MESOSCALE PRECIPITATION DISCUSSION 0650...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
847 PM EDT MON AUG 07 2017

CORRECTED FOR ADJUSTMENT TO GRAPHIC TO INCORPORATE MORE OF
NORTHERN GA

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

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

VALID 080035Z - 080535Z

SUMMARY...SLOW-MOVING SHOWERS AND THUNDERSTORMS WITH VERY HEAVY
RAINFALL ARE EXPECTED TO CONTINUE OVER THE NEXT FEW HOURS. SOME
FLASH FLOODING IS POSSIBLE.

DISCUSSION...RADAR IMAGERY IS SHOWING AN ELONGATED W/E AXIS OF
VERY SLOW-MOVING AND EVEN LOCALLY TRAINING SHOWERS AND
THUNDERSTORMS EXTENDING FROM NORTHERN MS EAST ACROSS NORTHERN AL
AND GETTING READY TO ADVANCE INTO NORTHWEST GA. THE ACTIVITY IS
FOCUSING ALONG AND JUST SOUTH OF A QUASI-STATIONARY FRONTAL ZONE
AND AHEAD OF A SURFACE WAVE OF LOW PRESSURE.

SOME INCREASED SURFACE MOISTURE CONVERGENCE AND POOLING OF
INSTABILITY OVER THE LAST COUPLE OF HOURS COUPLED WITH SOME MODEST
RIGHT-ENTRANCE REGION JET DYNAMICS HAS ALLOWED FOR THE CONVECTION
TO BECOME A BIT BETTER ORGANIZED...AND OVER THE NEXT FEW HOURS THE
CONVECTION SHOULD CONTINUE ACROSS THIS REGION.

THE HIRES MODELS LED BY THE HRRR AND HRRRX DO NOT AGREE ON THE
EXACT PLACEMENT OF THE CONVECTION NOR THE AMOUNTS...BUT THEY
SIGNAL AS MUCH AS 3 TO 5 INCHES OF RAIN LOCALLY IN VICINITY OF THE
FRONT. GIVEN PWATS OF 2.25 TO 2.5 INCHES AND THE AFOREMENTIONED
THERMODYNAMIC SUPPORT...AND EVEN LARGER SCALE ASCENT...THESE
RAINFALL TOTALS SEEM FAIRLY REASONABLE DESPITE THE POOR OVERALL
MODEL AGREEMENT.

SOME FLASH FLOODING WILL BE POSSIBLE AND ESPECIALLY WITH THE RISK
OF CELL-TRAINING AND OVERALL SLOW CELL MOTION OFF TO THE EAST
ALONG THE FRONT.

ORRISON

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

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

LAT...LON   34988605 34978484 34918391 34358375 34018525
            33938645 33868788 33728893 33868951 33979001
            34349028 34728991 34828935 34858861 34898773
            34938730