Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 271359
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
958 AM EDT SUN JUL 27 2014

...VALID 15Z SUN JUL 27 2014 - 12Z MON JUL 28 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
20 SW HLG 25 S AOO 20 NNE ROA 35 NNW OQT 25 ESE AJG 20 NW UNI
20 SW HLG.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
40 ENE CAO 40 ENE LVS 15 SSE SKX 35 SSE MYP 40 W AFF 30 ESE COS
30 SW LAA 40 ENE CAO.


...OH VALLEY TO THE UPSLOPE REGION OF THE APPALACHIANS...

THE MODELS DEVELOP ADDITIONAL CONVECTION LATER TODAY FROM THE
SOUTHERN GREAT LAKES TO THE OH AS THE BETTER JET DYNAMICS APPROACH
THE REGION WITH BETTER INSTABILITY.  WITH PRECIPITABLE WATER
VALUES IN THE 1.75 TO 2 INCH RANGE...LOCALLY HEAVY RAINFALL WILL
BE POSSIBLE...ESPECIALLY IN THE UPSLOPE REGIONS OF THE CENTRAL
APPALACHIANS WHERE THE MOISTURE TRANSPORT INTO THE COMPLEX TERRAIN
IS MAXIMIZED. ENSEMBLES SUPPORT POCKETS OF 2 INCHES OR MORE OVER
WV WHICH SHOULD BE ENOUGH TO PRODUCE AREAS WHERE RAFL EXCEEDS
FLASH FLOOD GUIDANCE.

...WESTERN NY...

A SHORTWAVE ROTATING AROUND THE PERIPHERY OF A CLOSED LOW OVER
QUEBEC WILL PROVIDE THE FOCUS FOR A SEPARATE AREA OF SHOWERS AND A
FEW THUNDERSTORMS AS IT MOVES FROM THE EASTERN GREAT LAKES THIS
MORNING TO EASTERN NEW ENGLAND AND THE CANADIAN MARITIMES THIS
EVENING.  SOUTHERLY FLOW AHEAD OF THE SHORTWAVE AND AHEAD OF THE
AMPLIFYING TROF WILL TRANSPORT MOISTURE INTO THE AREA...AND HIGHER
RESOLUTION GUIDANCE IS SUGGESTING LOCALIZED HIGHER AMOUNTS IN
PARTS OF INTERIOR NEW ENGLAND.

THE WPC PSEDUO BIAS CORRECTED SHOWED A FAIRLY BROAD SWATH OF 2 AND
3 INCH AMOUNTS OVER PARTS OF WESTERN NY WHICH LOOKED OVER DONE.
HOWEVER SOME DOWNPOURS MAY BE CAPABLE OF PRODUCING LOCALIZED
PROBLEMS DUE TO RUNOFF.  THE POSSIBILITY EXISTS FOR ISOLATED
RUNOFF PROBLEMS MAY OCCUR IN THE HILLY TERRAIN OF INTERIOR NEW
ENGLAND GIVEN AMOUNT OF MOISTURE BEING DRAWN INTO THE AREA.

...SOUTHWESTERN U.S TO COLORADO...

WITH THE AMPLIFICATION OF THE UPR TROF THRU THE GREAT LAKES...THE
PRONOUNCED UPR RIDGE OVER THE SRN ROCKIES IS EXPECTED TO EXPAND
NWD INTO THE NRN INTERMOUNTAIN REGION THIS PD. LINGERING MSTR
TRAPPED UNDER THE BUILDING RIDGE WILL MAINTAIN THREAT OF ISOLD TO
SCTD CONVECTION THRU MUCH OF THE 4 CORNERS REGION...MOSTLY DIURNAL
IN NATURE.

MODELS INDICATE WEAK S/WV ENERGY TRACKING WNWWD ALONG THE SRN
PERIPHERY OF THE UPR RIDGE ACRS NRN MEX THAT MAY ENHANCE
CONVECTION OVER SE AZ/SW NM SUN AFTN...OTHERWISE FORCING REMAINS
ILL DEFINED.  ACRS CO AND THE ADJACENT HIGH PLAINS...THERE IS GENL
MODEL AGREEMENT SHOWING ENHANCED SE/E UPSLOPE FLOW BEHIND SWD
MOVING COLD FRONT INTO THE ERN SLOPES OF THE CNTL/SRN CO MTNS ON
SUN WITH PWS INCREASING TO OVER 1.5 INCHES OVER SE CO SUN AFTN.
WHILE THE SPREAD IN MODEL GUIDANCE REMAINS LARGE...THE GFS/ARW AND
STORM SCALE ENSEMBLE AND 27 KM ECMWF GENERATE AT LEAST AN INCH AND
A HALF OF QPF OVER SOUTHEAST CO INTO NORTHEAST NM LATER THIS
EVENING AND INTO THE OVERNIGHT HOURS...SUGGESTING SOME POTENTIAL
FOR FLASH FLOODING.

BANN/JAMES
$$





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