MESOSCALE PRECIPITATION DISCUSSION 0001...RETRANSMITTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
142 AM EST SAT JAN 03 2015
 
AREAS AFFECTED...EASTERN TX, NORTHWEST LA, PORTIONS OF AR 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 030632Z - 031232Z
 
SUMMARY...THUNDERSTORMS WITH HEAVY RAINFALL SHOULD PERSIST ACROSS
PORTIONS OF EASTERN TX, NORTHWEST LA, AND AR OVER THE NEXT SEVERAL
HOURS.  RAIN RATES UP TO 2" AN HOUR COULD LEAD TO FLASH FLOODING
OVER SATURATING SOILS.

DISCUSSION...THUNDERSTORMS OVER THE PAST SEVERAL HOURS HAVE BEEN
SATURATING AREA SOILS NEAR THE TX/LA BORDER ALONG A
TROWAL/INVERTED TROUGH FEATURE TO THE NORTHEAST OF A DEVELOPING
SURFACE LOW.  ONGOING CONVECTION ALONG WITH A SECOND THUNDERSTORM
BAND MOVING IN FROM CENTRAL TX AT 30-40 KNOTS COULD LEAD TO
PERIODS OF HEAVY RAINFALL, APPROACHING THREE-HOURLY FLASH FLOOD
GUIDANCE VALUES. CLOUD TOPS HAVE BEEN COOLING IN THIS REGION,
WHICH IS ENHANCING RAINFALL RATES. DE QUEEN AR REPORTED OVER 1.6"
IN ONE HOUR AND NEAR 2.3" IN THREE HOURS, CLOSE TO AREA FLASH
FLOOD GUIDANCE VALUES.  PRECIPITABLE WATER VALUES OF 1.50-1.75" --
2-2.5 SIGMAS ABOVE THE NORM FOR EARLY JANUARY -- INHABIT THE
REGION PER RECENT RAP RUNS, AND 850 HPA INFLOW HAS INCREASED TO
40-50 KTS PER VAD WIND PROFILES, APPROACHING THE MAGNITUDE OF THE
850-400 HPA MEAN WIND PER NAM FORECASTS.  

THE DEEP-LAYERED FLOW IS ATTEMPTING TO BECOME MORE
SOUTHERLY/UNIDIRECTIONAL WITH TIME AS A WARM FRONT LIFTS NORTHWARD
THROUGH SOUTHEAST TX AND SOUTHWEST LA EAST OF THE SURFACE LOW. 
THE LATEST 00Z MESOSCALE QPF GUIDANCE ADVERTISED 2-4" NEAR THE
TX/LA BORDER WITH LOWER AMOUNTS UP IN AR (CLOSE TO 2") THROUGH
12Z.  FADING CAPE VALUES -- DUE TO ONGOING THUNDERSTORM ACTIVITY
-- FROM NORTH TO SOUTH SHOULD CAUSE LESSENING RAINFALL RATES
ACROSS AR OVER THE NEXT 2-3 HOURS, WITH A LINE OF CONVECTION
MOVING IN FROM CENTRAL TX ENDING THE THREAT FROM WEST TO EAST OVER
THE NEXT SEVERAL HOURS ACROSS EASTERN TX AND WESTERN LA.  TRAINING
CELLS WITHIN THE TWO BATCHES OF THUNDERSTORMS ARE THE MAIN
CONCERN. WITH HOURLY RAIN RATES APPROACHING 2", FLASH FLOODING IS
CONSIDERED POSSIBLE.

ROTH

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

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

LAT...LON   35229286 35189170 34639148 32709213 30979336 
            30949462 31779531 33509498 34709412