MESOSCALE PRECIPITATION DISCUSSION 0233
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
942 AM EDT WED MAY 30 2018

AREAS AFFECTED......CENTRAL TO SOUTHERN ALABAMA...

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 301345Z - 301845Z

SUMMARY...HEAVY RAINFALL RATES WITH STORMS IN CENTRAL TO SOUTHERN
ALABAMA EXPECTED TO CONTINUE INTO THIS AFTERNOON...WITH FLASH
FLOODING LIKELY.

DISCUSSION...BIRMINGHAM AL RADAR CONTINUES TO SHOW TRAINING
CONVECTION PRODUCING RAINFALL RATES OF 1-3 IN/HR ACROSS CENTRAL
ALABAMA.  AN OBSERVATION FROM EUTAW AL HAD 3.55 INCHES IN THE LAST
6 HOURS WITH THE CORE OF HEAVIEST RAIN SOUTH OF THERE WITH THE
LIKELIHOOD OF 5-6 INCHES JUST SOUTH OF EUTAW.

THE TRAINING MOTION IS LEADING TO HEAVY TOTALS BOTH IN THE
OBSERVED AND FORECAST AMOUNTS. THE 06Z NAM CONUS NEST AND 11-12
HIGH RES RAPID REFRESH RUNS HAVE PICKED UP ON THE EVENT BUT THE
ACTIVITY HAS BUILT SOUTH OF THOSE FORECASTS, SO THE THREAT AREA
ALIGNS WITH BOTH CONTINUITY AND THE EXPECTATION OF THE
SHOWERS/STORMS BUILDING TOWARDS THE AXIS OF HIGHER MIXED LAYER
CAPES TO THE SOUTH AND ALSO TOWARDS THE RELATIVE MAXIMA IN THE 850
MB FLOW...WHERE THE NAM AND GFS ARE FORECASTING 850 MB CONVERGENCE
MAXIMA.  HIGH MOISTURE REMAINS IN PLACE WITH THE 12Z RAP ANALYSIS
SHOWING 2-2.2 INCHES OF PRECIPITABLE WATER.

A SERIES OF SHORTWAVES ROTATING AROUND THE BASE OF AN UPPER LEVEL
TROUGH OVER MS
PROVIDE FAVORED DIFLUENT FLOW WITH MULTIPLE 300 MB DIVERGENCE
MAXIMA FORECAST BY THE RAP THROUGH THIS AFTERNOON, SUPPORTING
ADDITIONAL STORMS DEVELOPING.

VERY EFFICIENT RAINFALL PROCESSES ALONG WITH TRAINING CONVECTION
SHOULD CONTINUE INTO THIS AFTERNOON...PRODUCING HEAVY RAINFALL
AMOUNTS ACROSS AREAS WITH NEARLY SATURATED TO SATURATED
SOILS...MAKING  FLASH FLOODING LIKELY.  ANOTHER 2-4 INCHES OF RAIN
IS LIKELY WITH ISOLATED POCKETS OF 5-6 INCHES LIKELY.

PETERSEN

ATTN...WFO...BMX...FFC...MOB...

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

LAT...LON   33288560 33168530 32838507 32348503 32008547
            31828608 31638647 31528735 31598828 31958838
            32268834 32448807 32618750 32618733 32758667
            32998614