Area Forecast Discussion
Issued by NWS Portland, OR

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FXUS66 KPQR 291721
AFDPQR

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
921 AM PST THU JAN 29 2015

.SYNOPSIS...A WEAK UPPER DISTURBANCE THAT MOVED INTO THE PACIFIC
NORTHWEST OVERNIGHT DISRUPTED FOG DEVELOPMENT...AND WHAT FOG AND LOW
CLOUDS THAT DID FORM WILL TEND TO CLEAR THIS AFTERNOON. THE HIGHER
CLOUDS AND FEW REMAINING SPRINKLES FROM THIS DISTURBANCE WILL MOVE
OFF TO THE EAST LATER TODAY AND TONIGHT. A BUILDING UPPER RIDGE WILL
THEN MOVE IN FOR MILD AND DRY WEATHER OVER SOUTHWEST WASHINGTON AND
NORTHWEST OREGON THROUGH FRIDAY AND SATURDAY. MODERATE EASTERLY
GRADIENTS THROUGH THE GORGE TODAY 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...THE WEAK UPPER DISTURBANCE THAT SPREAD CLOUDS AND A FEW
SPRINKLES ONSHORE LAST NIGHT AND THAT STILL LINGERS THIS MORNING
AFFECTED THE FORMATION OF FOG AND LOW CLOUDS OVERNIGHT...AND THE
COVERAGE IS STILL ON THE PATCHY SIDE THIS MORNING. AS THE WEAK
DISTURBANCE MOVES SOUTH AND EAST TODAY INTO TONIGHT...WILL SEE SOME
FILTERED SUNSHINE MANY AREAS...AND THE FOG AND LOW CLOUDS THAT ARE
AROUND WILL TEND TO CLEAR IN THE AFTERNOON. WITH THE CONTINUED RATHER
MILD AIR MASS OVER THE REGION FOR JANUARY...HAVE UPPED TEMPS THIS
AFTERNOON TO BE SIMILAR TO WHAT WE SAW OCCUR WEDNESDAY.

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 SE MORE AREAS OF VALLEY FOG IN THE NIGHTS AND MORNINGS
AS WELL.

THE EASTERLY GRADIENT THROUGH THE GORGE HAS REACHED JUST OVER 6 MB
THIS MORNING...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 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. THE NEXT FRONT PROBABLY IS NOT UNTIL NEXT SUNDAY. TOLLESON

.LONG TERM...NO CHANGES. PREVIOUS DISCUSSION FOLLOWS...
SATURDAY NIGHT THROUGH WEDNESDAY...AS WE ENTER A MORE ZONAL FLOW
PATTERN...MODELS CONTINUE TO DISAGREE ON PRECIPITATION DISTRIBUTION
AND TIMING SUNDAY AND MONDAY AS A WARM FRONT SPREADS INTO THE REGION.
CONTINUED THE IDEA THAT RAIN IS LIKELY DURING THIS PERIOD...BUT
DETAILS STILL REMAIN FAIRLY UNCERTAIN. DESPITE THESE
DIFFERENCES...BOTH THE GFS AND EC AGREE SHORTWAVE RIDGING WILL PUSH
BACK INTO THE REGION EARLY TO MID NEXT WEEK. POPS WERE TRENDED
DOWNWARD DURING THIS PERIOD...BUT DID NOT GO COMPLETELY DRY JUST YET
GIVEN UNCERTAINTY. ANOTHER FRONT MAY PUSH INTO THE REGION LATE IN THE
WEEK SO POPS WERE TRENDED BACK UPWARDS TOWARDS DAY 7. /NEUMAN
&&

.AVIATION...PATCHY FOG REMAINS ACROSS THE NORTHERN AND SOUTHERN
VALLEY THIS MORNING...AS WELL AS THE NORTH COAST. THIS WILL GRADUALLY
IMPROVE THROUGH THIS MORNING...AND LIKELY IMPROVES TO VFR UNDER
GENERALLY CLEAR SKIES FOR NEARLY EVERYWHERE BY MIDDAY. KHIO MAY
LINGER IN IT A BIT MORE THROUGH EARLY AFTERNOON. SURFACE PRESSURE
GRADIENT WILL SUPPORT INCREASING OFFSHORE WINDS TODAY... WITH GUSTS
TO 35 KT POSSIBLE AT KTTD AND GUSTY EAST WINDS ALSO MATERIALIZING AT
KPDX AND ALONG THE COAST AT TIMES TODAY. AFTER THE CLEARING TODAY AND
WITH HIGH PRESSURE BUILDING ALOFT...EXPECT WIDESPREAD FOG TO DEVELOP
ACROSS MOST TERMINALS TONIGHT. KTTD WILL LIKELY REMAIN GENERALLY
CLEAR WITH CONTINUING GUSTY E WINDS.

KPDX AND APPROACHES...SOME SHALLOW PATCHY FOG CONTINUES THIS
MORNING...BUT WILL BURN OFF QUICKLY AND CLEAR AROUND 19Z WITH VFR
CONDITIONS PREVAILING THE REMAINDER OF TODAY. EAST WINDS LIKELY
DEVELOP AT THE TERMINAL AROUND 21Z. POTENTIAL FOR DEVELOPING FOG AFT
12Z...ESPECIALLY OVER THE APPROACHES. LOWER CONFIDENCE FOR THE
TERMINAL...PARTICULARLY IF E WINDS CONTINUE AS THIS WOULD PROMOTE
CONTINUED CLEARING RATHER THAN FOG DEVELOPMENT...BUT DO EXPECT
PERIODS OF FOG AT TIMES LATE TONIGHT/EARLY FRIDAY. CULLEN
&&

.MARINE...HIGH PRESSURE BUILDING OVER THE WATERS TODAY WILL PERSIST
THROUGH THE END OF THE WEEK. WINDS REMAIN OFFSHORE THIS MORNING...
BUT WILL BECOME INCREASINGLY NORTHERLY LATER TODAY AS A COASTAL LOW
PRESSURE BUILDS NORTH UP THE PACIFIC COAST INTO SOUTHERN OREGON.
GUSTS MAY INCREASE TO NEAR 20 KT LATE THIS AFTERNOON THROUGH
TONIGHT...PRIMARILY FROM NEWPORT SOUTH. WINDS BECOME 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 LARGELY LOOK TO REMAIN
BETWEEN 5 FT AND 8 FT THROUGH EARLY NEXT WEEK. MODELS SUGGEST A MORE
ACTIVE PATTERN NEXT WEEK...BUT CONFIDENCE IN DETAILS REMAINS LOWER.
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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