Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 281810
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1008 AM PST SAT FEB 28 2015

.SYNOPSIS...A DEEP UPPER TROUGH CONTINUES TO DIG SOUTHWARD INTO
CALIFORNIA...WITH HIGH PRESSURE SETTLING INTO THE PACIFIC NORTHWEST
BEHIND IT. DRY NORTHERLY FLOW WILL LEAD TO PLENTY OF SUNSHINE THIS
WEEKEND...WITH SEASONABLY COOL NIGHTS AND AFTERNOON TEMPERATURES IN
THE 50S FOR THE LOWLANDS. A WEAKER UPPER TROUGH WILL DIG DOWN THE
BRITISH COLUMBIA COAST SUNDAY...WITH INCREASING HIGH CLOUDS LATER
SUNDAY. SOME LIGHT RAIN AND MOUNTAIN SNOW WILL BE POSSIBLE SUNDAY
NIGHT AND MONDAY...WITH SNOW LEVELS AS LOW AS THE FOOTHILLS. HOWEVER
ANY SNOW ACCUMULATIONS SHOULD BE VERY LIGHT. ANOTHER DRY SPELL IS
EXPECTED THEREAFTER AS ANOTHER STRONG HIGH PRESSURE SYSTEM BUILDS
OVER THE REGION FOR MUCH OF THE COMING WEEK.

&&

.MORNING UPDATE...SKIES HAVE CLEARED ACROSS MOST OF THE FORECAST AREA
THIS MORNING AS HIGH PRESSURE AND DRY NORTHERLY FLOW TAKES OVER. SOME
LINGERING CLOUDINESS NEAR WILLAMETTE PASS MAY STILL PRODUCE A FLURRY
OR TWO OVER THE NEXT COUPLE HOURS...BUT SKIES SHOULD CLEAR THERE BY
THIS AFTERNOON. ADJUSTED THE GRIDS ACCORDINGLY. THE CLEAR SKIES AND
DECREASING WIND SHOULD ALLOW TEMPS TO FALL BELOW FREEZING TONIGHT FOR
MOST OF THE OUTLYING VALLEYS... WHILE URBAN AREAS HOVER NEAR OR JUST
ABOVE FREEZING. SOME PATCHY FOG IS POSSIBLE IN SHELTERED VALLEYS
TONIGHT AND SUN MORNING.

FORECAST DISCUSSION BELOW REMAINS ON TRACK FOR SUNDAY AND BEYOND...
MODELS STILL SHOW A WEAK SYSTEM DIGGING DOWN THE COAST SUNDAY NIGHT
AND MONDAY. 12Z NAM BUFR SOUNDINGS INDICATE SOME PRETTY LOW FREEZING
LEVELS AS PRECIP TRIES TO MOVE IN...SO THE FOOTHILLS ABOVE 1500-2000
FEET MAY GET A LIGHT DUSTING OF SNOW BY MONDAY MORNING. DRIER WEATHER
WILL BE QUICK TO RETURN AS ANOTHER STRONG HIGH PRESSURE SYSTEM BUILDS
DOWN FROM WESTERN CANADA.

SNOW TOTALS THURSDAY AND FRIDAY WERE LESS THAN IMPRESSIVE...BUT
GIVEN OUR SNOW DROUGHT WE DECIDED TO PUT TOGETHER A PUBLIC
INFORMATION STATEMENT (PDXPNSPQR) FOR THOSE CURIOUS HOW MUCH SNOW
THE CASCADES RECEIVED THE PAST COUPLE DAYS.  WEAGLE

.SHORT TERM...ECHOES ON NATIONAL WEATHER SERVICE DOPPLER RADAR HAVE
DECREASED DRAMATICALLY EARLY THIS MORNING AS AN UPPER LEVEL LOW THAT
HAD BEEN OVER THE PACIFIC NORTHWEST ON FRIDAY WAS MOVING SOUTH OF THE
AREA. CLOUDS WILL BE DECREASING FROM THE NORTH THIS MORNING. A FEW
LINGERING SHOWERS ARE POSSIBLE THIS MORNING IN THE OREGON CASCADES
BEFORE THE CLOUDS COMPLETELY CLEAR. OTHERWISE LOOK FOR INCREASING
SUNSHINE TODAY WITH BREEZY NORTHEAST WINDS ACROSS THE AREA.

AN UPPER LEVEL RIDGE WILL HAVE ITS AXIS OFFSHORE ALONG 140W THROUGH
AT LEAST THE SHORT TERM PERIOD WITH COOL NORTHERLY FLOW ALOFT ACROSS
THE PACIFIC NORTHWEST IN THE WAKE OF THE DEPARTING LOW. THE OFFSHORE
FLOW WILL DECREASE TONIGHT AND SUNDAY...THEN START TO TURN ONSHORE
LATE SUNDAY AND ESPECIALLY SUNDAY NIGHT AS A SHORT WAVE DROPS SOUTH
ALONG THE COAST SUNDAY NIGHT INTO MONDAY...MOVING SOUTH OF THE AREA
BY LATER MONDAY. THIS SYSTEM APPEARS IT WILL HAVE ENOUGH OVERWATER
TRAJECTORY TO GIVE OUR AREA SOME PRECIPITATION. DUE TO THE PATH OF
THIS SYSTEM...THE MODELS FOCUS THE BEST QPF OVER THE COAST WATERS
AND ALONG THE COAST...WITH SOME PRECIPITATION SPREADING INLAND AS
WELL. THE ECMWF MODEL IS THE MOST BULLISH IN PUSHING PRECIPITATION
INLAND...WHILE THE GFS IS THE LEAST BULLISH. HAVE OPTED FOR A BLEND
RIGHT NOW. SNOW LEVELS WILL BE LOW ENOUGH FOR SOME SNOW IN THE
CASCADES TO NEAR OR A BIT BELOW PASS ELEVATIONS. AMOUNTS WILL BE
QUITE MODEST HOWEVER...MUCH LESS THAN WHAT FELL THURSDAY NIGHT AND
FRIDAY. TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
MONDAY NIGHT THROUGH FRIDAY...THE MEAN UPPER RIDGE POSITION RETURNS
TO WHERE IT HAS BEEN MUCH OF THIS WINTER TUE/WED...OVER THE NE
PACIFIC. THEREFORE EXPECT AT LEAST A COUPLE DAYS OF DRY WEATHER
TUE/WED...PROBABLY LONGER. IT APPEARS THE BULK OF THE COLD AIR BEHIND
THE SUN NIGHT/MON SYSTEM WILL STAY EAST OF THE ROCKIES...WITH ONLY A
SMALL PIECE OF IT PUSHING INTO THE MID-COLUMBIA BASIN. THUS EXPECT
NEAR NORMAL TEMPERATURES AND DRY WEATHER THROUGH MIDWEEK... CLEAR AND
CHILLY NIGHTS WITH SUNNY DAYS AND AFTERNOON TEMPS IN THE 50S FOR THE
LOWLANDS. OFFSHORE FLOW SHOULD LIMIT FOG FORMATION. HELD POPS BELOW
CLIMO TOWARD THE END OF THE WEEK AS MODELS CONTINUE TO SHOW THE MEAN
RIDGE POSITION ANCHORED NEAR THE WEST COAST.  WEAGLE
&&

.AVIATION...LOW PRES OVER N CALIFORNIA CONTINUES TO SLIDE SOUTHWARD
THIS MORNING...WHICH HAS ALLOWED NORTHERLY WINDS TO PUSH SOUTHWARD
ACROSS THE AREA THIS AM. THIS HAS CLEARED OUT MOST OF THE CLOUD
COVER FOR VFR CONDITIONS ACROSS THE AREA. THERE HAS BEEN  SOME
PATCHY FOG OBSERVED SOUTH OF CORVALLIS...BUT THIS IS QUICKLY
CLEARING OUT THIS MORNING. VFR CONDITIONS WILL CONTINUE THROUGH THE
DAY TODAY. WINDS WEAKEN THROUGH THE DAY TODAY WHICH WILL ALLOW FOR
SOME PATCHY FOG TO DEVELOP OVERNIGHT TONIGHT. THIS COULD BRING CIGS
AND VIS DOWN AT INLAND SITES TO IFR/LIFR IF FOG DEVELOPS OVER TAF
SITES...BUT EAST WINDS AT KPDX AND KTTD WILL KEEP THESE SITES VFR.
OFF-SHORE NORTHEASTERLY WINDS ALONG THE COAST WILL PROBABLY STILL BE
STRONG ENOUGH TO KEEP COASTAL SITES PRIMARILY VFR OVERNIGHT TONIGHT.

KPDX AND APPROACHES...VFR CONDITIONS THIS MORNING WILL CONTINUE
THROUGH TONIGHT. WILL SEE EAST WINDS PICK UP A BIT AFTER
18Z...BUT GENERALLY IN 10 TO 15 KT RANGE. NO CHANGE TONIGHT WITH
VFR AND DRY EAST WINDS. -MCCOY

&&

.MARINE...LOW PRES OVER S OREGON/N CALIFORNIA COAST WILL CONTINUE
SLIDING SOUTHWARD TODAY ALLOWING THE PRESSURE GRADIENT TO RELAX
OVER THE OREGON AND WASHINGTON COASTAL WATERS. THIS WILL WEAKEN
WINDS BACK DOWN BELOW 20 KTS BY THIS EVENING IN THE NORTHERN
WATERS...AND LATER TONIGHT IN THE SOUTHERN WATERS. SEAS AT BUOY 89
HAVE BEEN HANGING AROUND 9-10 FT THIS MORNING...BUT SHOULD BE
DROPPING THROUGH THE DAY TODAY SO WILL ALLOW SMALL CRAFT ADVISORY
FOR SEAS TO EXPIRE AT 10 AM.

HIGH PRES BUILDS BACK OVER THE NE PAC MONDAY AND TUESDAY. A WEAK
SYSTEM MOVES THROUGH SUNDAY NIGHT INTO EARLY MONDAY PRIMARILY JUST
SHIFTING WINDS FROM NNE TO NNW FOR THE BEGINNING OF NEXT WEEK.
SEAS EXPECTED TO FALL BACK DOWN AND STAY WELL BELOW 10 FT THROUGH
MIDWEEK. -MCCOY

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 3 PM PST THIS AFTERNOON
     FOR WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR FROM 10
     TO 60 NM.

     SMALL CRAFT ADVISORY FOR WINDS UNTIL 9 PM PST THIS EVENING FOR
     WATERS FROM CASCADE HEAD TO FLORENCE OR FROM 10 TO 60 NM.

&&

$$

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.



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