MESOSCALE PRECIPITATION DISCUSSION 0428
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
207 AM EDT SUN JUL 02 2017

AREAS AFFECTED...FAR SOUTHERN AR...NORTHERN LA...FAR WEST CENTRAL
MS

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

VALID 020610Z - 021000Z

SUMMARY...SLOW MOVING CONVECTION COULD TRAIN OR BACKBUILD ACROSS
PORTIONS OF SOUTHERN AR/NORTHERN LA AND FAR WEST CENTRAL
MS...WHICH COULD RESULT IN A SHORT TERM FLASH FLOOD THREAT.

DISCUSSION...CONVECTION IS FIRING ALONG AN AXIS OF 1.75/2.00 INCH
PRECIPITABLE WATER AIR... WHERE THE MLCAPE VALUES ARE HOVERING
BETWEEN 500-1000 J/KG. THE KSHV RADAR SHOWED HOURLY RAINFALL RATES
NEAR 1.25 INCHES WITH THE ACTIVITY ACROSS FAR SOUTHERN AR. MODEL
SOUNDINGS HERE SHOWED A FAIRLY MOIST COLUMN...AS WELL AS WET BULB
ZERO VALUES CLOSE TO THE FREEZING LEVEL (WHICH IS ABOVE 14000
FEET). THESE VALUES INDICATE A COLUMN THAT COULD SUPPORT HIGHLY
EFFICIENT RAINFALL ASSOCIATED WITH THE DEVELOPING CONVECTION...AS
WARM RAIN PROCESSES DOMINATE.

A WEAK SHORT WAVE MOVING SLOWLY EASTWARD ACROSS FAR NORTHEAST TX
SHOULD PROVIDE SUFFICIENT SYNOPTIC ASCENT FOR GREATER CONVECTIVE
DEVELOPMENT. MOST OF THE HIGH RESOLUTION GUIDANCE (INCLUDING THE
MOST RECENT HRRR) ARE NOT BULLISH WITH THE RAINFALL AMOUNTS FROM
THE DEVELOPING CONVECTION. HOWEVER...THE 00Z NAM CONUS NEST...AS
WELL AS THE 00Z NSSL WRF... SUGGEST ISOLATED 5.00 INCH RAINFALL
AMOUNTS WITH THIS ACTIVITY. THESE VALUES DO NOT SEEM OUT OF LINE
IF BACKBUILDING AND TRAINING OCCUR IN THIS ENVIRONMENT.

ONE AND THREE HOUR FLASH FLOOD GUIDANCE VALUES ALONG THE AR/LA
BORDER ARE AS LOW AS 1.50 INCHES...AND GIVEN THE MOIST ENVIRONMENT
IN WHICH THESE STORMS ARE FORMING...THESE VALUES ARE EASILY
ATTAINABLE. HOWEVER...THE AREAL EXTENT OF THE CONVECTION COULD END
UP PREVENTING A LARGER FLASH FLOOD THREAT. SO AT THIS TIME...FLASH
FLOODING IS ONLY CONSIDERED POSSIBLE.

HAYES

ATTN...WFO...JAN...LZK...SHV...

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

LAT...LON   33749153 33749152 33639062 33188997 32539064
            32619398 33159437 33599376