Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 242126
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND
225 PM PDT SUN MAY 24 2015

.SYNOPSIS...AN UPPER LEVEL LOW IN SOUTHERN B.C. THIS AFTERNOON WILL
SLOWLY MOVE INTO EASTERN WASHINGTON MONDAY AND INTO IDAHO LATER
TUESDAY AND WEDNESDAY. THIS WILL MAINTAIN THE LOW LEVEL ONSHORE FLOW
ACROSS SOUTHWEST WASHINGTON AND NORTHWEST OREGON FOR THE NEXT SEVERAL
DAYS WITH LITTLE OR NO CLEARING IN THE AFTERNOONS. IT WILL ALSO
PROVIDE THE POSSIBILITY OF SOME NIGHT AND MORNING DRIZZLE OVER THE
AREA...AS WELL AS A FEW LATE DAY SHOWERS OR EVEN A THUNDERSTORM IN
THE HIGHER CASCADES. AN UPPER LEVEL RIDGE WILL MOVE INTO THE PACIFIC
NORTHWEST DURING THE SECOND HALF OF THE WEEK...WEAKENING THE ONSHORE
FLOW AND ALLOWING MORE SUNSHINE TO BREAK THROUGH WITH TEMPS WARMING
ABOVE NORMAL. SOUTHWEST FLOW ALOFT NEXT WEEKEND MAY BRING A RETURN TO
THE MARINE LAYER AND POSSIBLY A FEW THUNDERSTORMS OVER THE CASCADES
AGAIN.
&&

.SHORT TERM...WE HAVE SEEN A NEAR REPEAT OF THE LAST FEW DAYS AS
CLOUDY CONDITIONS COVER MOST OF SOUTHWEST WASHINGTON AND NORTHWEST
OREGON THIS AFTERNOON. THERE ARE SOME THINNING SPOTS NEAR THE NORTH
OREGON COAST RANGE BUT SUSPECT THAT ANY CLEARING THIS AFTERNOON AND
EVENING WILL BE LIMITED. ONSHORE FLOW CONTINUES TO BE MODERATELY
STRONG AS ANOTHER LOW IS IN SOUTHERN B.C.  THIS LOW HAS ALSO TURNED
THE WINDS ALOFT TO MORE WEST AND NORTHWESTERLY AS WELL WHICH IS
MAINTAINING THE ONSHORE FLOW. SOME CONVECTION IS TRYING TO DEVELOP
ALONG THE EAST SLOPES OF THE CASCADES THIS AFTERNOON BUT IS DRIFTING
OFF TO THE EAST. ANY THREAT THIS AFTERNOON AND EVENING WILL BE
CONFINED TO NEAR THE CREST.

TEMPS ARE RUNNING CLOSE TO THOSE SATURDAY...BUT THE THIN SPOTS MAY
ALLOW A FEW AREAS TO REACH THE MID 60S THIS AFTERNOON.

THE SOUTHERN B.C. LOW WILL DROP INTO CENTRAL AND EASTERN WASHINGTON
ON MONDAY...REINFORCING THE STRONG ONSHORE FLOW AND THE POSSIBILITY
NIGHT AND MORNING DRIZZLE AROUND THE AREA. BELIEVE THE CLOUDS WILL
HAVE A TOUGH TIME BREAKING UP MONDAY...WITH TEMPS STAYING IN THE LOW
TO MID 60S. WITH THE LOW CENTERED IN CENTRAL AND EASTERN
WASHINGTON...WE MAY SEE OUR NORTHERN CASCADES ZONES MAINLY NEAR THE
CREST CLIPPED BY A FEW SHOWERS OR THUNDERSTORMS IN THE FLOW ON THE
BACKSIDE OF THE LOW.

THE LOW IS MOVING INTO IDAHO BY LATER TUESDAY. THE ONSHORE FLOW
SHOULD CONTINUE...THOUGH WE MIGHT SEE A FEW MORE SUN BREAKS LATE IN
THE DAY AND THE EVENING VS MONDAY...AND THIS MAY ALLOW TEMPS TO GET
CLOSER TO 70. THE BIT MORE SUNSHINE IN THE HIGHER CASCADES COMBINED
WITH THE RETURN FLOW ON THE BACK SIDE OF THE LOW WILL MAINTAIN A
CHANCE OF LATE DAY SHOWERS OR THUNDERSTORMS NEAR THE CREST OF OUR
NORTHERN CASCADE ZONES.

ON WEDNESDAY THE LOW IS FARTHER EAST...AND 500 MB HEIGHTS CLIMB AS
WELL. WE SHOULD SEE MORE CLEARING INLAND IN THE AFTERNOON...AND
INLAND TEMPS SHOULD HAVE A CHANCE TO REACH AT LEAST THE MID 70S AND
POSSIBLY HIGHER. WE STILL HAVE A CHANCE OF SOME LATE DAY SHOWERS OR
THUNDERSTORMS IN THE HIGHER CASCADES CREST...AIDED BY THE INCREASED
SUNSHINE. TOLLESON

.LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...A WEAK RIDGE BUILDS
OVER THE PACNW MIDWEEK...DRYING OUT THE REGION. CONTINUED WEAK
ONSHORE FLOW WILL CONTINUE TO BRING MARINE CLOUDS INLAND
OVERNIGHT...BUT STRATUS SHOULD FOR THE MOST PART CLEAR OUT BY MIDDAY
ALLOWING TEMPERATURES TO REACH INTO THE UPPER 70S AND MAYBE LOW 80S
INLAND. A THERMAL LOW DEVELOPS IN NORTHERN CALIFORNIA ON THURSDAY AND
STARTS TO PUSH NORTHWARD ON FRIDAY AND SATURDAY...WHICH COULD HELP
DEVELOP SOME AFTERNOON SHOWERS AND MAYBE A FEW THUNDERSTORMS ALONG
THE CREST OF THE CASCADES ON FRIDAY THROUGH SUNDAY. BACKGROUND FLOW
WILL BE OUT OF THE WEST-NORTHWEST THOUGH...WHICH SHOULD KEEP THESE
STORMS FROM DRIFTING WESTWARD INTO THE VALLEY. -MCCOY
&&

.AVIATION...CONDITIONS ACROSS THE REGION ARE CURRENTLY A MIXTURE OF
MVFR/VFR WITH CIGS BETWEEN 020 AND 040. VIS SATELLITE IMAGERY IS
SHOWING SUN BREAKS ALONG THE COAST RANGE AND CENTRAL COAST. THESE
BREAKS LOOK TO SPREAD INTO THE INTERIOR VALLEY OVER THE NEXT SEVERAL
HOURS AND SHOULD ALLOW THE DECK TO SCATTER OUT BRIEFLY THIS
AFTERNOON. HIGH-END MVFR CIGS OVER THE INTERIOR WILL LIFT TO VFR
THROUGH 23Z. MVFR CIGS WILL LIKELY PERSIST OVER THE NORTH COAST THIS
AFTERNOON/EVENING WHILE THE CENTRAL COAST WILL SEE A MIXTURE OF
MVFR/VFR CIGS. ANY VFR CIGS THAT DO DEVELOP THIS AFTERNOON SHOULD
FILL IN AND LOWER AFTER SUNSET. EXPECT CIGS TO FALL BELOW 025
TONIGHT...WITH IFR CIGS AND VSBY POSSIBLE ALONG THE COAST BETWEEN
25/06-15Z. TOMORROW WILL LIKELY BE A REPEAT OF TODAY WITH MVFR CIGS
EARLY AND SUN BREAKS IN THE AFTERNOON.

KPDX AND APPROACHES...MVFR CIGS WILL LIFT TO AROUND 045 THIS
AFTERNOON AND COULD EVEN SCATTER OUT FOR A FEW HOURS. EXPECT ANY
CLEARING TO BE SHORT LIVED WITH MVFR CIGS FALLING BELOW 020 AFTER
25/09Z. VFR CIGS POSSIBLE AFTER 25/18Z. /64
&&

.MARINE...HIGH PRES CONTINUES TO REMAIN OFFSHORE WITH LOW PRES OVER
THE INLAND PAC NW FOR THE NEXT SEVERAL DAYS. EXPECT MILD CONDITIONS
OVER THE WATERS WITH NW WINDS GENERALLY BELOW ADVISORY CRITERIA.
THERE MAY BE BRIEF PERIODS OF ISOLATED ADVISORY GUSTS ABOVE 21 KT
SOUTH OF NEWPORT THIS AFTERNOON/EVENING AND AGAIN TOMORROW
AFTERNOON/EVENING. HOWEVER...DO NOT THINK THEY WILL BE WIDESPREAD
ENOUGH TO WARRANT ISSUING AN ADVISORY. MIXED SEAS WILL CONTINUE
THROUGH MOST OF THIS WEEK...WITH CHOPPY CONDITIONS EXPECTED AT TIMES
DUE TO A FRESH NW SWELL. /64
&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...NONE.

&&

$$

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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