Here is a new Mesoscale Discussion from the Storm Prediction Center…
It indicates that the cap is just about gone over Central Alabama. This is borne out by the developing of cells in East Central Alabama. The airmass is certainly unstable with a CAPE Of 2917 and LI of -7 on the 18z (1 p.m.) special balloon release at Birmingham. The CINH or convective inhibition was virtually gone. This means we coudl see rapid developmetn of thunderstorms soon along and south of the boundary, which has pushed back north of Birmingham.
There is not much shear, so the main severe threats this afternoon will be from hail and downburst winds. And don’t forget the lightning and very heavy rainfall.
Still more severe activity through the overnight hours.
MESOSCALE DISCUSSION 0863
NWS STORM PREDICTION CENTER NORMAN OK
0228 PM CDT SAT MAY 10 2008
AREAS AFFECTED…CENTRAL AL…FAR ECENTRAL MS
CONCERNING…SEVERE POTENTIAL…WATCH POSSIBLE
VALID 101928Z – 102130Z
LINE OF TOWERING CU DEVELOPING ALONG EFFECTIVE FRONTAL BOUNDARY OVER
CENTRAL AL…WWD INTO FAR ECENTRAL MS MAY DEVELOP INTO TSTMS WITHIN
THE NEXT 1-2 HRS. AREA IS BEING MONITORED FOR A POSSIBLE WW.
LATEST SATELLITE IMAGERY SHOWS TOWERING CU ALONG A DIFFERENTIAL
HEATING BOUNDARY /EFFECTIVE SFC FRONT/ EXTENDING E-W FROM NEAR
TUPELO IN ECENTRAL MS EWD TO NEAR TALLADEGA IN ECENTRAL AL. SOUTH OF
THIS BOUNDARY…MODERATE AMT OF CLOUD COVER HAS LIMITED
DESTABILIZATION /NOTED BY THE 18Z JAN SOUNDING/. HOWEVER…WHERE THE
TOWERING CU WAS FORMING…SUFFICIENT HEATING HAS NEARLY REMOVED
REMAINING CINH /PER THE 18Z BMX SOUNDING/. MODERATE INSTABILITY
/2500-3000 MUCAPE/ COMBINED WITH MODERATE VERTICAL SHEAR /40-50 KTS
PER THE 18Z SOUNDING/ WILL BE SUPPORTIVE OF SUPERCELL-TYPE STORM
MODE WITH ANY TSTM THAT DOES DEVELOP WITH LARGE HAIL/DMGG WINDS THE
PRIMARY THREATS INITIALLY. GIVEN THE UNCERTAINTY IN THE LARGE SCALE
FORCING AND LIMITED SFC CONVERGENCE TSTM INITIATION AND COVERAGE ARE
SOMEWHAT UNCERTAIN. THUS THE AREA WILL CONTINUE TO BE MONITORED FOR
A POSSIBLE WW.
..CROSBIE.. 05/10/2008
