Quantitative Precipitation Forecast
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FOUS30 KWBC 221457
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1056 AM EDT MON SEP 22 2014

...VALID 15Z 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
45 W CVS 25 ENE ROW 30 ENE CNM 25 WNW INK PEQ 25 N E38
10 NW E38 MRF 10 WNW MRF 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 45 W CVS.

MODERATE RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
25 WSW ROW 20 S ATS 30 SE CNM 40 SSE CNM 30 ESE GDP 20 SE GDP
GDP 10 W GDP 30 WNW GDP 45 SE ALM 15 ENE ALM 15 WSW SRR
20 SSW 4CR 30 SE 4CR 25 WSW ROW.


1400 UTC UPDATE

ONLY SOME SLIGHT CHANGES MADE TO THE PREVIOUS EXCESSIVE RAINFALL
POTENTIAL OUTLOOK.  THE SLIGHT AND MODERATE RISK AREAS WERE
EXPANDED TO THE SOUTHEAST INTO FAR SW TX TO COVER THE LOWER FFG
VALUES ACROSS THIS AREA.  OTHERWISE--NO SIGNIFICANT CHANGES TO THE
PREVIOUS FORECAST THINKING AT THE MOMENT.

ORAVEC

PREVIOUS DISCUSSION

...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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