MESO: Nws Weather Prediction Center College Park Md

AWUS01 KWNH 310957
FFGMPD
LAZ000-ARZ000-TXZ000-311355-

MESOSCALE PRECIPITATION DISCUSSION 0286
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
556 AM EDT THU OCT 31 2013

AREAS AFFECTED...EASTERN TX/SOUTHERN AR/WESTERN LA...

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 310955Z - 311355Z

SUMMARY...THE THREAT FOR FLASH FLOODING HAS SHIFTED EASTWARD
TOWARD THE TX/LA BORDER ALTHOUGH CONCERNS STILL LINGER UPSTREAM
FROM AUSTIN TX NORTHEASTERN TO NEAR TYLER TX.

DISCUSSION...A VERY IMPRESSIVE BAND OF CONVECTION HAS PERSISTED
MUCH OF THE OVERNIGHT HOURS WITH NUMEROUS REPORTS OF FLOODED
ROADS...EVACUATIONS...AND EVEN A FEW WATER RESCUES. MESONET
OBSERVATIONS HAVE DEPICTED A WIDESPREAD 1 TO 2 INCHES OF RAINFALL
PER HOUR WITH ISOLATED AREAS OF 3 INCH RAIN RATES. DURING THE PAST
6 HOURS...DOPPLER ESTIMATES SUGGEST 9 TO 12 INCHES OF RAIN MAY
HAVE FALLEN OVER THE AFFECTED REGION SINCE 03Z. ALTHOUGH CLOUD
TOPS HAVE BEGUN TO WARM ACROSS THE TX HILL COUNTRY...RESIDUAL RAIN
FALLING ATOP THE SATURATED GROUNDS WILL AID IN ADDITIONAL RAINOFF
AND FURTHER FLASH FLOOD CONCERNS.

LOOKING DOWNSTREAM...THE AXIS OF HEAVY RAINFALL HAS BEGUN
EXPANDING CLOSER TO THE TX/LA BORDER WHERE MANY LOCATIONS HAVE
VERY LOW FFG VALUES. THIS REGION IS WELL ENTRENCHED WITHIN THE
2.00 TO 2.25 INCHES PWATS WITH CELL MOTIONS REMAINING SLOW.
ALTHOUGH THE ACTIVITY IS NOT CURRENTLY TRAINING...SUCH
TRAJECTORIES REMAIN POSSIBLE DURING THE EARLY MORNING HOURS BEFORE
AN UPSTREAM SHORTWAVE EVENTUALLY LEADS TO A PROGRESSIVE STORM
MODE. AS HAS BEEN COMMON MUCH OF THE NIGHT...THE AIR MASS CLOSER
TO THE WESTERN GULF COAST REMAINS UNSTABLE WITH MLCAPE VALUES
ABOVE 1000 J/KG ACCORDING TO THE 09Z RAP. THIS CONVECTION SHOULD
CONTINUE TO SPAWN WITHIN THE UNSTABLE AIR MASS AND MOVE
NORTHEASTWARD INTO THE RAIN-COOLED AIR. GIVEN THE 75 DEGREE PLUS
DEW POINTS COMBINED WITH HIGHLY ANOMALOUS PWATS...THIS SHOULD
CONTINUE TO FAVOR RATHER HIGH RAINFALL RATES. WITH THAT
SAID...FLASH FLOODING WILL REMAIN A DISTINCT
POSSIBILITY...PARTICULARLY IN AREAS OF TRAINING/BACKBUILDING
CONVECTION.

THE HIGH-RESOLUTION MODELS SHOW SUFFICIENT CLUSTERING WITH THE
PLACEMENT OF THE HEAVY RAINFALL WHICH FURTHER INCREASES THE
CONFIDENCE IN THIS OUTLOOK. PARTICULARLY GIVEN THE RECENT TRENDS
ON RADAR/SATELLITE.


RUBIN-OSTER

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

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

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

LAT...LON 29209621 29449661 29429773 29769844 30509839 31119771
32209617 33009508 33409448 33929328 33659238 33189191
32329171 31529203 30959312 30409406 29129554 29209621

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