Understanding the Reasons Behind Decreasing North American Snowfall Coverage (credit: Climate Central)
DISCUSSION: In light of an increasingly more tumultuous situation defined by gradually increasing global temperature trends, this also has had definite impacts on other factors as well. One such factor is the degree of coverage of North American snowfall which has varied somewhat over the course of the past 30 to 40 years. There is no question that North American snowfall coverage has experienced a definitive gradual decreasing trend over the past few decades. However, there is much more to this issue than "meets the eye."
In looking at recent historical North American snowfall coverage, a key component of this issue is the degree to which certain regions during the Fall to Winter transition period do or do not have snowfall cover by a given time. The reason for this issue is that by not having snowfall on the ground for a given first snowfall event, the ground is more susceptible to absorbing ultraviolet and infrared radiation from the Sun which will keep the upper-most layers of soil relatively warm. Thus, even when the first substantial snowfall event does occur in the given region of choice, a warmer upper-most layer of soil would inhibit a good portion of snowfall earlier on in the first major event from sticking which would limit net snowfall potential. Thus, anticipating longer-term snowfall trends is not as simple as one may think.
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©2017 Meteorologist Jordan Rabinowitz
DISCUSSION: As we get further into the 2017-2018 Winter season, there is no question that there are a lot of important questions which still remain. One big question is as to whether or not there will be prolonged periods of particularly colder weather across the northern tier of the United States. This is a critical question which bears much concern due to the fact that more frequent Arctic air outbreaks can often times lead to there being a greater propensity for more memorable winter storms. That is chiefly due to the fact that when colder air is more prevalent throughout a given winter, there is consequently a greater prevalence of geographic regions characterized by stronger baroclinicity (i.e., a more rapid change in temperature over some given horizontal distance). Thus, with stronger baroclinicity in place, this facilitates a more favorable atmospheric environment for any low-pressure systems which develop with these "baroclinic zones." Attached above is a typical storm track and temperature/moisture trend map for both the warm and cold phase of ENSO courtesy of the NOAA NWS Climate Prediction Center.
Moreover, when such low-pressure systems are suppressed further south (e.g., often in the vicinity of the Gulf Coast region), this allows those low-pressure systems to pick up plenty of warm, moist "tropical" air which frequently sets the stage for a classic coastal winter storm or more often referred to as a "Nor'easter." Thus, monitoring larger-scale climate patterns such as the Arctic Oscillation which is effectively a proxy by which the semi-permanent statistically-identified "Arctic low-pressure system" is measured with respect to its average strength (i.e., based upon its shorter- and longer-term minimum central pressure). When this semi-permanent "Arctic low" is weaker in strength, this more often than not allows for colder air to make its way towards the mid-latitude regions of the world. A perfect example of this situation is precisely what is happening at the present time across the North-Central and the Northeastern regions of the United States where a lobe of the core of the Arctic air from the southern edge of the Arctic Circle has descended down into the northern tier of the United States. Depending upon how long this and other cold air outbreaks persist along with how active the more southern storm-track remains, this will largely dictate how active the Winter season is.
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©2017 Meteorologist Jordan Rabinowitz
On November 2, 2017, scientist at the National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) have stated that the ozone hole, located over Antarctica, is the smallest observed since 1988. The hole forms each September. This year, the hole only grew 7.6 million square miles as opposed to the average of 10 million square miles in 1991. To put that into perspective, that is about two and a half times the size of the United States. The Antarctic ozone hole was first detected in the 1980s. The hole forms during the Southern Hemisphere’s late winter when the return of the “sun’s rays accelerate reactions involving man-made forms of chlorine and bromine, like chlorofluorocarbons, that concentrate over Antarctica during winter. These reactions destroy ozone molecules.” Oddly enough, the reason for the smaller ozone hole is due to an unstable and warmer circulation pattern in the Antarctic stratosphere that minimized the presence of high-altitude clouds. The Montreal Protocol on Substances that Deplete the Ozone Later was signed 30 years ago that regulated the compounds that were responsible for the depletion of the ozone. Scientists expect the ozone hole to be back to 1980 levels by roughly 2070.
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ⓒ 2017 Meteorologist Brandie Cantrell
Discussion: Countless decisions are made by humans every single day due to the weather; similarly, climate impacts daily lives. When it comes to wine production, the most likely pair of weather and climate are the primary environmental concern for viticulture, the process of grape-growing. Wine is produced in different climate zones across the globe from Australia to Brazil, South Africa to China, and of course here in the U.S.
Let’s explore the ways in which weather and climate are important factors for wine production. In short, an article in the Journal of Wine Economics explained that temperature affects fruit ripening (warmer temperatures yield more sugar accumulation) and the best quality wine is made from grapes with a high sugar level. Water deficit impairs photosynthesis, which reduces the size of the grape, and vine water status is dependent upon rainfall.
Global wine production has hit a 56-year low and this type of poor harvest is expected to become a common phenomenon in future years. Earlier this year, a trio of extreme weather events in three of the largest wine-producing countries (Italy, Spain, and France) was the primary cause of harvest losses. While all three countries experienced a severe spring frost, there was a lengthy summer heat wave in Italy and a historic drought in Spain. Just last year, El Niño related extreme rainfall drowned out more than a quarter of Argentinian vineyards. Since these events have had negative impacts on the wine industry in the past, there is an increased concern for the future of the wine industry.
In recent years, wine quality has increased in most wine-growing regions due to higher temperatures and frequent water shortages while yields have decreased. High quality wines in warmer and dryer climates produce economically acceptable yields. Vines are best grown in the mid-latitudes. An ideal climate for vineyards is described as having adequate precipitation and warmth to grow and ripen the grapes. Then, abundant sunshine and warm temperatures are needed during flowering. Summer growth should consist of dry and hot conditions; and when ripening, it needs to be dry with “moderately high daytime temperatures” and “progressively cooler nights”. All the while, extreme weather events and frost must stay out of sight.
Knowing these factors is just the tip of the iceberg to understanding the impact of weather and climate to viticulture. While many environmental factors determine the level of success of a wine production season, studies have found that a warm and dry climate is preferred for lucrative harvests and good quality wine production. As a final thought for those wine lovers, though the future of wine production and viticulture as a whole will change with our changing climate, growers are already applying measures of adaptation to vineyards and wineries.
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©2017 Weather Forecaster Amber Liggett
It’s the spookiest day of the year and NOAA’s National Center for Environmental Information has released some spooktacular climate facts about temperature and precipitation in the month of October. October is a month where some states start seeing snow and cold while others hold onto the last days of summer warmth. Overall in October, the average temperature in the lower forty-eight was 54° F. The warmest October recorded was back in 1963 with an average temperature of 54.9° F, while the coldest October occurred back in 1925 with an average temperature of 48.9° F. Since the recording of temperature values began back in 1895, October temperatures have warmed at a rate of 0.8° F per century.
Say it isn’t snow but October usually heralds in the first snowfall of the season for regions of the United States like the Rockies, the Northern Plains, and the Central Plains into the Upper Midwest regions. The average October snowfall is approximately 2 inches. The Eastern coast of the US is no stranger to snow but it’s usually the higher elevations that see snow in October. Back in 1952, the driest October was recorded with just 0.54 inches of precipitation that had fallen. The wettest October on record occurred in 2009. 4.29 inches of precipitation was recorded. Since the record began back in 1895, October precipitation has increased at a rate of 0.4inches per century. In the table below, check out some climate normals for some spooky named places across the United States. For more interesting climate stories and facts be sure to click here!
©2017 Meteorologist Shannon Scully
Temperatures and dew points across southwest Florida finally dipped below 70 degrees Fahrenheit (F), yesterday morning (Oct. 25, 2017); this is a sure sign that the area has finally entered the autumn season. The last 70-degree temperature reading at Naples Municipal Airport (call sign APF), that did not involve cooler thunderstorm outflow winds, was back on May 11 of this year. Similar comparisons can be found across southwest Florida…To read the full story, click here - http://www.weatherworks.com/lifelong-learning-blog/?p=1429
© 2017 H. Michael Mogil
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DISCUSSION: There are numerous temperature records archived around the globe which have consistently shown that the Earth's average temperature is continuing to warm more and more with time. In fact, many global temperature records have shown that the rate of temperature increase at many locations around the world have actually gradually increased with time. There are some many consequential concerns for other atmospheric phenomena as a result of this gradually increasing rate of temperature increase from a global perspective. First and foremost, a higher average global temperature corresponds to there being a higher average capacity for a given parcel of air to hold more water.
Therefore, there is an inherently larger amount of water suspended within the lower to middle parts of the atmosphere within a planet which has a higher average temperature. As a consequence, there is a greater threat for heavier rainfall events as well as increasingly more potent tropical cyclones from a global perspective due to a higher atmospheric water content. Though, there is not a direct mathematical correlation between higher water content and more intense tropical cyclones, the fact is that tropical cyclones thrive within atmospheric environments which have a greater amount of atmospheric water content. Thus, with an atmosphere with greater water content, there typically is a greater propensity for greater tropical cyclone activity (and more intense activity often times as well).
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©2017 Meteorologist Jordan Rabinowitz
Left: Snow beginning to fall on I-80 west of Laramie on Sunday, September 24th at 4:16 pm local time; Right: Partly cloudy skies looking south from Juneau Harbor toward the Gastineau Channel on Sunday, September 24 at 4:16 AKDT
There are some illusions surrounding Alaska’s temperature and climate, specifically cooler temperatures in the summer and early fall months. But, what makes a location’s climate unique? Weather is comprised of individual events and climate is the average of these conditions. Proximity to a body of water, topography, and elevation all can play a factor in shaping the climate.
For the purposes of comparison, Albuquerque, New Mexico is one of the highest elevation cities at an average elevation of 5300 feet and a latitude of 35°N. This city lies at the northern edges of the Chihuahuan Desert, and thus, experiences large ranges in diurnal temperatures due to the specific heat of dry air being less than that of water (humid air takes longer to heat and cool than dry air does). Laramie, WY (located in southeast Wyoming along the Colorado Front Range) is located at 41°N and 7220 feet above sea level. Similar to Albuquerque, Laramie is also a semi-arid climate, but the high plains location is susceptible to long, cold winters.
Juneau, Alaska (fondly referred to as Capital City by locals) is nestled between the Gastineau Channel to the west and several large mountainous peaks to the east, separating it from Canada. It is located at 58°N, with the Article Circle beginning at a latitude 65°N. Juneau is considered a maritime climate due to the stabilizing presence of the Pacific Ocean. Temperatures are relatively mild here and small variations may exist between high and low temperatures, contrary to what its latitude may suggest.
During the last week of September, several differences were noticed for these locations. A slow-moving Pacific storm system hit Laramie, WY with its first “measurable” snow (greater than or equal to 0.01”) on Sunday, September 24th . With about a month and half away from its first predicted snowfall, Juneau experienced a heavy rain event beginning Monday evening the 25th through the 28th with up to 2.5” of precipitation in some areas, as a front pushed through the southeast Alaska panhandle. A separate backdoor cold front backed into eastern New Mexico and moved through the central portion of the state by Wednesday, September 27th. Meanwhile, Juneau International Airport experienced a maximum temperature of 59°F, almost 6 degrees above normal. The overnight low of 55°F in Juneau was almost 10 degrees warmer than portions of New Mexico, Colorado, and Wyoming (49°F in Albuquerque and a mere 36 degrees in Laramie, WY).
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©2017 Meteorologist Sharon Sullivan
1941: The Wettest September on Record in New Mexico_Part 1 (Photo Credit: West Kentucky Genealogical Society)
The year 1941 stands out as being the highest annual precipitation value for the state of New Mexico. The value for 1941 looks out of place compared to the average statewide precipitation of 14 inches that New Mexico receives each year, but it is no mistake in the data. The record for 1941 is 26.25 inches. The graph shows almost 6 inches of precipitation for September 1941 alone and a second large peak in the month of May. The month of September seems to experience the largest range in precipitation values for New Mexico. The September events for 1941 were thought to have been associated with a strong monsoon moisture plume and/or tropical system(s) and consisted of two major storm periods.
September is the most likely month for New Mexico to be affected by tropical storm remnants, having flash flooding and large amounts of precipitation about every three out of 5 years. Tropical storm records for the eastern Pacific are not available for 1941, but historic records indicate that three tropical storms tracked along the west coast of Mexico in September of 1941. On September 20, 1941, a tropical disturbance advisory was issued for New Orleans and Jacksonville and strong high pressure over the Atlantic States. Warm, moist air from the Gulf is bringing great moisture to the Plains and Middle Rockies. Similarly, an influx of moisture from TS 4 on September 28th combined with a strong cold frontal passage produced heavy rain over the central and eastern portions of the state.
Between July and September, there is normally an increase in precipitation in New Mexico due to a surge of monsoon moisture. The 1941 monsoon season had the 20th highest total rainfall for June-September precipitation. Most months throughout the 1941 calendar year were not outrageously wet, but precipitation continued at anomalous rates for 9 out of 12 months that year.
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© 2017 Meteorologist Sharon Sullivan