MESOSCALE PRECIPITATION DISCUSSION 0644
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1024 AM EDT MON AUG 07 2017

AREAS AFFECTED...SOUTHEAST AR...NORTHERN MS...WEST CENTRAL AL

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

VALID 071425Z - 071930Z

SUMMARY...MODEST ASCENT/INSTABILITY THOUGH A NARROW CORRIDOR WITH
TRAINING CELL MOTION PROFILE SUGGEST POSSIBLE FLASH FLOODING
CONCERNS.

DISCUSSION...COMPLEX SURFACE PATTERN DUE TO OVERNIGHT MCS ACROSS
AR INTO TX HAVE PRODUCED EFFECTIVE BOUNDARIES THAT WILL SERVE AS
FOCUS FOR MOISTURE CONVERGENCE TO SPARK ADDITIONAL CONVECTION. 
STRONGER MCV/MESO LOW NEAR GGG IS CONNECTED TO WEAKER MESO
LOW/TRIPLE POINT NEAR CDH BEFORE EXTENDING NEAR DUE EAST AS A
MESO-WARM FRONT NORTH OF LLQ TO GLH TO GWO.

STRONG MCV IS PRESSING FURTHER EAST SUPPORTING SWLY LLJ ACROSS LA
TO FOCUS STRONGER MOISTURE CONVERGENCE ACROSS THIS EFFECTIVE WARM
FRONT IN AR AS FAR WEST AS NORTHEAST MS.  DEEP LAYERED CLOUD
BEARING FLOW IS GENERALLY PARALLEL (PERHAPS A SHADE NORTHEAST
FURTHER EAST IN MS/AL) TO THE BOUNDARY SUPPORTING A CONTINUED
TRAINING ENVIRONMENT.

CURRENTLY AND THROUGH THE NEXT 3-4 HOURS...LLJ IS EXPECTED TO
REMAIN FAIRLY WEAK AND INSTABILITY IS STILL TRYING TO RECHARGE BUT
REMAINS LIMITED TO AROUND 500-1000 J/KG...THOUGH CLEARING IN
CENTRAL MS SHOULD SUPPORT 2000+ J/KG TOWARD LATE MORNING/EARLY
AFTERNOON.  THIS SHOULD LIMIT THE OVERALL CONVECTIVE COVERAGE
ALONG THE BOUNDARY. STILL WITH CONFLUENT LOW LEVEL FLOW INTO THE
BOUNDARY...A POOL OF DEEPER MOISTURE IS AVAILABLE WITH TPWS AOA
2.2" PER SHV/JAN 12Z SOUNDINGS AND THE TRAINING PROFILE...THERE
REMAINS AN ISOLATED THREAT FOR RAIN RATES OF 1.75-2.25"/HR AND
POTENTIAL POCKETS OF 2-4" TOTALS.

HYDROLOGICALLY...THE EFFECTIVE BOUNDARY/TRAINING CORRIDOR IS VERY
CLOSE TO LOWERED FFG VALUES/SATURATED GROUND CONDITIONS FROM
GREENWOOD TO STARKVILLE MS WHERE AHPS DEPARTURE FROM NORMAL IS
ABOUT 300-500% OF NORMAL.  THREAT FOR FF ALSO INCREASES IF WARM
SECTOR/CLEARING ACROSS CENTRAL MS CONVECTS...IF SO RATES WILL BE
HIGHER 2-2.5" BUT ALSO SHIFT CONCERNS FOR FF SOUTH A LINE OR TWO
OF COUNTIES IN MS...AS SUCH BROADENED THE MPD AREA OF CONCERN
SOUTHWARD.  

GALLINA

ATTN...WFO...BMX...JAN...LZK...MEG...

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

LAT...LON   34249061 34178803 33528753 32878815 32999111
            33549279 34139270 34189171