Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 280342
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
842 PM PDT SUN JUL 27 2014

.SYNOPSIS...AN UPPER LEVEL RIDGE WILL BE CENTERED INLAND OVER THE
PACIFIC NORTHWEST THROUGH THE COMING WEEK WITH AN UPPER LOW CENTERED
OFF THE B.C. COAST. THIS WILL BRING WARM AND DRY WEATHER TO
SOUTHWEST WASHINGTON AND NORTHWEST OREGON...EXCEPT FOR A SLIGHT
CHANCE FOR THUNDERSTORMS IN THE CASCADES NEAR THE CREST IN THE
AFTERNOONS AND EARLY EVENINGS AS A FEW WEAK DISTURBANCES LIFT
NORTHEAST THROUGH THE REGION THROUGH THE UPCOMING WEEK. THE MARINE
LAYER WILL BE SHALLOW AND MOSTLY CONFINED TO THE COAST.
&&

.UPDATE...ONLY SIGNIFICANT CHANGE WAS TO REMOVE THE THUNDERSTORM
MENTION FOR THE CASCADES TONIGHT. THERE WAS TOO MUCH HIGH CLOUD
COVER AND THAT LIMITED GROUND HEATING AS A TRIGGER. CONVECTIVE
ACTION OVER SISKIYOU COUNTY CALIFORNIA ALSO DID NOT HAVE QUITE
ENOUGH PUNCH AND FAILED TO PRODUCE A STORM. WILL SEE SOME DEBRIS
FROM THERE MOVE NORTH AND DISSIPATE AS IT APPROACHES LANE COUNTY
THIS EVENING. THUS DO NOT SEE MUCH THREAT FROM STORMS ADVECTING OVER
THE AREA EITHER. THEREFORE...GENERALLY EXPECT A REPEAT FROM LAST
NIGHT WITH SOME PATCHY GROUND FOG AT THE COAST AND MILD CONDITIONS
INLAND. /JBONK

&&

.PREV DISC... /ISSUED 234 PM PDT SUN JUL 27 2014/

SHORT TERM...AN UPPER LOW OFF THE B.C. COAST AND AN UPPER LEVEL
RIDGE ANCHORED INLAND OVER THE WESTERN U.S. WILL BE THE WEATHER
PATTERN THAT WILL AFFECT THE PACIFIC NORTHWEST AND SOUTHWEST
WASHINGTON AND NORTHWEST OREGON THROUGH THIS WEEK. THIS WILL PRODUCE
LIGHT SOUTH TO SOUTHWEST FLOW ALOFT WITH HIGH 500 MB HEIGHTS...WHOSE
ASSOCIATED SUBSIDENCE WILL ALLOW A SHALLOW MARINE LAYER AT MOST ALONG
THE COAST.

THE UPPER RIDGE WILL PUSH 850 MB TEMPS UP CLOSE TO 20 DEG C FOR THE
NEXT COUPLE OF DAYS...WHICH SHOULD BE HIGH ENOUGH TO PUSH INLAND
TEMPS IN THE AFTERNOON INTO THE LOWER OR EVEN MID 90S THE NEXT FEW
DAYS. EVEN THE COAST SHOULD REACH THE 70S IN MANY AREAS.

WE ARE SEEING HIGHER LEVEL CLOUDS ASSOCIATED WITH A DISTURBANCE THAT
WAS MOVING NORTHEAST FROM CALIFORNIA THROUGH OREGON TODAY AND
TONIGHT. MOST OF THE MOISTURE IS VERY HIGH BASED...BUT IT DOES APPEAR
THERE IS A SLIGHT CHANCE OF THUNDERSTORMS OVER THE OREGON CASCADES
THIS AFTERNOON AND EVENING AS THIS FEATURE MOVES THROUGH. THE
AVAILABLE MOISTURE IS HIGH BASED...SO ANY THUNDERSTORMS THAT DO
DEVELOP WILL BE HIGH BASED AND DRY.

THERE IS NOT MUCH CHANGE IN THE PATTERN ON MONDAY...WITH SIMILAR
TEMPS AND NOT MUCH CHANGE IN THE MORNING LOW CLOUD PATTERN...EXCEPT
PERHAPS A BIT MORE COVERAGE OVER THE COASTAL WATERS. THERE IS NOT
REALLY ANY FORCING FOR THUNDERSTORMS ON MONDAY WHEN COMPARED TO THE
DISTURBANCE MOVING THROUGH TODAY...BUT ENOUGH MOISTURE IS NEARBY FOR
A SLIGHT CHANCE IN THE HIGHER OREGON CASCADES AGAIN MONDAY AFTERNOON
AND EVENING. MOISTURE WILL AGAIN BE HIGH BASED AND SPARSE...SO ANY
THUNDERSTORMS THAT DO DEVELOP WILL BE DRY.

THE SAME PATTERN CONTINUES ON TUESDAY. TEMPS INLAND WILL BE SIMILAR
TO THOSE ON MONDAY...LOWER TO MID 90S. THE MODELS SHOW ANOTHER WEAK
DISTURBANCE LIFTING NORTH TUESDAY AFTERNOON AND EVENING...SO THIS
LOOKS LIKE A BETTER CHANCE OF THUNDERSTORMS IN THE CASCADES THAN
ON MONDAY. THE MODELS ARE STARTING TO SHOW PRECIPITABLE WATER VALUES
EXCEEDING AN INCH ON TUESDAY AFTERNOON AND EVENING...SO WHILE THE
THUNDERSTORMS WILL STILL TEND TO BE ON THE DRY SIDE...A FEW MAY START
TO PRODUCE A BIT OF PRECIPITATION. THE HIGHER OREGON CASCADES ARE
MOST AT RISK...AND THERE IS SOME THREAT LINGERING AFTER MIDNIGHT
TUESDAY NIGHT.

WEDNESDAY LOOKS VERY SIMILAR TO TUESDAY WITH A CHANCE OF
THUNDERSTORMS AGAIN OVER THE CASCADES IN THE AFTERNOON AND EVENING.
IT APPEARS THAT ON WEDNESDAY THUNDERSTORMS MAY AGAIN STAY SOUTH OF
THE COLUMBIA RIVER AGAIN. THE MODELS IMPLY THE MARINE LAYER MAY
BECOME MORE SOLID ALONG THE COAST WEDNESDAY...BUT STILL NOT MUCH
EXPECTED INLAND. TEMPS INLAND WILL CONTINUE TO BE VERY WARM
WEDNESDAY...UP AROUND 90. TOLLESON

LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...MODELS ARE IN AGREEMENT
THAT THE UPPER-LEVEL RIDGE POSITIONED OVER WESTERN U.S. WILL REMAIN
FAIRLY STATIONARY THROUGH THE WEEK THIS WEEK.  NORTH-NORTHWESTERLY
ONSHORE FLOW DUE TO THE SURFACE RIDGE AXIS BEING POSITIONED TO OUR
SOUTH WILL ALLOW LOW-LEVEL STRATUS DEVELOP OVERNIGHT ALONG THE COAST
AND THE LOWER COLUMBIA RIVER.  DECREASED CLOUD COVER SOUTH OF THIS
AXIS LATER THIS WEEK...BUT ONLY A LITTLE DUE TO MODEL UNCERTAINTY ON
THE LOCATION OF THIS AXIS. CHANCE OF THUNDERSTORMS ALONG THE CASCADE
CREST DUE TO SHORTWAVE IMPULSES RIDING UP ALONG THE WESTERN EDGE OF
THE UPPER-LEVEL RIDGE. THESE STORMS SHOULD MAINLY OCCUR DURING
AFTERNOON-EVENING HOURS...BUT SOME MAY LINGER OVERNIGHT DEPENDING ON
TIMING. -MCCOY
&&

.AVIATION...WIDESPREAD VFR PERSISTS UNDER HIGH PRESSURE. PATCHY FOG
AND IFR STRATUS WILL DEVELOP ALONG THE COAST FOR AN HOUR OR TWO
AROUND 13Z MONDAY. THIS IS MOST LIKELY TO OCCUR AT KONP.
ADDITIONALLY...A TEMPORARY HIGH END IFR DECK IS POSSIBLE AT KTTD
AROUND THE SAME TIME...BUT CONFIDENCE IS EVEN LOWER.

KPDX AND APPROACHES...HIGH PRESSURE AND DRY AIR ALOFT WILL LEAD TO
VFR CONDITIONS THROUGH 06Z TUESDAY. /NEUMAN

&&

.MARINE...HIGH PRESSURE OVER THE NORTHEAST PACIFIC AND THERMAL LOW
PRESSURE OVER NORTHERN CALIFORNIA WILL CONTINUE FOR MUCH OF THE
WEEK. THIS WILL LEAD TO LITTLE CHANGE IN THE OVERALL WEATHER
PATTERN...WITH PERIODS OF GUSTY NORTHERLY WINDS...AND POTENTIALLY
STEEP CHOPPY SEAS OF 4 TO 7 FT.

ALL MODEL GUIDANCE OVER PREDICTED WINDS ACROSS THE CENTRAL OREGON
WATERS THIS AFTERNOON AND EVENING. WITH A NEAR IDENTICAL PATTERN
MONDAY AND TUESDAY...WENT AHEAD AND REDUCED THE WIND FORECAST
ACROSS THE CENTRAL WATERS...AND BUMPED WINDS A BIT ACROSS THE
NORTHERN WATERS. /NEUMAN

&&

.PQR WATCHES/WARNINGS/ADVISORIES...
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FOR WINDS UNTIL 3 AM PDT TUESDAY FOR
     COASTAL WATERS FROM CAPE SHOALWATER WA TO CASCADE HEAD OR OUT 60 NM.

&&

$$

MORE WEATHER INFORMATION ONLINE AT...HTTP://WEATHER.GOV/PORTLAND

INTERACT WITH US VIA SOCIAL MEDIA
WWW.FACEBOOK.COM/US.NATIONALWEATHERSERVICE.PORTLAND.GOV
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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