MESO: Nws Weather Prediction Center College Park Md

AWUS01 KWNH 130911
FFGMPD
TXZ000-131345-

MESOSCALE PRECIPITATION DISCUSSION 0274
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
510 AM EDT SUN OCT 13 2013

AREAS AFFECTED...CENTRAL AND SOUTHEAST TX

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

VALID 130900Z - 131345Z

SUMMARY...SLOW-MOVING MCS SHOULD CONTINUE TO FOSTER HEAVY RAINS
PAST SUNRISE WHILE SLOWLY ADVANCING SOUTHEAST. EXPECTING
ADDITIONAL FLASH FLOOD CONCERNS AT LEAST LOCALLY.

DISCUSSION...THE LATEST IR SAT IMAGERY SHOWS A BKN COLD-TOPPED MCS
ADVANCING VERY SLOWLY SSEWD ACROSS PORTIONS OF CNTRL AND SERN TX
OUT AHEAD OF A STALLED OUT FRONTAL ZONE. THE CONVECTION IS
EMBEDDED WITHIN A SHARP INSTABILITY GRADIENT AS COMPARED TO THE
LATEST RAP ANALYSIS. IN FACT...THE LATEST RAP ANALYSIS SHOWS SOME
IMPRESSIVELY UNSTABLE AIR SOUTH OF THE MCS CONSIDERING THE LACK OF
DIURNAL HEATING...WITH MUCAPE VALUES OF 3000 TO 4000 J/KG. THE
FAVORABLE THERMODYNAMIC ENVIRONMENT MEANWHILE IS BEING
COMPLEMENTED BY LARGER SCALE DYNAMICAL FORCING ASSOCD WITH H25 RRQ
JET DYNAMICS INVOLVING THE SUBTROPICAL JET. THIS ENERGY IS BEING
ENHANCED BY THE OUTFLOW ASSOCD WITH T.S. OCTAVE IN THE E PAC SOUTH
OF MEXICO. HIGHER LVL MOISTURE ASSOCD WITH THE T.S. AND VORT
ENERGY EMBEDDED WITHIN THE JET CORE ARE HELPING TO ENHANCE THE
CONVECTIVE ACTIVITY OVER THE REGION.

GIVEN THE LARGER SCALE ASCENT AND INSTABILITY ENVIRONMENT...THE
MCS MAY MAINTAIN SOME ORGANIZATION THROUGH SUNRISE...WITH SOME
ADDITIONAL POTENTIAL FOR BACK-BUILDING AND MERGING CONVECTIVE
CELLS. GOES-SOUNDER PWATS RANGE FROM 1.75 TO 2 INCHES...AND THIS
WILL SUPPORT VERY HEAVY RAINFALL RATES. FFG VALUES ARE LOCALLY
RATHER HIGH...BUT WITH OBSERVED RAINFALL RATES ALREADY UP TO 2.5
INCHES/HR...AND THE SLOW MOVEMENT...THERE WILL BE ADDITIONAL
CONCERNS FOR FLASH FLOODING...AT LEAST LOCALLY.

ORRISON

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

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

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

LAT...LON 31549895 31219788 31119687 31089593 30979530 30529488
29979487 29499514 29059574 28929660 28909757 28849853
28649953 28560023 28800098 29480148 30170090 30880063
31350023 31579958 31549895

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