MESOSCALE PRECIPITATION DISCUSSION 0281
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1241 PM EDT TUE OCT 15 2013
 
AREAS AFFECTED...CENTRAL AND NORTHEAST TX 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 151640Z - 152110Z
 
SUMMARY...MOISTURE AHEAD OF THE ELONGATED MID-LEVEL CIRCULATION
FORMERLY ASSOCIATED WITH TROPICAL DEPRESSION OCTAVE CONTINUES
STREAKING ACROSS TX.  AS HEAVY RAINS ARE EXPECTED ACROSS SATURATED
GROUND, REGIONAL FLASH FLOODING IS CONSIDERING POSSIBLE OVER THE
NEXT SEVERAL HOURS ACROSS CENTRAL AND NORTHEAST TX.

DISCUSSION...A SUBTROPICAL MOISTURE STREAM -- INCLUDING THE
ELONGATING MID-LEVEL CIRCULATION FROM TROPICAL DEPRESSION OCTAVE
-- IS STREAKING AHEAD OF AN EASTWARD-MOVING MID- TO UPPER-LEVEL
SHORTWAVE ACROSS CHIHUAHUA STATE ACROSS NORTHWEST MX.  RECENT
RADAR TRENDS INDICATE RAINFALL RATES NEAR THE RED RIVER OF THE
SOUTH HAVE COME DOWN WHILE CONVECTION MAINTAINS ITSELF ACROSS
CENTRAL TX...WHICH APPEARS TO BE HANDLED WITHIN THE 00Z ARW
GUIDANCE CAPE FIELD.  LOW-LEVEL INFLOW OF 20-25 KTS IS INDICATED
BY AREA VAD WIND PROFILES AND THE 15Z RAP GUIDANCE.  PRECIPITABLE
WATER VALUES OF 2-2.5 INCHES LIE ACROSS TX, WHICH ARE IN THE 90TH
TO 95TH PERCENTILES FOR MID-OCTOBER, AND ARE ACTING TO HELP OUT
PRECIPITATION EFFICIENCY.  SATELLITE TRENDS SHOW WARM TOPS TO
ONGOING CONVECTION, INDICATING WARM RAIN PROCESSES ARE AT WORK. 
THIS NORMALLY ALLOWS HEAVIER RAINFALL WITH BELOW AVERAGE CAPES,
WHICH ARE NEAR 500 J/KG WITHIN THE SATURATED AIR MASS ACROSS TX
PER RECENT ARW RUNS.

A COLD FRONT IS MOVING INTO THIS REGION, WHICH IS EXPECTED TO
CAUSE INCREASING CONVECTION/RAINFALL RATES ACROSS CENTRAL TX LATE
THIS MORNING INTO EARLY THIS AFTERNOON DUE TO INCREASING LOW-LEVEL
CONVERGENCE -- RAINFALL RATES OF 1-2" PER HOUR ARE EXPECTED. 
REGIONAL FLASH FLOOD GUIDANCE VALUES ARE ROUGHLY NEAR 2.5 INCHES/3
HOURS, THOUGH THEY ARE MUCH LOWER NEAR THE PECOS RIVER VALLEY. 
THE 00Z/12Z ARW INDICATE CAPE VALUES COULD SLOWLY INCREASE ACROSS
CENTRAL AND NORTHEAST TX INTO THE AFTERNOON HOURS, WHICH IS ALSO
SUGGESTED BY TRENDS IN THE HRRR SINCE ITS 11Z RUN AND THE NAM
CONEST SINCE ITS 06Z RUN.  WHEN COMBINED WITH THE CORFIDI VECTORS,
LOW-LEVEL INFLOW, AND 850-400 HPA LAYER WINDS ALL BEING PARALLEL
TO THE CURRENT MOISTURE BAND, CONVECTION, AND INVADING FRONTAL
BOUNDARY, REGIONAL FLASH FLOODING IS CONSIDERED POSSIBLE.

ROTH

ATTN...WFO...SHV...FWD...EWX...SJT...MAF...

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

LAT...LON   31649569 31089640 30119817 29659957 29390112 29740247
            30230292 31130224 31360145 31650040 32079902 32809804
            33319724 33769600 33209526 32299524 31649569