DISCUSSION: It was only 72 hours ago at the National Weather Service (NWS) National Hurricane Center office located in Miami, Florida became increasingly concerned about the prospects of a potentially dangerous tropical cyclone developing somewhere within the eastern half of the Gulf of Mexico. However, as of 48 to 60 hours prior to what would end up being the landfall of Hurricane Michael, there was little confidence in this tropical cyclone becoming a major hurricane due to the presence of moderate vertical wind shear as well as an increased presence of dry air. But, as is quite common with the wonders of the Earth’s atmosphere, there are often surprises which arise during a given forecast process. The situation with Hurricane Michael went on to be no exception to this “golden rule”.
Within 2 days and then 1 day prior to landfall, the NWS National Hurricane Center quickly started adapting to the evolving forecast was for what was Tropical Storm Michael and then on to a Category 1 Hurricane Michael. At that point, there was approximately 24 to 36 hours left which was the point at which the intensity forecast continued to evolve even more quickly with time. It was at that point that Hurricane Michael continued to fend off the impacts of the nearby low/mid-level dry air as well as earlier vertical wind shear which was not anticipated earlier on in the forecast process. As this continued to unexpectedly happen with time, this led the forecasters working the Monday and Tuesday shifts to quickly adapt and project Michael to become at least a Category 2 or Category 3 (i.e., a major) hurricane by the time of landfall. However, what they could not foresee were the two distinct periods of rapid intensification which occurred in association with Hurricane Michael. The second of which occurred during the 24-hour period preceding the point of landfall on early Wednesday afternoon (EDT). Attached above is neat graphic courtesy of Dr. Philip Klotzbach which helps to put the maximum intensity of Hurricane Michael as a Category 4 hurricane (and a borderline Category 5 hurricane which it flirted with by being with 2 mph short of that intensity pending further review in the coming weeks and months ahead) into a more historical context. Note how with respect to minimum central pressure for U.S. landfalling hurricanes, Hurricane Michael ranks number 3 of all landfalling U.S. hurricanes on record. Thus, it goes without saying that Hurricane Michael will now go down in history for the rest of time with some of the worst tropical cyclones to impact the contiguous United States in recorded history. To learn more about other high-impact weather events impacting North America, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz
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 DISCUSSION: As of earlier this evening, many people along the mid-Atlantic coastline along the East Coast of the United States were likely breathing a slight sigh of relief when they heard that the recent period of rapid intensification which had unfolded in association with Hurricane Florence had finally come to at least a temporary end. The reason for this temporary break in this latest round of rapid intensification with Florence could have been due to any number of different sensitive storm-relative factors. However, the most likely culprit for this brief respire in the more rapid intensification of Florence would be what is referred to as an eye wall replacement cycle.
When it comes to dealing with more intense tropical cyclones, there are quite often very unpredictable and relatively frequent changes in intensity regardless of how subtle they may be. These brief periods wherein a tropical cyclone is temporarily halting further intensification may be seen by the general public as a good sign that the storm has finally reached its peak intensity. However, this unfortunately cannot be farther from the actual truth. In reality, this is in all likelihood just a brief "break" from the storm potentially undergoing even further intensification which may take it closer to a Category 5 hurricane depending on much deeper the actual low-pressure system gets down to at the core of the tropical cyclone. Therefore, there are some major considerations to make NOW and TAKE ACTION in response to. First and foremost, if you are in any coastal sections of South Carolina, North Carolina, and/or Virginia, you will DEFINITELY want to consider making a full and complete evacuation from your residence since it will simply be unsafe for you to remain in such a location as Hurricane Florence make its final approach. Moreover, even if you are further inland, you will also want to make strong preparations as well since inland areas of these states and beyond will also more than likely experience heavy rainfall as well as gusty, tropical-storm force winds. Thus, with there still being a solid 48 to 60 hours left prior to the onset of the first impacts from Hurricane Florence across at least those 3 states noted above, there is still time to make corresponding plans for what to do and where to go as regional highways will all be directed out of major coastal cities as of tomorrow morning in locations with the currently projected "strike zone" of Florence. Finally, even if you happen to be located beyond the immediate coastal evacuations, once again you are not "out of the woods" from Florence and you should take this INCREDIBLY seriously as there will likely be tremendous flooding from this upcoming hurricane landfall even 50 to 60 + miles from the immediate coastline. For more updates be sure to look at updates from your local National Weather Service office, from the National Hurricane Center, and from right here at the Global Weather and Climate Center! To learn more about other high-impact weather events occurring across North America, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz  (A cicada nymph exoskeleton, Graysville, TN August, 2015) Discussion: One sure sign we are moving into the hottest days of the summer is the loud buzzing sound of cicadas. It seems the hotter it gets, the louder they sing. It gets to the point where it’s hard to hear your friend talking while you share an iced tea on the porch. For some, it’s a loud nuisance and for others it’s one of those comforting outdoor sounds. However, to scientists, the loud cicada song means so much more.
There are many reasons why cicadas sing. The main reason is to attract a female for mating and to induce reproduction of their species. There are over 2,500 different species of cicada with each having its own distinctive mating song. The two most common cicadas are the Annual Cicada and the Periodical Cicada. Annual cicadas hatch as larva and burrow underground for two to five years. They then emerge from the ground as nymphs when their life cycle nears adulthood. Cicadas, in the second part of their life stage, are called nymphs. Nymphs have a hard shell or exoskeleton that protect them when underground. Once they emerge from the ground, they shed that skin (like a butterfly exiting a cocoon) and climb up the nearest tree. Periodical cicadas are famous for their long lifespan. About every 13 to 17 years, the nymphs reach their adult stage, emerging from the ground in large quantities called “broods”. Whether it be Annual Cicadas or Periodical Cicadas, when soil temperatures in the summer reach above 64 degrees Fahrenheit eight inches deep, they emerge from the ground, climb up the nearest tree, shed their exoskeleton, and make an exceptionally loud chorus. Along with many different types of cicadas and their many different songs, their song increases in volume for only one reason, temperature. Cicadas are active throughout the day, however, make the most noise during the hours of the afternoon. This is often the average time when the diurnal temperature range reaches its maximum. During this time of day, a cicada’s song can reach up to 105 to 120 decibels which is about as loud as a chain saw. A cicada’s song varies in pitch and frequency due to different temperature cues. Richard Alexander and Thomas Moore of Ohio State University observed that periodical cicadas sang quieter or hardly at all on cloudy, cooler days compared to hot and sunny days. These examples are indicators that cicadas are highly temperature dependent when it comes to their song. The reason for this is within their biology. Cicadas love it when it gets hot, because it often indicates the courting of a female. Within the cicada’s abdomen there is a muscular membrane in which they vibrate rapidly. This membrane is used to create their loud chorusing throughout the day. A study done by Jerome Sueur and Allen Sanborn showed that when cicadas sing, the vibration of the muscles creates friction and heat within their bodies. This heat creates tension in the muscles which then increases the intensity of their sound, much like tightening a guitar string. With friction creating heat in the cicada’s body, they have the ability to create a body temperature that exceeds that of the air temperature. When the air is hotter outside it helps the male cicadas to increase their sound and make themselves more audible to female cicadas. According to scientists, cicadas are very temperature dependent because it plays a large role in the cicadas song. They love the heat and the hotter it gets the louder they get. So, when you are trying to have a conversation on the porch over iced tea and you hear the cicadas singing their little hearts out, it would be fun to mention to your friend what you learned in this article. For more interesting weather related information click here! © Meteorologist Alexandria Maynard  DISCUSSION: Over the past five to seven days and them some across the Great Plains in particular, there has been a persistent period of excessive heat which has unfolded. There is no doubt that Summer-time heat waves are not completely unprecedented. However, something which is not all that common is the total coverage of the 600 decameter height contour which was analyzed on the 500 millibar height map for the evening of July 4th. The reason for why this observation is so significant is due to the fact that higher pressure contour values in the mid-levels of the atmosphere indicate the presence of a stronger high-pressure system being in place.
Therefore, as shown above, the vast coverage of the 600 decameter height contour at 500 millibars is a classic indication of a robust high-pressure system being in control at that point in time. It is also important to understand that underneath a strong high-pressure system, there is a corresponding propensity for strong sinking motion which allows for the compressional warming of associated air parcels. Thus, the effective sinking of air underneath this multi-regional high-pressure system allowed for notably warm (and in many cases, sizzling) day-time high temperatures. This multi-regional heat wave impacting the lives of millions of people across many parts of the Central and Eastern United State as they often do. Thus, many millions of people who were unfortunate underneath to be positioned under this massive high-pressure system felt the full-force of its widespread heat-producing capacity. It is also worth noting that even in the days since the Fourth of July, there is still expected to be notably high temperatures during the daytime with highs in excess of 90 degrees Fahrenheit across many parts of the Central United States. Therefore, be sure to stay cool and hydrated if you are living and/or travelling to these areas in the coming days. To learn more about other interesting weather stories occurring across North America, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz 
There is no question that Summer-time convection can be very hard to predict and anticipate over a shorter-term forecast time-frame. This is perfectly captured by the great regional convective example which unfolded across parts of Colorado, Nebraska, Kansas, and a few other nearby states. During Tuesday afternoon, there was a complex group of nearby convective outflow boundaries which interacted with one another. As these convective outflow boundaries moved towards one another along with a potent supercell thunderstorm approaching the collection the group of nearby outflow boundaries, quite an interesting event transpired. However, that still does not tell the entire story.
In addition to a supercell thunderstorm approaching from the west, there was also a tightly-knitted cluster of weaker thunderstorms approaching the from the south. Moreover, the truly interesting part about the entire situation was the fact that as the supercell thunderstorm collided with the outflow boundaries and the northward-moving cluster of weaker thunderstorms, this allowed the supercell thunderstorm to be absorbed by the larger cluster of storms moving in from the south. During this process, the ultimate result was that the collision of these respective components led to a broadening of the rotation within the larger area of convection. This larger area of rotation as shown in the animated radar imagery gif attached above is more commonly and scientifically referred to as a mesoscale convective system. The other interesting part about this case was that as the respective components collided and merged, there was a substantial concentrated increase in the density of corresponding regional lightning strikes. This is not too uncommon though by the same token since whenever you have a collision of various regional convective storm(s) and/or cluster(s) thereof, there is quite often a corresponding increase in regional lightning strike density because of new storm initiation being triggered. Thus, as new storms fire along the colliding convective outflow boundaries, very interesting convective events can unfold as a result of older convection interacting along with newer convection firing up. To learn more about other interesting events occurring across North America, be sure to click here! ©2018 Meteorologist Jordan Rabinowitz Can A Cold Front Be Detected via Dual-Polarization-Based Radar? (credit: Met. Jordan Rabinowitz)6/7/2018 
DISCUSSION: Predominantly during the Winter-time/Spring-time months, meteorologists (i.e., working in operations and/or research) often look to anticipate both regional and larger-scale weather changes via monitoring the progress of frontal boundary types including (but certainly not limited to) warm fronts and cold fronts. Such frontal boundary types are key factors to monitor when it comes to trying to accurately predict either short-term or longer-term weather changes during the course of a given day since frontal boundaries are often the “dividing line” between various air masses or at least a change in wind direction and/or wind speed which often will gradually bring changing conditions with new air stream flow orientation.
In addition, many of these frontal boundary approaches can now be physically monitored in a three-dimensional context because of the onset of the dual polarization radar technology that was installed at all radar locations across the contiguous United States between 2012 and 2013 for the most part in the majority of cases. More specifically, as a relatively strong cold front is approaching a given radar location, the frontal boundary itself can often be identified as a linear weak precipitation echo approaching but is in fact the leading edge of the relatively warmer air mass being lifted along the longer axis of the approaching cold front. Hence, in the cases of the brief animated radar imagery attached above, you can clearly see such an example of this process occurring with a cold front which was approaching the Lincoln, Illinois radar site during the late-night hours of 5 June 2018. As you can see very clearly in the loop, there is clear cold front dropping southwestward with time during this brief radar imagery loop. It is worth noting that in this case, there was also a notable temperature change tied to this relatively quick frontal passage which is less and less common during the Summer-time months since regional temperature fields often tend to be more similar within shorter distances. Thus, it just goes to show that cold front passage impacts are not remotely limited to the Winter-time months by any means at all. To learn more about other interesting and/or high-impact weather events occurring across North America, be sure to click here! Above Average Temperatures Expected for the Mid-Atlantic States! (Photo Credit: Brandie Cantrell)4/29/2018  The Mid-Atlantic states have been in a period of cooler weather since the beginning of March. While April did have a few warm days, the warmer temperatures did not last and sunk back into the 50’s and even 40’s. This week, however, temperatures are expected to near 90ºF by Thursday. While Sunday will be the coolest day, the forecasted high temperatures will continue to rise until after Friday. The weekend is expected to be nice with temperatures hanging in the 70’s. To put this into perspective, the average temperature for the month of April is 70ºF while the average temperature for the month of May is 78ºF.
A low pressure that is currently sitting over the New England states is the culprit for bringing the cooler temperatures and windy conditions to the Mid-Atlantic states on Sunday. The low pressure is expected to move off of the coast by tonight which will allow the warmer temperatures from a high pressure (that will be centered to the southeast of the region). High pressures rotate clockwise in the Northern Hemisphere, so this high pressure will grab ahold of the warmer temperatures near the Gulf of Mexico and push them northward into the region. This same system will also be the culprit of severe weather in the Midwest. The lack of rain coupled with low humidity will serve as the ingredients for fire weather. Even though some areas received two to four inches with the past two weeks worth of storms, the wind has dried much of the area out. Winds can also play a factor as they can help spread the fire faster. The next chance of showers will be on Friday lasting through at least Sunday. Even though temperatures are expected to reach into the upper 80’s this week, the Mid-Atlantic states still need to get through Sunday night. The winds should diminish, and the clouds should clear, making conditions conducive for dew or frost. Because temperatures will drop into the 30’s, frost will be the likely visitor. For anyone who has already started their garden, make sure you either bring them in, or cover them so the frost won’t kill them. Stay up-to-date with the latest weather stories at www.globalweatherclimatecenter.com ⓒ 2018 Meteorologist Brandie Cantrell Quickly-Moving Cold Front Across North Texas in High-Resolution (credit: NOAA GOES-16 Satellite)4/4/2018 
DISCUSSION: Over the past 24 to 48 hours, there has been an abundance of interesting weather events unfolding across the nation as we enter the first week of April 2018. One such example of this interesting weather was a strong cold front moving southward quickly across the south-central Plains region of the United States. This particular cold front was caught "in the flesh" by way of the NOAA GOES-16 satellite imager in incredible resolution. Attached above is a neat video which contains animated low-level water vapor satellite imagery which captures the fluid movement of the cold front in incredibly high-resolution. Note how in the low-level water vapor satellite imagery shown above, you can even detect the presence of subtle cloud-based ripples and undulations in light of the approaching cold front. This is not all that uncommon with quickly-approaching cold fronts based on the fact that Spring-time cold fronts often pack quite a punch and bring a substantially strong return flow.
Thus, when there is a strong return flow with the passage of a Spring-time cold front, there is often quite a show to be seen and the NOAA GOES-16 satellite imager is now allowing us to see this motion at a higher resolution than ever before. It is remarkable to view such high resolution satellite imagery since it allows atmospheric scientists to project corresponding initiation of frontal precipitation development as well as initiation of deeper, convective storms in some cases as well. Hence, it is very useful for weather forecasters to use such information for the advantage of improving the quality and accuracy of current and future weather forecasting. To learn more about other high-impact weather events occurring across North America, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz Nor'easter Continues To Facilitate Wrap-Around Lake-Enhanced Snowfall (credit: WeatherTap)3/14/2018   DISCUSSION: As the Northeast continued to clean up from from the latest nor'easter, there was no debate that a decent percentage of people living across much of New England (and interior sections of the Northeastern United States (U.S.)) are probably getting a little worn out from all of the recent snowfall. This is a result of the fact that there have now been 3 nor'easters impacting the Northeastern U.S. over the span of just 11 days. What makes things even more impressive is that even as we head deeper into mid-March, there still remains a slight possibility for the development of 4th nor'easter during the early part of next week due to a fairly locked up storm track. This locked up storm track is predominantly due to the presence of what is most commonly referred to as a persistent Greenland blocking high. Blocking high-pressure systems most often have a larger-scale impact observed as a slowing down the forward progression of weather systems (including but certainly not limited to) extra-tropical low-pressure systems.
Hence, in the case of 2 of these most recent 3 nor'easters, the rate of their forward progression was slowed somewhat by the blocking high-pressure system positioned over much of Greenland during this period of time. It is worth noting that these blocking high-pressure systems which often are given the nickname "Greenland blocks," often are seen in concert with prolific snowstorms since blocking highs will prevent a given storm from advancing at a routine pace. Thus, allowing a given snowstorms to dump more snowfall over a given period of time. However, the main focus of this story happens to be that even as this nor'easter now makes its way across the Canadian Maritimes and further along towards its final stage of gradual decay, it is still creating problems across the Northeastern U.S. More specifically, in the wake of the return flow on the back-side of this nor'easter, there has been an ideal northwest wind flow. This northwesterly flow coming across the Finger Lakes and Lake Ontario across central and northwestern New York State have helped to facilitate a combination of lake-induced and lake-enhanced snowfall. In fact, during the day on Wednesday this lake-enhanced snowfall got so intense that moisture downwind of these regions helped to produce very light additional accumulations across western New England and a little less across portions of Central New York and the Southern Tier region of New York. Therefore, this goes to show that even many hours after the worst impacts from a nor'easter have passed, its impacts can still be felt long after the heaviest snowfall and strongest winds subside. To learn more about other high-impact weather events occurring across North America, be sure to click on the following link: https://www.globalweatherclimatecenter.com/north-america! © 2018 Meteorologist Jordan Rabinowitz  DISCUSSION: A recent GWCC article described the impacts of a snow drought in the mountains of the western U.S. and also mentioned that snowfall in the southern Rockies is often contributed by a few large storms as opposed to more frequent smaller snowfalls. One such storm recently occurred dumping several feet of snow in some places in the Sierra Nevada. This was great news for ski resorts, but it comes at a cost - a higher risk of avalanches. In particular, the snowfall associated with this storm fell in layers of drier, colder and warmer, wetter snow. These layers don't always freeze to one another so well and provide surfaces along which snow can easily slide. In fact, avalanches occurred at two California ski resorts (Squaw Valley and Mammoth Mountain Ski Resorts [a sign from the latter pictured above]). Fortunately, there were no reports of missing people or fatalities from these avalanches.
For those who enjoy skiing and other similar types of recreational activities, there is always a potential avalanche risk. So, to avoid being killed by one, it is important to take certain precautions (e.g., not skiing in particularly dangerous weather conditions, always skiing with a friend, having a GPS beacon so that you can be located in case you are buried, etc.). To learn more about other high-impact weather stories from across North America, be sure to click here! © 2018 Meteorologist Dr. Ken Leppert II Snowfall Coverage Concerns Across the Western and Central United States (credit: Climate Central)3/3/2018  DISCUSSION: When it comes to the world of skiing, there is no debate that a snow drought is the absolute worst possible nightmare which can come to life. However, as we began and got deeper into the 2017-2018 Winter season, this issue became an increasingly more widespread issue across parts of Western and Northwestern United States. As many areas across the Western and Central United States experienced notably above-normal temperatures and below-normal precipitation, this led to an unfavorable combination for ski- and snow-lovers alike. Moreover, when there is a snow drought of any magnitude across the Western and Central United States, this also creates concerns regarding both the near-term and long-term status of water resources across these regions. This is due to the fact that a solid portion (i.e., at least 20 to 30%) of fresh water comes from such resources and if a shortage of snowfall coverage persists for the duration of the 2017-2018 Winter season, this could create much larger issues as North America shifts into the Spring-time months. That being a result of the fact Spring-time is when snow-pack melts and gets deposited into regional reservoirs.
Hence, a lack of snowfall across the Western and Central United States represents a much larger problem that simply the happiness or disappointment of skiers, snow-boarders, and kids looking to get off from school after heavy snowfall events. Attached below is an exact excerpt from the article produced by the team at the NASA Earth Observatory which explains how this situation may be able to turn around before Winter comes to an end: "Experts say there is still time for improvement. Snowpack in the Southern Rockies tends to come from a few big storms, in contrast to more frequent snowfalls to the north. Experts will know more in springtime, when NASA’s Airborne Snow Observatory (ASO) resumes annual flights that use lidar to measure the snow. Data from ASO—characterizing everything from snow depth, snow water equivalent, and albedo are an important guidance tool for water managers. The ASO team plans to survey California in March, and then head east for a survey over Colorado." To learn more about this particular story from the NASA Earth Observatory and re-shared by the Climate Central team, click on the following link: https://earthobservatory.nasa.gov/IOTD/view.php?id=91757&src=eoa-iotd&utm_content=buffer85c4d&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer! To learn more about other high-impact weather stories from across North America, be sure to click on the following link: https://www.globalweatherclimatecenter.com/north-america! © 2018 Meteorologist Jordan Rabinowitz Convective Precipitation Invigoration Along Winter-time Boundary (credit: Meteorologist Stu Ostro)2/24/2018 
DISCUSSION: Just three days ago, there was a very impressive convective weather event observed across parts of central, southern, and southeastern Texas. This interesting convective weather event was best characterized by convective storms being generated along an elongated southward-moving boundary through central and southern Texas. Attached above is a great perspective of this event (courtesy of Meteorologist Stu Ostro from The Weather Channel) which clearly shows how as the boundary associated with a larger-scale cold front moved southward over a relatively short period of time. During that relatively short period of southward movement, this boundary which was separating the shallow, colder air mass from the warm, moist air mass created quite a pronounced air mass contrast regime. This sharp contrast helped to generated a scenario wherein there was enhanced lifting of warmer air parcels positioned out ahead of the approaching boundary associated with the larger-scale cold front.
As a result of said warmer air parcels being lifted in accordance with the swiftly-approaching boundary, this forced a relatively rapid destabilization of the warmer air parcels. This rapid destabilization consequently facilitated the condensation of clouds and storm cells along the rounded (i.e., circular-shaped) southward-moving boundary which induced locally heavy downpours in association with those single-cell and clustered storms which formed. It goes without saying that even with these relatively brief convective storm cells, there can still be fairly prolific rainfall totals unleashed on towns and cities in the path of these convective cells. Therefore, if and when you are in the path of a convective storm forecast zone, be sure to take the forecast seriously and monitor real-time changes to the forecast as a given day moves along since convective storm expectations can change quickly. To learn more about other high-impact weather events occurring across North America, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz Current Northeast Low Pressure System Ready To Usher In Next Round of Cold Air (credit: GOES-16)2/1/2018  
DISCUSSION: As of this evening, a low-pressure system (and its strong cold front to be exact) has quickly been approaching the Hudson Valley of New York State. As it continued traveling to the south and east with time, the attendant cold front is dragging along with it a much colder air mass than has been in place over the past several days. This is due to the fact that the oscillation of the variable Arctic low (i.e., the statistical position of the more dominant collection of low-pressure systems residing in the vicinity of the Arctic Circle) has allowed colder air to descend from northern and central Canada. Thus, this next round of cold air will be ushered in by this latest incoming and now developing extra-tropical cyclone. You can also denote the position of the colder air in both the image and the animated satellite imagery attached above via the darker blue-colored region over northern Michigan and southern/southeastern Canada.
Thus, this colder air rushing into both interior and coastal sections of the Northeastern United States is facilitating the occurrence of a brief (but in some cases) heavy burst of wet snow. Hence, many roads such as (but certainly not limited to) Interstate 81 North/South as well as the New York Thruway will quickly become incredibly hazardous to drive on both tonight and throughout the day tomorrow. This is also due in part to the fact that surface and near-surface air temperatures will be quickly falling well-below the freezing mark tonight. Thus, any untreated roads and surfaces will quickly and effectively become complete "ice rinks." Therefore, if you need to travel tonight and/or tomorrow, be sure to leave extra time when heading out since the roads will still make for a slow go of it come the morning rush across many parts of the coastal and semi-interior Northeast. To learn more about other high-impact weather events occurring across North America, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz  DISCUSSION: A low-pressure system first developing near the Rocky Mountains impacted the United States as it travelled in a northeast direction. A low-pressure system is a system associated with cloudy or stormy weather that has lower pressure in its center as opposed to the areas around it. In the Northern Hemisphere, winds spin in a counter-clockwise rotation around a low-pressure system. This particular low-pressure system slammed the Midwest with vast amounts of snow and ice before moving towards New England where it mostly deposited freezing rain.
The largest impact from this storm occurred in the Plains and then spread into the Midwest. The winter storm dropped an impressive amount of ice and snow in its path. From 6 A.M. CST January 22 to 6 A.M. CST January 23, Prescott, Wisconsin and Winnebago, Minnesota respectively received 14.1 and 17.0 inches of snow. All of that within a 24-hour period! Pictured above is the total snowfall analysis from over this 24-hour period. From the color bar scale on the lower right-hand side, you can see that a significant amount of snow fell in these areas. The interesting fact about this storm is how it greatly impacted three separate regions across the United States. First, Idaho and Colorado were affected. Moving east, it seemed to drop the most amount of precipitation over the Midwest before finishing off in the northeastern tip of New England. Currently, the low-pressure system is moving away from New England, but still affecting certain areas. Maine experienced freezing rain with coatings up to a quarter inch of ice. It has recently switched over to moderate snow showers. Flood watches and warnings are also in effect for areas of Southern Maine, as well as Lancaster and York counties located in southeastern Pennsylvania. The center of the low is moving rapidly towards the Canadian Maritimes. Effects from this storm will diminish shortly-- if they have not done so already. To learn more about other interesting storms impacting North America, be sure to click here! © 2018 Meteorologist Claudia Pukropski  DISCUSSION: Over the past several weeks there has been a substantial increase in the degree of national snowfall coverage. This is due in part to the fact that a number of different Colorado lows as well as Alberta Clipper systems have traversed across portions of the Central and North-Central United States. Hence, you can see how the inter-mountain portion of the Western United States was one of the first parts of the United States to receive a sizable amount of measurable snowfall. In addition, you will note how the Great Lakes region was one of the other regions to receive notable amounts of snowfall earlier on in the 2017-2018 Winter season.
There is no question that orographic features spread across the United States are major influences on heavy snowfall potential. This is largely due to the fact that when air parcels are forced to rise up and over higher terrain, increasingly larger amounts of water vapor are forced out of corresponding air parcels. Thus, when greater amounts of water vapor are "squeezed" out of said air parcels, this greatly increased the localized potential for heavier precipitation events (i.e., heavier snowfall totals in the case of winter storm situations). Hence, there is no debate that orography plays a pivotal role in facilitating greater potential for major snowfall events both across the United States and the world for that matter. To learn more about other high-impact weather events occurring across North America, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz  DISCUSSION: A massive blast of cold air is currently hitting Florida bringing overnight low temperatures below 40 degrees Fahrenheit across much of the state. An exception to this is the southeast coast including Miami and Palm Beach which have overnight low temperatures in the 40s. The cause of the extreme cold temperatures to reach this far south is a massive ridge of high pressure across much of the Mississippi and Ohio River valleys as well as the very large low off the Atlantic Coast which is bringing heavy snow to the Northeast. There also is a heavy presence of sinking air which is pumping cold dry air down towards the ground which in addition to the cold air being advected at the surface is what is driving the temperatures to remain cold.
The cold air has also helped bring snow to parts of Florida including Tallahassee on Wednesday as the massive low was around the coast of Florida. The storm also brought above average precipitation values for much of the state (including over an inch of rain in Orlando). The below-average temperatures are expected to increase slightly through the weekend due to the ridge moving south as well as the massive low remaining over the Atlantic Coast which would increase a cold northerly flow. Many of the low temperatures recorded ranged from 12 to 18 degrees colder than average but were not record breaking by a few degrees. The cold air has caused unusual events to occur such as iguanas fell out of trees frozen as well as sea turtles to become inactive. In addition, airports including Orlando International have had to use de-icing trucks on many of the planes parked there. Citrus growers were on high alert as well, because of the possibility that the cold air will damage or destroy the citrus plants. To learn more about other high-impact weather events occurring across North America, be sure to click here! ©2018 Meteorologist JP Kalb  Party goers waited in near zero wind chills as they watched the ball drop in Times Square on New Year’s Eve. Winds chills in Nashville fell below 0 degrees Fahrenheit, -10°F in D.C., Oklahoma City dropping to -12°F, Chicago at -25°F, North Dakota in the -30°F range, Boston remaining sub 20 degrees for several days in a row, and the Florida panhandle expecting freezing rain. Even Fairbanks, Alaska seemed warmer than the Midwest, Great Lakes, and Northeast with positive single digit wind chills amidst the blast of cold Arctic air. But, what is wind chill exactly? Wind chill states how cold it “feels” when the wind is blowing. It was developed in the 1940's by two American scientists stationed in Antarctica that found wind speed and temperature to be the greatest factors in the freezing rates of a water bottle they had placed on the top of their hut. In reality, it measures the heat loss of exposed skin through convection. The rate of convection depends on the difference in the temperature of a surface and the fluid surrounding it. Moving air allows cooler air to be placed against a warm surface, increasing the rate of heat loss for faster wind speeds and reducing objects to the ambient temperature more quickly.  However, there are several assumptions that the wind chill equation makes. It assumes that it’s nighttime with clear skies and that you are in an open field, walking 3 mph straight into the wind, 5 feet tall, and feeling the wind against your bare skin. Wind chill also only uses average wind speed, not wind gusts. Most ASOS (Automated Surface Observing Systems) stations record wind speed and direction every 5 seconds and a 2-minute average of these speeds and directions are reported. The peak wind speed is the greatest 5-second average exceeding 25 knots (~28 mph) in the last hour. The reasoning behind using average wind speed in calculating wind chill is that it provides a more accurate representation of the body’s thermal equilibrium response.
Hypothermia can set in anytime it falls below 50°F and winds speeds greater than 3 mph, but affects people differently based on age and gender. Wind chills less than -35°F can cause frostbite in as little as 30 minutes. The best way to prepare for cold weather is to prepare your car with extra supplies, dress in layers, and only go out in the cold if you must. To learn more about North American weather and other large-scale weather phenomena , please click here! © 2018 Meteorologist Sharon Sullivan  Tonight’s weather across the United States will be a cold one for the majority of us, with more then two-thirds of the country, east of the Rocky Mountains, experiencing significantly below average temperature. Locations in the continental northeast, and as far south as Kansas into Ohio, will be around zero degrees Fahrenheit at midnight, with wind chills into the -20 to -40 degrees. Portions of the Midwest and Northeast are currently under a wind chill warning along with wind chill advisories throughout the night.
The picture above shows the global average temperature anomalies from December 27th until January 3rd. As you can see, the eastern two-thirds of the country will remain well below average temperatures, like it has been for the past few days, with nearly every other portion of earth being well above average. For more updates on weather pertaining to North America click here! ⓒ 2017 Meteorologist Claudia Pukropski  We are nearing the end of 2017, and it’s time to take a look back at this year’s weather events in the United States. From blizzards, to tornadoes, to hurricanes, to wild fires; 2017 left everything out on the table. In no particular order, the following are some of this year’s worst weather events:
Keep up with weather around the world in the New Year here! ⓒ 2017 Meteorologist Brandie Cantrell It’s time to kiss the autumnal warmth of the past few weeks across the Central U.S. goodbye, as arctic air arrives in the U.S. with a vengeance…To read the full story, click here - http://www.weatherworks.com/lifelong-learning-blog/?p=1441 © 2017 H. Michael Mogil To learn more about other high-impact weather events affecting North America, be sure to click here!  From Floods to Droughts (Photo Credit: WPC, US Drought Monitor, SPC, Univ of Rutgers, NWS)12/23/2017  DISCUSSION: Earlier this year during the spring months, portions of Arkansas and southern Missouri experienced record flooding. Details on this previous event can be found here. Currently, a few months later, these same places are now considered to be in a moderate to severe drought, as shown by the US drought monitor image, but possibly not for long. Current conditions show an elongated frontal boundary with a weak wave of low pressure moving northeast as the precipitation follows suit. A general 0.5 – 1 inches with up to 2+ inches of precipitation fell yesterday, December 22nd, into the overnight hours across southern Missouri and Arkansas with precipitation stretching into Louisiana as this front brought thunderstorm type activity last night. This precipitation yesterday evening shows up well when looking at the synoptic scale features that were in play alleviating some of these drought conditions.  The 850 mb map shown below, which plots heights (dam), isotherms (degrees C, dotted yellow), and dew point temperatures filled (degrees C), valid 12/23/00Z, shows southerly winds bringing warm air advection, which leads to upward vertical motion, across Arkansas and working its way into southern Missouri. Gulf of Mexico moisture is being advected into the region moistening up the atmosphere enhancing the heavy precipitation threat. Accompanied with this, favorable upper level jet dynamics are present enhancing divergence (yellow contours) in the upper levels (streamlines and isotachs in knots are also plotted) of the atmosphere as shown in the 300 mb analysis valid 12/23/00Z. This enhances the rising air in this region and the chance for precipitation.   These factors come together nicely when looking at the radar imagery from yesterday evening shown below, which illustrates a nice area of precipitation where it was expected in the drought areas based on this synoptic scale analysis.  Stay tuned for future updates here across the Mississippi Valley to see if more drought alleviation is on the way!
©2017 Forecaster Joseph DeLizio Evaluating the Lower- and Upper-level Flow over North America (credit: Thermodynamic Solutions)12/7/2017  DISCUSSION: As the present national weather pattern stands, there is quite an interesting set-up in place across the United States. One of the first thing atmospheric scientists (i.e., operational forecasters and/or broadcast meteorologists) execute when doing a given forecast is to ascertain a more concrete foundation of what is currently happening at that given time near both the top, middle, and bottom portions of the "active" atmosphere. The "active" part of the atmosphere referring to the portions of the atmosphere within which a large majority of the global weather phenomena occur within the confines of. As you can clearly see in the graphic above (courtesy of the Thermodynamic Solutions Weather Company), there are very different atmospheric flow regimes in place closer to the surface and towards the middle-to-upper portions of the atmosphere.
This is chiefly due to the fact that in the middle-to-upper part of the atmosphere, there is presently a "ridge" (or an area of high-pressure) in place over and across a good portion of Western North America which is shown on the right-hand side of the graphic attached above. To the east of any ridge can often be found a "trough" (or an upper-level region of lower pressure) which is also reflected by the "dip" or "deep left-turning curve" in the deep-blue colored flow shown on the right-hand side of graphic above as well. On the right side of any trough is where you nearly always find a higher probability of there being a greater likelihood of low-pressure formation. This is a combined result of there being stronger cyclonically-turning winds from the surface upwards on the eastern side of a trough which is much more favorable for surface-layer cyclogenesis which can then extend into the mid-levels of the atmosphere as well under the right conditions. Sure enough, very far downstream, there is a strong low-pressure system parked over part of Southeastern Canada which is helping to amplify a good portion of the ongoing lake-effect snow events downwind of Lake Erie, Lake Ontario, Lake Michigan, and Lake Superior. Thus, it is always neat to see how atmospheric science theory works out in real-life application. To learn more about other interesting weather events occurring across North America, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz  DISCUSSION: As a classic Arctic air blast makes it way into portions of the North-Central and the Northeastern United States, this will set the stage for another aspect of winter weather. That particular aspect being referred to is this instance is lake-effect snow. Lake-effect snow occurs as a result of when cold, moist air travels across relatively warmer water contained within the near-surface layer of various spread across the United States (and the world for that matter). In this particular situation, the combination of the cold air and the projected wind forecast will align the larger-scale flow such that areas to the east and east-northeast of both Lake Erie and Lake Ontario will likely get hit the hardest with periods of heavy lake-effect snowfall. As shown in the graphic above, some location may end up being able to measure snow in feet (rather than in inches). Therefore, it is imperative to respect the power of Mother Nature if you are currently situated within any of these forecast areas as trying to travel while under a lake-effect snow-band is quite often a very life-threatening precedent. So, be mindful of that as you plan your travel over the next few days.
To learn more about other high-impact weather events occurring across North America, be sure to click here! ©2017 Meteorologist Jordan Rabinowitz Huge Amounts of Precipitation Blanket the Northeast (Credit: Meteorologist David Tedesco)10/30/2017  Photo credit from iweathernet.com DISCUSSION: For those living in the Northeast, this past weekend has been a soaker. A low pressure system moved up the coast dropping insane amounts of precipitation (mostly rain, but higher elevations even saw snow!) The above map details how much liquid-equivalent precipitation was recorded in the past 48 hours. Areas in orange received around an inch (2.54 cm), while whole states like Delaware, New Jersey, Connecticut, and Rhode Island were blanketed by over 2 inches (5.08 cm) of rain! The central parts of New York and Pennsylvania have seen the worst of the storm, getting almost 4 inches (10.16 cm) of rain! The storm underwent bombogenesis, a term used by meteorologists to describe a rapidly intensifying storm, bringing high winds and precipitation. Millions of people in the Northeast are without power, where some areas experiences flooding, mudslides, and of course, transit problems. Approximately 5 years ago, Superstorm Sandy made landfall in the Northeast, bringing colossal destruction to the area. Some may say this storm was the ghost of Sandy. For more severe weather impacts around North America, be sure to click here! © 2017 Meteorologist David Tedesco  DISCUSSION: It has been fall on the calendar in South Florida for almost 4 weeks, but if you went outside you would not notice it. In fact, when September 22 rolls around I don’t refer to as the first day of fall, but as the first day of “Summer Extension”. So, when does fall really arrive in South Florida? Well, it all depends on your definition. I normally define it as the first day in which the morning low temperature falls below 70 degrees. That usually occurs sometime in mid-October. On the local TV station, they were defining the first day of fall as when the first cold front comes completely through the South Florida area bringing in noticeably cooler and/or drier air. With their definition, that event occurred on October 20 in 2016, October 6 in 2015, and October 22 in 2014.
However you want to define it, I for one cannot wait until that day occurs. Here in South Florida, the joke that floats around is what is the difference between fall up North and fall in South Florida? Up North it is fall when the leaves change colors, in South Florida it is fall when the license plate change colors. © 2017 Meteorologist Michael Leiba |
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