MESOSCALE PRECIPITATION DISCUSSION 0148
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
153 PM EDT THU JUL 04 2013
AREAS AFFECTED......FL PANHANDLE TO ADJACENT SOUTHERN AL/SOUTHWEST
GA...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 041753Z - 042253Z
SUMMARY...BANDS AND CLUSTERS OF HEAVY RAIN ARE FORECAST TO
CONTINUE TO MOVE ONSHORE AND PRODUCE HEAVY RAIN AND CONTINUE A
THREAT OF FLASH FLOODING.
DISCUSSION...THE COMBINATION OF ENHANCED MOISTURE AND LIFT WHERE
HEAVY RAIN HAS OCCURRED OVERNIGHT AND THIS MORNING CONTINUES THE
THREAT OF FLASH FLOODING IN THE FL PANHANDLE TO ADJACENT SOUTHERN
AL AND SOUTHWEST GA.
THE ECMWF SHOWS CONTINUED 300 MB DIVERGENCE AND A WELL DEFINED
BOUNDARY LAYER MOISTURE CONVERGENCE IN THE FL PANHANDLE THROUGH
00Z. SATELLITE AND RADAR SHOWS CLUSTERS OF SHOWERS WITH EMBEDDED
THUNDERSTORMS WITH SPORADIC OVERSHOOTING TOPS. THE MOTION OF THE
CLUSTER WAS TOWARDS THE FL PANHANDLE FROM THE GULF OF MEXICO WHILE
RADAR SHOWS MERGING BANDS AND A POSSIBLE MID LEVEL CIRCULATION ON
THE EGLIN AFB RADAR NEAR THE FL/AL BORDER. RAINFALLS OF TWO
INCHES IN 3 HOURS HAVE BEEN OBSERVED THIS MORNING IN THE FL
PANHANDLE.
HIGH AVAILABLE MOISTURE IS IN PLACE WITH PW VALUES AROUND 2.25
INCHES. THESE VALUES ARE FORECAST TO PERSIST AS WATER VAPOR
IMAGERY SHOWS LITTLE CHANGE IN THE AXIS OF HIGHEST MOISTURE
STREAMING ONSHORE AND INLAND. 850-700 MB MOISTURE FLUX ANOMALIES
OF 4-5 STD DEVIATIONS ABOVE NORMAL REINFORCE THE MOISTURE
AVAILABLE TO PRODUCE HEAVY RAIN.
MEAN LAYER WINDS ARE OUT OF THE SOUTH NEAR 25 KT SO THIS PROVIDES
PRIMARY NORTH CELL/CLUSTER MOTION ACROSS THE PANHANDLE. CORFIDI
VECTORS ARE LIGHT TO THE SOUTHEAST...SO THE RESULTANT MOTION IS TO
THE NORTH-NORTHEAST. THE RESULT MAY BE THAT THE ONGOING HEAVY
RAIN CONTINUES AND PRODUCES RAIN CAPABLE OF EXCEEDING THE 3-4 INCH
FLASH FLOOD GUIDANCE IN THIS AREA.
THE 12Z HIRES WRF-NMM/12Z SPC WRF/06Z NAM CONUS NEST/15Z HIGH
RESOLUTION RAPID REFRESH ALL AGREE ON A CONTINUED THREAT OF 3-4
INCHES 18-00Z. WITH LATEST FLASH FLOOD GUIDANCE VALUES NEAR 4
INCHES IN 6 HOURS...SMALL AREAS MAY RECEIVE MORE RAIN THAN THE
FLASH FLOOD GUIDANCE VALUES.
PETERSEN
ATTN...WFO...FFC...TAE...BMX...
ATTN...RFC...SERFC...
LAT...LON 29678615 31118602 31878562 31998501 31838472 31188429
30238414 29438423 29268498 29678615