Quantitative Precipitation Forecast
Issued by NWS

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000
FOUS30 KWBC 220659
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
258 AM EDT MON SEP 22 2014

...VALID 06Z MON SEP 22 2014 - 12Z TUE SEP 23 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
15 SW PEQ 55 NW MRF 25 SE MMCS 65 SW MMCS 130 SE DUG 15 E DUG
SAD 30 S SJN 10 ENE GNT 40 WSW SKX 35 S RTN 25 NW TCC 30 NNE ROW
15 SW PEQ.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 ESE ALM 15 WSW SRR 20 SSW 4CR 30 SE 4CR 25 SW ROW 40 SW ATS
25 ESE ALM.



...WESTERN TEXAS INTO NEW MEXICO AND EXTREME SOUTHEASTERN
ARIZONA...

RATHER BROAD SLIGHT RISK AREA WAS MAINTAINED DURING THE NEW DAY 1
PERIOD (THROUGH 12Z TUE)...WITH THE MODERATE RISK CONFINED TO THE
SACRAMENTO AND GUADALUPE RANGES IN SOUTHEASTERN NEW MEXICO. AS THE
UPPER RIDGE AXIS SHIFTS EAST OF THE AREA TODAY...A SHEAR AXIS/ MID
LEVEL VORT LOBE ON THE TAIL END OF THE MID/UPPER LEVEL CIRCULATION
CURRENTLY OVER THE GREAT BASIN WILL PROVIDE THE FORCING FOR
ADDITIONAL NUMEROUS SHOWERS/TSTMS TODAY INTO THIS EVENING. AS HAS
BEEN THE CASE OVER THE PAST SEVERAL DAYS...PERSISTENT E-SE LOW
LEVEL FLOW WILL MAINTAIN THE MOISTURE FLUX OUT OF THE WESTERN
GOMEX...ALONG AN AXIS OF CONTINUED ANOMALOUS PWS (STILL 2-3
STANDARD DEVIATIONS ABOVE NORMAL DURING THIS PERIOD). THE SLOW
CELL MOTIONS (WEAK UPWIND PROPAGATION) WILL AGAIN ALLOW FOR
ADDITIONAL LOCALLY HEAVY (POTENTIALLY EXCESSIVE) RAINFALL AMOUNTS
IN THE CURRENT THERMODYNAMIC ENVIRONMENT...THOUGH GIVEN THE DEEP
LAYER MOISTURE AND (THUS) WEAK (NEAR MOIST ADIABATIC) LAPSE RATES
ALOFT...DEEP LAYER INSTBY WILL BE SOMEWHAT CAPPED AROUND 500-1000
J/KG THROUGH THIS EVENING. WHILE THIS MAY CUT DOWN ON THE
SHORT-TERM RAINFALL RATES...THE FLASH FLOOD GUIDANCE REMAINS
RELATIVELY LOW ACROSS THE OUTLOOK AREA GIVEN THE ANTECEDENT WET
CONDITIONS. THE LATEST FFG INDICATES  A BROAD AREA OF 1-1.5 INCHES
(OR EVEN LOWER IN ISOLATED AREAS) WITHIN 3 HOURS. AS A
RESULT...THE CURRENT SSEO 40 KM NEIGHBORHOOD PROBABILITIES OF QPF
EXCEEDING 3 HOURLY FFG GET CLIMB ABOVE 30 PERCENT IN THE SLIGHT
RISK AREA...AND ABOVE 50 PERCENT IN THE MODERATE RISK. THE LATEST
MESOSCALE GUIDANCE CONTINUES TO SHOW THE POTENTIAL FOR ISOLATED
RAINFALL AMOUNTS OF 3-6+ INCHES THIS PERIOD.

HURLEY

$$





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