Graphic for MPD #0217

MESOSCALE PRECIPITATION DISCUSSION 0217
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
830 PM EDT FRI MAY 12 2017

AREAS AFFECTED...NORTHERN MS...NORTHERN AL

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 130030Z - 130630Z

SUMMARY...SLOW-MOVING THUNDERSTORMS WITH HEAVY RAINFALL RATES UP
TO 2 INCHES/HR WILL CAUSE SOME CONCERNS FOR FLASH FLOODING THROUGH
THE EVENING HOURS.

DISCUSSION...NUMEROUS SHOWERS AND THUNDERSTORMS ARE FOCUSING NEAR
A QUASI-STATIONARY FRONT OVER NORTHERN MS AND OUT AHEAD OF THE
APPROACHING COMPACT MID LEVEL LOW CENTER NOW EXITING AR AND MOVING
INTO MS. MLCAPE VALUES ARE GENERALLY NEAR 1000 J/KG ALONG THE
AFOREMENTIONED FRONT WHICH EXTENDS EAST-NORTHEAST INTO NORTHERN AL
AS WELL. MID AND UPPER LEVEL DYNAMICAL FORCING ASSOCIATED WITH THE
APPROACHING HEIGHT FALLS IS RATHER WELL ESTABLISHED OVER THE
REGION...AND THIS ENERGY INTERACTING WITH THE MOIST AND UNSTABLE
AIRMASS POOLED ALONG THE FRONT WILL CONTINUE TO FOSTER ADDITIONAL
THUNDERSTORMS OVER THE NEXT SEVERAL HOURS.

PWATS OF AROUND 1.5 INCHES AND THE AFOREMENTIONED INSTABILITY WILL
FAVOR RAINFALL RATES AS HIGH AS 2 INCHES/HR...BUT THE BIGGER
CONCERN IS THE SLOW MOVEMENT OF THE CELLS GIVEN THE RELATIVELY
WEAK STEERING FLOW. THIS WILL ENCOURAGE HEAVY RAINFALL TOTALS
THROUGH THE EVENING. THE LATEST HRRR GUIDANCE STRONGLY SUPPORTS
CONVECTION BECOMING RATHER CONCENTRATED ALONG THE STATIONARY FRONT
EAST OF THE SURFACE LOW CENTER. THE INITIAL CONVECTION FOCUSED
OVER NORTHERN MS WILL GRADUALLY SHIFT EAST INTO NORTHERN AL LATE
THIS EVENING. AS SUPPORTED BY THE HRRR...RAINFALL TOTALS OF 2 TO 4
INCHES...AND ISOLATED TOTALS NEAR 5 INCHES CAN BE EXPECTED THROUGH
06Z. THIS WILL RESULT IN CONCERNS FOR FLASH FLOODING AND
PARTICULARLY OVER URBAN AREAS.

ORRISON

ATTN...WFO...BMX...HUN...JAN...MEG...

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

LAT...LON   34638782 34408602 33558584 32768766 32638950
            33279027 34028982


Last Updated: 838 PM EDT FRI MAY 12 2017