MESOSCALE PRECIPITATION DISCUSSION 0095
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
729 AM EDT SUN MAY 17 2015
 
AREAS AFFECTED...NORTHEAST TX...EXTREME SOUTHEAST OK...CENTRAL AND
SOUTHWEST AR...EXTREME NORTHWEST LA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 171120Z - 171500Z
 
SUMMARY...VERY HEAVY RAINFALL POTENTIAL WILL CONTINUE OVER THE
NEXT SEVERAL HOURS AS A WAVY QLCS CONTINUES TO SLOWLY ADVANCE EAST.

DISCUSSION...THE LATEST RADAR IMAGERY SHOWS A CONTINUOUS AXIS OF
STRONG CONVECTION CONTINUING IN A WAVY FASHION FROM NEAR THE BIG
BEND AREA OF TX NORTHEAST INTO WESTERN AR. THE QLCS IS
CHARACTERIZED BY MULTIPLE BOWS AND INFLECTION POINTS...WHICH IS
ALLOWING FOR CONVECTION TO LOCALLY HANG UP AND TRAIN OVER THE SAME
AREA. THIS IS ESPECIALLY THE CASE OVER AREA EXTENDING FROM JUST
WEST OF KCRS TO KGVT TO NEAR KHOT WHERE THE EASTWARD ADVANCE OF
CONVECTION HAS SLOWED SIGNIFICANTLY.

CLOUD TOPS HAVE BEEN COOLING A BIT FURTHER OVER SOUTHWEST AR AND
SEVERAL OVERSHOOTING TOPS HAVE BEEN NOTED VIA THE GOES-OTD
ALGORITHM WHICH SUGGESTS ENHANCED FORCING/LIFT AND VERY INTENSE
RAINFALL RATES. RAINFALL RATES UPWARDS OF 2 INCHES/HR ARE LIKELY
WITH THIS ACTIVITY. THE CONVECTION IS BEING AIDED BY A PERSISTENT
FETCH OF A VERY MOIST AND AT LEAST MODESTLY UNSTABLE AIRMASS
ADVANCING IN OFF THE WESTERN GULF OF MEXICO. ADDITIONALLY...THERE
CONTINUES TO BE FOCUSED LARGER SCALE ASCENT OVER NORTHEAST TX AND
AR IN ASSOCIATION WITH THE RIGHT-ENTRANCE REGION OF THE EXITING
SHORTWAVE/JET STREAK OVER THE CENTRAL PLAINS. 

OVER THE NEXT SEVERAL HOURS...THE STRONGER DYNAMICS SHOULD BEGIN
TO EXIT THE REGION...BUT THERE WILL STILL BE A FETCH OF VERY MOIST
AND RELATIVELY UNSTABLE AIR UP ACROSS THE LOWER MS VALLEY.
SO..EXPECTING THE CURRENT AXIS OF CONVECTION TO SUSTAIN ITSELF FOR
SOME TIME THIS MORNING...WHILE GRADUALLY WEAKENING.

THE LATEST ARW AND NAM-CONEST SOLUTIONS FAVOR AN ENVIRONMENT
CONDUCIVE FOR ADDITIONAL CELL-TRAINING...AND SUGGEST ADDITIONAL
RAINFALL AMOUNTS OF 3 TO 5 INCHES AT LEAST LOCALLY THROUGH THIS
MORNING. THUS...EXPECT THERE TO BE AN ELEVATED RISK OF FLASH
FLOODING AND RUNOFF PROBLEMS.

ORRISON

ATTN...WFO...FWD...HGX...LZK...SHV...TSA...

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

LAT...LON   35379255 35039185 34089198 32319406 31389502 
            30809595 30989674 31469696 32349671 33479590 
            34249493 35039352