Delightful December Day

| December 18, 2012 @ 6:19 am

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FOGGY START IN SPOTS: We should note that some dense fog has formed in some places, especially over Northwest Alabama, where temperatures have fallen into the 30s. Visibility will be pretty restricted until the fog lifts a little later this morning. Otherwise, the day will be sunny with a high near the 60 degree mark.

Tomorrow will be dry as well with a high in the upper 60s, but to the west strong to severe storms will develop late in the day, and SPC maintains their standard “slight risk” of severe weather for much of Mississippi, Arkansas, West Tennessee, and North Louisiana.

SEVERE WEATHER POTENTIAL THURSDAY MORNING: The storms to the west should form into a long squall line, or QLCS (quasi linear convective system), moving into Alabama during the pre-dawn hours Thursday. The main window for storms will come from about 3:00 a.m. until 12:00 noon. SPC has roughly the southern half of Alabama in standard “slight risk” of severe weather for Thursday.

This will be a typical cool season event with very limited instability, but high shear (veering of the wind with altitude). The low level jet will be screaming (850 mb winds possibly in excess of 60 knots), and dynamic forcing looks impressive. Take a few minutes to watch the Weather Xtreme video and you will see all of the maps and charts to explain the meteorological setup for this event.

As the squall line moves through early Thursday morning, we will have potential for strong, perhaps damaging straight line wind. And, we can’t rule out the chance of a few small, spin-up tornadoes along the line, but remember providing a warning for these is difficult if not impossible, much like the December 10 EF-1 in North Birmingham. Go here to see a great report on this from the NWS in Birmingham.

Rain and storms will end from west to east during the midday hours.

FRIDAY AND THE WEEKEND: The weather turns sharply colder Thursday night with cold air coming over a fresh snow pack over the Midwest. We are projecting lows in the 20s Friday and Saturday morning, with low 30s early Sunday. These three days will be cool and dry; I don’t think we get out of the 40s Friday… then look for a high in the 50s Saturday and Sunday.

CHRISTMAS STORMS? Another very dynamic storm system will impact Alabama next week, advertised by both the GFS and the ECMWF. As you might expect this far out, there are timing differences, but the idea of a high impact storm is quite credible.

The ECMWF (Euro) solution brings the main risk of rain and storms into Alabama Christmas afternoon into Tuesday night, while the GFS holds off until the day after Christmas (Wednesday). A warm front will be moving northward through Alabama, along and south of that warm front a significant severe weather threat could develop, while north of the warm front, a cool, heavy rain event is likely. We can’t determine the warm front position a week in advance, but by the end of the week we should have a very good idea of the placement of the highest severe weather risk.

And, for travelers, we should note this has the potential to bring a huge snow event to the nation’s mid-section in the cold air northwest of the surface low. Again, take some time to watch the Weather Xtreme video with a day by day walkthrough, along with all of the maps and graphics.

Following this storm, we could very well have the coldest air so far this season. If you believe the ECMWF, we might have a hard time getting above freezing by December 27/28, with lows in the teens. It will be a very interesting week of weather for sure.

WEATHER BRAINS: Don’t forget you can listen to our weekly 90 minute netcast anytime on the web, or on iTunes. This is the show all about weather featuring many familiar voices, including our meteorologists here at ABC 33/40. Scroll down for the show notes on the new episode we recorded last night.

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I will be doing a weather program for the third graders at Elvin Hill Elementary School this morning… and I will kick off the 26 hour Toys for Toys final drive on ABC 33/40 News this evening at 4, 5, and 6:00 at Legacy BBQ on Highway 150 in Hoover. Please consider bringing a new, unwrapped toy by since we need an additional 40,000 toys to meet the needs of families that are struggling this Christmas. I should have time to crank out an afternoon Weather Xtreme video before I head out to the live shot; it will be posted by 3:30.

Enjoy the day!


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Category: Alabama's Weather

About the Author ()

James Spann is one of the most recognized and trusted television meteorologists in the industry. He holds the AMS CCM designation and television seals from the AMS and NWA. He is a past winner of the Broadcast Meteorologist of the Year from both professional organizations.

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