Severe weather analysis – 1130 pm

Severe storms continue tonight to our west, from east of Paducah to Dyersburg, TN to northern Louisiana.

The storms are associated with a strong upper-level trough moving from the central US toward the Ohio Valley.  Fortunately, the upper-level storm may be weakening some.  In addition, the air is not very unstable over Alabama yet, and probably won’t be until southerly low-level flow kicks in after midnight.  Even then, dewpoints in western and central Alabama should not rise above 63 or 64 in most places.  There will be some CAPE, maybe 500 J/kg or so by early morning, but nothing extreme.

The main problem is wind shear.  This is winter time, so systems tend to be very sheared and we expect helicity of 300-500 m2/s2 over north Alabama from now through tomorrow morning.  Due to dynamic processes, storms can often stay much stronger with a lot of wind shear even with little instability, so we do expect a line of storms to move through Alabama between 1 am and late morning.  The main line of storms will most likely arrive in BHM just before sunrise.  Given the extreme shear, a few tornadoes can not be ruled out, but the main threat will likely be from damaging straight-line winds, maybe up to 60 mph.

A few severe storms have formed out ahead of the main line over Mississippi, and we’ll have to keep an eye on these as they will get into west AL shortly, and a tornado warning is in effect in eastern MS, southwest of Hamilton.  See Bill’s post below for more info.

You should take this seriously and leave the NOAA Weather Radio on overnight.  60 mph winds can still knock down trees and power lines, too.

Category: Severe Weather