Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 271636 RRA
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND
936 AM PDT WED MAY 27 2015


.SYNOPSIS...PESKY UPPER LOW CENTERED OVER THE OR/WA/ID BORDER TODAY
WILL SLOWLY PUSH EAST INTO THE NRN ROCKIES LATER TODAY AND THU. THIS
WILL USHER IN A WARMER AND DRIER AIR MASS. 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.

&&

.MORNING UPDATE...BASED ON THE VISIBLE SATELLITE IMAGERY THIS
MORNING...CUT BACK THE FCST SKY COVER FOR THE LATE MORNING AND EARLY
AFTERNOON. THERE WAS A MARINE STRATUS PUSH...BUT IT WAS PRETTY WEAK
WITH CLOUDS PUSHING INTO THE COASTAL GAPS AND UP THE LOWER COLUMBIA
INTO THE PORTLAND/VANCOUVER METRO AREA. THERE HAS ALSO BEEN SOME
PATCHY FOG OBSERVED DOWN IN THE SOUTHERN WILLAMETTE VALLEY. GIVEN THE
SHALLOWER MARINE LAYER AND THE DECREASED CLOUD COVER TO START...IT
LOOKS LIKE MOST OF THE INTERIOR WILL HAVE FULL SUNSHINE FOR THE
AFTERNOON. SO HIGHS IN THE UPPER 70S FOR MOST LOCATIONS SEEMS LIKE A
GOOD BET. PYLE

.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...THE SUMMERTIME STRATUS PATTERN LOOKS TO CONTINUE FOR
THE NEXT SEVERAL DAYS. IFR/MVFR STRATUS WILL LINGER ALONG THE
COAST FOR THE NEXT SEVERAL HOURS. COASTAL STRATUS LOOKS TO CLEAR
THIS AFTERNOON BETWEEN 21-03Z. A DEVELOPING SEA BREEZE WILL ALLOW
STRATUS TO RETURN INLAND THIS EVENING WITH IFR/MVFR CONDITIONS
THROUGH THU MORNING. INLAND TERMINALS LOOK TO REMAIN MOSTLY VFR
TODAY WITH SCATTERED SHOWERS POSSIBLE ALONG THE CASCADES THIS
AFTERNOON. HOWEVER...THE METRO TERMINALS WILL CONTINUE TO SEE
IFR/MVFR STRATUS THROUGH AROUND 18Z BEFORE THE DECK SCATTERS OUT.
MVFR STRATUS LIKELY RETURNS INLAND THU MORNING. CONDITIONS THU
LOOK TO BE A CARBON COPY OF TODAY.

KPDX AND APPROACHES...IFR/MVFR STRATUS LOOKS TO SCATTER OUT AROUND
18Z. EXPECT VFR CONDITIONS THIS AFTERNOON WITH SCATTERED SHOWERS
AND THUNDERSTORMS POSSIBLE ALONG THE CASCADES BETWEEN 20-04Z. MVFR
STRATUS LIKELY RETURNS EARLY THU MORNING. /64

&&

.MARINE...NO SIGNIFICANT CHANGES. PREVIOUS DISCUSSION FOLLOWS...
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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