Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 271153 AAA
AFDPQR

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND
453 AM PDT WED MAY 27 2015

UPDATED AVIATION FOR LOWER CLOUD DECKS THIS MORNING

.SYNOPSIS...PESKY UPPER LOW OVER NRN ROCKIES WILL SLOWLY PUSH
FURTHER EAST. THIS WILL USHER IN DRIER AIR MASS...WITH TEMPERATURES
GRADUALLY WARMING. ANOTHER UPPER LOW WILL APPROACH LATER THIS
WEEKEND...BRING INCREASING ONSHORE FLOW AND CLOUDS WITH COOLER
TEMPERATURES...AND A THREAT OF SHOWERS...FOR EARLY NEXT WEEK.
&&

.SHORT TERM...TONIGHT THROUGH FRIDAY...
THE PESKY PATTERN WITH THE SLOW MOVING UPPER LOW OVER THE NORTHERN
ROCKIES AND EASTERN WASHINGTON WILL SLOWLY PUSH ON TO THE EAST OVER
THE NEXT 24 HOURS. STILL HAVE ENOUGH MOISTURE ROTATING AROUND THE
BACKSIDE OF THE LOW THAT WITH THE AFTERNOON HEATING AND THE UPSLOPE
COMPONENT...WILL SEE A FEW SHOWERS AND MAYBE A THUNDERSTORMS POP OVER
THE SOUTH WASHINGTON CASCADES...AND PERHAPS A BIT FURTHER TO THE
SOUTH OVER THE FAR NORTH OREGON CASCADES. NOT ALL THAT CONFIDENT THAT
WILL SEE MUCH OF ANY SHOWERS TO SOUTH OF MT HOOD AS FLOW BECOMES LESS
FAVORABLE.  BUT WILL KEEP A 20 PERCENT CHANCE THERE WITH BEST THREAT
OVER THE SOUTH WASHINGTON CASCADES. ALL SHOWERS WILL END SOON AFTER
SUNSET THIS EVENING.

OTHERWISE...AFTER MORNING CLOUDS...SHOULD HAVE AN ABUNDANCE OF
SUNSHINE OVER MUCH OF THE REGION TODAY. COAST WILL BE LAST TO LOSE
THE CLOUDS. SHOULD GET INTO THE MID TO UPPER 70S FOR THE INTERIOR
LOWLANDS...BUT COAST WILL HOLD IN THE LOWER TO MID 60S.

ONSHORE FLOW WEAKENS FURTHER ON THU AND FRI...SO SUSPECT THAT THE
MARINE LAYER CLOUDS WILL BE CONFINED TO THE COASTAL AREAS.  THIS LACK
OF CLOUDS INLAND WILL ALLOW TEMPERATURES TO CLIMB INTO THE LOWER TO
MID 80S.  EVEN THOUGH THE UPPER LOW HAS PUSHED OFF TO THE EAST...WILL
STILL HAVE VERY WEAK INSTABILITY OVER AREAS TO EAST OF THE CASCADES
EXTENDING WESTWARD TO THE CASCADES CREST. SO WILL KEEP A VERY MINOR
THREAT OF A SHOWER OVER THE HIGH CASCADES IN THE AFTERNOON AND
EVENINGS.THAT SAID...MY CONFIDENCE IS RATHER LOW THAT WILL ANYTHING
OTHER THAN SOME SCRAWNY AFTERNOON CUMULUS.  ROCKEY.

.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY...WEAK RIDGING OVER THE
PACNW FRIDAY NIGHT INTO SATURDAY IS PUSHED OFF TO THE EAST AS A
TROUGH OF LOW PRESSURE MOVES ONSHORE SUNDAY NIGHT. SATURDAY WILL BE
A LOT LIKE FRIDAY WITH CLOUDY SKIES EARLY CLEARING TO PARTLY CLOUDY
SKIES IN THE AFTERNOON. THERE WILL ALSO BE A SLIGHT CHANCE FOR SOME
AFTERNOON/EVENING SHOWERS OR THUNDERSTORMS NEAR THE CASCADE CREST.
WITH THE APPROACH OF THE LOW PRESSURE SYSTEM FROM THE
SOUTHWEST...EXPECT SKIES TO REMAIN MOSTLY CLOUDY TO PARTLY SUNNY ON
SUNDAY KEEPING TEMPERATURES A BIT COOLER...TOO. UNDER WESTERLY FLOW
MODELS STILL SUGGEST A SLIGHT CHANCE FOR SHOWERS OR THUNDERSTORMS IN
THE CASCADES SUNDAY AFTERNOON/EVENING. WHETHER THESE
SHOWERS/THUNDERSTORMS OCCUR WILL DEPEND ON HOW MUCH CLOUD COVER
CLEARS OUT OVER THE CASCADES BY THE AFTERNOON. SUNDAY NIGHT OR EARLY
MONDAY AS THE FRONT MOVES THROUGH ASSOCIATED WITH THE UPPER-LEVEL
LOW PRESSURE SYSTEM...MODELS SUGGEST SHOWERS WILL SPREAD ACROSS THE
AREA THROUGH THE DAY MONDAY. A CHANCE FOR SOME SCATTERED SHOWERS
BEHIND THE FRONT WILL CONTINUE THROUGH TUESDAY. -MCCOY

&&

.AVIATION...HEADING INTO SOMEWHAT OF A SUMMERTIME STRATUS PATTERN
FOR THE NEXT COUPLE DAYS. HIGH END IFR/LOW END MVFR STRATUS WILL
LINGER NEAR THE COASTLINE WITH PERHAPS SEVERAL HOURS OF CLEARING
ROUGHLY 21-03Z BEFORE THE SEA BREEZE PULLS IT BACK OVER LAND FOR THE
LATE EVENING THROUGH THE MORNING. INLAND TERMINALS WILL ALSO LIKELY
SEE A HIGH END IFR/LOW END MVFR STRATUS DECK 008-015 AGL GENERALLY
DURING A 12Z TO 18Z PERIOD WITH OTHERWISE MAINLY SCT CLOUDS.
MODERATE CUMULUS AND SHOWERS POSSIBLE 18-04Z TODAY MAINLY NEAR THE
CASCADE CREST.

KPDX AND APPROACHES...IFR CIGS HAVE MOVED OVER THE FIELD AND WILL
REMAIN THROUGH AROUND 17Z OR SO AS THEY SHOULD BE FAIRLY THIN.
THEREAFTER...EXPECT SCATTERED SHALLOW CUMULUS MAINLY OVER THE
EASTERN APPROACHES AND THUNDERSTORMS POSSIBLE ALONG THE CASCADE
CREST AND EAST SLOPES. CLOUDS WILL DISSIPATE AROUND SUNSET. ANOTHER
SET OF LOW STRATUS PROBABLY WILL RETURN LATE OVERNIGHT. /JBONK

&&

.MARINE...BROKEN RECORD CONTINUES WITH FAIRLY BENIGN CONDITIONS
THROUGH THE WEEKEND. A PAIR OF DOMINANT SWELL TRAINS HAVE ARRIVED
TO THE WATERS AND WILL REMAIN IN SOME FORM FOR THE NEXT SEVERAL
DAYS. STILL HAVE SOME FRESH SWELL FROM NORTHWEST WINDS OFF THE
WESTERN BC COAST COMBINING WITH THE SWELLS TO PRODUCE SOMEWHAT
CHOPPY SEAS. COMBINED SEAS WILL HOVER BETWEEN 6 AND 7 FT THE NEXT
COUPLE DAYS BEFORE EASING TO AROUND 5 FT THROUGH THE WEEKEND.
WINDS WILL STAY FROM THE WEST OR NORTHWEST WITH ONLY BRIEF AND
LOCALIZED GUSTS PUSHING TO 20 KTS OVER THE FAR SOUTHERN EXTENT OF
THE CENTRAL OREGON WATERS. /JBONK
&&

.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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