Flash Flood Guidance
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000
AWUS01 KWNH 031934
FFGMPD
LAZ000-TXZ000-040000-

MESOSCALE PRECIPITATION DISCUSSION 0783
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
233 PM EST SAT DEC 03 2016

AREAS AFFECTED...SOUTHEAST TX...SOUTHWEST LA

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

VALID 031930Z - 040000Z

SUMMARY...TRAINING CORES/ISENTROPIC ASCENT ACROSS SW LA MAY LEAD
TO FLOODING CONCERNS THOUGH BULK OF HVY RAINFALL LIKELY TO BE
OFFSHORE.

DISCUSSION...CURRENT GOES-E VISIBLE, RADAR MOSAIC AND SFC OBS
DENOTES COLD POOL FROM CONVECTION THAT DUMPED 3-7" ALONG COASTAL
TX HAS KICKED AN OUTFLOW BOUNDARY OFFSHORE.  THIS IS COINCIDENT
WITH TRAILING SW TO NE ORIENTED MID-LEVEL TROF OF THE EXITING
SHORTWAVE ACROSS S AR FURTHER REDUCING BEST UPPER LEVEL
ASCENT/SUPPORT.  STILL STRONG HEIGHT FALLS FROM DEEPER UPSTREAM
TROF ALLOWS FOR CONTINUED STRONG WESTERN GULF SURFACE FLOW AND
MOISTURE CONVERGENCE LEADING TO SOME ISENTROPIC ASCENT AND
CONVECTIVE DEVELOPMENT INTO THE NEAR COAST OF TX AT THIS
TIME...LEADING TO A BROADER WEDGE OF SHALLOWER MORE BROKEN
CONVECTION OVER THE NEXT FEW HOURS.  THESE SHOWERS MAY HAVE SOME
SHORT BURST RAIN TOTALS UP TO 1" THAT MAY HELP COMPOUND ONGOING
FLOODING BUT LIKELY WILL NOT RESULT IN ANY SIGNIFICANT INCREASES
OR THREATS OVER SE TX THAT ARE NOT ALREADY EXPERIENCING FLOODING.

RECENT FEW HOURS OF THE HRRR, ESRL EXP HRRR AND 12Z ARW HAVE BEEN
PERFORMING WELL AND SUPPORT THIS TREND. STILL AS THE OUTFLOW
ENHANCED FRONTAL BOUNDARY WILL STILL FOCUS DEEPER CONVECTIVE
DEVELOPMENT SOUTH/SSW OF SABINE PASS WHERE BEST INSTABILITY
REMAINS WELL SOUTH OF THE FRONT.  DEEPER UNIDIRECTIONAL FLOW WILL
SUPPORT TRAINING OF DEEPER CORES WITH RATES OF UP TO 1.5"/HR TO
AFFECT DOWNSTREAM SW LA WITH ADDITIONAL TOTALS OF 2-3" REMAINING
POSSIBLE THROUGH THIS EVENING.

GALLINA

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

ATTN...WFO...HGX...LCH...

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

LAT...LON   30639327 30339235 29649266 29759327 29699389
            29489443 29249477 28869543 29099545 29489496
            30479377


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