MESOSCALE PRECIPITATION DISCUSSION 0185
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
536 PM EDT WED MAY 03 2017

AREAS AFFECTED...SOUTHWEST AR...FAR NORTHEAST TX...FAR NORTHWEST
LA

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

VALID 032135Z - 040030Z

SUMMARY...CONVECTION TRAINING ACROSS AREAS WITH SATURATED SOILS
POSES A RISK FOR FLASH FLOODING INTO THE LATE AFTERNOON AND EARLY
EVENING.

DISCUSSION...CONVECTION CONTINUES TO FIRE ON AN AXIS OF 2500-3500
J/KG MLCAPE EXTENDING FROM FAR NORTHEAST TX INTO SOUTHWEST AR AND
NEARBY NORTHWEST LA....AS IT TRACKS NORTHEAST. THE EXPERIMENTAL
GOES-16 IR LOOP SHOWED BURSTS OF COOLING TOPS WITH THIS CONVECTION.

THE CONVECTION IS ROOTED IN A STRIPE OF 1.60 INCH PRECIPITABLE
WATER AIR...AND THE KSHV RADAR WAS INDICATING HOURLY RAINFALL
RATES NEAR 2.00 INCHES. RECENT SPOTTER REPORTS INDICATED THE
PRESENCE OF HAIL... AND THIS IS NOT SURPRISING GIVEN THE CELLULAR
LOOK OF THE RADAR RETURNS IN FAR NORTHEAST TX.

FURTHER NORTHEAST INTO SOUTHWEST AR AND FAR NORTHWEST LA...THE
CONVECTION IS NOT AS CELLULAR...AS THE LINE MOVES SLOWLY SOUTHEAST
AHEAD OF A FRONTAL BOUNDARY. RAINFALL RATES HERE ARE NOT AS HIGH
(AS THE INSTABILITY IS NOT AS ROBUST). HOWEVER...THE CONVECTION IS
MOVING OVER AREAS THAT THE LATEST HRRR SOIL SATURATION PRODUCT
INDICATED WAS NEARLY SATURATED. EVEN THROUGH THE CONVECTION IS
EXPECTED TO BE AT LEAST SOMEWHAT PROGRESSIVE AREA OF A LONG WAVE
TROUGH DROPPING INTO CENTRAL AND SOUTHERN PLAINS...THE ADDITIONAL
RAINFALL COULD RESULT IN A FLASH FLOOD THREAT.

THE BULK OF THE HIGH RESOLUTION GUIDANCE PRODUCES LOCAL 1.50 TO
2.50 INCH RAINFALL AMOUNTS OVER FAR SOUTHWEST AR AND FAR NORTHWEST
LA WITH THE CONVECTION...WITH SOME OF THIS OCCURRING IN AN HOUR OR
TWO. GIVEN WHAT IS OCCURRING NOW...THESE AMOUNTS SEEM REASONABLE.
AS MENTIONED EARLIER...THE ADDITIONAL RAINFALL COULD PRODUCE
LOCALIZED FLASH FLOODING INTO THE EARLY EVENING.

INSTABILITY IS EXPECTED TO WANE AFTER 01Z...SO THE THREAT OF
ADDITIONAL FLASH FLOODING IS EXPECTED TO DROP OFF AFTER THAT TIME.

HAYES

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

ATTN...RFC...ABRFC...LMRFC...WGRFC...

LAT...LON   34399290 33129145 32419246 31569430 32499502