Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 200803
QPFERD

EXCESSIVE RAINFALL DISCUSSION...UPDATED.
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
402 AM EDT SAT SEP 20 2014

...VALID 06Z SAT SEP 20 2014 - 12Z SUN SEP 21 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 SW DRT 35 S 6R6 105 S E38 50 SSW MRF 50 S GDP 30 SE SRR
45 WSW CVS 40 ENE CVN 45 NE PVW 25 SW F05 30 NE ABI 15 SSW 6R9
25 S 3T5 15 SW LBX 20 ENE KBQX 10 N KMZG KOPM 20 E BRO
30 SSE MMRX 30 SSW MMNL 55 SSE MMPG 25 SW DRT.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
55 S CVS 10 SSE PVW 60 NNE SNK 15 NNE SWW 35 NW SJT 65 SE MAF
25 ENE FST 15 SSW PEQ 20 SSW CNM 20 ESE ATS 55 S CVS.


SOUTHEAST NEW MEXICO INTO WESTERN/CENTRAL/SOUTHERN TEXAS
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

SOME MINOR ADJUSTMENTS MADE TO THE PREVIOUS OUTLOOK...MAINLY TO
SHRINK THE MODERATE RISK AREA. ODILE`S REMNANT CIRCULATION HAS
LONG SINCE DIMINISHED...HOWEVER THE OVERALL PATTERN AND
THERMODYNAMIC SETUP REMAINS IN PLACE ACROSS THE AREA TO FAVOR
ADDITIONAL CONVECTIVE FORMATION THIS PERIOD WITH AREAS OF HEAVY
AND POTENTIALLY EXCESSIVE RAINFALL. CONTINUED SOUTHEASTERLY
LOW-LEVEL FLOW WILL MAINTAIN FAVORABLE MOISTURE TRANSPORT FROM THE
WESTERN GULF...WITH THE AREA ONCE AGAIN ALIGNED ALONG THE AXIS OF
MAXIMUM PW VALUES RANGING FROM ~1.5 INCHES IN SERN NM TO NEAR 2.4
INCHES IN SERN TX. OVER THE ENTIRE AREA...THESE PW VALUES ARE
2-2.5 STANDARD DEVIATIONS ABOVE NORMAL.

THE PERSISTENT SERLY LOW-LEVEL INFLOW WILL AGAIN GET A NOCTURNAL
BOOST EARLY THIS AM AND AGAIN OVERNIGHT SAT-SUN...WHICH WILL
LIKELY AID TO MORE MULTI-CELLULAR ORGANIZATION AND SLOW
PROPAGATION INTO THE LOW-LEVEL INFLOW (INCREASED THREAT FOR CELL
TRAINING) DURING THESE TIMES. EXPECT THE MORE DIFFERENTIAL HEATING
(DEEPER INSTBY/HIGHER MUCAPES) DURING THE DAY TO LEAD TO
LESS-ORGANIZED... MORE PULSE TYPE ACTIVITY WITH MORE PROGRESSIVE
OUTFLOW BOUNDARIES. DYNAMICALLY SPEAKING...WHILE ALL GLOBAL MODELS
CONTINUE TO GRADUALLY WEAKEN THE MCV CURRENTLY NEAR THE SERN
NM/WRN TX BORDER...BROAD UPPER LEVEL DIFFLUENCE WILL REMAIN IN
PLACE IN BETWEEN THE CLOSED UPPER HIGH OVER NW MEXICO AND THE
FASTER WESTERLIES/HEIGHT FALLS MOVING INTO THE MID MS VLY.

THE MODERATE RISK AREA WAS DRAWN TO ACCOUNT FOR WHERE THE HIGHEST
AREAL-AVERAGE RAINFALL (.50-1.5 INCHES) PER THE ENSEMBLE OF THE
GLOBAL AS WELL AS HIGH-RESOLUTION GUIDANCE IS JUXTAPOSED WITH THE
LOWEST FLASH FLOOD GUIDANCE...I.E. WHERE THE SSEO 40 KM
NEIGHBORHOOD PROBABILITIES OF 3/6 HOUR QPF EXCEEDING 3/6 HOUR FFG
IS AOA 50%.

ACROSS SOUTH-CENTRAL AND SOUTHEASTERN TX...AREAL AVERAGE TOTALS
WILL LIKELY BE UNDER .75 INCH...HOWEVER GIVEN THE MOISTURE RICH
ENVIRONMENT (PWS AROUND 2.25+ INCHES) ALONG WITH THE DIFFERENTIAL
HEATING/DEEPER CONVECTION...HOURLY RAINFALL RATES OF 2.5+ INCHES
AND/OR 3-5+ INCHES WITHIN A FEW HOURS (SUPPORTED BY THE MESOSCALE
GUIDANCE) WILL LIKELY LEAD TO MORE ISOLATED AREAS OF FLASH
FLOODING TODAY.


FLORIDA
~~~~~~~

A BROAD UPPER LEVEL TROUGH WITH A DEFINITIVE MID-LEVEL VORT
LOBE/SHEAR AXIS AND AN ASSOCIATED SFC FRONTAL BOUNDARY WITHIN THE
FL PENINSULA WILL FOCUS MORE NUMEROUS SHOWERS/TSTMS AND POTENTIAL
FOR HEAVY RAINFALL ACROSS THE SRN HALF OF THE FL PENINSULA
(PARTICULARLY CENTRAL FL). PWS OF ~2" ALONG WITH EXPECTED BOUNDARY
LAYER MOISTURE CONVERGENCE FROM THE 00Z MODEL GUIDANCE FORCED THE
CENTER OF ACTION TO CENTRAL FL...WHICH WAS IN LINE WITH THE
CLIMATOLOGY-BASED QPF REFORECAST FROM THE 0919/00Z CYCLE. HIGHEST
AREAL-AVERAGE TOTALS RANGE FROM .5 TO 1+ INCHES ACROSS CENTRAL
FL...HIGHEST TOWARD THE GULF COAST GIVEN THE BETTER UPPER
DIVERGENCE AND LOW-LEVEL INFLOW/MOISTURE TRANSPORT/FLUX
CONVERGENCE SIGNATURE PER THE MODELS. LOCALIZED AMOUNTS OF 2-4+
INCHES WILL BE POSSIBLE AS PER THE HIGH RESOLUTION GUIDANCE GIVEN
THE FORCING AND THERMODYNAMIC ENVIRONMENT...AGAIN...ESPECIALLY
TOWARD THE GULF COAST WHERE THE PRE-FRONTAL SOUTHWESTERLY
LOW-LEVEL INFLOW (AND UPWIND PROPAGATION/POTENTIAL FOR CELL
TRAINING) WILL BE HIGHEST. GIVEN THE ANTECEDENT HIGH FFG
VALUES...ANY SHORT-TERM RUNOFF ISSUES ARE LIKELY TO BE ISOLATED AT
MOST.

HURLEY
$$




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