Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 210650
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
249 AM EDT SUN SEP 21 2014

...VALID 06Z SUN SEP 21 2014 - 12Z MON SEP 22 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 WSW ENV 35 SSW DPG 20 WSW MLF 45 SW SGU VGT 30 NNE DRA
20 ENE TPH 60 NW TPH 25 ESE NFL 30 E LOL 25 ESE B23 45 WSW ENV.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 NNE CVN 40 SSE LBB 30 S BPG 35 ESE FST 25 SSE E38 60 WNW MRF
30 SSE ALM 30 NW SRR 25 W LVS 25 W RTN 20 ESE RTN 50 NW TCC
35 NNE CVN.


...NV/WESTERN UT...

AXIS OF HIGHLY ANOMALOUS PWS (+3.5-4.0 STANDARD DEVIATIONS ABOVE
NORMAL PER THE SREF/GEFS) WILL CONTINUE TO PULL NORTHWARD INTO THE
AREA EARLY IN THE PERIOD AHEAD OF THE MID/UPPER LEVEL LOW
CURRENTLY ACROSS CENTRAL CA. MEANWHILE...LARGE-SCALE FORCING
(UPPER DIVERGENCE/DIFFLUENCE AND DEEP-LAYER ASCENT) WILL CONTINUE
TODAY AHEAD OF THE MID/UPPER LEVEL LOW...ALLOWING FOR MORE
WIDESPREAD SHOWERS/TSMS AND SOMEWHAT ATYPICAL AREAL-AVERAGE
RAINFALL FOR THE TIME OF YEAR (GENERALLY .25 TO .75 INCH). THE
RELATIVELY DRYER LOW LEVELS/HIGH-BASED NATURE OF THE CONVECTION
WILL TEND TO LIMIT RAINFALL EFFICIENCY/RATES...WHILE ALSO CAPPING
MUCAPES AROUND 500-1000 J/KG. THIS WILL LIMIT THE THREAT/COVERAGE
OF ANY EXCESSIVE RAINFALL...THOUGH LOCALIZED AMOUNTS OF 2-3"
WITHIN A FEW HOURS AS PER THE HIGH RESOLUTION GUIDANCE COULD LEAD
TO RUNOFF ISSUES GIVEN THE CURRENT FFG.


...WEST TEXAS/EASTERN NEW MEXICO...

RATHER STAGNANT PATTERN ACROSS THE AREA DURING THIS PERIOD...WITH
LITTLE SHIFT IN THE FEATURES ALOFT WHILE THE FAVORABLE
THERMODYNAMIC PROFILE REMAINS IN PLACE. ONCE AGAIN...LARGE-SCALE
FORCING WILL BE LACKING UNDERNEATH THE BROAD UPPER
RIDGE...HOWEVER...PERSISTENT WEAK UPPER LEVEL DIFFLUENCE BETWEEN
THE CLOSED UPPER HIGH ACROSS WRN MEXICO AND THE FASTER
WESTERLIES/HEIGHT FALLS DROPPING INTO THE MID MS VLY WILL ALLOW
FOR THE DEVELOPMENT OF MORE ORGANIZED CONVECTION...AIDED AGAIN BY
THE PERSISTENT E-SE (UPSLOPE) LOW-LEVEL FLOW AND MOISTURE
TRANSPORT. WPC UTILIZED A MULTI-MODEL BLEND WITH THE
QPF...INCORPORATING SOME OF THE HIGHER RESOLUTION DATA THAT
APPEARS TO BE VERIFYING BETTER IN THE NEAR TERM (NSSL
WRF...WRF-ARW...AND SSEO MEAN)...WHICH MAINTAINS DECENT CONTINUITY
FROM THE PREVIOUS WPC FORECAST AND ALIGNS WELL WITH THE REFORECAST
DATA FROM THE 00Z 09/20 CYCLE. AREAL AVERAGE AMOUNTS RANGE BETWEEN
0.50-1.5 INCHES...HOWEVER...PER THE AFOREMENTIONED 4KM
GUIDANCE...LOCALIZED AMOUNTS OF 2-5 INCHES ARE EXPECTED
(ESPECIALLY INTO ERN NM)...WHICH GIVEN THE RELATIVELY LOW 1-3 HR
FFG...WILL MAINTAIN A FLASH FLOOD THREAT.

HURLEY

$$





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