MESOSCALE PRECIPITATION DISCUSSION 0423
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1143 AM EDT TUE JUL 05 2016
 
AREAS AFFECTED...AL...GA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 051542Z - 052042Z
 
SUMMARY...INCREASING CONVECTIVE COVERAGE MAY LEAD TO AN ISOLATED
FLASH FLOOD THREAT INTO THIS AFTERNOON.

DISCUSSION...WATER VAPOR IMAGERY SHOWS A MID LEVEL SHORTWAVE
CROSSING NORTHERN MS AS OF 15Z. ENHANCED FORCING AHEAD OF THIS
FEATURE HAS ALLOWED FOR A RECENT EXPANSION IN CONVECTIVE COVERAGE
ACROSS PORTIONS OF AL AND GA WHERE MIXED LAYER CAPE VALUES ARE AT
OR ABOVE 1000 J/KG. LOW LEVEL INFLOW OF EQUAL MAGNITUDE TO THE
MEAN CLOUD LAYER FLOW SHOULD CONTINUE TO ALLOW FOR SOME
BACKBUILDING OF THE CONVECTIVE ELEMENTS...RESULTING IN A PERIOD OF
TRAINING. RECENT GPS PRECIPITABLE WATER READINGS FROM ACROSS THE
AREA SHOW 2"+ VALUES...WHICH IS ABOVE THE 90TH PERCENTILE FOR THIS
TIME OF YEAR. COMBINE THIS WITH RELATIVELY THIN CAPE PROFILES AND
STORMS SHOULD BE EFFICIENT RAINFALL PRODUCERS. 

GIVEN THE WIDESPREAD COVERAGE OF CONVECTION...THIS SHOULD RESULT
IN AT LEAST AN ISOLATED FLASH FLOOD THREAT INTO THIS AFTERNOON.
FLASH FLOOD GUIDANCE IS RELATIVELY HIGH...BUT WITH HOURLY RAINFALL
TOTALS OF 1-2"...AND SOME TRAINING...WOULD EXPECT TO SEE LOCAL
AMOUNTS APPROACH THE 3-4" RANGE...WHICH WILL BEGIN TO APPROACH
FLASH FLOOD GUIDANCE VALUES. CAPE IS LIMITED...AND THE WIDESPREAD
NATURE OF STORMS SHOULD EVENTUALLY EAT AWAY THIS INSTABILITY. THUS
WOULD EXPECT STORM INTENSITY TO PEAK FOR A FEW HOURS AT ANY ONE
LOCATION BEFORE BECOMING MORE STRATIFORM AND LESS INTENSE IN
NATURE. THIS SHOULD PREVENT ANY WIDESPREAD FLASH FLOOD RISK...BUT
AS MENTIONED ABOVE...AN ISOLATED THREAT MAY EXIST. THE HIGH RES
GUIDANCE HAD BEEN STRUGGLING WITH THIS ACTIVITY...ALTHOUGH RECENT
RUNS OF THE HRRR AND PARALLEL HRRR ARE BEGINNING TO CATCH ON TO
SOME HIGHER AMOUNTS ACROSS NORTHERN AL/GA.

CHENARD

ATTN...WFO...BMX...FFC...HUN...

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

LAT...LON   34988589 34708420 33558434 33088502 32958636 
            33058676 33328720 34458807 34968789