MESOSCALE PRECIPITATION DISCUSSION 0526
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
903 AM EDT MON SEP 28 2015
 
AREAS AFFECTED...SOUTHERN ALABAMA...FLORIDA PANHANDLE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 281302Z - 281732Z
 
SUMMARY...VERY FOCUSED CONVECTIVE WEDGE HUGGING THE
COASTLINE...3+"/HR RATES FOR LIKELY FLASH FLOODING IN SHORT TERM  

DISCUSSION...A DELICATE BALANCE OF INFLOW AND UPSTREAM SUBTROPICAL
JET ENERGY/DIFFLUENCE CONTINUES TO MAINTAIN A CLASSIC WEDGE SEEN
IN IR WITH CYCLING NEW CELLS OCCASIONALLY COOLING TO
-70C...INDICATIVE OF STRONG UPDRAFTS CAPABLE OF HIGHLY EFFICIENT
RAIN RATES.  VERY STRONG AND INCREASING LOW LEVEL JET PARALLEL TO
THE BACK SIDE OF THE CURVED BAND CURRENTLY ALONG THE FL PANHANDLE
STRONGLY CONVERGES WITH WEAK SOUTHERLY FLOW SOUTH OF MOBILE BAY
WHERE A WEAK SURFACE WAVE COULD BE SEEN IN SWIR...LEADING TO THE
WEDGE.  WITH SUCH A BROAD 60-80 DEGREES OF CONVERGENT FLOW WITH
TPWS IN THE RANGE OF 2.3-2.6" PER GPS/BLENDED TPW PRODUCTS...RATES
IN EXCESS OF 3"/HR ARE EXPECTED WITH ISOLATED HIGHER AMOUNTS WITH
THESE VERY COLD TOWERS EVERY HOUR OR SO. 

WITH A PASSING OF A VERY WEAK SHORTWAVE FEATURE (WITH THE
CONVERGENCE BAND EXTENDING SOUTHEAST) NOW LIFTING INTO S
ALABAMA...AND INCREASING LOW LEVEL FLOW...PROPAGATION VERY SLOWLY
TOWARD THE EAST OR EVEN SOUTHEAST MAY BE EXPECTED IN THE NEXT 2-3
HOURS AS SUGGESTED WITH A WEAKENING OF THE 7H FLOW BY 15Z IN THE
MOST RECENT RAP AND HRRR.  THIS WOULD BE THE BEST CASE SCENARIO
KEEPING THE FORCING JUST OFFSHORE REDUCING THE OVERALL THREAT.  AS
SUCH WILL LIMIT THIS DISCUSSION FOR THE NEXT 4 HOURS TO REASSESS
THE STORM SCALE A BIT BETTER. 

DOWNSTREAM INTO SOUTHERN ALABAMA...THOUGH INSTABILITIES ARE
LIMITED...STRONG ISENTROPIC FORCING CONTINUES WITHIN THIS
EXTREMELY MOIST ENVIRONMENT EFFICIENT STRATIFORM RAINFALL WITH
SOME POTENTIAL ISOLATED CONVECTIVE ELEMENTATION COULD COMPOUND
TOTALS OVER A LONGER DURATION FOR SOME MINOR PONDING AND/OR URBAN
ISSUES. 

GALLINA

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

ATTN...RFC...SERFC...

LAT...LON   31388723 31348657 30868631 30688617 30378578 
            30028604 30158683 29828748 30068800 30658775 
            31168752