918
FXUS66 KPQR 150505 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
905 PM PST WED JAN 14 2026
UPDATED AVIATION DISCUSSION.
SYNOPSIS
AN ANOMALOUS AREA OF HIGH PRESSURE REMAINS PLANTED
OVER THE PACIFIC NORTHWEST INTO NEXT WEEK LIKELY (90%) MAINTAINS
DRY WEATHER THROUGH AT LEAST JAN. 20-21ST. FOR VALLEY LOCATIONS
BELOW ROUGHLY 1000 FT FOG (DENSE AT TIMES), LOW STRATUS, AND
COOL TEMPERATURES CONTINUE INTO THURSDAY. ELEVATIONS ABOVE 1000
FT WILL REMAIN MUCH WARMER AND DRIER, WITH CLEAR SKIES GOING
FORWARD. HOWEVER, AS OFFSHORE FLOW STRENGTHENS ON FRIDAY
BREEZY/GUSTY EAST WINDS ARE EXPECTED TO IMPACT THE CASCADES
GAPS/FOOTHILLS, WESTERN COLUMBIA RIVER GORGE AND PORTIONS OF THE
PORTLAND METRO. AT LEAST THIS CHANGE SHOULD ALSO BRING AN END
TO THE PROLIFIC FOG AND LOW STRATUS IN THE LOWLANDS WITHIN REACH
OF THOSE EASTERLY WINDS - MORE PROTECTED AREAS LIKE THE
SOUTHERN WILLAMETTE VALLEY MAY STILL SEE FOG LINGER OVERNIGHT.
DISCUSSION...NOW THROUGH TUESDAY NIGHT
AN UNUSUALLY STRONG
AREA OF HIGH PRESSURE WILL DRIVE OUR WEATHER IMPACTS FOR THE
NEXT 6-7 DAYS AS IT GENERALLY SITS OVERHEAD. THIS HIGH PRESSURE
IS COUPLED WITH A RATHER DEFINED TEMPERATURE INVERSION WHICH
ALREADY HAS RESULTED IN VASTLY DIFFERING WEATHER CONDITIONS FOR
ELEVATIONS BELOW 1000 FEET COMPARED TO ELEVATIONS ABOVE 1000
FEET - THIS TREND CONTINUES THROUGH AT LEAST THURSDAY FOR MUCH
OF THE REGION. ABOVE 1000 FT EXPECT CLEAR SKIES AND WARMER
TEMPERATURES COMPARED TO BELOW 1000 FEET WHERE COOLER, CLOUDIER
AND FOGGIER PERSIST. HEADED INTO THURSDAY MORNING AREAS OF DENSE
FOG ARE LIKELY YET AGAIN FOR THE LOWLAND VALLEYS WITH THE REFS
PROJECTING A 70-95% CHANCE TO SEE <0.25 MILE VISIBILITY FOR
MUCH OF THE I-5 CORRIDOR INCLUDING THE PORTLAND/VANCOUVER. IF
YOU WOKE UP WITH DENSE FOG THIS (WEDNESDAY) MORNING, YOU'LL MORE
THAN LIKELY GET A REPEAT TONIGHT. BE PREPARED TO DRIVE SLOWLY
IF YOU MUST COMMUTE AS FOG WILL POSE A TRAVEL HAZARD.
PEDESTRIANS AND BIKERS SHOULD WEAR REFLECTIVE CLOTHING. NOTE
WITH THE CONTINUED STAGNANT AIRMASS IN PLACE, AIR QUALITY MAY
BECOME DEGRADED AT TIMES OVER THE LOWLANDS THROUGH THURSDAY
NIGHT AS WELL.
AS MENTIONED EARLIER, ELEVATIONS ABOVE 1000 FEET
WILL BE WARMER AND SIGNIFICANTLY DRIER AS THEY POKE INTO THE
UPPER PORTIONS OF THE LOW-LEVEL TEMPERATURE INVERSION AND SEE
PLENTY OF SUNSHINE. IN FACT, HIGH TEMPERATURES IN THE LOW TO MID
60S ARE IN THE FORECAST FOR THE CASCADE FOOTHILLS, COAST RANGE
LOWLANDS AND CENTRAL OREGON COAST, WARMEST IN THE LANE COUNTY
CASCADE FOOTHILLS. IT'S WORTH HIGHLIGHTING HUMIDITY VALUES
BETWEEN 2000-4000 FEET WHERE THE DRIEST PORTION OF THE
INVERSION INTERFACES WITH THE TERRAIN WILL EXPERIENCE EXTREMELY
POOR AFTERNOON AND NIGHTTIME RELATIVE HUMIDITY VALUES FOR THIS
TIME OF YEAR WITH MANY RAWS STATIONS IN THE EXPOSED PORTIONS IN
THE CASCADES AND COAST RANGE REPORTING RHS IN THE SINGLE DIGITS
TO TEENS. GIVEN THESE DRY ANTECEDENT CONDITIONS THE THIN STRIP
BETWEEN THE LOW LEVEL MOISTURE IN THE VALLEYS AND WHERE SNOW IS
PRESENT AT ELEVATION WILL BE A PLACE TO MONITOR WHEN EAST WINDS
INCREASE.
BY THURSDAY NIGHT/FRIDAY MORNING, MODELS AND THEIR ENSEMBLES
CONTINUE TO SUGGEST LOW-LEVEL OFFSHORE FLOW WILL RAPIDLY
STRENGTHEN, BRINGING BREEZY/GUSTY EAST WINDS TO THE CASCADES,
CASCADE FOOTHILLS, TOPS OF THE COAST RANGE, WESTERN COLUMBIA
RIVER GORGE, AND PORTIONS OF THE PORTLAND METRO. EAST WINDS ARE
FORECAST TO REACH THE COAST AS WELL AS A SURFACE THERMAL TROUGH
ALONG THE SOUTHERN/CENTRAL OR COAST BEGINS TO SHIFT SLIGHTLY
OFFSHORE. THIS WILL BRING AN END TO FOG AND AIR STAGNATION FOR
THESE LOCATIONS. MEANWHILE, THE CENTRAL AND SOUTHERN WILLAMETTE
VALLEY MAY SEE AT LEAST SOME PATCHY FOG OCCUR AGAIN THURSDAY
NIGHT/FRIDAY MORNING AGAIN AS THIS WIND-SHELTERED AREA WILL
HAVE MINIMAL INFLUENCE FROM THE INCREASING OFFSHORE FLOW.
OFFSHORE FLOW WILL MOST LIKELY REMAIN IN PLACE FRIDAY NIGHT
THROUGH THE UPCOMING WEEKEND, ALBEIT IN A WEAKER STATE AS THE
CROSS-CASCADE PRESSURE GRADIENT EASES. THIS SHOULD MAINTAIN
MOSTLY CLEAR CONDITIONS OVER THE AREA, ASIDE FROM THE CENTRAL
AND SOUTHERN WILLAMETTE VALLEY WHERE LOW STRATUS AND FOG
CONCERNS WILL LIKELY PERSIST. NOTE OVERNIGHT TEMPERATURES ARE
EXPECTED TO REMAIN CHILLY EACH NIGHT THROUGH AT LEAST MONDAY
NIGHT, PARTICULARLY IN THE WILLAMETTE VALLEY AND UPPER HOOD
RIVER VALLEY WHERE BELOW FREEZING LOW TEMPERATURES ARE EXPECTED.
THAT SAID, APPARENT TEMPERATURES ARE NOT FORECAST TO BE COLD
ENOUGH TO WARRANT ANY COLD WEATHER ADVISORIES AT THIS TIME.
ENSEMBLE GUIDANCE HINTS AT THE RIDGE FINALLY BREAKING DOWN
AROUND WEDNESDAY OF NEXT WEEK HOWEVER THERE IS SIGNIFICANT
UNCERTAINTY REGARDING THE EXACT TIMING OF THIS CHANGE. -99/23
AVIATION
HIGH PRESSURE REMAINS FIRMLY IN CONTROL OVER THE AREA,
SUPPORTING IFR/LIFR STRATUS AND AREAS OF DENSE FOG THROUGHOUT THE
WILLAMETTE VALLEY. LOCATIONS SOUTH OF THE METRO HAVE PRETTY MUCH
BEEN SOCKED IN THROUGH THE DAY WITH NO IMPROVEMENT EXPECTED UNTIL
POSSIBLY THURSDAY AFTERNOON. CONDITIONS ALONG THE COAST ARE
EXPECTED TO FLUCTUATE A BIT MORE. MVFR STRATUS COVERS KAST WITH
GUIDANCE SUGGESTING POSSIBLE VIS REDUCTIONS OVERNIGHT BUT THIS MAY
NOT PERSIST FOR LONG. IN THE SOUTHERN WILLAMETTE VALLEY AROUND
KEUG, TEMPERATURES WILL FALL NEAR OR BELOW FREEZING AGAIN.
THEREFORE THERE IS AN INCREASED CHANCE FOR FZFG THROUGH THE
MORNING.
EASTERLY WINDS WILL BEGIN TO INCREASE AFTER 12Z DUE TO AN
INTENSIFYING PRESSURE GRADIENT. THROUGH THE COLUMBIA RIVER GORGE,
GUSTY WINDS WILL INITIATE AS EARLY AS 15Z THU WITH SPEEDS OF 20 KT
OR GREATER. AT KTTD, BY 18Z THU, MODELS ARE SUGGESTING GUSTS UP
TO 30 KT.
KPDX AND APPROACHES...STRATUS BRIEFLY SCATTERED OUT EARLIER THIS
EVENING BUT IS ALREADY BEGINNING TO REFORM. FOG IS ALSO EXPECTED
TO DEVELOP AGAIN WITH MODELS SUGGESTING 1/2 MI VISIBILITY
DEVELOPING BETWEEN 6-8Z. EASTERLY WINDS FROM THE GORGE WILL MAKE
IT INTO THE TERMINAL THURSDAY MORNING. WILL NOT SEE SPEEDS NEARLY
AS STRONG, BUT COULD SEE GUSTS UP TO 20 KT, AND VIS IMPROVING
CONSIDERABLY. MODELS ARE ALSO SUGGESTING CIGS IMPROVING BEFORE
NOON AS THE STRONGER WINDS MIX OUT THE CLOUDS. /19
MARINE
HIGH PRESSURE OVER THE AREA WILL MAINTAIN MORE SETTLED
CONDITIONS THROUGH THE NEXT WEEK. IN THE SHORT-TERM, SEAS HAVE
BEGUN TO RISE WITH HEIGHTS OF 8-11 FT AT 13 SECONDS. THESE SEAS
TOOK A BIT LONGER THAN PREVIOUSLY FORECAST, BUT ARE WELL ON THEIR
WAY FOR CONTINUED SMALL CRAFT ADVISORY HEIGHTS THROUGH AT LEAST
THURSDAY MORNING. ON THURSDAY, THE THERMAL TROUGH WILL DEVELOP
WITH A NORTHERLY WIND INCREASING. WILL SEE THE WAVE BASED SMALL
CRAFT ADVISORY TRANSITION INTO ONE BASED ON WIND SPEEDS. DUE TO
THE LOCATION OF THE RIDGE, THE NORTHERN AND INNER WATERS ARE LESS
LIKELY TO EXPERIENCE GUSTS GREATER THAN 25 KT. THEREFORE, THE
ADVISORY REMAINS IN PLACE FOR THE CENTRAL AND SOUTHERN WATERS.
ON FRIDAY, WINDS WILL EASE AND UNREMARKABLE CONDITIONS WILL
PREVAIL. NO CONCERNS IN THE LONG-TERM FORECAST. -27
PQR WATCHES/WARNINGS/ADVISORIES
OR...AIR STAGNATION ADVISORY UNTIL 4 AM PST FRIDAY FOR ORZ109>111-
114>118.
DENSE FOG ADVISORY UNTIL NOON PST THURSDAY FOR ORZ114>118.
WA...AIR STAGNATION ADVISORY UNTIL 4 AM PST FRIDAY FOR WAZ205-206.
PZ...SMALL CRAFT ADVISORY UNTIL 1 AM PST THURSDAY FOR PZZ251-271.
SMALL CRAFT ADVISORY UNTIL 10 PM PST THURSDAY FOR PZZ252-253-
272-273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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X.COM/NWSPORTLAND
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