Rain Ends, Christmas Storms

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Rain and embedded thunderstorms should come to end across much of Central Alabama late this morning. At this writing, most of the radar echoes were from Birmingham east and south. By late this afternoon around sunset time, we might even see a few peeks at the sun if we can get some breaks in the clouds.

The next trough, and a significant one at that, comes our way from the southern Rockies on Christmas Day. A surface low will form in Southeast Texas and then move northeastward across the Tupelo/Muscle Shoals area to near Nashville by Wednesday midday. Both the ECMWF and the GFS are in good agreement on the positioning and strength of the surface low which generates good confidence in the unfolding weather scenario. Looking closer at the severe weather parameters, instability is not tremendous but it is sufficient for severe weather to occur. Surface dew points are expected to climb to around 60 or so Christmas afternoon, giving us plenty of low level moisture for the strong storm system to work with. Shear is abundant with Bulk Shear values well above the 40 threshold for rotating storms. And while I did not mention it in the video, the LCL levels are low which the NWS in Birmingham has found to be a favorable element in severe weather events in Central Alabama.

After the surface low moves into Tennessee on Wednesday morning, cold air arrives as the moisture is departing, typical for us. There may be enough moisture as the cold air arrives to see the light rain mixed with some light snow or perhaps the precip to change over to snow flurries before ending completely. See the video for the parameters for this including 850 temperatures and precipitable water.

Winter weather is going to be a factor for the Central US from Oklahoma into Ohio. Winter storm watches have already been posted for the swath of the US where 2 to 4 inches of snow is likely to occur. If you have travel plans north and northwest of Birmingham, you may want to check on road conditions so you can make your travel as safe as possible.

The upper trough and the surface low move into the Mid-Atlantic states on Thursday allowing us to dry out for Thursday and Friday. It will be chilly with lows dipping into the 20s and highs in the 40s warming into the 50s Friday. Rain returns to the forecast on Saturday with the approach of another upper level short wave. This one zips by so the rain should be confined to Saturday with dry conditions returning on Sunday and Monday. Temperatures do stay seasonal as we head to the end of 2012.

The big message from the GFS long range projections is that the overall pattern remains pretty dynamic with quickly moving troughs providing us with weather systems about every two to three days. There does not appear to be any really cold or really warm patterns for the first week of January, although, the pattern around the 8th would suggest a substantial cold shot perhaps for the 10th or so, but then that is really far out!

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Just a reminder that we remain on a one-a-day schedule until the start of 2013. But stay up with the latest weather information by checking with the Blog for later posts. You can also catch my weather forecast on ABC 3340 at 5, 6, and 10 pm today. Be safe and Godspeed.

-Brian-

Category: Alabama's Weather