434
FXUS66 KPQR 131913 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1113 AM PST TUE JAN 13 2026
UPDATED AVIATION DISCUSSION AND PQR WATCHES/WARNINGS/ADVISORIES.
SYNOPSIS
A STRONG AND PERSISTENT AREA OF HIGH PRESSURE WILL REMAIN
LOCKED IN PLACE OVER THE PACIFIC NORTHWEST THROUGH THE WEEK. THIS
PATTERN WILL SUPPORT AN EXTENDED PERIOD OF DRY WEATHER, LIGHT WINDS,
AND TEMPERATURES RUNNING ABOVE SEASONAL NORMS. IN CONTRAST, PORTIONS
OF THE INTERIOR LOWLANDS, PARTICULARLY THE WILLAMETTE VALLEY, WILL
LIKELY EXPERIENCE COOLER DAYTIME TEMPERATURES DUE TO FOG AND LOW
STRATUS DURING THE OVERNIGHT AND MORNING HOURS OVER THE NEXT FEW
DAYS. LATE IN THE WEEK, COLD EASTERLY WINDS WILL FLOW THROUGH THE
COLUMBIA RIVER GORGE, WITH SUB-FREEZING OVERNIGHT TEMPERATURES LIKELY
IN THE UPPER HOOD RIVER VALLEY AND MUCH OF THE WILLAMETTE VALLEY.
DISCUSSION...NOW THROUGH MONDAY
LITTLE HAS CHANGED IN THE
OVERALL FORECAST SINCE YESTERDAY AFTERNOON. WEATHER CONDITIONS NOW
THROUGH JAN. 20TH WILL BE FAIRLY CONSISTENT EACH DAY DUE TO AN
ANOMALOUSLY STRONG UPPER-LEVEL RIDGE CENTERED OVER THE PACIFIC
NORTHWEST AND NORTHEAST PACIFIC. MODELS STILL SUGGEST 500 MB HEIGHTS
WILL PEAK AROUND 585-590 MB ALONG THE RIDGE AXIS TODAY INTO TONIGHT
IN WESTERN OR/WA, HIGHEST TO THE SOUTH. THESE VALUES ARE AROUND THE
99TH PERCENTILE COMPARED TO CLIMATOLOGY, SIGNIFYING THE UNUSUAL
STRENGTH OF THIS HIGH PRESSURE SYSTEM. ENSEMBLE GUIDANCE REMAINS IN
STRONG AGREEMENT THAT THIS RIDGE WILL PERSIST THROUGH THE UPCOMING
WEEKEND, RESULTING IN CALM, DRY, AND RELATIVELY MILD CONDITIONS FOR
MID-JANUARY, ESPECIALLY FOR ELEVATIONS ABOVE 1000 FEET WHERE FOG AND
LOW STRATUS WILL NOT BE A FACTOR. WHILE SOME GUIDANCE INDICATES WEAK
SHORTWAVE ENERGY MAY ROTATE AROUND THE PERIPHERY OF THE RIDGE THIS
WEEKEND, THESE FEATURES ARE EXPECTED TO REMAIN MOISTURE-STARVED AND
SHOULD NOT DISRUPT THE DRY PATTERN. THE TIMING OF A MORE MEANINGFUL
PATTERN CHANGE REMAINS UNCERTAIN, THROUGH A GROWING SUBSET OF
ENSEMBLE GUIDANCE (AROUND 75%) SUGGESTS A POTENTIAL BREAKDOWN OF THE
RIDGE AND A RETURN OF AT LEAST LIGHT PRECIPITATION SOMETIME BETWEEN
JANUARY 21 TO 23. UNTIL THEN, DRY WEATHER WILL CONTINUE EACH DAY FROM
TUESDAY THROUGH AT LEAST MONDAY.
ONE EXCEPTION TO THE OTHERWISE CALM CONDITIONS WILL BE INCREASING
EASTERLY WINDS IN THE WESTERN COLUMBIA GORGE, CASCADES, AND PORTIONS
OF THE EAST PORTLAND AND VANCOUVER METRO AREA LATE THURSDAY INTO
FRIDAY AS OFFSHORE PRESSURE GRADIENTS STRENGTHEN. WITH THE AIRMASS
ORIGINATING FROM THE COLUMBIA BASIN, EXPECT COOLER TEMPERATURES TO
ADVECT INTO THE UPPER HOOD RIVER VALLEY, COLUMBIA RIVER GORGE AND
WILLAMETTE VALLEY. THE UPPER HOOD RIVER VALLEY COULD SEE OVERNIGHT
MINIMUM TEMPERATURES FALL BELOW FREEZING IN THE MORNINGS THURSDAY
THROUGH AT LEAST SUNDAY (20-40% CHANCE FOR OVERNIGHT TEMPS TO FALL
BELOW 32 F). LOW TEMPERATURES ARE FORECAST TO DROP TO NEAR FREEZING
ACROSS MOST OF THE WILLAMETTE VALLEY AS WELL.
OTHERWISE, DENSE FOG AND LOW STRATUS REMAINS THE MAIN CONCERN FOR THE
INTERIOR LOWLANDS THIS WEEK, ESPECIALLY DURING THE OVERNIGHT AND
MORNING HOURS TODAY THROUGH THURSDAY WHEN REDUCED VISIBILITIES WILL
POSE A TRAVEL HAZARD FOR MANY COMMUTERS. NOTE WEBCAM AND SURFACE
WEATHER OBSERVATIONS FROM 3 AM TUESDAY SHOWED WIDESPREAD FOG OVER
MOST OF THE WILLAMETTE VALLEY WITH VISIBILITIES FALLING BELOW 1/2-1
MILE. FOG WAS ALSO BEING OBSERVED IN THE COAST RANGE LOWLANDS.
THEREFORE, A DENSE FOG ADVISORY REMAINS IN EFFECT FOR THESE AREAS
THROUGH THIS MORNING. IN CONTRAST, AREAS ABOVE THE VALLEY INVERSION,
INCLUDING THE COAST RANGE, CASCADE FOOTHILLS, AND HIGHER TERRAIN IN
THE CASCADES WILL EXPERIENCE SIGNIFICANTLY WARMER AND SUNNIER
CONDITIONS, WITH HIGHS COMMONLY IN THE UPPER 50S TO MID 60S. COASTAL
AREAS WILL ALSO TREND MILD, WITH AFTERNOON TEMPERATURES WELL INTO THE
50S AND NEAR 60 DEGREES.
THE PROLONGED PERIOD OF HIGH PRESSURE WILL ALSO FAVOR STAGNANT
AIR CONDITIONS WITH LIMITED VERTICAL MIXING. THESE CONDITIONS
ARE CONDUCIVE TO THE ACCUMULATION OF AIR POLLUTANTS NEAR THE
SURFACE, PARTICULARLY IN VALLEY LOCATIONS PRONE TO INVERSIONS.
AN AIR STAGNATION ADVISORY REMAINS IN EFFECT FOR THE WILLAMETTE
VALLEY AND MAY BE EXPANDED AS THE WEEK PROGRESSES. STATE AIR
QUALITY AGENCIES CONTINUE TO RECOMMEND AVOIDING OUTDOOR BURNING
AND MINIMIZING THE USE OF RESIDENTIAL WOOD-BURNING DEVICES.
RESIDENTS ARE ENCOURAGES TO MONITOR LOCAL AIR QUALITY INFORMATION AND
COMPLY WITH ANY BURN RESTRICTIONS ISSUED BY THEIR LOCAL AGENCIES.
-23/12
AVIATION
HIGH PRESSURE OVER THE AREA WILL MAINTAIN COOLER AND
CLEARER CONDITIONS THROUGHOUT THE AREA. AS OF 18Z TUESDAY,
WIDESPREAD FOG REMAINS WITHIN THE WILLAMETTE VALLEY AND SOME AREAS
ALONG THE COAST. WITH TEMPERATURES BELOW FREEZING, AIRPORTS AREA
THE SOUTHERN WILLAMETTE VALLEY (LIKE KEUG) ARE EXPERIENCING
INCREASED CHANCES FOR FREEZING FOG. DENSE FOG WILL STRUGGLE TO MIX
OUT TODAY IN SOME LOCATIONS LIKE KUAO AND KSLE DUE TO A LIGHT AND
VARIABLE WIND. HOWEVER, AS THE SUN CONTINUES TO RISE, A STEADY
BURN OFF IS EXPECTED. CONFIDENCE IS LOW IN REGARDS TO WHEN THE FOG
WILL DISSIPATE.
TONIGHT WILL BE ANOTHER WIDESPREAD AND FOGGY DAY. THERE IS HIGHER
CONFIDENCE IN DENSER AND MORE WIDESPREAD LIFR VIS WITH A POTENTIAL
FOR VIS OF M1/4SM OR LESS. BASED ON SOME MODELS, THERE IS NEARLY A
100% CHANCE OF FOG AROUND KEUG. BECAUSE WINDS WILL BE LIGHT AND
FROM THE NORTH, FOG MAY LINGER WELL PAST 18Z WEDNESDAY.
KPDX AND APPROACHES...FOG REMAINS IN THE AREA WITH SPOTTY
REDUCTIONS TO IFR VIS/CIGS MIXED WITH VFR CONDITIONS. WINDS ARE
LIGHT BUT TEMPERATURES ARE RISING WHICH IS ALLOWING FOR FOG TO
LIFT AND REFORM. OVER THE NEXT FEW HOURS, THERE WILL BE LITTLE
IMPROVEMENT ASIDE FROM BOUNCING CONDITIONS. CONFIDENCE IS LOW IN
THE EXACT BURN OFF TIME. OVERNIGHT, THERE IS HIGHER CONFIDENCE IN
FOG DEVELOPMENT, BUT EASTERLY WINDS FROM THE GORGE MAY KEEP THE
EASTERN HALF OF THE TERMINAL FOG-FREE. -27
MARINE
WINDS HAVE BECOME RELATIVELY LIGHT THIS MORNING AS HIGH
PRESSURE STRENGTHENS OVER THE REGION, WITH SEAS HOVERING BETWEEN
10-12 FT THIS MORNING BEFORE LOWERING TO 8-10 FT THIS AFTERNOON.
NORTHERLY WINDS DEVELOP LATE WEDNESDAY INTO THURSDAY AS A THERMAL
TROUGH BUILDS NORTHWARD UP THE SOUTH OREGON COAST, WITH SEAS
INCREASING BY A FOOT OR TWO. NORTHERLY WINDS WILL LIKELY PEAK IN
STRENGTH ON THURSDAY WITH GUSTS UP TO 25 KT OVER THE CENTRAL AND
SOUTHERN OUTER WATERS.
VERY CALM CONDITIONS ARE EXPECTED FRIDAY THROUGH MONDAY AS STRONG
HIGH PRESSURE STAYS LOCKED IN PLACE OVER THE REGION. WINDS SHOULD
STAY UNDER 10-15 KT THIS WEEKEND WITH SEAS AROUND 4-6 FT. -23
PQR WATCHES/WARNINGS/ADVISORIES
OR...DENSE FOG ADVISORY UNTIL 2 PM PST THIS AFTERNOON FOR ORZ104-
105-109-114>117.
AIR STAGNATION ADVISORY UNTIL 4 AM PST FRIDAY FOR ORZ109>111-
114>118.
WA...AIR STAGNATION ADVISORY UNTIL 4 AM PST FRIDAY FOR WAZ205-206.
PZ...SMALL CRAFT ADVISORY UNTIL NOON PST TODAY FOR PZZ210-251-252-
271-272.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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X.COM/NWSPORTLAND
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