MESO: Mesoscale Discussion 2171

ACUS11 KWNS 100405
SWOMCD
SPC MCD 100405
FLZ000-ALZ000-100700-

MESOSCALE DISCUSSION 2171
NWS STORM PREDICTION CENTER NORMAN OK
1005 PM CST MON NOV 09 2009

AREAS AFFECTED...PORTIONS SRN AL AND WRN FL PANHANDLE.

CONCERNING...HEAVY RAINFALL

VALID 100405Z - 100700Z

RELATIVELY CONCENTRATED AND PERSISTENT AREA OF HEAVY RAIN -- WITH
RATES GENERALLY 1-2 INCHES/HOUR -- IS EXPECTED TO SPREAD/MOVE
FARTHER INLAND ACROSS DISCUSSION AREA DURING NEXT FEW HOURS.

THIS EFFICIENT/WARM-CLOUD PRECIP REGIME IS ASSOCIATED WITH
WELL-DEFINED AND DEEP LOW-LEVEL CONVERGENCE ZONE LOCATED NE OF
CENTER OF T.S. IDA...AND CORRESPONDS LOOSELY TO AXIS OF COLDEST IR
CLOUD TOPS. ALTHOUGH CONSIDERABLE DRYING ALOFT IS EVIDENT ON
MOISTURE CHANNEL IMAGERY OVER SRN AND PARTS OF ERN
SEMICIRCLES...VERY RICH LOW LEVEL MOISTURE AND ISENTROPIC ASCENT N
OF WARM FRONTAL ZONE WILL CONTINUE TO SUPPORT PROFUSE PRECIP
PRODUCTION. RELATIVE MAX IN ASCENT SHOULD REMAIN ROOTED IN ELEVATED
LAYER OF INTENSE LOW LEVEL WAA ATOP RELATIVELY COOL/INLAND BOUNDARY
LAYER. COMBINATION OF ELY/CONTINENTAL ORIGIN OF SFC WINDS AND
PERSISTENT PRECIP INTO THAT LAYER HAS REINFORCED NEAR-SFC STATIC
STABILITY. SFC MESOANALYSIS SHOWS WARM FRONTAL ZONE EXTENDING ESEWD
FROM CORE REGION OF IDA ACROSS ERN GULF...WELL OFFSHORE FL
PANHANDLE...MOVING NWD BUT FCST TO REMAIN OFFSHORE AT LEAST FOR NEXT
FEW HOURS. MAIN LIMITING FACTOR FOR MORE VIGOROUSLY CONVECTIVE
RAINFALL ENHANCEMENTS WILL BE LACK OF ROBUST INSTABILITY. WITH
SBCAPE ESSENTIALLY NIL...MODIFIED RAOBS AND FCST SOUNDINGS SUGGEST
ELEVATED MUCAPE GENERALLY 250-500 J/KG IS ROOTED WELL ABOVE SFC...IN
650-750 MB LAYER. AS WARM FRONTAL ZONE APCHS COAST LATER
TONIGHT...DEPTH OF BUOYANT LAYER MAY INCREASE...BUT WITH SOME OFFSET
BY DRIER AIR AND STABLE LAPSE RATES ALOFT.

..EDWARDS.. 11/10/2009

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

ATTN...WFO...TAE...MOB...

LAT...LON 30278816 30888806 31338767 31658678 31158606 30668574
30568605 30408658 30278816

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