Alabama Has a Front Row Seat to the Developing Storm System

A very dynamic situation is unfolding across the eastern half of the country as a big winter storm gets ready to wallop the Northeast.

Here is Alabama, we will have a front row seat, but will be out of the main action.

Here are the players:
…A big upper level trough over eastern Oklahoma that is sweeping rapidly east.
…A split polar jet with the northern branch over the Northeast and the southern branch over northern Florida.
…A developing jet stream wind maximum over Central Alabama, on the eastern side of the trough.
…A weak low over the northern Gulf of Mexico.
…Surface low over Missouri.
…A powerful surface low that will form off the South Carolina coast tonight.

Several things to watch in the order they will affect us:

SHOWERS ACROSS CENTRAL ALABAMA NOW
Light to moderate showers have developed over Central Alabama underneath the developing wind maximum at the jet stream level over Central Alabama. Those are now mainly southeast of Birmingham and are moving northeast. You can see those in the large panel on the right.

OUR MAIN LINE OF SHOWERS FOR LATER TODAY
The main area of rain is approaching the Northwest corner of Alabama at this hour. This band of showers will sweep across the state this afternoon, exiting East Alabama late this evening. It does not seem that rain along the Gulf Coast associated with the weak Gulf low is going to cut off our moisture enough to weaken the area of rain approaching from the northwest. You can see the current regional radar in the top left panel. In the lower left panel you can see the projected movement of the precipitation according to the HRRR. It shows the main line of showers over Birmingham about 7 p.m.

DEVELOPMENT OF THE MAIN SURFACE LOW THAT WILL BE THE NOR’EASTER
The twin jets are critical to the rapid deepening of the low pressure system that we will see late tonight off the South Carolina coast. The left front quadrant of the southern branch wind max will be positioned adjacent to the right rear quadrant of the northern branch wind max. This sets up a double barreled upward motion enhancement. As cold air interacts with the warm air over the Gulf Stream, powerful thunderstorms will form and the low pressure system will deepen rapidly as it moves northeast.

WRAPAROUND MOISTURE
A few showers will wrap back into Northwest Alabama tonight and as the low ramps up tomorrow, the circulation will pull some instability showers into the state from the north. This really isn’t being talked about much, but is a real possibility. Couldn’t rule out a snow flurry or two over the Tennessee Valley tomorrow. It will be windy tomorrow and colder with highs remaining in the 40s. Winds could gust to 25 mph at times.

SIGNIFICANT FREEZE TUESDAY NIGHT AND WEDNESDAY NIGHT
Lows Tuesday night will drop into the middle and upper 20s (24-27F on average. Wednesday night lows will be in the same ballpark. This will result in an areawide freeze. Wind chills over North Central Alabama could drop into the 15-20F range.

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