MESOSCALE DISCUSSION 0471
   NWS STORM PREDICTION CENTER NORMAN OK
   0522 PM CDT MON APR 13 2009
   
   AREAS AFFECTED...NRN FL INTO PARTS OF THE FL PEN
   
   CONCERNING...TORNADO WATCH 150...
   
   VALID 132222Z - 132345Z
   
   THE SEVERE WEATHER THREAT FOR TORNADO WATCH 150 CONTINUES.
   
   AN ADDITIONAL WW WILL LIKELY BE ISSUED ACROSS REGION BY 23Z.
   
   A CONVECTIVELY GENERATED SURFACE BOUNDARY IS ADVANCING WITH A
   VIGOROUS STORM CLUSTER OFF THE GEORGIA COAST AT THE PRESENT TIME. 
   THIS BOUNDARY TRAILS TO THE WEST SOUTHWEST...THROUGH THE FLORIDA BIG
   BEND REGION...WHERE IT IS QUASI-STATIONARY OR ONLY SLOWLY ADVANCING
   SOUTHEASTWARD IN THE WAKE OF A WAKE SUBTROPICAL IMPULSE WHICH
   APPEARS TO HAVE MIGRATED INLAND ACROSS NORTHERN FLORIDA INTO
   GEORGIA.  WHILE IT APPEARS THAT THERE COULD BECOME A RELATIVE LULL
   IN SEVERE POTENTIAL EARLY THIS EVENING...AN UPSTREAM IMPULSE
   SHIFTING SOUTHEAST OF THE CENTRAL GULF COAST TOWARD NORTHERN FLORIDA
   COULD CONTRIBUTE TO AN INCREASING RISK FOR DAMAGING WINDS ...PERHAPS
   ISOLATED TORNADOES...ACROSS PARTS OF NORTHERN FLORIDA BETWEEN
   TALLAHASSEE AND GAINESVILLE BY 02-03Z.  WESTERLY LOWER/MID
   TROPOSPHERIC FLOW IS PROGGED TO STRENGTHEN WITH THE APPROACH OF THIS
   FEATURE...WHICH MAY ACCELERATE AHEAD OF A STRONGER POLAR SHORT WAVE
   TROUGH PIVOTING THROUGH THE LOWER MISSISSIPPI VALLEY. 
   AND...ASSOCIATED FORCING...COUPLED WITH A MOIST INFLOW CHARACTERIZED
   BY 70F SURFACE DEW POINTS...MAY SUPPORT INTENSIFICATION OF AN
   ONGOING STORM CLUSTER OVER THE NORTHEASTERN GULF OF MEXICO...AS IT
   PROGRESSES TOWARD NORTHERN FLORIDA.  OTHERWISE...THE SLOW MOVING
   OUTFLOW BOUNDARY/CONFLUENCE ZONE DOWNSTREAM OF THIS CLUSTER WILL
   REMAIN A FOCUS FOR POTENTIALLY EXCESSIVE RAINFALL ACROSS NORTHERN
   FLORIDA INTO THE EVENING HOURS.
   
   ..KERR.. 04/13/2009
   
   
   ATTN...WFO...MLB...TBW...JAX...TAE...
   
   LAT...LON   29748516 30598411 30808151 30468115 29738105 29138159
               28428351 28488480 29128530 29748516