Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 191008
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
306 AM PDT FRI SEP 19 2014

.SYNOPSIS...HIGH PRESSURE IS NOW BUILDING INTO THE REGION BRINGING
MORE SETTLED WEATHER ACROSS THE AREA. ONE EXCEPTION IS ACROSS SW
WASHINGTON AND THE EXTREME NW OREGON COAST WHERE A FEW LIGHT SHOWERS
MAY OCCUR AS A DYING FRONT MOVES INTO WASHINGTON TODAY. THEN A DRY
AND WARM WEEKEND AS OFFSHORE FLOW STRENGTHENS. COOLER UNSETTLED
WEATHER ON TAP FOR NEXT WEEK.

&&

.SHORT TERM...FOR TONIGHT...VISIBLE SATELLITE IMAGERY SHOWS THE
REGION CAUGHT BETWEEN A LOW PRESSURE SYSTEM MOVING SOUTHWARD OFF THE
CALIFORNIA COAST AND WESTERLY FLOW PUNCHING INTO BRITISH COLUMBIA.
ASIDE FROM THE CENTRAL OREGON COAST...MOSTLY CLOUDY TO CLOUDY SKIES
ABOUND. A LOOP OF DOPPLER RADAR SHOWS MOST SHOWER ACTIVITY HAS
WEAKENED AND MOVED EAST OF THE CASCADES. BUT MAY STILL HAVE A FEW
SHOWERS AROUND...SO WILL LEAVE 20 PCT PROBABILITY FOR TONIGHT OVER
THE MOUNTAINS. WITH CLEAR BREAKS IN THE CLOUD COVER...COMBINED WITH
LIGHT WINDS...WILL HAVE PATCHY FOG TONIGHT INTO FRI AM.

TODAY AND TONIGHT WILL BE A TRANSITION PERIOD FROM ONSHORE TO
OFFSHORE FLOW FOR THE WEEKEND.CURRENT SATELLITE AND SURFACE
ANALYSIS SHOW WEAKENING FRONT ABOUT 150 MI OFF THE WASHINGTON COAST.
THIS FRONT WILL CONTINUE TO MOVE EAST AND LIKELY STALL AND DISSIPATE
NEAR THE WASHINGTON COAST. EXPECT SOME LIGHT PCPN REACHING THE S WA
AND N OREGON COAST TODAY. RAINFALL AMOUNTS LIKELY REMAIN BELOW A
TENTH OF AN INCH FOR THAT AREA. ELSEWHERE IN THE NORTHERN ZONES...A
FAIR AMOUNT OF CLOUDS OVER INTERIOR ZONES TODAY. FURTHER TO THE
SOUTH...CLOUDS MAINLY OVER THE CASCADES WILL DISSIPATE LATER IN THE
DAY DRIER NW FLOW DEVELOPS.

FOR SATURDAY AND SUNDAY...INCREASING OFFSHORE FLOW WILL BRING MUCH
WARMER TEMPERATURES TO THE REGION. EXPECT THE WARMEST TEMPERATURES
ALONG THE COAST AND PERHAPS THE SOUTHERN WILLAMETTE VALLEY ON
SATURDAY. EUGENE WILL STAND A GOOD CHANCE TO ADD TO THEIR RECORD 35
DAYS OF 90F OR PLUS OR HIGHER IN 2014. AS THERMAL LOW PRESSURE SHIFTS
NORTHWARD TO OFF WASHINGTON LATE SATURDAY INTO SUNDAY...COOLER MARINE
AIR SHOULD SPREAD INTO COASTAL LOCATIONS AND PERHAPS THE SOUTHERN
WILLAMETTE VALLEY SUNDAY...THEN ACROSS REST OF REGION SUNDAY EVENING.

EAST WINDS SATURDAY AND MUCH LOWER RELATIVE HUMIDITIES FOR MUCH OF
THE WEEKEND SHOULD ONCE AGAIN PRODUCE CONDITIONS MORE FAVORABLE FOR
WILDFIRE GROWTH...BUT NOT LIKELY EXPLOSIVE GROWTH.  AS A RESULT...AT
LEAST MODEST AMOUNTS OF SMOKE SHOULD SPREAD BACK INTO THE WILLAMETTE
VALLEY FROM THE 36 PIT AND DECEPTION COMPLEX FIRES. MODEL SOUNDINGS
INDICATE A TEMPERATURE INVERSION DEVELOPING AROUND 850-900 MB THIS
WEEKEND RESULTING IN RELATIVELY WARMER OVERNIGHT TEMPERATURES IN THE
CASCADES AND PARTS OF THE COAST RANGE. THE TEMPERATURE INVERSION
SHOULD BREAK IN THE AFTERNOONS TO ALLOW THE AIR MASS TO MIX.  /MH

.LONG TERM...MONDAY THROUGH THURSDAY...COOLER TEMPERATURES AND AN
INCREASE IN CLOUDS ARE EXPECTED TO RETURN TO THE REGION ON MONDAY
AHEAD OF AN APPROACHING UPPER LEVEL TROUGH. THE MODELS CONTINUE TO
HINT AT A WIDESPREAD RAIN EVENT STARTING ON WEDNESDAY...WITH RAIN
LIKELY CONTINUING THROUGHOUT THE EXTENDED PERIOD. TEMPERATURES IN
THE EXTENDED WILL GENERALLY TREND TOWARDS SEASONAL NORMALS.

&&

.AVIATION...CIGS MOSTLY VFR ACROSS SOUTHWEST WASHINGTON AND
NORTHWEST OREGON EARLY THIS MORNING...EXCEPT A MIXTURE OF IFR AND
MVFR CONDITIONS ALONG THE COAST IN ONSHORE FLOW. EXPECT SOME OF
THE MVFR CIGS TO SPREAD INLAND ALONG THE COLUMBIA RIVER AND INTO
THE NORTH VALLEY AREA AROUND OR JUST AFTER SUNRISE THIS MORNING.
CONDITIONS IN THE SOUTH...SUCH AS KONP AND KEUG WILL BE VFR BY
FAIRLY EARLY IN THE AFTERNOON. AREAS IN THE NORTH VALLEY SUCH AS
NEAR KPDX WILL LIFT TO VFR IN THE AFTERNOON...BUT CLOUDS MAY NOT
FULLY CLEAR UNTIL THE EVENING. NORTH COAST AREAS SUCH AS NEAR KAST
MAY STRUGGLE TO LIFT TO VFR CIGS UNTIL MID OR LATE AFTERNOON...AND
MAY SEE SOME SPOTTY LIGHT PRECIPITATION THIS MORNING. CLOUDS LOOK
AS THOUGH THEY WILL PERSIST ALONG THE NORTH COAST TONIGHT WITH
MVFR CONDITIONS AND PATCHY IFR CONDITIONS POSSIBLE. CENTRAL COAST
MAY SEE SOME PATCHY IFR CONDITIONS DEVELOP TONIGHT...WITH PATCHY
LOW CLOUDS INLAND TOWARD SUNRISE.

KPDX AND APPROACHES...VFR CIGS EARLY THIS MORNING...WITH A CHANCE
OF MVFR CIGS FROM ABOUT 13Z OR 14Z UNTIL 17Z OR 18Z. VFR CIGS MAY
THEN CONTINUE UNTIL EARLY AFTERNOON...WITH SCATTERED CLOUDS THE
REMAINDER OF THE AFTERNOON...CLEARING IN THE EARLY EVENING. THERE
IS A CHANCE OF PATCHY CLOUDS AT HIGHER IFR OR LOWER MVFR HEIGHTS
AROUND SUNRISE SATURDAY. PT
&&

.MARINE...WINDS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT CRITERIA
THROUGH THIS MORNING. THERMAL LOW PRESSURE IS EXPECTED TO DEVELOP
ALONG THE NORTHERN CALIFORNIA COAST LATE TODAY AND EXTEND NORTH
ALONG THE OREGON COAST TONIGHT INTO SATURDAY. THIS WILL RESULT
IN SMALL CRAFT ADVISORY NORTHERLIES SPREADING NORTH THROUGH THE
WATERS. WINDS WILL DECREASE SATURDAY AFTERNOON AND NIGHT. A
SOUTHERLY WIND REVERSAL AND STRATUS SURGE WILL THEN MOVE NORTH
ALONG THE OREGON AND WASHINGTON COASTS SATURDAY NIGHT AND SUNDAY.

SEAS ARE EXPECTED TO BE AROUND 5 FT TODAY WITH A MIX OF A LONG
PERIOD SOUTH SWELL AND A SHORTER PERIOD NORTHWEST SWELL. NORTHWEST
SWELL IS THEN FORECAST TO BECOME DOMINANT AS 8 TO 9 FT SEAS BUILD
IN FROM THE NORTHWEST TONIGHT AND SATURDAY. SEAS DROP BACK DOWN TO
5 OR 6 FT SUNDAY AND MONDAY.

SEAS MAY BUILD ABOVE 10 FT BY THE MIDDLE OF NEXT WEEK AS THE
PACIFIC BECOMES MORE ENERGETIC AS A STRONGER STORM APPROACHES...
POSSIBLY PRODUCING THE STRONGEST SOUTHERLY WINDS WE HAVE SEEN IN
SOME TIME. PT
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS FROM 5 PM THIS AFTERNOON TO 9 AM
     PDT SATURDAY FOR COASTAL WATERS FROM CASCADE HEAD OR TO
     FLORENCE OR OUT 60 NM.

     SMALL CRAFT ADVISORY FOR ROUGH COLUMBIA RIVER BAR FROM 1 AM TO
     5 AM PDT SATURDAY.

&&

$$

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 AS THE FORECAST AREA.


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