Quantitative Precipitation Forecast
Issued by NWS

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FOUS30 KWBC 222116
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
516 PM EDT WED JUL 22 2015

...VALID 21Z WED JUL 22 2015 - 12Z THU JUL 23 2015...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...

NRN INTERMOUNTAIN REGION...

AN INCREASING AREA OF SHWER/TSTMS ARE LIKELY ALONG AND BEHIND SLOW
MOVING PAC COLD FRONT PUSHING EWD AHEAD OF LONGWAVE UPR TROF ALONG
THE WEST COAST.  BROAD 85H-7H SWLY FLOW WILL DRAW INCREASING MSTR
NEWD ACRS THE REGION FROM THE POOL OF HIER PWS OVER CA...WITH
MODELS INDICATING STRENGTHENING RT ENTRANCE REGION JET DYNAMICS
LATE WED/WED NIGHT ACRS THE NRN GT BASIN INTO PORTIONS OF THE NRN
INTERMOUNTAIN REGION.  BROAD SCALE LIFT COUPLED WITH WEAK
INSTABILITY WILL LEAD TO POCKETS OF HEAVIER EMBDD RAINS ESPECIALLY
OVER PARTS OF MTNS OF ERN ID/SW MT AND WRN WY.  MODELS SUGGEST
AREAL AVG AMOUNTS OF BETWEEN .25 TO .50 INCH WITH ISOLD AMOUNTS
AROUND 1.5 INCHES IN STGR CONVECTIVE STORMS.  AS A RESULT...CAN
NOT RULE OUT ISOLD RUNOFF ISSUES ESPECIALLY OVER FAVORED
OROGRAPHIC AREAS OF WRN WY/SRN ID..AND SW MT.

LOWER/MIDDLE MS VALLEY...

THE AMOUNT AND DEPTH OF MOISTURE THAT CONTAINS PW VALUES NEAR OR
IN EXCESS OF 2 INCHES ALONG WITH SLOW CELL MOTIONS FAVOR RAIN
RATES NEAR OR POSSIBLY HIGHER THAN 2 INCHES PER HOUR FOR SHORT
DURATIONS FROM PORTIONS OF ARKANSAS EAST SOUTHEASTWARD ACROSS
NORTHERN PARTS OF MS/AL TONIGHT WHERE CONVECTION APPEARS MOST
LIKELY.  DUE TO THE LIMITED COVERAGE AND EXPECTED SHORT DURATION
OF THE RAIN RATES...THE PROBABILITY OF EXCEEDING LOCAL FFG VALUES
IS BELOW THE LOWER THRESHOLD FOR SLIGHT AREA.  THUS...THE RISK
AREA IS DENOTED AS SEE TEXT FOR ISOLATED PROBABILITIES.

TERRY/JAMES
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