humans if ticks start to inhabit more area than ever before.
According to Climate Central, a recent study concluded that deer ticks live longer in higher relative humidities. Relative humidities between 85-95% are favorable for deer ticks. With rising temperatures and increased humidity across western North America, reaching this favorable environment for deer ticks is likely. In Canada, these favorable conditions are increasing as well. Canada’s National Observer claims that in the past, ticks have been carried over by birds into Canada for years. "Only in the last 10 to 15 years, amid a changing climate and the creation of new habitats in the north, that populations of deer ticks have been able to establish a permanent beachhead in Canada.” as stated in the National Observer. There has already been an increase in the number of reported Lyme cases according to Canada’s Lyme surveillance efforts. The Lyme surveillance has a list of Lyme disease cases reported between 2009 and 2017. In 2009 there were 144 reported cases and in 2017 there were 2,025 reported cases. In 2016, over 88% of these cases were reported in Ontario, Quebec, and Nova Scotia. This shows that just like the United States, there is a trend of deer tick population increase in the east, rather than the west. Why are deer tick populations increasing in eastern North America and not western North America? The simple answer is climate differences between the regions. Climate Central explains that in the east, it tends to be more humid. In the west, there is usually less humidity creating a dry and hot environment which is not favorable for deer tick. This is however, favorable for another species of ticks called lone star ticks. These ticks do not carry Lyme's disease but, they do carry ehrlichiosis. This disease causes fatigue and aches. Overall, there is a trend of increasing tick populations in North America due to increasing temperatures, whether it increases relative humidity or not. This has resulted in a higher likelihood of getting a tick-borne disease. (Credit: Climate Central, Canada’s National Observer, Canada’s Surveillance of Lyme's disease) ©2019 Weather Forecaster Brittany Connelly  Tornadoes in California a Rarity? Not so!
If you were to ask the average Californian whether tornadoes were a common event in California, you’d likely receive an odd stare before a definite answer of “no.” However, this answer is completely incorrect, as tornadoes are much more a common phenomenon than many would think, with about six to seven being reported each year. Although California tornadoes are not quite to the scale and intensity that much of those in the midwest are recorded to be, they are still tornadoes nonetheless and pose just as much a danger, capable of uprooting trees, ripping off roof tiles, and knocking down power lines. So, how often do tornadoes in California occur, and when? California receives the majority of its severe thunderstorms and tornado warned or watched storms throughout March and April. As the springtime seasons begin, temperatures begin to warm, though the wintertime low pressure systems that bring California’s rain have not quite subsided. These conditions create a favorable environment for convective storms from which severe weather such as lightning, hail, heavy rain, and even tornadoes may form. The vast majority of these tornadoes form throughout the California valley, with the exception of the Los Angeles area along the coast. For the tornadoes that do form within the California valley, a significant amount of these occur in the northern Sacramento valley area in Butte County, California. From 1970-2014, Butte county had a recorded total of 16 tornadoes, though this number is outdated as Butte county has since experienced a few more tornadoes in the past few years. None of these tornadoes have ever exceeded an EF2 rating, but have nonetheless produced significant damage with one producing millions of dollars in damage to crops throughout the area. Tornadoes throughout California, although few, are nothing new nor rare. Weak and short-lived, they often do not cause much damage, but nonetheless can still pose a great danger to those living within the affected areas. To read more about weather and atmospheric phenomena within North America, click here! https://www.globalweatherclimatecenter.com/north-america-weather-climate-topics Sources: http://ggweather.com/ca_tornado.htm http://www.tornadohistoryproject.com/tornado/California/Butte © 2018 Weather Forecaster Alexis Clouser  Photo Credit: Pixcove Discussion: Many of us understand that radars are used to monitor hydro-meteorological phenomena, whether that be rain, snow, hail, and anywhere in between. However, radars do not just focus on capturing weather. Anything that flies into the range of the radar beam can appear as reflectivity. Migratory birds are one non-meteorological feature that are commonly seen on radar. A small group of birds on radar can show up as what appears to be small rain showers whereas large migratory groups are visualized as a larger mass of light to potentially moderate rain. There are other radar parameters that can be used to decipher actual rain showers from birds such as correlation coefficient (a measure of how uniform the object being observed is) where typical numbers at or below 0.8 are common for birds with rain closer to 1.  Here is an example of birds on radar migrating from Cuba to Key West, FL. The returns on the radar are close to 5-10 dBZ perhaps around a few lower teens in a few spots. This relates to a light to perhaps nearing a low-end moderate migration. The radar reflectivity correlation to the size classification of a migration is according to Gauthreaux et al. (1999) and stated on birdcast.info/research/review/.  As mentioned before, typical correlation coefficient values around 0.8 and below relate to objects other than rain. As seen above the cc values are near 0.8-0.9 and lower in some areas signifying a migration of birds from Cuba to Key West, Florida.  There are different weather factors that can trigger a bird migration. The major assisting factor is the wind direction and speed. Birds favor a tailwind regardless of the time of the year. During the spring migration, when birds are traveling north across the United States, a southerly flow is preferable. The forecast from the website birdcast.info shown above (this website has other information including a live map) the night of April 9th into the 10th features a sizeable migration from Texas on northward into the Mississippi Valley. The GFS MSLP forecast image for 06Z April 10th (below), during the nighttime hours, shows a strong low pressure across the central High Plains. Notice the similarities between the forecast medium migration region and where the pressure gradient (tight, packed close together lines running southwest to northeast) aka relatively strong southerly winds reside (Texas, Oklahoma, into the Mississippi Valley). This tailwind will trigger a low and in portions a medium migration according to the forecast.  Precipitation can act as a limiting factor. This is where uncertainty develops when forecasting migration. On the previous Birdcast image, the precipitation is outlined over the forecast. The site mentions where precipitation and favorable migration conditions coexist, variability and significant unknowns are present in the forecast.  Above, a “flying eagle” supercell typically known as a V-Notch. The shape looks like an eagle with the wings pointed upwards. Image courtesy of @tornadotrackers via radarscope. Radar imagery valid June 19, 2018.
On a loosely related note, there is a type of supercell that looks like a bird on radar. The image above shows a strong supercell thunderstorm with a configuration on radar that is typically known as a V-Notch or “Flying Eagle”. This is typically present with the strongest and tallest updrafts. Radar has great application to not only detecting powerful and dangerous supercells like the one shown above but other important features such as bird migratory patterns. To learn more about North American weather, how it impacts wildlife, and everywhere in-between, be sure to visit GWCC by clicking here! ©2019 Meteorologist Joe DeLizio Sources: https://ebird.org/news/fall-birding-basics/ 
— Mark Nissenbaum (@markniss_) April 2, 2019
DISCUSSION: As far as low-pressure systems go, there is little to no doubt that the 2 April 2019 Nor’easter will go down in history as one of the more impressive coastal storms of all-time. Despite the fact the worst of the impacts remained just offshore, this storm system still most certainly “strutted its stuff.” More specifically, as the developing storm system underwent a period of rapid intensification, there were successive rounds of impressively intense convection which consequently developed both just offshore and along the immediate coastal regions of North Carolina. Even with the storm being as intense as it was becoming during the evening hours of 2 April, there was still somewhat of a “gift” to the immediate coastal regions based on the fact that the majority of the system’s core circulation remained just offshore.
Thus, as a result of the bulk of the most intense part of the rapidly intensifying low-pressure system remaining just offshore from coastal North Carolina, the strongest winds, largest waves, and the heaviest rainfall also remained offshore for much of the night. However, even with the worst of the nor’easter remaining just offshore, there was still very substantial and impressive convection offshore during the evening and late evening hours as shown above (courtesy of imagery provided by Mark Nissenbaum). As the convection continued to intensify with time (as shown above), you can also see how the deepest convection also gradually experienced a “curling effect” in a cyclonic fashion in accordance with the corresponding wrap-up of this extra-tropical cyclone. This became even more impressive with time since as the storm intensified and wrapped up (or deepened in other words) with time, the core part of the system’s circulation took on an appearance that what somewhat resembled a supercell thunderstorm at certain points. To be clear, supercell thunderstorms are more typically Spring and Summer-time convective storm types which form most often across the U.S. Plains states. This just goes to show that even a large low-pressure system such as a nor’easter can take on appearances akin to much smaller mesoscale atmospheric phenomena if the atmospheric dynamics are truly profound and come together just right. To learn more about other interesting and high-impact weather events occurring across North America, click here! © 2019 Meteorologist Jordan Rabinowitz 
DISCUSSION: It is the heart of a true Arctic air intrusion and the only thing which most people are thinking about are the implications of the cold weather on how they will dress or what sort of social life they will likely plan during the extent of a given cold weather stint. However, there are several other atmospheric phenomena which can unfold during various parts of a cold air outbreak. One such example occurs when a very cold air mass moves over a relatively warmer lake, bay, or ocean surface. As this colder air moves over the warm body of water of some variable size, the cold air is modified and undergoes a reasonable degree of destabilization which sometimes leads to the development of shallower convection in the form of lake effect snow (i.e., when the shallower ocean, bay, or lake-driven convection is sufficiently organized).
This Winter-time atmospheric phenomenon is most common during the Winter-time months across various parts of North America and Europe if there is a sufficiently low amount of lake, sea, or ocean-based ice coverage present. The reason for why minimal ice coverage is a critical factor involved with lake effect snow is a result of the fact that substantial ice coverage will prevent the essential surface fluxing (i.e., the process of warmer water vapor being released from the warmer water body surface) from occurring. In the case of this past week across the full extent of Lake Ontario (and even Lake Erie for the most part), this was very far from the situation at hand. More specifically, as the heart of the coldest air associated with the brief visit from the “Polar Vortex” circulation moved over and across the Great Lakes region (and particularly across the extents of Lake Erie and Lake Ontario), this triggered a substantial lake response off Lake Erie and a truly prolific response off Lake Ontario. In the brief animated gif attached above (courtesy of Meteorologist Tom Niziol from The Weather Channel in Atlanta, Georgia), you can clearly see how the full extent of Lake Ontario exhibited a classic long-lake axis parallel (LLAP) response to the severely cold air mass traversing across the full extent of the lake (Steiger et al. 2013). As a result of this incredibly efficient lake response, this allowed a truly EPIC lake effect snow band to develop and maintain itself over a long period of time with relatively minimal movement from a north-to-south perspective. In addition, in the latter part of this gif, you can also see this recent lake effect snow band from a three-dimensional perspective near the peak of its existence. Note how you can also see the clear gradual intensification of the shallowed lake-based convective cells which developed (per the growing blue-colored “puff-shaped” figures which were moving towards the eastern shoreline of Lake Ontario back on 31 January. Furthermore, you can also see how the blue-colored cells darkened somewhat as they approached the eastern shoreline which indicated that further intensification of the lake effect convection was occurring in earnest (i.e., leading to heavier snowfall occurring along and just east of Lake Ontario’s easternmost sections). To learn more about other interesting weather topics occurring across North America, click here! References: Steiger, S., Schrom, R., Stamm, A., Ruth, D., Jaszka, K., Kress, T., Rathbun, B., Frame, J., Wurman, J. and Kosiba, K. (2013). Circulations, Bounded Weak Echo Regions, and Horizontal Vortices Observed within Long-Lake-Axis-Parallel–Lake-Effect Storms by the Doppler on Wheels*. Monthly Weather Review, 141(8), pp.2821-2840. © 2019 Meteorologist Jordan Rabinowitz Northern California has a below-average first quarter of 2019 Water Year (Photo Credit: NWS)12/30/2018  DISCUSSION: As 2018 draws to a close, so does the first quarter of the water year for Northern California. The water year begins on October 1 and ends on September 30 as set by the United States Geological Survey (USGS) in order to accurately take account of snow that would fall in autumn and winter and not melt until the following summer. So far, across much of Northern California, the amount of precipitation has been below average to date.
A very dry October across much of Northern California has been one of the biggest factors in the below-average rainfall total in the region. In fact, much of the rain that has fallen was early in the month due to a flow of monsoon moisture that reached the San Francisco Bay Area bringing only a few hundredths of precipitation to areas including San Jose and Oakland while not producing any rain in the areas that usually get more such as Napa. The very dry October came as a result of several persistent high-pressure ridges which kept much of the storms from the Gulf of Alaska away from Northern California and steered them towards Oregon and Washington. November began the same way October ended with very dry conditions dominating for most of the month until the day before Thanksgiving, when the first storm from Alaska moved in. This was the first storm in a series which came through for a few days until the end of the month. The storms had brought enough rain to Northern California to help reduce nearly all the deficit from the dry October and even in some places finished above average for the season. However, the Crescent City area near the border of Oregon finished with another below average month which increased its deficits while the other more northern coastal areas like Ukiah and Eureka finished above average. In addition, the precipitation that came at the end of the month was instrumental in helping with the containment of the Camp Fire as well as clearing out the smoke from the Bay Area. December started with the last of the storms from November before having storms come in at a period of once a week. However, these storms produced about the same as November, but it was below average as December is a wetter month for Northern California. Northern California typically gets most of its rain in December through February as the jet stream which helps with the movement of storms is positioned further south. However, this year, the storm track has not moved as far south due to high pressure ridges that lasted longer in between the storm systems. It is only the first quarter of the water year and the months with the typical heaviest rainfall are yet to come for Northern California. To learn more about other high-impact weather events from across North America, be sure to click https://www.globalweatherclimatecenter.com/north-america ! ©2018 Meteorologist JP Kalb  California is a world leader in the fight against climate change and harmful polluting emissions, due to a surplus of cutting edge, bold laws put into place by CA governor Jerry Brown. With the signing of SB 100 this past September that commits the state to 100% clean energy by 2045, and the executive order B-55-18 that commits the states entire economy to complete carbon neutrality by 2045, one would think the pollution in California to be quite low in comparison to other states. However, this is not the case as the American Lung Association rated Sacramento the 5th worst city in the nation for ozone pollution. A quick visit to their website, lung.org, reveals that many other prominent CA cities such as Bakersfield, Los Angeles, Modesto, Fresno, and Visalia to be in the top ten worst polluted cities in the US for both short-term and year-round particle pollution. So why does CA, despite its efforts to curb energy and industrial emissions, rank so poorly for air pollution?
Much of the problem has to do with California’s topography. Cities situated in the valley, such as Modesto, Bakersfield, Fresno, Visalia, and Sacramento, are surrounded by mountain ranges like the Sierra Nevadas, the Cascades, Coastal, Klamath, and Transverse. The mountains work as a bowl, in which air is trapped and sits, and little to no air circulation occurs. Here, pollution continually accumulates and compounds bringing it up to unhealthy levels. The problem is then exacerbated in winter as temperature inversions occur, trapping cold stagnant air below a layer of warmer air in which pollutants have no chance to be “vented” out as they might during the summer, thanks to the physical property of heat rising. Another factor in this excessive pollution has been the increase in population throughout California, especially the central valley. This has led to an increase in cars, most of which run off gasoline or diesel combustion engines. These vehicles emit harsh pollutants such as volatile organic compounds, nitrous oxide, carbon monoxide, sulfur dioxide and more. In warmer temperatures, such as the summertime months, some of these pollutants are involved in a series of chemical reactions involving sunlight in which they are transformed into ozone, an extremely corrosive and dangerous pollutant that can cause chest pain, coughing, throat irritation, or even worsen the condition of those with chronic respiratory illnesses such as asthma. These issues are especially common in the more central valley of California. The California central valley, home to cities such as Visalia, Modesto, and Fresno, is one of the most productive agricultural regions throughout the state. Alongside quantities emitted by enormous amounts of diesel guzzling and polluting farm equipment, more pollution occurs when crops are burned at the end of the season, typically in fall, to prepare the land for the next year’s crop. However, aside from the smoke that the burning produces, it leaves another pollution source in its wake, long after the flames and ash have died down: bare soil. In particularly dry and drought-stricken years, wind seamlessly picks up loose soil and dirt, and disseminates the tiny dust and dirt particles throughout the air, adding to the particulate matter. Often this occurs in winter when fields are bare and or left to fallow, as there exists no crop roots to hold down and compact soil. With no rain, soil is parched and easily moved about, pollutants hover and compact in the atmosphere, and residents using wood-burning stoves and fireplaces only exponentiate the issue. With these multiple sources and traps of pollution, it’s no wonder that California has such horrid pollution, enough to classify it as the worst in the United States. Many measures have been passed in order to curb and control these emissions, at least from industry, but it is not nearly enough. Change cannot be made to the California topography. So, it is advisable that going forward, not only industry, but residents take action as well to help reduce these harmful pollutants. Be it switching from gas guzzlers to electric vehicles, replacing wood burning fireplaces for natural gas or electric, or simply using less energy, there is much that can be done to reduce toxic pollution and emissions. To learn more about other high-impact weather events from across North America, be sure to click https://www.globalweatherclimatecenter.com/north-america ! Sources: https://www.lung.org/our-initiatives/healthy-air/sota/city-rankings/most-polluted-cities.html https://www.sfchronicle.com/business/article/California-to-go-100-percent-clean-energy-by-2045-13218236.php https://sacramento.cbslocal.com/2018/04/18/sacramento-air-quality-sucks/ https://airlief.com/air-pollution-during-winter/ https://www.ucsusa.org/clean-vehicles/vehicles-air-pollution-and-human-health/cars-trucks-air-pollution#.W--cvehKjIU https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners http://www.capradio.org/articles/2015/04/29/california-cities-rank-high-on-unhealthy-air-report/ https://www.dmv.ca.gov/portal/wcm/connect/5aa16cd3-39a5-402f-9453-0d353706cc9a/official.pdf?MOD=AJPERES © 2018 Weather Forecaster Alexis Clouser  Discussion: Portions of north-central Montana from time to time experience high wind events. Typically winds downslope off the Northern Rockies creating these downslope wind storms which are high impact events for motorists, pilots, etc. The setup for December 18th-19th showed signs of such an event and prompted high wind warnings by the NWS (light gold color) across a large section of central Montana. This article will examine a way to predict strong downslope winds.  This image above is from the article “An Operational Technique Used to Detect ‘Mountain Wave Signatures’: A Forecast Methodology for Severe Westerly Winds in the Mountains of West Texas” by Todd and Coty Lindley, and Jeffrey Cupo, NWS WFO Lubbock, Midland, TX. One method to forecast a potential downslope wind storm is to take a cross section of the atmosphere perpendicular to the mountain range and analyze the vertical motions present. Based on the article referenced above the vertical cross section should display strong descending air coupled with weaker ascending air just downwind of the mountain peak with an upwind tilt with height. The image above is a cross section down in Texas through the Guadalupe Mountains, notice the upward and downward vertical motions with an upwind tilt in each event with the surface gusts noted below each image.  The cross section starts at point A and runs northeast to point B. Downward vertical motion is represented in grays and whites, upward in pinks. Winds are plotted, equivalent potential temperature, as well as relative humidity. The terrain and elevation are plotted on the bottom of the image with the associated pressure level on the left-hand side. Luckily, tropicaltidbits.com has a function to create cross sections. This cross section is produced from the GFS at 18Z on the 18th (location marked in the upper right corner point A to point B. Right after the start time of the high wind warning the coupled strong downward and upward vertical motion downwind of the highest terrain shows up in the model in a similar fashion to the previous example.   What did the actual wind observations read during this downsloping windstorm? Attached below are the observations from Blackfeet, MT. Surface winds gusted (purple numbers on the right-hand side) into the 40s around 11AM local time, 18Z, with gusts into the 40s and 50s over the next few hours and even a 60-mph reading at 2PM local, 21Z. The setup for downsloping winds also create conditions that result in mountain waves. Not only are the strong surface gusts hazardous to trucks and other vehicles on the roadways but mountain waves are extremely turbulent and dangerous for aircraft aloft. To learn more about high wind events and North American weather in general click here! ©2018 Meteorologist Joe DeLizio 
DISCUSSION: There is increasing confidence of there being a short but intense burst of heavier snow across both the Hudson Valley in southern New York state as well as across parts of southern Connecticut during the day tomorrow. This is going to most certainly induce substantial travel delays as this heavier snowfall burst moves through these parts of the Northeastern United States. However, it is also important to understand how and why this burst of heavier snowfall is projected to unfold in the first place. To understand this, it is important to explain to explain a fundamental concept which is directly tied to heavy snow banding within Winter-time coastal low-pressure systems.
This critical process which is directly associated with heavier snow banding which forms in association with heavier snow banding features within Winter-time coastal low-pressure systems (which are also referred to as Nor’easters) is known as frontogenesis. Frontogenesis in the simplest terms is essentially the process by which air-streams in the lower-to-middle parts of the atmosphere converge from opposite directions which forces locally-driven upward motion. When this regionally forced upward motion occurs along a horizontal axis in the vicinity of a coastal or semi-coastal region along a region such as the U.S. East Coast, this will often facilitate the generation of features known as mesoscale snow bands. Mesoscale snow bands are often longer and relatively narrower snow bands which form within larger precipitation (i.e., mostly snow) shields within a Nor’easter and are directly fueled by the low/middle-level convergence associated with strengthened low-level frontogenesis. Thus, the frontogenetic forcing is the primary ingredient which when combined with sufficiently colder air, leads to locally heavier snowfall potential. Attached above is a recent graphic (courtesy of the Tropical Tidbits website which is directed by Meteorologist Levi Cowan) which perfectly illustrates this concept via the forecast for the North American Model (NAM)-12km 700 hectopascal Temperature (in degrees Celsius), Temperature Advection, Frontogenesis, and Wind for the next 24 to 36 hours. You will note how there is a brighter red-colored band which moves through a good portion of Connecticut and the lower Hudson Valley tomorrow which is the frontogenetic feature which is projected to generate this heavier snow band. Thus, it will certainly be interesting to watch and see how this winter weather event unfolds for these areas and beyond. Be sure to stay tuned with us right here at the Global Weather and Climate Center website and on Twitter as well as Facebook for the latest updates! To learn more about other high-impact weather events occurring across North America, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz  Haleiwa, HI: Image Courtesy: Meteorologist Jessica Olsen DISCUSSION: Autumn officially began September 22nd and ends on December 21st 2018 in the Northern Hemisphere. Fall marks the transition from summer to winter, a time when many changes are evident in the Northern Hemisphere.
Some of these transitions include:
In addition to differences in daylight and times observed for such, temperatures trend on the decreased side of the spectrum as tilt moves away from the sun in the Northern Hemisphere. This has seemingly brought early snows to places like Wichita KS, Woodstock VT, and even Cortland (Central) NY! This is a time where fall foliage is peak in upstate New York, central Colorado and parts of northern Wisconsin. As we near mid-November more than half of CONUS is past peak, experiencing cooler weather despite the possibilities for tropical development near the Lesser Antilles, as we still are reminded it is still hurricane season in the Atlantic until the 30th. Crop harvesting is apparent for nearly every state in the U.S. Some often fall harvest vegetables are beets, beans, turnips, green onions and of course apples and pumpkins. These being heavily popular among families looking for great activities during the fall transition period. Hawaii seeing some different harvests as the fall season is well underway, such as various avocados 9often available different times of the year), apple bananas, cabbage and carrots often harvested year-round, limes, oranges an so much more. With Hawaii home to nearly 11 of the 13 climate zones in the world, it is a great environment to grow a variety of fruits and vegetables and use a great deal of these seasonally to supplement any meal! Lastly, the transition of summer to fall signals the time for advanced surfers to pull out the boards for big-wave surf. During this seasonal progression, winds can increase, humidity decrease with an increase in swell height. Often we see the swell increase on north and west facing shores throughout the island chain, marking a time for World Surf League events such as the Vans Triple Crown, Beachwaver Maui Pro, Billabong Pipe Masters and more! Autumn is a great season to see some of these changes occur despite the lack of foliage change in Hawaii. It is an opportune time to view many big-wave events, try seasonal fruits and vegetables, and maybe spot a stray whale coming in for the winter season. For information on fall changes in Hawaii or CONUS visit the Global Weather and Climate Center! © 2018 Meteorologist Jessica Olsen |
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