MESOSCALE DISCUSSION 0163
   NWS STORM PREDICTION CENTER NORMAN OK
   1216 PM CST FRI FEB 27 2009
   
   AREAS AFFECTED...PARTS OF SRN AR....N CNTRL MS INTO W CNTRL AL
   
   CONCERNING...SEVERE THUNDERSTORM WATCH 37...
   
   VALID 271816Z - 271945Z
   
   THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 37
   CONTINUES.
   
   TRENDS ARE BEING MONITORED FOR THE POSSIBILITY OF INCREASING
   TORNADIC POTENTIAL...A NEW TORNADO WATCH WILL LIKELY BE ISSUED SOON.
   
   ATTEMPTS AT DEEP CONVECTIVE DEVELOPMENT ALONG A LOW-LEVEL CONFLUENT
   ZONE ACROSS SOUTHEAST MISSISSIPPI INTO WEST CENTRAL ALABAMA HAVE
   BEEN SUPPRESSED BY CAPPING ELEVATED WARM LAYER.  THIS MAY REMAIN THE
   CASE...THOUGH THE MOIST BOUNDARY LAYER CONTINUES TO WARM WITH
   INSOLATION.
   
   STRONGER STORMS REMAIN FOCUSED ALONG A WEST-NORTHWEST TO EAST-
   SOUTHEAST MID-LEVEL THERMAL GRADIENT AT THE EDGE OF THE WARM
   LAYER...WHERE LOWER/MID TROPOSPHERIC WARM ADVECTION IS CONTRIBUTING
   TO LARGE-SCALE ASCENT.  THE INFLUENCE OF A RESIDUAL STABLE LAYER
   NEAR THE SURFACE CONTINUES TO PROVIDE UNCERTAINTY CONCERNING THE
   SEVERE THREAT BEYOND THE RISK FOR LARGE HAIL...PARTICULARLY IN THE
   NEAR TERM.  HOWEVER...IN RESPONSE TO THE DIGGING UPSTREAM
   TROUGH...THERE HAS BEEN A TENDENCY FOR A NORTHWARD SHIFT OF AN
   ONGOING EVOLVING CONVECTIVE BAND...WITH NEW CELLS DEVELOPING JUST TO
   ITS SOUTH.  AND...THE MODIFICATION OF THE BOUNDARY LAYER WITHIN A
   NEAR SURFACE BAROCLINIC ZONE ASSOCIATED WITH THE RAIN COOLED AIR MAY
   BE ENOUGH TO SUPPORT INCREASING TORNADIC POTENTIAL THROUGH THE
   AFTERNOON.  MODELS SUGGEST SOME STRENGTHENING OF SOUTHWESTERLY 850
   MB FLOW THROUGH THE AFTERNOON ...WHICH SHOULD YIELD INCREASINGLY
   LARGE CLOCKWISE CURVED LOW-LEVEL HODOGRAPHS THROUGH THE 20-22Z TIME
   FRAME.
   
   ..KERR.. 02/27/2009
   
   
   ATTN...WFO...BMX...MOB...JAN...LZK...
   
   LAT...LON   33019178 33539170 33579083 33378980 32928841 32368786
               32228818 32498934 32859069 33019178