Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 180737
QPFERD

EXCESSIVE RAINFALL DISCUSSION...CORRECTED.
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
336 AM EDT MON AUG 18 2014

...VALID 06Z MON AUG 18 2014 - 12Z TUE AUG 19 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
90 SW OLS 30 ENE YUM 50 NE BLH 15 WSW IFP 30 SE HND 15 ENE LSV
25 W SGU 40 E SGU 45 N GCN 25 NNE FLG 25 ESE INW 30 SE SJN
55 NE SAD 15 NE SAD 20 SE SAD 40 ENE DUG 95 SE DUG 80 NE MMHO
90 SW OLS.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 ENE MQY 30 NNW JKL 30 SSW EKN 20 SE NYG 30 ESE WAL 95 SE WAL
55 E FFA 10 SSE RWI DAN 15 ENE GEV 25 NW AVL 15 W FTY 15 N NMM
10 WNW BQP 20 ESE TXK 10 N M89 25 W UTA 35 SE MKL 35 ENE MQY.


...PORTIONS OF THE LOWER MISSISSIPPI VALLEY...TENNESSEE
VALLEY...LOWER OHIO VALLEY...AND MID ATLANTIC...

A FAIRLY FLAT...ELONGATED TROUGH ALOFT ALONG WITH AN ASSOCIATED
SLOW-MOVING SURFACE FRONTAL BOUNDARY WILL SET THE STAGE FOR
MULTIPLE ROUNDS OF DIURNALLY-ENHANCED...SLOW MOVING SHOWERS/TSTMS
ACROSS THE OUTLOOK AREA DURING THE PERIOD. THE ACTIVITY WILL BE
AIDED BY THE ROBUST PRE-FRONTAL THERMODYNAMIC ENVIRONMENT...AS
PWATS INCREASING TO 2.00+ INCHES ALONG WITH HIGH WET BULB ZERO
LEVELS (ABOVE 12KFT) ENSURE A DEEP WARM CLOUD LAYER AND THUS
RAINFALL EFFICIENCY. DYNAMICAL SUPPORT FOR DEEP-LAYER LIFT WILL BE
LACKING...AND AS SUCH THE TOTAL EXPECTED RAINFALL ACROSS THE
OUTLOOK AREA WILL AVERAGE UNDER 2 INCHES. HOWEVER...ISOLATED
RAINFALL RATES OF 2-2.5 INCHES WITHIN AN HOUR AND/OR 3-4+ INCHES
WITHIN 3 HOURS WILL LEAD TO SOME SHORT-TERM RUNOFF ISSUES...AS
SOME OF THE HIGHER RESOLUTION/MESOSCALE GUIDANCE INDICATE ISOLATED
24 HOUR AMOUNTS ABOVE 4 INCHES (INCLUDING THE 4KM NAM
CONEST...WRF-ARW...AND NSSL WRF).


...UPPER MISSISSIPPI VALLEY...

AN UPPER TROUGH ACROSS THE NORTHERN PLAINS WILL PUSH SLOWLY E-SE
ACROSS THE UPPER MIDWEST DURING THE PERIOD. AS A RESULT...THE AXIS
OF ANOMALOUS PW VALUES (BTWN 1.5-1.75 INCHES) AND HIGHER LLVL
THETA-E ALONG THE TROWAL ZONE REMAIN ACROSS THE AREA THROUGH EARLY
TUE. THE PRE-FRONTAL LLVL INFLOW NEARLY PARALLEL TO AND AT TIMES
EXCEEDING THE MEAN 850-300 MB FLOW WILL CONTINUE TO ALLOW FOR SLOW
PROGRESSION OF THE CONVECTIVE CLUSTERS...AND AS SUCH ISOLATED
RAINFALL RATES AROUND 2 INCHES WITHIN AN HOUR AND/OR 3-4 INCHES
WITHIN 3 HOURS WILL LIKELY LEAD TO LOCALIZED SHORT-TERM RUNOFF
ISSUES. OTHERWISE...AREAL AVERAGE RAINFALL ACROSS THE OUTLOOK AREA
WILL RANGE BETWEEN 1-1.5 INCHES.


...SOUTHWEST...


DRAWN BY SOUTHERLY FLOW AHEAD OF AN UPPER LOW DROPPING SOUTH ALONG
THE CA COAST... A WEALTH OF MONSOONAL MOISTURE WILL LIFT INTO
ARIZONA TODAY AND ESPECIALLY DURING THE AFTERNOON AND OVERNIGHT.
WHILE DIFFERING SOMEWHAT WITH THE DETAILS (DEPENDING ON THE MODEL
RESOLUTION)...THE GUIDANCE REMAINS FAIRLY CONSISTENT WITH THE
HEAVY RAINFALL SIGNAL ACROSS THIS REGION. AREAL-AVERAGE TOTALS ON
A 20 KM SCALE AREA EXPECTED TO RANGE ANYWHERE BETWEEN .25 AND 1.5
INCHES ACROSS THE OUTLOOK AREA (HIGHEST ALONG AND SOUTH OF THE
MOGOLLON RIM)...HOWEVER...ISOLATED TOTALS OVER 4 INCHES WERE NOTED
ON ALL OF THE HIGHER RESOLUTION MODELS. AS PWATS CLIMB TO 1.5-1.75
INCHES...ISOLATED RAINFALL RATES AROUND 2 INCHES PER HOUR AND/OR
2-4 INCHES WITHIN 3 HOURS WILL LEAD TO LOCALIZED FLASH FLOODING.

FOR FURTHER DETAILS REGARDING ANY ACTIVE MESOSCALE PRECIPITATION
DISCUSSIONS (MPD) WITHIN THE EXCESSIVE RAINFALL OUTLOOK
AREAS...PLEASE REFER TO THE LINK FROM THE WPC HOME PAGE ABOVE THE
TOP NEWS OF THE DAY... OR GO DIRECTLY TO THE MPD PAGE:
WWW.WPC.NCEP.NOAA.GOV/METWATCH/METWATCH_MPD.PHP.

HURLEY
$$




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