MESOSCALE PRECIPITATION DISCUSSION 0527
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
159 PM EDT MON SEP 28 2015
AREAS AFFECTED...WESTERN FLORIDA PENINSULA....SOUTHERN ALABAMA
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 281758Z - 282158Z
SUMMARY...SMALLER CONVECTIVE COVERAGE AND WEAKENING TRENDS
REDUCING COVERAGE OF FLASH FLOOD THREAT. STILL ISOLATED HIGH
EFFICIENT STORMS STILL POSE SOME ISOLATED THREATS
DISCUSSION...ENVIRONMENTAL CONDITIONS APPEAR TO BE REDUCING IN
AREAL FLOODING THREAT BECOMING MORE ISOLATED IN NATURE. SATELLITE
IMAGERY SHOWS AREA OF CONCERN IS NOW ALONG THE EASTERN SIDE OF THE
APPROACHING SUBTROPICAL JET AXIS. THIS HAS ALREADY REDUCED THE
CLASSIC FF WEDGE SIGNATURE IN IR/WV AND A REDUCTION OF VERTICAL
GROWTH OF CONVECTIVE TOWERS. STILL 25-30KT SOUTHEASTERLY LOW
LEVEL FLOW WITHIN A WEAKLY UNSTABLE (250-500 J/KG) ENVIRONMENT
REMAINS SUFFICIENT FOR SOME NEW ACTIVATION ALONG THE SSW TO NNE
REINFORCED CONVERGENCE BAND. THIS ACTIVITY HAS TRENDED TO BE
OFFSHORE BUT WITH CELL MOTIONS INCREASED TOWARD THE NORTH UNDER
STRONGER FLOW ALOFT...CELLS COULD MOVE ASHORE POTENTIALLY OVER
AREAS ALREADY AFFECTED BY HIGH TOTALS.
VISIBLE LOOP SHOWS TIGHT PACKING OF AGITATED CU/TCU FOR THIS
CONTINUATION IN AT LEAST THE NEAR TERM (1-3HRS). AFTER THAT...
REDUCED INSTABILITY WITHIN SOUTHEAST INFLOW FROM WORKED OVER AIR
FROM EARLIER CONVECTION FURTHER SOUTHEAST ALONG THE SHEAR AXIS CAN
BE SEEN REDUCED LOW LEVEL AGITATION EMERGING FROM THE CIRRUS
CANOPY. GIVEN THE TEMP/DEWPOINT DIFFERENCES WITHIN THE
OBSERVATION NETWORK ARE LESS THAN 5 DEGREES ACROSS THIS
ZONE...CONFIDENCE IS NOT PARTICULARLY HIGH THAT THIS WILL FULLY
DIMINISH THE THREAT.
OVERALL HI-RES CAMS SEEM TO BE TOO STRONG WITH THE SURFACE/850MB
WAVE MOVING NORTHEAST WHICH WOULD REDUCE INFLOW BY 00Z...BUT
OBSERVATIONS DO NOT CONFIRM THIS TREND. THE ESRL EXPERIMENTAL
HRRR APPEARS TO BE THE WEAKEST WITH THIS FEATURE AND RETAINS SOME
STRONG CONVECTION NEAR/ALONG THE WESTERN FL PANHANDLE THROUGH 00Z.
GALLINA
ATTN...WFO...MOB...TAE...
ATTN...RFC...SERFC...
LAT...LON 31448619 31368575 30708575 30288577 29958634
30338731 30848732 31158686