MESOSCALE PRECIPITATION DISCUSSION 0425...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
445 PM EDT SAT JUL 01 2017

CORRECTED FOR SIZE OF GRAPHICAL THREAT AREA

AREAS AFFECTED...FAR NORTHERN LA...FAR SOUTHERN
AR...CENTRAL/NORTHERN MS ...CENTRAL/NORTHERN AL

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

VALID 012035Z - 020145Z

SUMMARY...AN ELONGATED AXIS OF HEAVY SHOWERS AND THUNDERSTORMS IS
LIKELY TO SET UP THROUGH THE LATE AFTERNOON AND EARLY EVENING
HOURS. SLOW CELL MOTION AND INTENSE RAINFALL RATES MAY RESULT IN
SOME FLASH FLOODING.

DISCUSSION...STRONG DIURNAL HEATING AND A VERY MOIST BOUNDARY
LAYER CONTINUES TO FOSTER A MODERATE TO STRONGLY UNSTABLE AIRMASS
ACROSS MUCH OF THE SOUTH THIS AFTERNOON...AND THIS IS ALLOWING FOR
AN EXCELLENT THERMODYNAMIC ENVIRONMENT FOR EXPANDING AND
ORGANIZING CLUSTERS OF HEAVY SHOWERS AND THUNDERSTORMS.

MEANWHILE...CONVECTION OVER THE LAST COUPLE OF HOURS HAS BEEN
SEEING BECOMING A BIT MORE FOCUSED AND ESPECIALLY ACROSS PARTS OF
FAR NORTHERN LA/SOUTHERN AR JUST OUT AHEAD OF A LONG-LIVED MCV
MOVING NORTHEAST TX...AND ALSO DOWNSTREAM NOW ALONG A WELL-DEFINED
MESOSCALE BOUNDARY/SURFACE TROUGH EXTENDING EAST ACROSS
NORTH-CENTRAL MS...NORTHERN AL AND INTO FAR SOUTHEAST TN. THIS
SHOWS UP WELL ON THE LATEST EXPERIMENTAL GOES-16 0.64 MICRON/VIS
IMAGERY AND IS ALSO REFLECTIVE OF A WELL-DEFINED INSTABILITY
GRADIENT. BROADLY CONFLUENT FLOW FROM THE GULF OF MEXICO MEANWHILE
CONTINUES TO POOL THIS GREATER MOISTURE AND INSTABILITY UP ALONG
THE BOUNDARY AND SHOULD HELP FACILITATE ADDITIONAL CONVECTIVE
DEVELOPMENT THROUGH THE LATE-AFTERNOON AND EARLY EVENING HOURS.

EXPECT AS MUCH AS 3 TO 6+ INCHES OF RAIN LOCALLY GIVEN RAINFALL
RATES OF 2.5 INCHES/HR...SLOW CELL-MOTION AND CONCERNS OVER W/E
TRAINING ALONG THE MESOSCALE BOUNDARY. FLASH FLOODING IS POSSIBLE.

ORRISON

ATTN...WFO...BMX...HUN...JAN...LZK...MEG...MRX...SHV...

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

LAT...LON   35018574 34668555 34078576 33328697 32708915
            32359199 32449393 33439420 33779344 33979077
            34248898 34598772 34908655