MESOSCALE PRECIPITATION DISCUSSION 0147
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
801 AM EDT THU JUL 04 2013
AREAS AFFECTED......FL PANHANDLE TO SOUTHERN AL...
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 041200Z - 041800Z
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 YESTERDAY AND OVERNIGHT CONTINUES THE
THREAT OF FLASH FLOODING IN THE FL PANHANDLE TO ADJACENT SOUTHERN
AL.
06Z GFS SHOWS CONTINUED 300 MB DIVERGENCE AND A WELL DEFINED
BOUNDARY LAYER MOISTURE CONVERGENCE IN THE FL PANHANDLE THROUGH
18Z. 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 OVER THE FL PANHANDLE. RAINFALLS OF ONE
INCH IN AN HOUR HAVE BEEN OBSERVED AT CRESTVIEW FL.
HIGH AVAIALBLE 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 AVAILABE
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. THE
MOTION BECOMES MORE SOUTHWEST TO NORTHEAST OVER COASTAL AL.
CORFIDI VECTORS ARE LIGHT AND VARIABLE...SO NO MAJOR DEVIATION IS
EXPECTED FROM THE DEEP LAYER FLOW. 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 00Z HIRES WRF-ARW/ NSSL WRF/SPC WRF/06Z NAM CONUS NEST/09Z
HIGH RESOLUTION RAPID REFRESH ALL AGREE ON A CONTINUED THREAT OF
3-4 INCHES 12-18Z
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...TAE...MOB...
ATTN...RFC...SERFC...
LAT...LON 29808739 30918746 31298681 31408599 31268520 30968484
30388467 29658465 29388552 29808739