412
FXUS66 KPQR 141739 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PORTLAND OR
1039 AM PDT MON SEP 14 2026
UPDATED AVIATION DISCUSSION
SYNOPSIS
THE REGION IS TRANSITIONING FROM THE COOL PATTERN
OF THE PAST SEVERAL DAYS TOWARD A MUCH WARMER AND DRIER REGIME.
MONDAY AND TUESDAY WILL REMAIN ON THE COOL SIDE WITH AREAS OF
MORNING LOW CLOUDS AND FOG, BUT TEMPERATURES BEGIN A SHARPER
CLIMB WEDNESDAY AS HIGH PRESSURE BUILDS INLAND. INTERIOR HIGHS
ARE EXPECTED TO REACH THE 80S WEDNESDAY AND THURSDAY,
ACCOMPANIED BY STRENGTHENING EASTERLY WINDS IN THE COLUMBIA
RIVER GORGE, CASCADES AND ADJACENT FOOTHILLS. CONFIDENCE
DECREASES TOWARD THE END OF THE WEEK AS THE RIDGE BEGINS TO
WEAKEN, ALTHOUGH DRY WEATHER REMAINS FAVORED.
DISCUSSION...NOW THROUGH SUNDAY
THE MOST NOTABLE CHANGE IN
THE FORECAST IS THE TRANSITION IN THE LARGE-SCALE PATTERN FROM
THE RECENTLY COOL AND UNSETTLED REGIME TO A WARM, DRY SETUP BY
MIDWEEK. THE WEEKEND UPPER LOW HAS MOVED EAST OF THE AREA, AND
PRECIPITATION WILL NO LONGER BE A SIGNIFICANT CONCERN ACROSS THE
LOWLANDS. SOME RESIDUAL MOISTURE COMBINED WITH LIGHT WINDS AND
PARTIAL CLEARING WILL FAVOR LOW CLOUDS AND AREAS OF FOG THIS
MORNING, LIKE MORE WIDESPREAD THAN DENSE. VISIBILITY COULD STILL
BECOME LOCALLY POOR IN SHELTERED LOCATIONS.
TEMPERATURES WILL BE SLOW TO RECOVER AT FIRST. INTERIOR HIGHS
MONDAY AND TUESDAY SHOULD ONLY REACH THE UPPER 60S TO LOW 70S,
REMAINING ROUGHLY 5-7 DEGREES BELOW THE SEASONAL AVERAGE.
ANOTHER ROUND OF MORNING FOG IS POSSIBLE TUESDAY, PARTICULARLY
IN PROTECTED VALLEYS WHERE A STRONGER LOW-LEVEL INVERSION IS
EXPECTED. OTHERWISE, DRY WEATHER AND GRADUALLY INCREASING
SUNSHINE WILL SET THE STAGE FOR THE MUCH WARMER PATTERN ARRIVING
MIDWEEK.
BY WEDNESDAY, THE OFFSHORE RIDGE WILL BEGIN EXERTING MORE
INFLUENCE ON THE PACIFIC NORTHWEST. MEANWHILE, THE SHORTWAVE
DROPPING SOUTH FROM BRITISH COLUMBIA IS EXPECTED TO CLOSE OFF
OVER NORTHERN CALIFORNIA. THIS EVOLVING PATTERN FAVORS BOTH
RAPID WARMING AND INCREASING EASTERLY FLOW. INTERIOR
TEMPERATURES SHOULD REACH THE UPPER 70S TO LOW 80S WEDNESDAY
THROUGH FRIDAY, WITH THURSDAY CURRENTLY FAVORED TO BE THE
WARMEST DAY. THE LATEST NBM GIVES A MUCH LOWER PROBABILITY OF
REACHING 90 DEGREES COMPARED TO YESTERDAY, WITH NOW A 5-10%
CHANCE ACROSS THE NORTH WILLAMETTE VALLEY AND LESS THAN 5%
ELSEWHERE ON THURSDAY AND FRIDAY, AND LITTLE TO NO CHANCES ON
WEDNESDAY. THIS CHANGE CONTINUES TO SUGGEST WIDESPREAD 90-DEGREE
HEAT UNLIKELY, BUT HIGHS SHOULD STILL RUN APPROXIMATELY 5-10
DEGREES ABOVE THE SEASONAL AVERAGE.
EASTERLY WINDS WILL BECOME INCREASINGLY IMPORTANT ACROSS
ELEVATED TERRAIN WEDNESDAY INTO THURSDAY. A COMBINATION OF EAST-
NORTHEASTERLY FLOW ALOFT AND A NORTHWARD-SURGING THERMAL TROUGH
NEAR THE SURFACE SHOULD STRENGTHEN EASTERLY WINDS WEDNESDAY
INTO THURSDAY MORNING. WHILE THE LATEST NBM HAS TRENDED TOWARDS
SLIGHTLY WEAKER WINDS, GUSTS AROUND 20-30 MPH ARE STILL EXPECTED
IN THE MORE WIND-PRONE PORTIONS OF THE COLUMBIA RIVER GORGE,
CASCADES AND ADJACENT FOOTHILLS, WITH ISOLATED GUSTS UP TO 35
MPH. THE HIGHER TERRAIN OF THE COAST RANGE COULD ALSO BECOME
BREEZY, ALTHOUGH CONFIDENCE IS LOWER. RELATIVE HUMIDITY MAY FALL
INTO THE 30-35% RANGE DURING THE WARMEST PART OF THE PERIOD.
TAKEN TOGETHER, THE WARMER TEMPERATURES, LOWER HUMIDITY AND
INCREASING EAST WINDS COULD CREATE A PERIOD OF ELEVATED FIRE-
WEATHER CONCERNS.
THE DEGREE TO WHICH THE WARM PATTERN PERSISTS BEYOND THURSDAY
IS LESS CERTAIN. ENSEMBLE GUIDANCE CURRENTLY SPLITS INTO TWO
GENERAL SOLUTIONS FOR FRIDAY, WITH ROUGHLY 40-50% OF MEMBERS
KEEPING THE RIDGE CLOSE ENOUGH TO MAINTAIN MID 80S TEMPERATURES
ACROSS THE INTERIOR LOWLANDS, WHILE 50-60% FAVOR A QUICKER
BREAKDOWN AND HIGHS BACK IN THE 70S. IN SHORT, CURRENT GUIDANCE
SUGGESTS HIGH TEMPERATURES ANYWHERE BETWEEN 72 AND 86 ON FRIDAY.
SATURDAY CARRIES SIMILAR UNCERTAINTY, ALTHOUGH THERE IS A
GENERAL TREND TOWARD COOLER TEMPERATURES EVEN AMONG THE WARMER
SOLUTIONS (HIGH TEMPERATURES ANYWHERE BETWEEN 68 AND 83
DEGREES). DESPITE THIS TEMPERATURE SPREAD, THE PRECIPITATION
SIGNAL REMAINS MUCH MORE CONSISTENT, WITH A 90% CHANCE OF DRY
WEATHER CONTINUING THROUGH FRIDAY AND INTO THE WEEKEND. ~12
AVIATION...THROUGH 18Z TUESDAY
NORTHWEST FLOW ALOFT BECOMES
MORE WESTERLY TONIGHT AS AN UPPER LEVEL TROUGH DROPS SOUTH OUT OF
WESTERN CANADA. MARINE STRATUS ALONG THE COAST AND LOW CLOUDS
INLAND THIS MORNING ARE EXPECTED TO GRADUALLY BECOME SCATTERED
THROUGH THE AFTERNOON. PRIMARILY VFR CONDITIONS ARE EXPECTED WITH
CIGS OF AROUND 5-6 KFT. IFR CONDITIONS AT KEUG THIS MORNING ARE
EXPECTED TO CLEAR OUT BY 19Z. STRATUS LIKELY PUSHES BACK ONSHORE
TO THE COAST LATER THIS EVENING, WITH AROUND A 20-40% CHANCE OF
MVFR CONDITIONS AFTER 04-06Z TUESDAY. CONFIDENCE REMAINS TOO LOW
TO INCLUDE IN THE TAFS. OTHERWISE, LIGHT AND VARIABLE WINDS BECOME
NORTH TO NORTHWEST AROUND 4-8 KT BY MID-AFTERNOON.
KPDX AND APPROACHES...VFR EXPECTED THROUGH THE TAF PERIOD, WITH
CLOUDS GRADUALLY SCATTERING OUT THIS AFTERNOON. LIGHT WINDS BECOME
NORTHWEST AROUND 4-6 KT THIS AFTERNOON. /DH
MARINE
CURRENT WEST WINDS WILL VEER OUT OF THE NORTH BY
LATE THIS AFTERNOON AS HIGH PRESSURE BUILDS OFFSHORE. THE RIDGE
WILL CONTINUE TO STRENGTHEN THROUGH MIDWEEK, INTENSIFYING
NORTHERLY WINDS TO 15-20 KT WITH GUSTS TO 25 KT BY WEDNESDAY
AFTERNOON. THERE IS A 60-90% CHANCE SUSTAINED WINDS WILL PEAK
ABOVE 21 KT ON WEDNESDAY TO THE SOUTH OF CAPE FALCON, WITH
LOWER CHANCES, 10-40%, ON BOTH TUESDAY AND THURSDAY.
ADDITIONALLY, THERE IS A 10-35% CHANCE OF WIND GUSTS OF 30 KT
OR GREATER ON WEDNESDAY. WINDS THEN EASE INTO NEXT WEEKEND AS
HIGH PRESSURE WEAKENS.
SEAS AROUND 5 FT EARLY THIS WEEK WILL SIMILARLY BUILD TO 6-7 FT
AS WINDS STRENGTHEN. A PERSISTENT NORTHWESTERLY SWELL AT 8-9
SECONDS OTHERWISE CONTINUES THROUGH THE WEEK, WITH SEAS EASING
INTO NEXT WEEKEND AS HIGH PRESSURE AND WINDS WEAKEN. ~12/36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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