MESOSCALE PRECIPITATION DISCUSSION 0524
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
104 AM EDT MON SEP 28 2015
 
AREAS AFFECTED...EXTREME SOUTHEASTERN MS/SOUTHERN AL/WESTERN FL
PANHANDLE... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 280503Z - 280933Z
 
SUMMARY...ADDITIONAL HEAVY RAINFALL EXPECTED TONIGHT AS THE
MOISTURE CONVEYOR BELT AIMS AT THE EASTERN GULF COAST. GIVEN
ANTECEDENT CONDITIONS IN THE SOILS ARE WET FROM EARLIER HEAVY
RAINFALL...EXPECT THE POTENTIAL FOR FLASH FLOODING OVER THESE SAME
AREAS.

DISCUSSION...A BROAD MID/UPPER LEVEL CENTERED ALONG THE UPPER TX
COAST HAS CONTINUED TO CIRCULATE DEEP TROPICAL MOISTURE TOWARD THE
EASTERN GULF COAST REGION. THE BLENDED-TPW PRODUCT AND GPS DATA
SUPPORT 2 TO 2.25 INCH PWATS ACROSS THE MPD AREA. IN ADDITION TO
THE ABUNDANT MOISTURE IN PLACE...SURFACE OBSERVATIONS SHOW A
DISTINCT REGION OF WEST-EAST ORIENTED CONVERGENCE ALONG SOME SORT
OF MESOSCALE BOUNDARY. THIS APPEARS TO BE A FOCUS FOR CONVECTIVE
REGENERATION WHICH SEEMS TO ALIGN WITH THE MODEL-DERIVED BUOYANCY
GRADIENT. WHILE THE BEST INSTABILITY REMAINS OFFSHORE...THE 03Z
RAP OBJECTIVE ANALYSIS SHOWS 500 TO 1000 J/KG OF MUCAPE TRICKLING
TOWARD THE AL/FL BORDER. RECENT DUAL-POL RADAR DATA OUT OF KMOB
SHOWS THE STRONGEST UPDRAFTS REMAIN OFFSHORE BUT HAVE BEEN
SUPPORTING 1 TO 2 INCH HOURLY RATES. IF THESE CONVECTIVE ELEMENTS
ARE MAINLY TO SPREAD INLAND...THIS COULD LEAD TO A THREAT FOR
FLASH FLOODING...PARTICULARLY OVER LOCATIONS OF FAR SOUTHEASTERN
MS/SOUTHWESTERN AL WHERE 6 TO 8 INCHES OF RAIN FELL EARLIER TODAY.

THERE IS A MIXED SIGNAL IN THE RECENT CAMS OF WHERE THE HEAVIEST
CONVECTION WILL CONGREGATE. GIVEN THE IMPRESSIVE MOISTURE FLUXES
LIFTING OUT OF THE GULF OF MX COMBINED WITH PREVIOUS HEAVY
RAINFALL...WILL KEEP THIS MPD IN EFFECT THROUGHOUT THE NIGHT AND
RE-ASSESS AROUND 0930Z.

RUBIN-OSTER

ATTN...WFO...LIX...MOB...

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

LAT...LON   31438819 31228695 30158655 29298732 29838882 
            30918892