Graphic for MPD #0367

MESOSCALE PRECIPITATION DISCUSSION 0367
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
126 PM EDT THU JUN 22 2017

AREAS AFFECTED...CENTRAL/SOUTHERN AL...WESTERN FL PANHANDLE

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

VALID 221725Z - 222300Z

SUMMARY...BANDS OF TRAINING SHOWERS AND THUNDERSTORMS WITH VERY
INTENSE RAINFALL RATES ARE EXPECTED THIS AFTERNOON. THIS WILL
CONTINUE TO RESULT IN LOCALLY SIGNIFICANT FLASH FLOODING CONCERNS.

DISCUSSION...DEEP LAYER SOUTHERLY FLOW AROUND THE FAR EASTERN
FLANK OF T.D. CINDY CONTINUES TO TRANSPORT EXTREMELY HIGH PWATS
NORTH UP ACROSS THE CENTRAL GULF COAST REGION...WITH PWATS UP
AROUND 2.5 INCHES ACROSS MUCH OF CENTRAL/SOUTHERN AL AND THE
WESTERN FL PANHANDLE. IN FACT...SURFACE DEWPOINTS ARE GENERALLY IN
THE MID TO UPPER 70S AND THIS IN CONJUNCTION WITH INCREASED
DIURNAL HEATING/BOUNDARY LAYER INSTABILITY IS RESULTING IN
NUMEROUS TRAINING BANDS OF SHOWERS AND THUNDERSTORMS WITH
EXTREMELY  HEAVY RAINFALL RATES.

RAINFALL RATES AS HIGH AS 3 INCHES/HR ARE EXPECTED THIS AFTERNOON
AS CONVECTION CONTINUES TO DEVELOP WITH THE AID OF NOT ONLY THE
FAVORABLE THERMODYNAMIC ENVIRONMENT BUT ALSO A NOTABLY CONFLUENT
FLOW REGIME FROM THE SURFACE UP TO AROUND 700 MB. THE UPPER LEVELS
ARE ALSO BECOMING MORE DIFFLUENT WHICH IS HELPING TO PROVIDE MASS
FIELD EVACUATION ALOFT AND GENERALLY AIDING THE EXPANSION OF
COLDER CONVECTIVE TOPS.

THE HIRES MODELS ARE DOING A VERY POOR JOB WITH THE CURRENT
CONVECTIVE EVOLUTION...WITH THE 12Z ARW/NMMB SOLUTIONS THE WORST
PERFORMING. HOWEVER...EVEN THE HRRR GUIDANCE APPEARS TO BE
MISPLACING THE AXIS OF CONVECTION AND NOT SUSTAINING THE ORGANIZED
NATURE OF IT LONG ENOUGH OVER THE NEXT SEVERAL HOURS. THE HRRRX
OVERALL APPEARS TO BE THE BEST PIECE OF GUIDANCE COMPARED TO THE
LATEST SATELLITE/RADAR TRENDS...BUT STILL LOOKS A BIT UNDERDONE.

THE LATEST THINKING IS THAT LOCALLY 3 TO 5 INCHES OF ADDITIONAL
RAIN WILL BE POSSIBLE THROUGH ABOUT 23Z...WITH ISOLATED HEAVIER
TOTALS TO AROUND 6 INCHES OR SO WHERE MORE FOCUSED TRAINING OF
CELLS OCCUR. THESE ADDITIONAL RAINS...ESPECIALLY FOR SOUTHERN
AL...WILL RESULT IN THE POTENTIAL FOR SIGNIFICANT FLASH FLOODING
AND/OR RUNOFF PROBLEMS GIVEN THE EARLY RAINFALL OF THIS MULTI-DAY
HEAVY RAINFALL EVENT.

ORRISON

ATTN...WFO...BMX...HUN...MOB...TAE...

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

LAT...LON   34008698 33708611 33338576 32398561 31178587
            30468622 30198673 30238728 30138783 30198832
            31128816 32168806 32688795 33518774


Last Updated: 126 PM EDT THU JUN 22 2017