Quantitative Precipitation Forecast
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000
FOUS30 KWBC 200553
QPFERD

EXCESSIVE RAINFALL DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1252 AM EST SAT DEC 20 2014

...VALID 06Z SAT DEC 20 2014 - 12Z SUN DEC 21 2014...
...REFERENCE AWIPS GRAPHIC UNDER...DAY 1 EXCESSIVE RAINFALL...


SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
45 E TDO 15 S CZK 45 WNW RDM 60 NE MFR 35 ENE MFR 35 ENE SXT
15 S RBG 35 SW MFR 40 SW MFR 35 ESE CEC CEC 25 S OTH ONP
10 SW S47 25 N AST 15 E UIL CLM 25 SSE CLM 10 WNW OLM TDO
10 ESE TDO 15 ESE RNT SMP 45 E TDO.

SLIGHT RISK OF RAINFALL EXCEEDING FFG TO THE RIGHT OF A LINE FROM
35 ESE ALW 20 ESE 5J0 20 SW 5J0 25 NW 5J0 15 WSW MEH ALW
35 ESE ALW.



WA TO NRN CA COASTAL RANGES INTO THE WA/OR CASCADES AND BLUE MTNS
OF OREGON...

A POWERFUL 150+ KT E/W UPR JET WILL TAKE AIM AT THE PAC NW COAST
THIS PD AND WITH IT WILL COME A SIGNIFICANT HEAVY TO EXCESSIVE
RAINFALL EVENT FOR MUCH OF THE COASTAL RANGES AND CASCADES.
MODELS SURPRISINGLY SEEM TO HAVE HAD A GOOD HANDLE ON THIS SYSTEM
FOR THE PAST SEVERAL RUNS..AND CONTINUE TO SHOW RATHER GOOD MASS
FIELD AGREEMENT.  SATL INDICATES A DEEP/LONG MSTR FETCH EMANATING
FROM THE SUBTROPICS BEING RAPIDLY DIRECTED INTO COASTAL AREAS OF
WA INTO NRN CA ON SAT.  LEAD EMBEDD S/WV BRINGS LOW PRES AND ASSOC
COLD FRONT TOWARD COASTAL AREAS BY LATE SAT..BUT LITTLE IN THE WAY
OF DRYING IS EXPECTED BEHIND THE SYSTEM AS WAA LIFT QUICKLY ENSUES
SAT NIGHT WITH ANOMALOUSLY HIGH MSTR TRANSPORT 3-4 STDS ABOVE
NORMAL CONTINUING TO FOCUS ACRS THE PAC NW COAST..ESPECIALLY OVER
OREGON.  THE DEEP LAYERED AND VERY STG WLY FLOW WITH 85H WINDS
INCREASING TO 40-50 KTS WILL LEAD TO VERY STG OROGRAPHIC LIFT
THROUGH MUCH OF THE COASTAL RANGES INTO THE CASCADES.  LEANED
HEAVILY TOWARD SSEO MEAN AND CONTINUITY TO SMOOTH OUT SMALL
MESOSCALE DIFFERENCES WHILE MAINTAINING BETTER OROGRAPHIC DETAIL.
THE FCST AMOUNTS COMPARE FAVORABLY WITH DOWNSCALED REFORECAST GFS
AMOUNTS WITH AREAL AVG AMOUNTS OVER PORTIONS OF THE WA/OR/NRN CA
COASTAL RANGES INTO THE WA/OR CASCADES EXPECTED TO FALL IN THE 3
TO 5 INCH PLUS RANGE THIS PD.  SNOW LEVELS ARE EXPECTED TO RISE
WITH THE INCREASED PAC ONSHORE FLOW/WAA AND THE COMBINATION OF
EXPECTED VERY HEAVY RAINFALL AND SNOW MELT WILL LIKELY LEAD TO
RUNOFF ISSUES OVER LOWER ELEVS OF THE CASCADES AS WELL AS OVER THE
COASTAL RANGES.  FARTHER E...EXPECT COMBO OF HEAVY RAIN...OVER 2
INCHES IN SOME SPOTS...AND SNOW MELT TO LEAD TO PSBL RUNOFF
PROBLEMS ACRS LOWER ELEVS AROUND THE BLUE MTNS OF ERN OREGON.

SULLIVAN
$$




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