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Mesoscale Discussion 1990
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   MESOSCALE DISCUSSION 1990
   NWS STORM PREDICTION CENTER NORMAN OK
   0703 PM CST TUE DEC 23 2014

   AREAS AFFECTED...CENTRAL AND SRN AL...FL PANHANDLE...AND WRN/SWRN GA

   CONCERNING...TORNADO WATCH 561...

   VALID 240103Z - 240230Z

   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 561 CONTINUES.

   SUMMARY...IN THE SHORT-TERM /THROUGH 02Z/...TWO PRIMARY ZONES OF WW
   561 CAN EXPECT TO HAVE A CONTINUED THREAT FROM STRONG TO SEVERE
   STORMS.  TWO NNE-SSW ORIENTED LINES OF STORMS MOVING EWD THROUGH
   CENTRAL AND SWRN AL AND THE WRN FL PANHANDLE WILL RESULT IN A THREAT
   FOR DAMAGING WINDS AND A TORNADO OR TWO.  FARTHER EAST...A SW-NE
   ORIENTED CORRIDOR OF STRONG TO SEVERE STORMS WILL CONTINUE TO AFFECT
   THE ERN FL PANHANDLE INTO SWRN GA...WITH A TORNADO THREAT AND
   DAMAGING WINDS.

   SOME COUNTIES NEAR AND SOUTH OF ATLANTA GA MAY NEED TO BE ADDED TO
   WW 561 BY 02Z...IF THE AIR MASS CAN DESTABILIZE SUFFICIENTLY TO
   SUSTAIN A SEVERE WEATHER THREAT FROM A FAST-MOVING LINE OF STORMS IN
   CENTRAL AL.

   DISCUSSION...AT 0030Z...MOSAIC RADAR IMAGERY SHOWED A FAST-MOVING
   LINE OF STORMS TRACKING ENEWD AT 40-50 KT ACROSS CENTRAL AL...WITH
   THESE STORMS EXTENDING FROM NRN SHELBY COUNTY SSWWD TO MONROE
   COUNTY.  IN THIS LATTER COUNTY...THE AFOREMENTIONED LINE OF STORMS
   AND ATTENDANT OUTFLOW BOUNDARY WERE BEGINNING TO MERGE WITH A
   NNE-SSW ORIENTED PRE-FRONTAL CONFLUENCE ZONE OVER SWRN AL.  THE
   FAST-MOVING LINE OF STORMS WAS LOCATED SOUTH OF THE WRN PORTION OF A
   SYNOPTIC WARM FRONT WHICH EXTENDED FROM NEAR KBHM INTO WEST-CENTRAL
   GA /NEAR KLGC/ THEN SEWD TO THE GA COAST NORTH OF KSSI.  STORMS
   ACROSS CENTRAL TO EAST-CENTRAL AL SHOULD PRODUCE A PRIMARY THREAT
   FOR DAMAGING WINDS...THOUGH ENHANCED LOW-LEVEL SHEAR /EFFECTIVE SRH
   OF 300-500 M2 PER S2/ WAS OBSERVED INVOF THE STRONGEST PORTION OF
   THE LLJ.  THIS WILL CONTINUE TO SUPPORT LOW-LEVEL STORM ROTATION AND
   A TORNADO THREAT...THOUGH THIS THREAT SHOULD BE SOMEWHAT LIMITED
   WITH NRN EXTENT GIVEN A MORE STABLE BOUNDARY LAYER AT BHM AND FFC
   PER 00Z SOUNDINGS.

   MEANWHILE...GREATER MOISTURE /SURFACE DEW POINTS INTO THE MID 60S/
   EXISTED FROM SWRN AL THROUGH THE WRN AND SRN PORTIONS OF THE FL
   PANHANDLE...GENERALLY ALONG A SECOND WARM FRONT MARKING THE NWD
   RETURN OF MARITIME-TROPICAL AIR.  THIS BETTER MOISTURE CONTENT AIR
   MASS AND STRONGER INSTABILITY SHOULD RESULT IN A GREATER TORNADO
   POTENTIAL TENDING TO BE NEAR AND SOUTH OF THIS WNW-ESE ORIENTED WARM
   FRONT.  EFFECTIVE SRH OF 200-400 M2/S2 IS MAXIMIZED ALONG THIS
   FRONT.

   ..PETERS.. 12/24/2014


   ATTN...WFO...JAX...FFC...TAE...BMX...MOB...

   LAT...LON   29868757 30628768 31168743 32448658 33758623 33668604
               33448505 32958414 32218332 31138322 30098317 29658297
               29178331 29238383 29188521 29168607 29818647 29868757 

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Page last modified: December 24, 2014
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