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[Printable]
770
FXUS66 KPQR 292201
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
201 PM PST THU JAN 29 2015

.SYNOPSIS...THE WEAK UPPER DISTURBANCE THAT MOVED INTO THE PACIFIC
NORTHWEST OVERNIGHT AND DISRUPTED FOG DEVELOPMENT WAS MOVING EAST OF
THE AREA THIS AFTERNOON. A BUILDING UPPER RIDGE WILL THEN MOVE IN FOR
MILD AND DRY WEATHER OVER SOUTHWEST WASHINGTON AND NORTHWEST OREGON
THROUGH FRIDAY AND SATURDAY...AS WELL AS GOOD RADIATIONAL CONDITIONS
FOR AREAS OF FOG FORMATION BENEATH A STRENGTHENING TEMPERATURE
INVERSION. MODERATE EASTERLY GRADIENTS THROUGH THE GORGE THROUGH
SATURDAY WILL PRODUCE SOME AREAS OF EAST WINDS AND DISRUPT THE FOG
SOME AROUND THE COLUMBIA RIVER...AND GIVE SOME AREAS OF CLEARING IN
THE AFTERNOONS IN THE VALLEYS. THE NEXT DECENT CHANCE OF RAIN IS
SUNDAY AND MONDAY INTO TUESDAY AS A PAIR OF SYSTEMS MOVE THROUGH.
&&

.SHORT TERM...TONIGHT THROUGH SUNDAY...THE WEAK UPPER DISTURBANCE
THAT SPREAD CLOUDS AND A FEW SPRINKLES ONSHORE LAST NIGHT WAS MOVING
EAST OF THE CASCADES THIS AFTERNOON WITH DECREASING CLOUDS OVER
SOUTHWEST WASHINGTON AND NORTHWEST OREGON. THIS DISTURBANCE DISRUPTED
FOG FORMATION OVERNIGHT. THERE ARE STILL SOME AREAS OF VALLEY LOW
CLOUDS MAINLY SOUTH AND ALONG THE COLUMBIA RIVER THAT ARE ERODING AND
HAVE A GOOD CHANCE OF COMPLETELY CLEARING THIS AFTERNOON.

AN UPPER RIDGE WILL BUILD IN TONIGHT AND EARLY FRIDAY AND CONTINUE
OVER THE PACIFIC NORTHWEST THROUGH SATURDAY. THIS WILL BRING DRY AND
MILD WEATHER TO THE AREA...WITH INCREASING TEMPERATURE INVERSIONS.
THUS THE WARMEST AREAS WILL AND AGAIN BE THE FOOTHILLS AND THE COAST
RANGE. WE WILL SEE MORE AREAS OF VALLEY FOG IN THE NIGHTS AND
MORNINGS AS WELL AS THIS UPPER RIDGE ALSO PROVIDES MUCH BETTER
RADIATIONAL CONDITIONS THE NEXT FEW NIGHTS.

THE EASTERLY GRADIENT THROUGH THE GORGE HAS REACHED 6.5 MB THIS
AFTERNOON...AND WILL LIKELY HANG IN THE 6 TO 7 MB RANGE THROUGH
SATURDAY. THIS WILL KEEP DECENT EAST WINDS THROUGH THE GORGE...WITH
GUSTS AT THE WINDIER AREAS UP AROUND 50 MPH AND NEAR CROWN POINT 60
MPH OR HIGHER. THIS MAY AFFECT THE FOG COVERAGE AROUND THE COLUMBIA
RIVER THE NEXT COUPLE OF DAYS...AND MAY GIVE SOME CLEARING SOUTHWARD
INTO THE WILLAMETTE VALLEY EACH AFTERNOON MORE THAN WE SAW EARLIER
THIS WEEK. VALLEY LOCATIONS THAT CLEAR WILL LIKELY SEE TEMPS UP INTO
THE 50S...AND IF ANY PLACE DOES NOT CLEAR THEN TEMPS WILL BE CLOSER
TO 50 OR THE UPPER 40S.

THE NEXT FRONT PROBABLY IS NOT UNTIL NEXT SUNDAY. THE GFS13 AND THE
ECMWF ARE IN BETTER AGREEMENT NOW THAN THEY HAD BEEN. TOLLESON

.LONG TERM...SUNDAY NIGHT THROUGH THURSDAY...NEXT WEEK LOOKS A BIT
MORE ACTIVE THAN THE LAST WEEK OR SO...BUT THERE IS STILL A HINT OF A
FLAT RIDGE ALONG THE WEST COAST THAT LIMITS THE STRENGTH OF ANY
SYSTEMS THROUGH THE FIRST HALF OR SO OF NEXT WEEK. NOT LOOKING FOR
MUCH SNOW TO HELP OUT THE SNOWPACK. THE MODELS HAVE NOT BEEN IN THE
BEST AGREEMENT WITH ANY DETAILS THOUGH THEY ARE COMING TOGETHER
BETTER ON THE GENERAL PATTERN. IT LOOKS LIKE ONE SYSTEM MOVES THROUGH
MONDAY AND MONDAY NIGHT...THEN ANOTHER WEDNESDAY INTO THURSDAY. IT IS
NOT LOOKING AS LIKELY THAT WE WILL GET SIGNIFICANT ENOUGH RIDGING MID
WEEK FOR A SUSTAINED DRY PERIOD THOUGH WE SHOULD SEE SOME PERIODS OF
DRYING BETWEEN THE SYSTEMS. TOLLESON
&&

.AVIATION...SKIES HAVE CLEARED ACROSS MOST OF AREA...WITH A DECK OF
SOME LINGERING IFR CIGS BANKED UP ALONG THE CASCADE FOOTHILLS AND IN
THE SOUTH WILLAMETTE VALLEY. THESE REMAINING CLOUDS WILL CONTINUE TO
ERODE AND SKIES REMAIN CLEAR THROUGH THIS EVENING. EXPECT CLEAR SKIES
COMBINED WITH FAIRLY LIGHT WINDS FOR MOST LOCATIONS TO PRODUCE NEARLY
IDEAL RADIATIONAL COOLING. THIS WILL PRODUCE WIDESPREAD AREAS OF IFR
FOG ACROSS THE CENTRAL AND SOUTH VALLEY...IN ADDITION TO POTENTIALLY
KHIO...THROUGH THE OVERNIGHT. ADDITIONALLY PATCHY FOG CAUSING MVFR
VSBYS EXPECTED ALONG THE COAST. KTTD REMAINS CLEAR WITH CONTINUED
GUSTY EAST WIND. LOWER CONFIDENCE FORECAST FOR KPDX/KVUO WHERE
DEVELOPMENT OF EAST WIND IS MORE UNCERTAIN. FOG THAT DEVELOPS SHOULD
BE MORE SHALLOW FOR MOST LOCATIONS...WITH CLEARING TO VFR BY 19Z.
HOWEVER...KHIO AND KAST MAY REMAIN IN FOG/LOW CLOUDS THROUGH EARLY
AFTERNOON.

KPDX AND APPROACHES...VFR UNDER MOSTLY CLEAR SKIES CONTINUE THIS
EVENING. SOME POTENTIAL FOR RADIATIONAL FOG TO DEVELOP TONIGHT WITH
CLEAR SKIES AND EASING WINDS LATE. BETTER CHANCES OVER THE APPROACHES
FOR FOG AFT 09Z...AND 12-17Z AT THE TERMINAL. IF EAST WINDS MAKE IT
TO THE TERMINAL...CONTINUED CLEARING LIKELY REMAINS THROUGH THE NIGHT
BUT IF WINDS GO CALM...COULD SEE IFR/LIFR CONDITIONS. THINK FOG THAT
DEVELOPS WILL BE MORE PATCHY AND LESS DENSE...LIKELY PRODUCING MVFR
VSBYS. EXPECT ANY FOG TO BEGIN CLEARING 17Z AND IMPROVE TO VFR UNDER
GENERALLY CLEAR SKIES BY 19Z...CONTINUING THROUGH FRI. CULLEN
&&

.MARINE...HIGH PRESSURE CONTINUES TO BUILD OVER THE WATERS TONIGHT
AND WILL PERSIST THROUGH THE END OF THE WEEK. WINDS HAVE BECOME  MORE
NORTHERLY IN RESPONSE TO A COASTAL LOW PRESSURE BUILDING NORTHUP
THE COAST INTO CENTRAL OREGON. GUSTS HAVE INCREASED TO 25 KT OVER
SOUTHERN OREGON WATERS BUT EXPECT THEM TO REMAIN 20 KT OR LESS OVER
CENTRAL OREGON WATERS...WITH STRONGEST GUSTS S OF NEWPORT. WINDS TURN
SOUTHERLY ON SUN AHEAD OF AN APPROACHING FRONTAL SYSTEM...THE FIRST
OF A FEW THAT WILL TRAVERSE THE WATERS EARLY NEXT WEEK. EACH WILL
BRING THE POTENTIAL FOR SMALL CRAFT WINDS AT TIMES THROUGH AT LEAST
THE FIRST HALF OF NEXT WEEK. SEAS HOLD AROUND 5 FT TODAY...AND WILL
BUILD AT TIMES WITH INCREASING WINDS AND PASSING FRONTS...BUT SHOULD
REMAIN BETWEEN 5 FT AND 8 FT THROUGH AT LEAST SUN. MODELS SUGGEST A
MORE ACTIVE PATTERN NEXT WEEK WITH A SERIES OF SYSTEMS...BUT NONE
PARTICULARLY STRONG THROUGH AT LEAST THE MIDDLE OF NEXT WEEK. CULLEN
&&

.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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