MESOSCALE PRECIPITATION DISCUSSION 0056
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1214 AM EST WED MAR 09 2016
 
AREAS AFFECTED...CENTRAL/NORTHEAST TX...NORTHWEST LA...FAR
SOUTHERN AR 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 090510Z - 091000Z
 
SUMMARY...HEAVY CONVECTIVE RAINS ARE EXPECTED TO EXPAND IN
COVERAGE OVER NORTHEAST TX AND CONTINUE OVER NORTHWEST LA OVER THE
NEXT FEW HOURS. SEVERE FLASH FLOODING WILL BE LIKELY OVER
NORTHWEST LA GIVEN HEAVY RAINS FROM EARLIER RAINS.

DISCUSSION...GOES-13 SATELLITE IMAGERY SHOWS VERY COLD CONVECTIVE
TOPS...AS COLD AS -75C TO -80C...WITH A STRONG CONVECTIVE WEDGE
SIGNATURE SEEN IN IR IMAGERY OVER FAR NORTHEAST TX AND ACROSS
NORTHWEST LA...WHERE LOCALLY SEVERE FLASH FLOODING HAS ALREADY
BEEN OCCURRING.

STRONG DEEP LAYER ASCENT ASSOCIATED WITH UPPER LEVEL DIVERGENT
FLOW CONTINUES OUT AHEAD OF STRONGER UPSTREAM SOUTHWEST FLOW ALOFT
AND APPROACHING SHORTWAVE ENERGY EJETING NORTHEAST AWAY FROM THE
BASE OF THE UPPER LOW OVER NORTHERN MEXICO.

A WELL-DEFINED FRONTAL ZONE OVER NORTH-CENTRAL TX AND INTO
NORTHWEST LA IS BEING CONVECTIVELY REINFORCED AND WILL CONTINUE TO
ACT AS A STRONG CATALYST FOR CONVECTIVE REDEVELOPMENT AND
EXPANSION OVER THE NEXT SEVERAL HOURS AS LOW LEVEL FLOW INCREASES
GRADUALLY FROM THE SOUTH AND OVERRUNS A STATIONARY FRONT. THE
AIRMASS SOUTH OF THE FRONT IS INCREASINGLY MOIST...WITH PWATS NOW
AS HIGH AS 1.5 TO 1.7 INCHES. THE BETTER INSTABILITY IS FARTHER
BACK TO THE SOUTHWEST TOWARD THE TX HILL COUNTRY...BUT STRONG UVVS
ASSOCIATED WITH THE WARM ADVECTION PATTERN AND STRONGER JET
DYNAMICS ALOFT ARE COMPENSATING.

MULTIPLE RUNS OF THE HRRR INSIST VERY HEAVY RAINS...ESPECIALLY
OVER NORTHAST TX AND NORTHWEST LA...WITH ADDITIONAL AMOUNTS OF 3
TO 5 INCHES EXPECTED ALONG WITH ISOLATED HEAVIER AMOUNTS THROUGH
10Z. GIVEN LOCALLY INTENSE RAINS THAT HAVE ALREADY FALLEN...THESE
ADDITIONAL AMOUNTS ARE LIKELY TO RESULT IN SEVERE FLASH
FLOODING/RUNOFF PROBLEMS.

ORRISON

ATTN...WFO...EWX...FWD...HGX...JAN...LZK...SHV...SJT...

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

LAT...LON   33389183 32959132 32459149 32039197 31679327 
            31529411 31249507 30699603 30239670 29859778 
            30019834 30759865 31569846 32449774 33049630 
            33369417