Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 011018
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
318 AM PDT FRI AUG  1 2014

.SYNOPSIS...AN UPPER LEVEL RIDGE CENTERED OVER THE ROCKIES AND GREAT
BASIN WILL REMAIN INTO THE WEEKEND...BEFORE FLATTENING OUT EARLY
NEXT WEEK. AN UPPER LEVEL SHORT WAVE MOVING VERY SLOWLY THROUGH THE
PACIFIC NORTHWEST ON THE WEST SIDE OF THE UPPER RIDGE WILL BRING
SOME THUNDERSTORMS TO SOUTHWEST WASHINGTON AND NORTHWEST OREGON THIS
MORNING. ADDITIONAL WEAK DISTURBANCES WILL KEEP A CHANCE OF MAINLY
AFTERNOON AND EVENING THUNDERSTORMS TO MAINLY THE CASCADES THROUGH
THE WEEKEND AND INTO EARLY NEXT WEEK. TEMPERATURES WILL REMAIN ABOVE
NORMAL...SLOWLY APPROACHING NORMAL LATER NEXT WEEK AT THE EARLIEST.
&&

.SHORT TERM...AN UPPER LEVEL SHORT WAVE THAT THE MODELS HAVE BEEN
ADVERTISING WOULD SLOWLY LIFT NORTH THROUGH NORTHWEST OREGON AND
SOUTHWEST WASHINGTON OVERNIGHT AND EARLY THIS MORNING WAS PRODUCING
ELEVATED NOCTURNAL THUNDERSTORMS FROM THE EAST SLOPES OF THE COAST
RANGE INTO THE CASCADES AND ON INTO CENTRAL OREGON. THE MODELS
INDICATED PRECIPITABLE WATER VALUES WITH THIS FEATURE JUST OVER AN
INCH. WHILE RAINFALL AMOUNTS HAD BEEN RATHER LIGHT MUCH OF THE
NIGHT...WE ARE NOW SEEING MORE MEASURABLE RAINFALL AMOUNTS HITTING
RAIN GAGES. SEVERAL GAGES HAVE SEEN SEVERAL HUNDREDTHS OF AN INCH...
AND EXPECT A FEW PLACES MAY HAVE HAD ONE OR TWO TENTHS. THE BACK OR
SOUTHERN EDGE TO THE ASSOCIATED INFRARED CLOUD MASS IS SLOWLY MOVING
NORTH AND SHOULD CLEAR OUR SOUTHWEST WASHINGTON ZONES LATER THIS
MORNING. UNTIL THEN...THERE WILL BE ISOLATED TO SCATTERED SHOWERS
AND THUNDERSTORMS MOVING NORTH ACROSS OUR FORECAST AREA.

THERE IS LITTLE IN THE WAY OF ANY FOG OR LOW CLOUDS ALONG THE
COAST...SO FAR IT IS MAINLY NEAR NORTH BEND. WE MAY SEE A NARROW
RIBBON FORM ALONG AT LEAST PARTS OF THE COAST THIS MORNING HUT IT
MAY NOT BE VERY SOLID.

THERE IS STILL SOME WEAK VORTICITY ALOFT OVER OUR AREA THIS
AFTERNOON...SO EXPECT A FEW MORE THUNDERSTORMS TO DEVELOP AGAIN OVER
THE CASCADES AND FOOTHILLS THIS AFTERNOON AND EVENING. BASED ON THE
POSITION OF THE SHORT WAVE...WILL ALSO INCLUDE A SLIGHT CHANCE OF
THUNDERSTORMS BACK WEST TOWARD THE WILLAPA HILLS AND THE NORTH OREGON
COAST RANGE...AND INCLUDE AN ADJACENT PIECE OF THE PORTLAND AND
VANCOUVER AREA AS WELL.

THE MODELS SHOW THE MARINE LAYER INCREASING ALONG THE COAST TONIGHT
IN THE WAKE OF THIS DISTURBANCE...WITH SOME LOW CLOUDS MOVING INLAND
ALONG THE COLUMBIA RIVER TOWARD PORTLAND BY SATURDAY MORNING. THE
MAIN SHORT WAVE FROM TODAY IS WELL NORTH OF OUR AREA ON SATURDAY...
BUT SOME WEAK TRAILING ENERGY SHOULD AGAIN GIVE A CHANCE OF AFTERNOON
AND EVENING THUNDERSTORMS OVER THE CASCADES SATURDAY.

THERE IS NOT A LOT OF CHANGE ON SUNDAY...WITH A CHANCE OF
THUNDERSTORMS OVER THE CASCADES AGAIN IN THE AFTERNOON AND EVENING.
THE INLAND PUSH OF LOW CLOUDS INTO THE COASTAL GAPS LOOKS BETTER BY
SUNDAY...AND EXPECT A DECENT AREA OF AROUND PORTLAND AND VANCOUVER
TOWARD THE CASCADE FOOTHILLS WILL HAVE LOW CLOUDS FOR SEVERAL HOURS
SUNDAY MORNING. AFTER SEVERAL DAYS AROUND 90...IF THIS OCCURS IT
SHOULD DROP THE TEMPS IN THE PORTLAND AND VANCOUVER AREA DOWN TO AT
LEAST THE MID 80S. TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...MODELS IN
PRETTY GOOD AGREEMENT IN SHOWING THE REGION UNDER A WEAK 500 MB FLOW
THROUGH MOST OF NEXT WEEK...WITH A CONTINUATION OF A MODEST LOW LEVEL
ONSHORE FLOW AS A RESULT OF THE HIGH OVER THE NE PACIFIC. OVERALL
LOOKS LIKE A DRY PATTERN WITH THE FLOW ALOFT SEEMING TO FAVOR A LIGHT
WESTERLY WIND...AND TEMPS REMAINING A BIT ABOVE NORMAL.
&&

.AVIATION...ISOLATED THUNDERSTORMS CONTINUE TO PUSH NORTH THROUGH THE
WILLAMETTE VALLEY WITH FREQUENT LIGHTNING OBSERVED. EXPECT VCTS TO BE
CARRIED THROUGH 18Z ACROSS THE PORTLAND METRO TAF SITES...BUT
PROBABLY ENDING BY 12Z-14Z FURTHER SOUTH CLOSER TO KEUG. MAY SEE
TEMPORARY VSBY REDUCTION TO MVFR IF A HEAVIER TSRA MOVES OVER A
TERMINAL...BUT OTHERWISE VFR FLIGHT CONDITIONS. STORM THREAT SHOULD
END ACROSS THE VALLEY BY MID MORNING FROM SOUTH TO NORTH. ALONG THE
COAST...MAY SEE SOME SCATTERED LOW CLOUDS START TO DEVELOP BUT SHOULD
REMAIN VFR TODAY AT THE COAST THROUGH THIS AFTERNOON...BEFORE SOME
MVFR/IFR STRATUS MAY PUSH ONSHORE AFT 00Z SAT.

KPDX AND APPROACHES...SOME THUNDERSTORMS CONTINUE TO MOVE FROM S TO N
TOWARDS THE TERMINAL. EXPECT VCTS THROUGH AROUND 18Z...WITH BEST
CHANCES FOR TSRA AT TERMINAL BETWEEN 10Z-17Z. THESE STORMS HAVE
PRODUCED ABUNDANT LIGHTNING OVERNIGHT SO THIS COULD IMPACT TERMINAL
OPERATIONS THROUGH AROUND 17Z. THUNDERSTORM CHANCES MAY PERSIST FOR
ANOTHER HOUR OR TWO OVER EASTERN APPROACHES.  CULLEN
&&

.MARINE...ONLY SUBTLE DAY TO DAY VARIATIONS EXPECTED IN THE WEATHER
PATTERN THROUGH THE WEEKEND AS HIGH PRESSURE REMAINS OVER NORTHEAST
PACIFIC. THIS WILL MAINTAIN A TYPICAL SUMMERTIME PATTERN OF NORTHERLY
WINDS...GENERALLY INCREASING EACH AFTERNOON THROUGH AROUND MIDNIGHT.

HIGH PRESSURE SAGGING SOUTHWARD FRIDAY AND SATURDAY WILL LIKELY KEEP
SMALL CRAFT ADVISORY LEVEL WIND GUSTS OF 25 KT FROM MATERIALIZING
ACROSS ALL THE WATERS EVEN THOUGH MODEL GUIDANCE SUGGESTS
OTHERWISE...THOUGH WOULD NOT BE SURPRISED TO SEE OCCASIONAL GUSTS TO
20-25 KT OVER THE NEAR SHORE WATERS TODAY.

NONETHELESS...THE GENERAL WEATHER PATTERN WILL CONTINUE TO PRODUCE
LOCALLY GENERATED WIND WAVES/FRESH SWELL....LEADING TO CHOPPY
SEAS...BUT WITH TOTAL WAVE HEIGHTS GENERALLY REMAINING 5 FT OR LESS
THROUGH EARLY NEXT WEEK. CULLEN
&&

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

$$

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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