SPC continues to warn that the threat of a strong tornado or two still continues over eastern Mississippi into West Central Alabama.
The low level jet is over 80mph! Pumping in very moist air, which is the fuel for these storms Instabilities are modest, but the wind shear is off the scale, but isolated strong tornadoes are very possible.
ACUS11 KWNS 090348
SWOMCD
SPC MCD 090347
ALZ000-TNZ000-MSZ000-090515-
MESOSCALE DISCUSSION 2222
NWS STORM PREDICTION CENTER NORMAN OK
0947 PM CST TUE DEC 08 2009
AREAS AFFECTED…ERN MS THROUGH WRN AND N CNTRL AL
CONCERNING…TORNADO WATCH 797…798…
VALID 090347Z – 090515Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 797…798…CONTINUES.
THREAT FOR ISOLATED TORNADOES…ONE OR TWO OF WHICH COULD BE STRONG…AND DAMAGING WIND WILL PERSIST NEXT SEVERAL HOURS WITH GREATEST THREAT FROM E-CNTRL MS THROUGH W-CNTRL AND N-CNTRL AL.
WARM FRONT CONTINUES TO LIFT SLOWLY NWD AND EXTENDS FROM SRN THROUGH W-CNTRL AL INTO N-CNTRL MS WHERE IT INTERSECTS A COLD FRONT. A 70+ KT LOW LEVEL JET HAS ADVECTED MID 60S DEWPOINTS THROUGH THE WARM SECTOR WHERE A RESERVOIR OF 500-1000 J/KG MLCAPE RESIDES FROM LA THROUGH CNTRL MS. INSTABILITY REMAINS AOB 500 J/KG FARTHER EAST INTO CNTRL AL WHERE 00Z BIRMINGHAM RAOB INDICATED A STABLE LAYER IN THE LOWEST 2 KM AND STORMS HAVE TENDED TO WEAKEN AS THEY MOVE INTO THE MORE STABLE AIR NORTH OF THE WARM FRONT. HOWEVER…THE ATMOSPHERE WILL DESTABILIZE FARTHER NEWD WITH TIME. STORMS WILL CONTINUE DEVELOPING AND TRAIN NEWD WITHIN ZONE OF ASCENT ASSOCIATED WITH PRE-FRONTAL CONFLUENCE BANDS AND THE LOW LEVEL JET. STRONG DEEP SHEAR AND EFFECTIVE STORM RELATIVE HELICITIES AROUND 500 M2/S2 WILL CONTINUE TO SUPPORT SUPERCELLS AND THE THREAT OF ISOLATED STRONG TORNADOES.
THE THREAT IS MORE LIMITED BY A STRONGER CAP WITH SWD EXTENT INTO AL AND BY WEAKER INSTABILITY WITH NWD EXTENT TOWARD SRN TN.
..DIAL.. 12/09/2009
