956
FXUS66 KPQR 122248
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
248 PM PST MON JAN 12 2026
SYNOPSIS
A STRONG AND PERSISTENT AREA OF HIGH PRESSURE CONTINUES TO
DOMINATE THE PACIFIC NORTHWEST THIS AFTERNOON AND IS EXPECTED TO
REMAIN FIRMLY IN PLACE THROUGH MUCH OF 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
RECURRING FOG AND LOW STRATUS BEGINNING EARLY TUESDAY AND
PERSISTING AT TIMES THROUGH MIDWEEK. LATER IN THE WEEK, COLD
EASTERLY WINDS WILL FLOW THROUGH THE COLUMBIA RIVER GORGE,
POSSIBLY BRINGING OVERNIGHT FREEZING CONDITIONS TO THE UPPER
HOOD RIVER VALLEY.
DISCUSSION...NOW THROUGH MONDAY
LITTLE HAS CHANGED IN THE
OVERALL FORECAST SINCE EARLY THIS MORNING. ANY LIGHT
PRECIPITATION THAT OCCURRED EARLIER THIS MORNING OVER PARTS OF
THE SOUTHWEST WASHINGTON COAST AND THE FAR NORTH OREGON COAST
HAS ENDED, AND DRY CONDITIONS ARE NOW FIRMLY ESTABLISHED ACROSS
THE FORECAST AREA. LOOKING AHEAD, WEATHER THROUGH THE NEXT 7
DAYS OR SO WILL CONTINUE TO BE GOVERNED BY AN ANOMALOUSLY STRONG
UPPER-LEVEL RIDGE CENTERED OVER THE PACIFIC NORTHWEST AND
NORTHEAST PACIFIC. ENSEMBLE GUIDANCE REMAINS IN STRONG AGREEMENT
THAT THIS RIDGE WILL PERSIST THROUGH THE WORK WEEK AND INTO
THE WEEKEND, RESULTING IN CALM, DRY, AND RELATIVELY MILD
CONDITIONS FOR MID-JANUARY.
THE UPPER-LEVEL PATTERN REMAINS HIGHLY AMPLIFIED, WITH THE
RIDGE POSITIONED BETWEEN TROUGHING WELL OFFSHORE TO THE WEST AND
ANOTHER TROUGH OVER THE CENTRAL TO EASTERN UNITED STATES. THIS
CONFIGURATION REFLECTS A CLASSIC BLOCKING REGIME, INITIALLY
RESEMBLING AN OMEGA BLOCK AND POTENTIALLY EVOLVING TOWARD A REX
BLOCK LATER IN THE WEEK. FORECASTED 500 MB HEIGHTS CONTINUE TO
PEAK AROUND 585 TO 590 DM OVER SOUTHERN OREGON AND NORTHERN
CALIFORNIA, FALLING WITHIN THE UPPER END OF THE HISTORICAL
DISTRIBUTION FOR THIS TIME OF YEAR AND UNDERSCORING THE UNUSUAL
STRENGTH AND LONGEVITY OF THE RIDGE.
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 MEMBERS
SUGGESTS A POTENTIAL BREAKDOWN OF THE RIDGE AND A RETURN OF
PRECIPITATION SOMETIME AROUND JANUARY 21 TO 23. UNTIL THEN, DRY
WEATHER IS FAVORED EACH DAY FROM TUESDAY THROUGH AT LEAST
SUNDAY. ONE EXCEPTION TO THE OTHERWISE CALM CONDITIONS MAY 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 THESE WINDS ORIGINATING FROM THE COLUMBIA
BASIN, EXPECT MUCH COOLER TEMPERATURES AS A RESULT FOR AREAS
AROUND THE GORGE SUCH AS THE UPPER HOOD RIVER 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).
FOG AND LOW STRATUS REMAIN A KEY CONCERN FOR THE INTERIOR
LOWLANDS. CLEAR SKIES AND LIGHT WINDS TONIGHT WILL AGAIN
PROMOTE EFFICIENT RADIATIONAL COOLING, WITH WIDESPREAD FOG
DEVELOPMENT EXPECTED LATE TONIGHT INTO TUESDAY MORNING.
PROBABILITIES FOR SURFACE VISIBILITIES OF ONE-HALF MILE OR LESS
REMAIN HIGH, ESPECIALLY ACROSS INLAND VALLEYS. WHILE SOME FOG
MAY LIFT OR THIN DURING THE AFTERNOON HOURS, LOW CLOUDS ARE
LIKELY TO PERSIST THROUGH MUCH OF THE DAY TUESDAY AND POSSIBLY
INTO WEDNESDAY. WITH MODERATE TO HIGH CONFIDENCE FOR WIDESPREAD
FOG, A DENSE FOG ADVISORY HAS BEEN ISSUED FROM 10 PM TONIGHT
TO 11 AM TUESDAY. OTHERWISE, HIGH TEMPERATURES IN VALLEY
LOCATIONS BELOW ROUGHLY 1000 FEET ARE EXPECTED TO REMAIN
RELATIVELY COOL, GENERALLY STAYING BELOW 50 DEGREES. IN
CONTRAST, AREAS ABOVE THE VALLEY INVERSIONS, INCLUDING THE COAST
RANGE, CASCADE FOOTHILLS, AND HIGHER TERRAIN 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 LOCALLY
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.
~12/23
AVIATION
HIGH PRESSURE BUILDS OVER THE REGION THROUGH THE NEXT
SEVERAL DAYS. HIGH CLOUDS REMAIN OVER THE REGION WITH MVFR CIGS
ALONG THE NORTH OREGON AND SOUTH WASHINGTON COAST. AROUND KAST,
FLIGHT CATEGORIES HAVE BEEN VARIABLE BOUNCING BETWEEN IFR, MVFR
AND VFR DUE TO A SEA BREEZE AND LOWERED CIGS. IN GENERAL WILL SEE
THIS SIMILAR PATTERN, BUT HAVE INCORPORATED A STRONGER TREND
TOWARDS MVFR CONDITIONS. FURTHER INLAND AND SOUTH, VFR CONDITIONS
PREVAIL. OVERNIGHT, WE WILL EXPERIENCE DIURNAL COOLING DUE TO
CLEAR SKIES. WIDESPREAD FOG IS EXPECTED IN THE LOWLANDS WHICH MAY
BECOME DENSE AT TIMES. AREAS MOST AT RISK WILL BE TERMINALS WITHIN
THE WILLAMETTE VALLEY AND VANCOUVER-METRO. AREAS THAT WILL
EXPERIENCE EASTERLY WINDS (KTTD, K4S2, ETC) HAVE SIGNIFICANTLY
LOWER PROBABILITY OF FOG FORMATION.
KPDX AND APPROACHES...EXPECT VFR FLIGHT CONDITIONS TO GIVE WAY TO
FOG AND LOW STRATUS AFTER 06Z TUESDAY, RESULTING IN AN ABRUPT
DROP TO LIFR/IFR CIGS AND VISIBILITIES (50-60% CHANCE FOR SURFACE
VISIBILITIES OF 1/2 SM OR LOWER BY 12Z TUESDAY). -27
MARINE
STEEP AND HAZARDOUS SEAS THROUGH THE REMAINDER OF THE
DAY WITH SEAS AS HIGH AS 14 FT AT 14 SECONDS. AROUND THE COLUMBIA
RIVER BAR, WAVES OF 10-14 FT HAVE BEEN OBSERVED. ELSEWHERE, A
SMALL CRAFT ADVISORY REMAINS IN EFFECT OVER THE SOUTHERN WATERS
WHERE SEAS ARE RELATIVELY LOWER COMPARED TO THE NORTHERN WATERS,
BUT STILL HIGH ENOUGH TO BE HAZARDOUS FOR SMALL CRAFT.
WINDS BECOME RELATIVELY LIGHT MONDAY NIGHT INTO TUESDAY
AS HIGH PRESSURE STRENGTHENS OVER THE REGION, WITH SEAS HOVERING
BETWEEN 8-10 FT. NORTHERLY WINDS THEN 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 SUNDAY 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. -27/23
BEACH HAZARDS
THERE IS A HIGH THREAT OF SNEAKER WAVES AT THE COAST
THROUGH THIS AFTERNOON DUE TO A CONTINUED LONG-PERIOD
SOUTHWESTERLY TO WESTERLY SWELL. SNEAKER WAVES CAN CREATE
POTENTIALLY LIFE-THREATENING CONDITIONS AS WAVES MAY RUN FARTHER
UP THE BEACH THAN EXPECTED. THESE WAVES CAN EASILY CATCH PEOPLE
OFF GUARD AND CAUSE BEACHGOERS TO BE KNOCKED OFF THEIR FEET AND
PULLED OUT INTO COLD OCEAN WATERS. NEVER TURN YOUR BACK TO THE
OCEAN. CAUTION SHOULD BE USED WHEN IN OR NEAR THE WATER, AND THOSE
WITH CHILDREN SHOULD BE ESPECIALLY WATCHFUL. SNEAKER WAVES CAN
LIFT OR ROLL LARGE, HEAVY LOGS OR ROCKS WHICH CAN LEAD TO SERIOUS
DEATH OR INJURY. KEEP OFF ROCKS, LOGS, AND JETTIES NEAR THE
WATERLINE ON BEACHES. -23
PQR WATCHES/WARNINGS/ADVISORIES
OR...AIR STAGNATION ADVISORY UNTIL 4 AM PST FRIDAY FOR ORZ109>111-
114>118.
DENSE FOG ADVISORY FROM 10 PM THIS EVENING TO 11 AM PST TUESDAY
FOR ORZ109>111-114>118.
WA...AIR STAGNATION ADVISORY UNTIL 4 AM PST FRIDAY FOR WAZ205-206.
DENSE FOG ADVISORY FROM 10 PM THIS EVENING TO 11 AM PST TUESDAY
FOR WAZ205-206.
PZ...HAZARDOUS SEAS WARNING UNTIL 6 PM PST THIS EVENING FOR PZZ210.
SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 10 AM PST TUESDAY
FOR PZZ210.
HAZARDOUS SEAS WARNING UNTIL 4 PM PST THIS AFTERNOON FOR PZZ251-
252-271-272.
SMALL CRAFT ADVISORY UNTIL 10 AM PST TUESDAY FOR PZZ251-252-271-
272.
SMALL CRAFT ADVISORY UNTIL 4 AM PST TUESDAY FOR PZZ253-273.
WWW.WEATHER.GOV/PORTLAND
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