Cold, Messy Pattern

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HEY ST. CLAIR COUNTY! The first stop on the Storm Alert 2011 tour is tonight at Springville Middle School… the show begins at 6:45, but come out early and meet the ABC 33/40 Weather Team. I will be there doing the weather live at 5:00 and 6:00… we hope to see many of you there.

VERY COLD AND UNSETTLED: Let me say up front this pattern is fraught with danger for weather forecasters… I can clearly tell you there will be some surprises over the next 7 to 10 days, so keep checking with us for forecast changes in a complex winter weather pattern for Alabama and the Deep South.

THIS MORNING: As I write this, the NWS in Birmingham is issuing a freezing rain a advisory for the U.S. 80 corridor… Demopolis to Selma to Montgomery to Opelika. This is where a band of light freezing has set up, and some icing has been reported in Montgomery and Auburn. The precipitation band is narrow and the freezing rain is light, but there could very well be some icy spots on bridges, so if you are in this part of the state be careful out there on you way in to work.

REST OF TODAY: Most of the precipitation should remain over the southern half of the state during the day; for the I-20/59 corridors the day will be just cloudy and cold with a high only in the 30s.

TONIGHT/TOMORROW: This is where the forecast gets really challenging. The precipitation shield over South Alabama will move north tonight, and we will have some combination of rain, freezing rain, and sleet around here (the cold air is too shallow for snow).

Be sure and watch the Weather Xtreme video for the graphics, but we will pretty much roll with the RPM, which is a mesoscale model best suited for this situation… the synoptic scale models will struggle.

ICING ISSUES: I think the precipitation will begin as a mix of sleet and freezing rain, and there could be some icing on exposed objects and bridges across a pretty good part of North-Central Alabama. But, the low levels will warm during the night, and it seems like temperatures will ease above 32 at some point between midnight and daybreak for Tuscaloosa, Birmingham, and Anniston. So, for these cities, some bridge icing is possible in scattered spots late tonight, but by the morning commute tomorrow the icing issues could be over.

Clearly the best chance of significant icing will be over Northwest Alabama, where the cold air is a little more entrenched. Areas west of a line from Reform to Jasper to Cullman to Huntsville could see 5 hours of freezing rain (or more), and this is where the greatest concern for really significant bridge icing and travel issues will be tomorrow morning. There might even be enough ice to gather on power lines and trees. But, even in this part of the state temperatures should warm into the mid 30s by late morning, and by the lunch hour all of Alabama should be in a cold, miserable rain with temperatures in the mid to upper 30s.

The scenario above is not set in stone, and I encourage just about everybody in Alabama north of U.S. 80 to get up extra early tomorrow to check on weather and road conditions.

SATURDAY: The RPM continues to suggest that the rain will change to light snow late tomorrow night into Saturday morning as the main upper trough passes overhead. There might be enough snow for a dusting, and again there could be some slick spots on bridges Saturday morning with temperatures near freezing. The light snow will end by late morning, and some partial clearing is possible by late afternoon. We should rise into the low 40s Saturday once the snow moves out.’

SUNDAY: This will be the nicest day of the weekend, with a mix of sun and clouds and a high in the low 50s.

NEXT WEEK: The clear message is that very cold air will settle in here by Tuesday and Wednesday, but all other details are as clear as Mississippi mud. The latest GFS and ECMWF runs have now developed the idea of a significant winter storm for Alabama Wednesday night into Thursday, but we don’t even want to go there right now; see the Weather Xtreme video for the details. Whatever happens, very cold air will be the story next week with some risk of winter weather mischief along the way. We will be deal with next week in better detail once tomorrow’s system gets out of here.

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I am speaking this morning at Oak Hill School in Tuscaloosa… look for the next Weather Xtreme video here by 3:30 this afternoon. Enjoy the day!