Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 011759
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
958 AM PST SUN MAR 1 2015

.SYNOPSIS...HIGH CLOUDS WILL BE ON THE INCREASE LATER TODAY AFTER A
SUNNY START. A WEAK DISTURBANCE WILL PUSH SOUTHWARD FROM BRITISH
COLUMBIA...CAUSING CLOUDS TO INCREASE AND BRINGING A CHANCE FOR RAIN
AND MOUNTAIN SNOW. WITH THE BRUNT OF THIS SYSTEM TRACKING OFFSHORE
THE BEST CHANCES FOR PRECIPITATION WILL BE NEAR THE COAST. HOWEVER
THIS SYSTEM WILL BE A FAST MOVER...AND SKIES WILL ALREADY BE CLEARING
BY MONDAY AFTERNOON. HIGH PRESSURE AND DRY NORTHERLY FLOW WILL THEN
DOMINATE FOR MUCH OF THE WEEK...THOUGH SOME MODELS HINT AT A SWITCH
TO ONSHORE FLOW AND A BETTER CHANCE FOR RAIN DEVELOPING BY NEXT
WEEKEND.

&&

.MORNING UPDATE...WALL TO WALL SUNSHINE CONTINUES ACROSS THE DISTRICT
THIS MORNING...ASIDE FROM SOME VERY ISOLATED FOG PATCHES IN THE
NEHALEM RIVER VALLEY. INFRARED SATELLITE SHOWS HIGH CLOUDS ALREADY
BEGINNING TO MOVE INTO THE OLYMPIC PENINSULA...THOUGH VISIBLE IMAGERY
SUGGESTS THEY ARE RATHER THIN. HOWEVER MODELS AGREE THAT CLOUDS WILL
GRADUALLY INCREASE AND THICKEN FROM NORTH TO SOUTH LATER THIS
AFTERNOON AND EVENING AS A DISTURBANCE PUSHES SOUTHWARD FROM BRITISH
COLUMBIA. SOME RAIN AND MOUNTAIN SNOW WILL BE POSSIBLE TONIGHT AND
EARLY MONDAY AS THE SYSTEM DIGS SOUTHWARD ALONG THE PAC NW COAST.
BEST CHANCES WILL BE ALONG THE COAST WITH DECREASING POPS FURTHER
INLAND. OVERALL...THE PREVIOUS FORECAST AND DISCUSSION ARE ON
TRACK...THOUGH WE DID WARM UP TODAYS TEMPS SLIGHTLY TO BRING THEM
CLOSER TO PERSISTENCE.WEAGLE

/PREV DISC ISSUED 225 AM PST SUN MAR 1 2015/

.SHORT TERM...THE BREEZY OFFSHORE FLOW OF SATURDAY WAS DECREASING
THIS MORNING AS THE NORTHEAST FLOW ALOFT ON THE NORTH SIDE OF AN
UPPER LOW IN CALIFORNIA CONTINUED TO MOVE AWAY. THIS OFFSHORE FLOW
LOWERED DEWPOINTS ACROSS THE AREA...AND HAS ALLOWED TEMPS TO FALL
CLOSE TO FREEZING IN MUCH OF THE AREA.

OTHERWISE...THE DOMINANT FEATURE AFFECTING THE PACIFIC NORTHWEST THIS
WEEK WILL BE AN UPPER RIDGE WITH ITS AXIS OUT NEAR 140W. THIS IS
PRODUCING A NORTHERLY FLOW ALOFT ACROSS THE PACIFIC NORTHWEST.

A WEAK SHORT WAVE WILL MOVE SOUTH THROUGH THE PACIFIC NORTHWEST TODAY
WITH MAINLY SOME HIGHER CLOUDS. A MORE SUBSTANTIAL SHORT WAVE WILL
DROP SOUTH ALONG THE B.C. COAST TODAY AND MOVE SOUTH ALONG THE
WASHINGTON AND OREGON COASTS TONIGHT. THE TRACK WILL GIVE THE BEST
CHANCE OF RAIN TO THE COASTAL WATERS AND THE COASTAL AREAS...WITH
DECREASING CHANCES INLAND. THIS SYSTEM WILL HAVE SOME COLDER AIR WITH
IT FOR SOME SNOW IN THE MOUNTAINS AND POSSIBLY THE FOOTHILLS AND
COAST RANGE...BUT AMOUNTS WILL BE PRETTY LIGHT AS YOU GO EASTWARD AND
IMPACTS WILL BE LIMITED.

THE SYSTEM MOVES SOUTH OF THE AREA PRETTY EARLY MONDAY FOR
DRAMATICALLY DECREASING SHOWERS AND FOR DECREASING CLOUDS. IT THEN
LOOKS DRY INTO THE MID WEEK PERIOD WITH MAINLY A FEW HIGHER CLOUDS AT
TIMES AS ANOTHER WEAK UPPER DISTURBANCE OR TWO MOVES THROUGH.
TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
TUESDAY NIGHT THROUGH SATURDAY...EXTENDED FORECAST MODELS CONTINUE TO
SHOW MARCH COMING IN LIKE A LAMB FOR THE PACIFIC NORTHWEST. THE MEAN
UPPER RIDGE POSITION LINGERS WHERE IT HAS BEEN MUCH OF THIS
WINTER...OVER THE NE PACIFIC AND ALONG THE WEST COAST. THIS SHOULD
KEEP THE PACIFIC JET STREAM WELL TO OUR NORTH...AS WELL AS ANY
CHANCES OF SIGNIFICANT PRECIPITATION. REMOVED MENTION OF ANY RAIN
FROM THE FORECAST TUESDAY THROUGH SATURDAY. CONDITIONS MAY BECOME
INCREASINGLY FAVORABLE FOR FOG IN THE VALLEYS...AS MOST GUIDANCE
PUSHES THE UPPER RIDGE AXIS ONSHORE LATE IN THE WEEK. OTHERWISE
EXPECT A GRADUAL RETURN TO ABOVE NORMAL TEMPERATURES WHICH MAY LAST
INTO NEXT WEEKEND.  WEAGLE

&&

.AVIATION...LIGHT OFFSHORE WIND WITH VFR THIS MORNING. WILL HAVE
POCKETS OF FOG MAINLY IN COWLITZ VALLEY. WEAK FRONT APPROACHING
FROM THE NW WILL BRING INCREASING CLOUDS THIS AFTERNOON. EXPECT
CIGS TO LOWER TO MVFR AFTER 02Z ALONG THE COAST...AND INLAND
AFTER 05Z. CIGS WILL REMAIN LOW TONIGHT WITH OCCASIONAL LIGHT RAIN
AND OBSCURED HIGHER TERRAIN.

KPDX AND APPROACHES...VFR CONDITIONS TODAY...WITH INCREASING MID
AND HIGH CLOUDS THIS AFTERNOON. WILL SEE INCREASING MVFR CIGS
AFTER 05Z AS FRONT APPROACHES FROM NW. BOWEN/ROCKEY

&&

.MARINE...HIGH PRES OVER THE NE PAC WILL BE THE DOMINANT WEATHER
PLAYER THIS WEEK. HOWEVER...A WEAK FRONT WILL DROP SOUTHWARD
ACROSS REGION TONIGHT INTO MON AM. NOT A LOT OF WIND EXPECTED
WITH FRONT...BUT ENOUGH TO POP 20 TO 25 KT GUSTS OVER THE OUTER
WATERS...MAINLY OFF CENTRAL OREGON COAST. WILL MAINTAIN SMALL
CRAFT ADVISORY FOR THAT AREA AND WATCH WINDS OFFSHORE THE NORTHERN
OREGON COAST FOR ANY SCA NEED THERE. SEAS HOLDING AT 4 TO 6 FT.

ANOTHER WEAK FRONT MAY PUSH INTO THE WATERS THU AND POSSIBLY
AGAIN NEXT WEEKEND...BUT WINDS WILL REMAIN UNDER 20 KT.
BOWEN/ROCKEY

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM MIDNIGHT TONIGHT TO NOON
     PST MONDAY 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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