Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 160113
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
912 PM EDT WED APR 15 2015

...VALID 03Z THU APR 16 2015 - 00Z FRI APR 17 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 SSW TOI 20 SSW OZR 15 SE DTS 10 SSW KVOA 10 S KEIR 20 S KGVX
20 NW RKP 25 ESE SSF 10 E AUS 25 WNW UTS 20 SW AEX 20 WSW PIB
45 W GZH 40 SSW TOI.


03Z UPDATE...
REMOVED SLIGHT RISK AREA ACRS SC AS ANY ORGANIZED EXCESSIVE RAIN
THREAT CONTNUES TO DIMINISH WITH LOSS OF DAYTIME
HEATING/INSTABILITY.  ACRS THE GULF STATES..SOME ISOLD POCKETS OF
TSTMS WILL REMAIN OVERNIGHT BUT FEEL MAIN THREAT OF ANY ORGANIZED
HEAVIER CONVECTIVE RAINS WILL BE ON THUR AS WAA PATRN ENSUES AND
AREA OF ENHANCED PWS LIFTS NWD TOWARD THE GULF COAST.  SULLIVAN
PREVIOUS FCST DISCUSSION FOR THAT AREA REMAINS UNCHANGED.

...GULF COAST STATES...

CONCERN FOR A MORE ORGANIZED PRECIPITATION EVENT IS GREATER ON
THURSDAY AS A WARM ADVECTION REGIME SETS UP FROM THE TEXAS HILL
COUNTRY INTO SOUTHWEST LOUISIANA AHEAD OF A DEEP WESTERN U.S.
TROUGH. THUNDERSTORMS WHICH DEVELOP WITHIN WARM ADVECTION THURSDAY
MORNING ALONG THE TX/LA GULF COAST MAY GROW UPSCALE AND PRODUCE
HEAVY RAIN DOWNSTREAM INTO SOUTHERN LA DURING THE DAY. THE MODELS
WERE CATCHING ONTO THIS NOTION...AND AN ASSOCIATED MID LEVEL
DISTURBANCE...WITH QPF HAVING TRENDED EASTWARD OVER THE PAST FEW
RUNS OF THE GLOBAL MODELS. WE DO NOTE...HOWEVER...THAT LOW LEVEL
INFLOW WILL BE ENHANCED BACK ACROSS CENTRAL TEXAS DURING THE DAY
THURSDAY...WHEREAS RELATIVELY MODEST 1-15 KNOT 850 MB FLOW OVER
SOUTHERN LOUISIANA MAY OFFER RESULT IN OUTFLOW DOMINANT AND
PROGRESSIVE CONVECTION THERE. CENTRAL TO SOUTHEAST TEXAS WILL LACK
DEEP ASCENT...BUT IF CONVECTION CAN BECOME INCREASINGLY SURFACE
BASED WITHIN THE WARM ADVECTION REGIME...CAPE/SHEAR COMBINATIONS
WILL FAVOR ORGANIZED STORM MODES...AND TRAINING OF LOCALLY HEAVY
RAIN MAY BECOME MORE LIKELY WITH TIME. WE DREW A BROAD SLIGHT RISK
AREA TO ENCOMPASS THE POTENTIAL FOR EXCESSIVE RAINFALL WITHIN THIS
ZONE OF MOIST...UNSTABLE...AND WEAKLY TO MODERATELY FORCED AIR
MASS ALONG THE GULF COAST AND EXTENDING TOWARD CENTRAL TEXAS.
RECENT HEAVY RAINS ALONG THE IMMEDIATE COASTAL AREAS ALSO FACTORS
INTO THE RISK.

BURKE
$$





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