MESOSCALE PRECIPITATION DISCUSSION 0017
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
943 AM EDT MON APR 07 2014
 
AREAS AFFECTED...SOUTHERN AL...PORTIONS OF GA...FL PANHANDLE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 071343Z - 071943Z
 
SUMMARY...A BAND OF THUNDERSTORMS IS MOVING INTO THE FL PANHANDLE,
SOUTHEAST AL, INTO CENTRAL GA AT 15-20 KTS, AND HAS BEEN PRODUCING
HEAVY RAINFALL OVER THE PAST SEVERAL HOURS.  CELL TRAINING ALONG
THE PRE-FRONTAL BAND REMAINS POSSIBLE.  REGIONAL FLASH FLOODING IS
CONSIDERED LIKELY.  

DISCUSSION...AN PRE-EXISTING BAND OF THUNDERSTORMS IS MOVING
SLOWLY EASTWARD INTO THE EASTERN GULF COAST.  EARLIER THIS
MORNING, LOCAL AMOUNTS OF AROUND 10" WERE INDICATED NEAR
GREENVILLE/PINE APPLE, AL PER RADAR ESTIMATES FROM THE FORT RUCKER
88-D, WITH MESONET RAINFALL AMOUNTS OF A BROAD 3-5" FALLING ACROSS
SECTIONS OF NORTHWEST GA, AL, AND PORTIONS OF SOUTHERN MS.  LATEST
RADAR ESTIMATES INDICATE HOURLY RAINFALL RATES FROM THE CORE OF
THE STRONGER THUNDERSTORMS EXCEEDS 2".  PRECIPITABLE WATER VALUES
NEAR THE RECORD FOR EARLY APRIL ARE LIKELY AIDING PRECIPITATION
EFFICIENCY.

A SOMEWHAT MOBILE AND BROAD AXIS OF BROAD INFLOW AT 850 HPA IN THE
NEIGHBORHOOD OF 50-60 KNOTS IS STREAMING INTO THE REGION FROM THE
GULF OF MEXICO HAS LED TO 40-50 KNOTS OF 0-3 KM SHEAR, WHICH
SHOULD CONTINUE TO ORGANIZE CONVECTION PER THE LATEST RAP
GUIDANCE.  THE BREADTH OF THE LOW-LEVEL INFLOW SHOULD COMPENSATE
FOR ANY FORWARD PROGRESSION OF THE THUNDERSTORM BAND.  COMBINED
WITH UPSTREAM CAPES OF 1000-2000 J/KG PER THE 00Z ARW AND GOES
SOUNDER INFORMATION, THE ENVIRONMENT IS EXPECTED TO REMAIN
FAVORABLE FOR WET MULTI-CELL CLUSTERS INTO THE AFTERNOON NEAR AND
SOUTH OF A WARM FRONT.  RAINFALL RATES ARE EXPECTED TO REMAIN
STEADY NEAR 2"/HOUR IN STRONGER CELLS, IMPLYING THAT 1.5-2 HOURS
OF RAIN IN ANY PARTICULAR LOCATION WOULD EXCEED FLASH FLOOD
GUIDANCE VALUES.  CORFIDI VECTORS BASED ON THE 06Z GFS INDICATE
THAT PROPAGATION IS EXPECTED TO REMAIN LIGHT EASTERLY TODAY. 
THERE IS A MODERATE SIGNAL IN THE MESOSCALE GUIDANCE FOR CONTINUED
HEAVY RAINFALL, INDICATING 2-3" ISOLATED AMOUNTS POSSIBLE. 
ADDITIONAL THUNDERSTORM ACTIVITY IS POSSIBLE ALONG THE ACTUAL
FRONTAL BOUNDARY FARTHER TO THE WEST LATER TODAY, WHICH COULD HOLD
UP THE PROGRESSION OF THE TAIL OF THE EXISTING THUNDERSTORM BAND,
OR LEAD TO REPEATED ROUNDS OF THUNDERSTORMS IN ALREADY SATURATED
REGIONS, WHICH WOULD EXACERBATE CURRENT FLASH FLOOD ISSUES.  FLASH
FLOODING IS CONSIDERED LIKELY.

ROTH

ATTN...WFO...CAE...FFC...TAE...BMX...MOB...

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

LAT...LON   30318799 31208737 32548608 32578489 33098329 33598190
            32268276 30908378 29778471 29588527 30058576 30308660
            30198752 30318799