 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
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 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 |
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