MESOSCALE PRECIPITATION DISCUSSION 0023
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
153 PM EDT SUN APR 28 2013
 
AREAS AFFECTED...NORTHERN AL/SOUTHEASTERN TN/NORTHERN GA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 281752Z - 282122Z
 
SUMMARY...GROWING CONVECTION UPSTREAM ACROSS THE CENTRAL GULF
COAST MAY AFFECT SECTIONS OF NORTHERN AL/GA AND SOUTHEASTERN TN
WHERE HEAVY RAINFALL HAS BEEN ONGOING.

DISCUSSION...A LARGE FLUX OF LOW-LEVEL MOISTURE CONTINUES TO BE
ADVECTED NORTHWARD AHEAD OF A SLOW-MOVING COLD FRONT. HEAVY
PRECIPITATION REMAINS ALONG THE NOSE OF THE 850-MB MOISTURE PLUME
WHICH IS EMBEDDED WELL WITHIN THE BEST INSTABILITY. THE PAST FEW
SCANS ON THE IR SATELLITE SUGGEST CLOUD TOPS WERE COOLING WITH
LIGHTNING ACTIVITY ON THE INCREASE. BASED ON RADAR TRENDS...MUCH
OF THIS CONVECTION SHOULD LIFT NORTHEASTWARD INTO THE AREA OF
CONCERN WHERE FFG VALUES HAVE ALREADY DECREASED IN THE PAST 6
HOURS. WHILE INSTABILITY SEEMS TO BE LACKING FURTHER TO THE NORTH
WITHIN THE RAIN-COOLED AIR...CONVECTION HAS BEEN MAINTAINED ALONG
THE SURFACE TO 850-MB BAROCLINIC ZONE. THE AVAILABLE HIGH-RES
GUIDANCE VARIES ON PLACEMENT OF THIS DEEP CONVECTION BUT DOES
DEPICT THE THUNDERSTORM ACTIVITY SHOULD GROW UPSCALE OR SUSTAIN
ITSELF WHILE MOVING TOWARD NORTHERN GA/AL THIS AFTERNOON. 

RUBIN-OSTER


ATTN...WFO...GSP...MRX...FFC...OHX...BMX...HUN...

LAT...LON   34918628 35668548 35708450 35078391 34458304 33948322
            34078458 33878597 33498705 33468767 34028780 34918628