Rain Rate at 1 to 2" per hour
Posted by JAC on 11/9/2009, 11:17 pm
 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 |
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