MESO: Nws Weather Prediction Center College Park Md

AWUS01 KWNH 131630
FFGMPD
TXZ000-131958-

MESOSCALE PRECIPITATION DISCUSSION 0276
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1229 PM EDT SUN OCT 13 2013

AREAS AFFECTED...CENTRAL TO SOUTHEAST TEXAS

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 131628Z - 131958Z

SUMMARY...THE POTENTIAL FOR ADDITIONAL FLASH FLOODING WILL
CONTINUE INTO THE EARLY AFTERNOON FROM W-CNTRL TX TOWARD THE
COASTAL PLAIN WITH RAINFALL RATES OF 2-3 IN/HR.

DISCUSSION...16Z SURFACE ANALYSIS PLACED AN OUTFLOW BOUNDARY FROM
NEAR COT EASTWARD TO JUST NORTH OF PSX WITH DEWPOINTS IN THE MID
TO UPPER 70S LOCATED TO ITS SOUTH. RECENT RADAR IMAGERY SHOWED TWO
MAIN CLUSTERS OF CONVECTION...FIRST TO THE NORTH OF A VCT TO SGR
LINE WHICH IR CLOUD TOPS HAVE INDICATED OVERALL WARMING/WEAKENING
OVER THE PAST COUPLE HOURS. SECOND IS ALONG THE WESTERN EDGE OF
THE OUTFLOW NEAR UVA. MORNING RAOBS SUPPORTED AN AXIS OF 15 TO 20
KTS AT 850 MB ALONG THE RIO GRANDE VALLEY WHICH SHORT TERM MODEL
GUIDANCE HAS CONTINUING THROUGH MUCH OF THE DAY. SPC MESOANALYSIS
INDICATED SURFACE BASED CAPE OF 1000-2500 J/KG TO THE SOUTH OF THE
OUTFLOW BOUNDARY WITH PRECIPITABLE WATER VALUES OF 2.00-2.25 IN
PER BLENDED TPW IMAGERY. CLOUD ELEMENTS IN VISIBLE IMAGERY
INDICATES MOISTURE RETURN WITHIN THE SOUTHEASTERLY LOW LEVEL FLOW
FROM THE GULF OF MEXICO FEEDING INTO AND OVER THE OUTFLOW BOUNDARY
WHILE UPPER LEVEL MOISTURE APPEARS TO BE TRANSPORTED DOWNSTREAM OF
T.S. OCTAVE IN THE EASTERN PACIFIC.

THE BIGGEST CONCERN IS ACROSS THE WESTERN PORTION OF THE THREAT
AREA WHERE CONTINUED TRANSPORT OF MOISTURE/INSTABILITY FROM THE
SOUTH ACROSS THE WESTERN PORTION OF THE OUTFLOW BOUNDARY MAY
CONTINUE TO SUPPORT A THREAT FOR LOCALIZED VERY HEAVY RAINFALL
OVER THE NEXT FEW HOURS...SUPPORTED BY SEVERAL HI-RES MODEL RUNS.
MEANWHILE ACROSS THE CENTRAL AND EASTERN PORTIONS OF THE THREAT
AREA...RENEWED DEVELOPMENT APPEARS POSSIBLE BASED ON ONSET OF
STRONGER DIABATIC HEATING WITHIN THE ALREADY UNSTABLE ENVIRONMENT
WITH THE OUTFLOW BOUNDARY ACTING AS AN AREA OF INCREASED LOW LEVEL
CONVERGENCE. DESPITE RELATIVELY HIGH FLASH FLOOD GUIDANCE VALUES
OF 3-4 IN/3 HRS...BELIEVE THESE VALUES COULD BE MET/EXCEEDED IN
SOME AREAS OVER THE NEXT FEW HOURS. TRENDS WILL CONTINUE TO BE
MONITORED AND UPDATED AS NEEDED INTO THE AFTERNOON.

OTTO

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

ATTN...WFO...HGX...CRP...EWX...SJT...

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

LAT...LON 28719548 28199617 27469686 27399781 27769884 28370018
28990073 30060101 31210100 31690061 31809990 31319931
30139843 30119708 30109544 29929460 29249456 28719548

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