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THEWEATHERMOGIL:: Snowfall gradients

Yesterday’s winter-spring storm produced lots of severe weather on its eastern flank, but it also generated a band of heavy snow to its west. Just to the east of Chicago, IL, the infamous “rain-snow” line helped to create a rather large snowfall gradient. That gradient (0.44 inches of snow per mile, across a 34-mile distance) gave the National Weather Service (NWS) office in Chicago an opportunity to play up such gradients (Fig. 1). Bravo!

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Yet, much larger gradients came into play for the Jan. 26-28, 2015 snowstorm in the mid-Atlantic and Northeast U.S. I refer readers of this blog site to an article I wrote after that event – THEWEATHERMOGIL:: Looking back at an almost perfect winter storm forecast (1/26-1/28/15). Gradients in that storm were some two to three times larger than the one near Chicago yesterday (Fig. 2).

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What’s important is that people realize that weather-related gradients (e.g., snow, rain, temperature, wind, cloudiness) can be large and affect the viability of current, highly localized forecasts. They can also play a role in how weather is treated in legal and insurance matters.

© 2016 H. Michael Mogil

Originally posted 2/25/16

weather

THEWEATHERMOGIL:: Out of balance temperatures rule the eastern U.S.

When the upper level winds (I’m talking altitudes of four to eight miles above the Earth’s surface) take on a high-amplitude wave pattern (Fig. 1), strong low-pressure systems often develop. Given the counter-clockwise wind flow around such lows in the Northern Hemisphere, surface or near-ground temperatures typically take on a similar wave-like pattern. One can argue cause and effect here, but suffice to say that these weather patterns are linked

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It’s important to realize that cold air masses tend to form over higher latitude regions due to snow cover, shorter days and lower sun angles. Similarly, warm air masses develop over lower latitudes. Air masses are just large volumes of air with similar temperature and moisture characteristics.

When upper-level troughs and associated storm systems develop, these air masses get transported far their homes. This means that cold air travels far south from its “source” region and warm air travels far north from its origin location. Such was the case early this Thursday morning.

Fig. 1 shows the upper level wind pattern at 7:00 p.m. E.D.T. yesterday that was associated with the low-pressure (or storm) system responsible for the deadly and destructive severe weather events of the past two days. Early this morning, that double-barreled surface low (with its counter-clockwise wind flow) was centered near western New York State.

To the east of the low, winds were blowing from the south and temperatures across southern New England were in the upper 50’s to lower 60’s. Fig. 2 shows that at 4:00 a.m. E.D.T., Boston, MA (BOS) was reporting a 61-degree reading (with thunderstorms). Far to the south of the low, where colder air had moved southward on northerly and northwesterly winds, Tampa, FL (TPA) was only at 57 degrees.

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A similar scenario existed between Minneapolis, MN (MSP) and Amarillo, TX (AMA). Both cities had readings in the upper 20’s this morning.

© 2016 H. Michael Mogil

Originally posted 2/25/16

weather

THEWEATHERMOGIL:: Stormy weather across the Eastern U.S.

There is a moderate risk of severe thunderstorms and tornadoes across North Carolina this afternoon and evening. From southeast Virginia into South Carolina there is a lesser risk of severe weather, but severe storms are still possible (Fig. 1). Already today, Feb. 24, 2016, there have been 44 severe weather reports (mostly high winds) since 7:00 a.m. E.S.T. This is on top of some 142 severe weather reports (including 35 tornadoes) from 7:00 a.m. E.S.T. Tues, Feb. 23, 2016, until 7:00 a.m. E.S.T. on Wed., Feb 24, 2016.

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A very strong low-pressure system is currently marching up the western side of the Appalachians and will be located near Cleveland, OH, by this evening. The storm is “huge,” covering almost the entire eastern half of the U.S. This radar image from late morning shows the overall extent of the storm system (Fig. 2).

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Ahead of the storm (east side) counterclockwise winds are bring warm and humid air northward. Temperatures and dew points are in the mid to upper 60’s across much of eastern North Carolina and parts of southeast Virginia early this Wednesday afternoon. When coupled with high speed, diffluent/divergent winds at high altitudes, the stage is set for strong thunderstorms, some with severe weather and locally heavy rainfall.

Across parts of Florida, some locally heavy thunderstorms, along with possible severe weather, are also on tap.

On the western flank of the storm, heavy snow and possible blizzard conditions are anticipated across parts of Indiana, Illinois and Michigan.

Elsewhere across the eastern part of the U.S. windy conditions will be the rule until later Thursday evening.

In short, almost any weather condition is showing itself across the eastern U.S. today (Fig. 3).

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© 2016 H. Michael Mogil

Originally posted 2/24/16

"Life", politics, weather

THEWEATHERMOGIL:: A vote for mostly nice weather

“Super Tuesday,” perhaps the biggest single day of primary election year voting, arrives in a little more than a week. Twelve states have Republican primaries or caucuses; ten states have Democratic primaries (with American Samoa holding a caucus). Six of the primary states are in the Deep South, with three states (Alabama, Georgia and Tennessee) in the Southeast and three (Oklahoma, Texas and Arkansas) across or near the southern Plains. All “Super Tuesday” states are noted in the listing below.

What are the Super Tuesday states?

Both Democrats and Republicans: Alabama, Arkansas, Colorado, Georgia, Massachusetts, Minnesota, Oklahoma, Texas, Vermont and Virginia.

Republicans only: Tennessee primary and Alaska caucus.

Democrats only: American Samoa caucus.

I singled out the states above because two areas are expected to have some weather problems that day. The Southeastern states will be faced with locally heavy rainfall and possibly severe storms (reminiscent in some ways to the Super Tuesday tornado outbreak of Feb. 5 – 6, 2008). Arkansas and the eastern parts of Texas and Oklahoma will have a chilly rain, followed by cloudy skies (Fig. 1).

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Otherwise, the weather should be mostly “good,” across the Nation.

As with election predictions, outcomes are subject to updating and change. Because of the importance of these primaries and caucuses, we’ll provide periodic updates during the next week or so to keep the weather in focus. We’ll follow that with further updates for the next three months, thanks to a spate of primaries that doesn’t end until June 14.

If you live in any of these states or territories, regardless of your chosen candidate, I encourage you to use your right and responsibility to vote. I will be voting in the Florida primary on Mar. 15, regardless of the weather.

© 2016 H. Michael Mogil

Originally posted 2/21/16

weather

THEWEATHERMOGIL:: Bow echo enroute to Collier County and Naples

It’s been just about one month since a strong downburst raced through Collier County. Early this Tuesday morning, another round of severe storms is impacting our area.

While several Doppler-indicated circulations prompted tornado warnings in the area earlier this morning, it is a large bow-echo (shaped like a backwards C and indicating strong straight line winds) that is charging toward the Collier County coast (Fig. 1). By 6:00 a.m. E.S.T., the bow echo should be landfalling and beginning its trek through Naples and then much of northern and central Collier County.

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Look for winds, possibly gusting to more than 60 miles with this bow echo. Warnings for strong straight-line winds will likely be posted shortly.  Meanwhile, a tornado watch covers much of southwest Florida until mid-morning.

© 2016 H. Michael Mogil

Originally posted 2/16/16