Area Forecast Discussion
Issued by NWS Portland, OR

Current Version | Previous Version | Text Only | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50

000
FXUS66 KPQR 222006
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1205 PM PST MON DEC 22 2014

UPDATED KPDX APPROACHES SECTION OF AVIATION DISCUSSION

.SYNOPSIS...PRECIPITATION HAS TAPERED OFF CONSIDERABLY THIS MORNING
AS AN UPPER LEVEL RIDGE BUILDS IN THE NORTHEAST PACIFIC AND UP
INTO THE GULF OF ALASKA. THIS HAS WEAKENED THE STALLED FRONTAL
BOUNDARY OVER CENTRAL OREGON AND IS SQUEEZING OFF THE SUPPLY OF
MOISTURE. THE STALLED FRONTAL BOUNDARY WILL LIFT NORTH AGAIN LATE
TODAY AND TONIGHT AS A WEAK FRONT AND MAY PRODUCE SOME AREAS OF LIGHT
RAIN. THE NEXT COLD FRONT WILL MOVE INTO WESTERN WASHINGTON ON
TUESDAY AND BEGIN TO AFFECT THE FAR NORTH PART OF OUR FORECAST
AREA...SLOWLY SAG FARTHER SOUTH INTO OUR AREA TUESDAY NIGHT...THEN
SWEEP THROUGH SW WASHINGTON AND NORTHWEST OREGON WITH A GOOD SHOT OF
RAIN AND LOWERING SNOW LEVELS ON WEDNESDAY AND EARLY WEDNESDAY NIGHT.
ANOTHER DISTURBANCE WILL BRING SOME SHOWERS TO THE AREA THURSDAY
NIGHT AND FRIDAY. THEN ANOTHER DECENT SYSTEM IS LIKELY BY THE
WEEKEND. SNOW LEVELS WILL BE LOWERING DURING THE SECOND HALF OF THE
WEEK...POSSIBLY AFFECTING THE CASCADE FOOTHILLS AND THE COAST RANGE.
&&

.SHORT TERM...UPPER LEVEL RIDGING IS BUILDING OVER THE NE PAC AND PAC
NW TODAY. THE FRONTAL BOUNDARY THAT WAS THE FOCUS OF THE HEAVY
RAINFALL OVER THE WEEKEND STALLED OVER THE LANE COUNTY CASCADES LAST
NIGHT AND BROUGHT SOME ADDITIONAL MODERATE RAINFALL. HOWEVER THE
PRECIPITATION HAS TAPERED OFF CONSIDERABLY THIS MORNING AS THE
BOUNDARY HAS WEAKENED AND THE AVAILABLE MOISTURE HAS WANED. LOW
CLOUDS AND PATCHY FOG FORMED OVER MUCH OF THE LOWLANDS AND ALONG THE
COAST EARLY THIS MORNING. WITH THE BUILDING HIGH PRES AND LITTLE IN
THE WAY OF LOW LEVEL FLOW EXPECTED TODAY...THE CLOUDS WILL LIKELY BE
SLOW TO CLEAR FOR THE INLAND VALLEYS. THE CEILINGS SHOULD EVENTUALLY
LIFT SOMEWHAT...BUT THE CLOUDS MAY STAY IN PLACE THROUGH MOST OF THE
DAY.

THE STALLED BAROCLINIC ZONE IS FORECAST TO SLOWLY LIFT NORTH
LATER TODAY AND TONIGHT AS A WEAK WARM FRONT AHEAD OF THE NEXT
SYSTEM. THE MODELS HAVE BEEN PERSISTENT AND COMING INTO BETTER
AGREEMENT WITH THE DETAILS OF SOME AREAS OF LIGHT RAIN SPREADING
NORTH THROUGH THE AREA TONIGHT INTO EARLY TUESDAY. AMOUNTS WILL BE
QUITE LIGHT.

THE COLD FRONT WITH THE NEXT SYSTEM WILL MOVE INTO WESTERN WASHINGTON
ON TUESDAY...BRUSHING OUR FAR NORTHERN ZONES...ESPECIALLY NORTH OF
PORTLAND. THIS FRONT SAGS VERY SLOW SOUTHWARD ON TUESDAY NIGHT...NOT
MAKING MUCH SOUTHWARD PROGRESS. THEN A TRAILING SHORT WAVE ON THE
TAIL OF THE FRONT DEVELOPS INTO A NEW LOW ALONG THE FRONT THAT THEN
SWEEPS THROUGH SOUTHWEST WASHINGTON AND NORTHWEST OREGON WEDNESDAY
AND EARLY WEDNESDAY NIGHT FOR A GOOD SHOT OF RAIN. RAINFALL AMOUNTS
OF A HALF INCH OR MORE ARE LIKELY...WITH SOME AREAS AROUND AN INCH.
SNOW LEVELS WILL FINALLY BE FALLING TO MORE SEASONAL VALUES ON
WEDNESDAY AND WEDNESDAY NIGHT...LIKELY AFFECTING THE CASCADE
FOOTHILLS AND THE COASTAL MOUNTAINS. SNOW AMOUNTS COULD REACH SNOW
ADVISORY THRESHOLDS WITH THIS SYSTEM IN THE CASCADES. PYLE/TOLLESON
&&

.LONG TERM...SOME SHOWERS WILL LINGER ON CHRISTMAS DAY BEHIND THE
RATHER VIGOROUS WEDNESDAY SYSTEM. THE MODELS ARE NOW ALL SHOWING A
SHORT WAVE DROPPING IN FROM THE NORTHWEST LATER THURSDAY NIGHT AND
FRIDAY FOR MORE SHOWERS. SNOW LEVELS WILL REMAIN NEAR OR A BIT BELOW
SEASONAL VALUES...WITH SNOW INTO THE CASCADE FOOTHILLS AND COASTAL
MOUNTAINS. THE MODELS ARE COMING INTO BETTER AGREEMENT FOR ANOTHER
COOL SYSTEM BY EARLY IN THE WEEKEND FOR MORE RAIN AND CASCADE
SNOW...WITH SNOW LEVELS REMAINING MORE SEASONAL. THE MODELS ARE NOW
SHOWING MORE DRYING EARLY NEXT WEEK WITH SOME EAST WINDS POSSIBLE.
FOR NOW HAVE LOWERED POPS FOR EARLY NEXT WEEK. TOLLESON
&&

.HYDROLOGY...RIVERS ARE MOSTLY RECEDING THIS MORNING...AND THE FLOOD
WATCH HAS BEEN CANCELLED. THE ONLY RIVERS REMAINING ABOVE FLOOD STAGE
ARE THE MARYS RIVER NEAR PHILOMATH AND THE LUCKIAMUTE NEAR SUVER.
THESE ARE RECEDING VERY SLOWLY AT BEST AND WILL REMAIN ABOVE FLOOD
STAGE FOR A WHILE TODAY. TOLLESON
&&

.AVIATION...JUST ENOUGH CLEARING TOOK PLACE EARLY THIS MORNING TO
ALLOW FAIRLY WIDESPREAD IFR CIGS/VSBYS TO DEVELOP IN THE
WILLAMETTE VALLEY. TOPS APPEAR TO BE BETWEEN 1000-1500 FT MSL.
WITH INCOMING SOLAR ENERGY BEING AS LOW AS IT GETS ALL YEAR...IT
MAY BE A TALL ORDER TO BURN OFF THE LOW CLOUDS. HIGH PRESSURE WILL
KEEP WINDS LIGHT AND PREVENT MUCH IN THE WAY OF MIXING. THEREFORE
WILLAMETTE VALLEY TERMINALS CAN EXPECT IFR/LOW MVFR CIGS TO
PERSIST TO AROUND 22Z...OR POSSIBLY ALL DAY. THE COAST IS ACTUALLY
SEEING BETTER CONDITIONS DUE TO WEAK OFFSHORE FLOW...MAINLY VFR.
WITH LOW-LEVEL AIR MASS REMAINING MOIST AND WINDS REMAINING
LIGHT...EXPECT IFR TO REDEVELOP MOST AREAS OVERNIGHT. SOME
-RA/-DZ FROM A WEAK WARM FRONT MAY CONTRIBUTE TO LOWER CIGS/VSBYS
OVERNIGHT AND EARLY TUE MORNING.

KPDX AND APPROACHES...UPDATED 2005Z...APPEARS LOW CLOUDS HAVE
CLEARED OUT A TAD EARLIER THAN EXPECTED IN AND AROUND KPDX. STILL
VERY MOIST IN THE LOW LEVELS...SO WOULD NOT BE SURPRISED TO SEE SOME
SCT/BKN CLOUDS NEAR 015 OCCASIONALLY BRINGING BRIEF PERIODS OF MVFR.
HOWEVER THE PREVAILING CONDITION SHOULD BE VFR THROUGH EARLY THIS
EVENING...WITH CONDITIONS DETERIORATING TO IFR/LOW MVFR OVERNIGHT AS
FOG AND LOW CLOUDS RE-FORM ACROSS THE KPDX METRO.  WEAGLE

&&

.MARINE...HIGH PRESSURE LEADING TO LIGHT WINDS OVER WATERS TODAY.
WARM FRONT WILL LIFT N ACROSS THE WATERS THIS AFTERNOON AND
EVENING...WITH ANOTHER RIDGE OF HIGH PRESSURE POKING NORTHWARD
FROM THE CALIFORNIA WATERS. APPROACHING COLD FRONT COULD PUSH
S WINDS TO SCA CRITERIA IN OUR NORTHERN WATERS TUE AFTERNOON AND
EVENING...BUT IT WILL BE MARGINAL. SOME MODELS ARE DEVELOPING LOW
PRESSURE ALONG THE FRONT AS IT PUSHES ACROSS THE S OR/N CA
WATERS...WHILE STRONG HIGH PRESSURE BUILDS IN BEHIND THE FRONT.
THIS COULD RESULT IN GUSTY N-NW FLOW MIDWEEK. A BIT OF A BREAK IN
THE WEATHER IS EXPECTED THU INTO FRI...BUT MODELS ARE STARTING TO
AGREE THAT A STRONGER LOW PRES/FRONTAL SYSTEM MAY PUSH THROUGH THE
COASTAL WATERS LATER FRI INTO SAT.

RESIDUAL SWELL FROM THE STORM SYSTEMS IN THE GULF OF ALASKA
FRI/SAT CONTINUES TO PRODUCE 10-13 FT SEAS WITH PERIODS AROUND 13
SECONDS. NEXT SWELL FRONT FROM A SYSTEM NEAR THE ALEUTIANS WILL
ARRIVE THIS EVENING...KEEPING W-NW SWELL 10-13 FT THROUGH TUE.
THEREFORE THE SCA FOR SEAS WILL CONTINUE THROUGH TUE...POSSIBLY
LONGER IF LOW PRES DEVELOPS NEAR HAIDA GWAII TUE AS THE 00Z/12Z
GFS HAVE BEEN SUGGESTING.  WEAGLE

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...COASTAL FLOOD ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR
     CENTRAL OREGON COAST-NORTH OREGON COAST.

WA...COASTAL FLOOD ADVISORY UNTIL 4 PM PST THIS AFTERNOON FOR SOUTH
     WASHINGTON COAST.

PZ...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 6 PM PST TUESDAY
     FOR COASTAL WATERS FROM CAPE SHOALWATER WA TO FLORENCE OR OUT
     60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR UNTIL 6 PM
     PST TUESDAY.

&&

$$

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/NWSPORTLAND
WWW.TWITTER.COM/NWSPORTLAND


THIS DISCUSSION IS FOR NORTHWEST OREGON AND SOUTHWEST WASHINGTON
FROM THE CASCADE CREST TO 60 NAUTICAL MILES OFFSHORE. THE AREA IS
COMMONLY REFERRED TO AS THE FORECAST AREA.
COMMONLY REFERRED TO AS THE FORECAST AREA.



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.