MESO: Mesoscale Discussion 0471

ACUS11 KWNS 132222
SWOMCD
SPC MCD 132222
FLZ000-GAZ000-132345-

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

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

ATTN...WFO...MLB...TBW...JAX...TAE...

LAT...LON 29748516 30598411 30808151 30468115 29738105 29138159
28428351 28488480 29128530 29748516

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