Mesoscale Discussion 41

Issued

Jan 21, 2012, 7:22 AM CST (13:22 UTC)

Expired

Jan 21, 2012, 8:45 AM CST

In force

83 min

Issued by

the Storm Prediction Center

The Birmingham radar (KBMX), 48 km from the middle of the area, began a volume at 13:22 UTC, the scan nearest the moment this went out.

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149 
ACUS11 KWNS 211323
SWOMCD
SPC MCD 211322
GAZ000-NCZ000-TNZ000-ALZ000-MSZ000-211445-

MESOSCALE DISCUSSION 0041
NWS STORM PREDICTION CENTER NORMAN OK
0722 AM CST SAT JAN 21 2012

AREAS AFFECTED...PORTIONS CENTRAL/ERN MS...CENTRAL/NRN AL...EXTREME
SERN TN...EXTREME SWRN NC...CENTRAL/NRN GA.

CONCERNING...TORNADO WATCH 3...

VALID 211322Z - 211445Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 3 CONTINUES.

CONTINUE VALID PORTIONS WW...EXCEPT FOR CLEARANCES RELATED TO COLD
FROPA.

SFC ANALYSIS INDICATED LOW HAS REACHED BLF AREA...WITH OCCLUDED
FRONT SWWD TO TRIPLE POINT OF DAMMING/WARM FRONT AND COLD FRONT OVER
EXTREME SERN TN.  WARM FRONT ARCS SWD THEN ENEWD ACROSS NWRN AND
NERN GA TO  CENTRAL SC...AND SHOULD CONTINUE TO MOVE NWD AS DAMMING
AIR MASS BECOMES MORE SHALLOW AND STATIC STABILITY WEAKENS.
MEANWHILE COLD FRONT WILL CONTINUE TO MOVE SEWD OVER WRN/NRN AL AND
OVER NWRN GA.  FRONT SHOULD BE ACCOMPANIED BY PRIMARY CONVECTIVE
BAND THAT CONTAINS OCNL LEWP/BOW FEATURES CAPABLE OF DAMAGING GUSTS.
BRIEF QLCS TORNADO CANNOT BE RULED OUT ALSO.

MEANWHILE PRE COLD-FRONTAL/WARM-SECTOR CONVECTION SHOULD CONTINUE TO
DEVELOP AND MOVE ENEWD ACROSS PORTIONS ERN MS...AL AND GA.  GIVEN
LACK OF SUBSTANTIAL CONVERGENCE/LIFT S OF FRONT...BUT CONTINUING
PRESENCE OF WEAK TO NO MLCINH JUXTAPOSE WITH SUBTLE DIABATIC/DIURNAL
HEATING...GRADUAL DEVELOPMENT/INTENSIFICATION OF PREFRONTAL
CONVECTION WILL OCCUR.  ACTIVITY SHOULD BE ORGANIZED IN BKN TO SOLID
BANDS THAT ARE ALIGNED NEARLY PARALLEL TO MEAN-WIND VECTOR.
INDIVIDUAL CELLS IN ERN PORTIONS OF WARM SECTOR SHOULD MOVE INTO
PROGRESSIVELY LOWER-THETAE AIR OVER GA AND SC AND WEAKEN...HOWEVER
OVERALL THETAE/BUOYANCY OVER THIS REGION SHOULD INCREASE WITH TIME.
NET EFFECT WILL BE TO SPREAD SVR POTENTIAL SEWD/EWD OVER WW.  AXIS
OF MLCAPE WITH VALUES 500-1000 J/KG...NOW FROM CENTRAL MS NEWD TO
NERN AL...WILL SHIFT EWD WITH TIME...AMIDST 45-55 KT EFFECTIVE SHEAR
MAGNITUDES.  ALTHOUGH PEAK VALUES IN LLJ SHOULD WEAKEN GRADUALLY AND
SHIFT EWD WITH TIME ALSO...300-500 J/KG EFFECTIVE SRH WILL BE
MAINTAINED IN SUPPORT OF POTENTIAL FOR LOW-LEVEL/STORM-SCALE
ROTATION.

..EDWARDS.. 01/21/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...CAE...GSP...MRX...FFC...BMX...HUN...MOB...MEG...
JAN...

LAT...LON   33318935 34038748 34988535 35678386 34938368 34098314
            33648240 32518256 32128520 32008665 32228814 32368885
            32718887 33009002 33318935

Mesoscale Discussions in Georgia, 2012Mesoscale Discussions in Alabama, 2012Mesoscale Discussions in Mississippi, 2012Every mesoscale discussion in 2012

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.