Daweathablog

Charles E. Roop giving his own forecasts, weather discussions, photos and adventures for the Starkville, MS area, Florida, and beyond.

Thursday, February 11, 2010

SnOMG?!

It has been a few weeks since my last post, which was on the possibility of winter precipitation in the area. Surprisingly, reports of sleet and snow came in from Ocala and Flagler County that early January night. Reports of sleet were even coming in south Florida.

Flash forward to the last couple of days where much of the United States has experienced what some have been calling "Snomagedon" or "Snopocalypse." The last two storm systems have broken many snowfall records and wrecked havoc for millions.

This next storm looks to be interesting, although this system doesn't seem to have many impacts on New England as the last two did. The southeast looks to be under the fire.

What's happening

Surface analysis from the Hydrometeorological Prediction Center (HPC) shows a low pressure system centered near Brownsville, Tx with an associated cold and warm front. Radar shows plenty of rain in southern Texas, southern Louisiana and southern Mississippi while snow is falling in northern Louisiana and north Texas. GFS and NAM guidance is showing a upper-level longwave trough (essentially a trough in the jet stream) over north Texas.

Friday's Synoptic Outlook

The system is expected to intensify and move east over the Gulf of Mexico. Starting Friday before noon, north Florida could start to see rain and pick up in intensity as the day wears on. The HPC forecasts, along with model guidance, seem to agree on the low reaching Florida near Tampa Bay around 7 pm Friday with the warm front remaining south of Gainesville.

So...snow?? Sleet? Anything?

The further north and west you go during the next 36 hours, the better the chances of winter precipitation. Within the last hour or so, sleet was reported in Crestview, FL (western panhandle) was well as Destin. There are some schools of thought of whether Gainesville could see anything.

NWS-Jacksonville is thinking of this (from their latest Area Forecast Discussion)...
SO...THE BEST CHANCE FOR A RA/SNOW MIX WILL EXIST ACROSS OUR NW GA
ZONES BEGINNING FRI MORNING. THE BEST CHANCE FOR POSSIBLE
ACCUMULATIONS WILL BE ACROSS THESE ZONES AFTER 18Z [2 PM EST] FRI AND
CONTINUING THROUGH 06Z [1 AM EST] SAT. THE BEST CHANCE FOR A WINTRY MIX
OF RA/S WILL BE ACROSS NE FL AFTER 21Z [4 PM EST] FRI AND FRI EVENING MAINLY
N OF THE I-10 CORRIDOR. THERE WILL BE A GOOD CHANCE FOR FLURRIES 06Z-12Z
[1 AM - 7 AM EST] SAT ACROSS A LARGE PORTION OF THE AREA DUE TO SHALLOW
WRAP-AROUND MOISTURE...MEAGER LIFT AND STRONG COLD AIR ADVECTION.
In other words, it would be a very slim chance for us. I have been warned by a fellow Twitterite and meteorologist that "warmer air from the Atlantic" could be a limiting factor by "not allowing the lower levels to cool enough." However, my thinking is if the temp is just cool enough below 850mb, we could enough moisture at the surface to have snow fall. He also suggests that the latest GFS and NAM runs don't really show any winter precip for the area.

Based on my look at temperature forecasts with some of the models, chances are slim for winter precip in the area. But that doesn't mean that it's impossible.

The winter precip event early last month had one limitation for Gainesville: surface dry air. During that night, radar indicated light precip in the area but it was not falling to the ground. Why? Too dry - it just evaporated before it even hit the surface.

Here are some examples of temperature profiles for snow (left) and sleet (right).


Basic Vertical Temperature Profile Associated with Snow at the Ground Basic Vertcal Temperature Profile of the Atmosphere Associated with Ice Pellets (Sleet) at the Ground
Image Source: NOAA

Summary

So, will we see snow or any winter precip in the area? Chances are slim, but you can count on dealing with lots of rain for most of your Friday. Bring that umbrella to school or work before you head out the door.

Also, keep any eye on my Twitter feed (twitter.com/daweathaman) for the latest. I might add a new weather post as conditions and free time warrant.

By the way, I always welcome discussion from meteorologists and other weather geeks for their expertise. I'm not too familiar with forecasting winter precip (wonder why?), so any advice would help. Let me know if you have any winter weather reports, too.

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