681
FXUS66 KPQR 072148
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
248 PM PDT WED OCT 7 2026
SYNOPSIS
UNSEASONABLY WARM AND DRY WEATHER WITH WEAK OFFSHORE
FLOW WILL PERSIST THROUGH THURSDAY, BEFORE A TROUGH BRINGS A RETURN
TO COOLER TEMPERATURES WITH CHANCES FOR LIGHT RAIN FRIDAY INTO
SATURDAY. COOL NIGHTS WILL BRING CHANCES FOR MORNING FROST IN RURAL
VALLEYS AWAY FROM URBAN CORES THIS WEEKEND INTO EARLY NEXT WEEK.
SHORT TERM...NOW THROUGH THURSDAY NIGHT
SATELLITE IMAGERY THIS
AFTERNOON SHOWS MOSTLY CLEAR SKIES WHILE BROAD UPPER LEVEL RIDGING
REMAINS OVER THE REGION. NEARLY IDENTICAL CONDITIONS ARE EXPECTED TO
PERSIST INTO THURSDAY AS HIGH TEMPERATURES INLAND TOP OUT IN THE
UPPER 70S TO NEAR 80 DEGREES. NORMAL HIGHS FOR THIS TIME OF YEAR ARE
IN THE UPPER 60S. DRY WEATHER IS EXPECTED TO CONTINUE THROUGH
THURSDAY NIGHT.
VERY WEAK THERMAL TROUGHING ALONG THE COAST WILL ONLY SUPPORT A
PRESSURE GRADIENT OF AROUND -1 MB BETWEEN TROUTDALE AND THE DALLES,
WHICH IN TURN SUGGESTS OVERNIGHT OFFSHORE WINDS IN THE CASCADES AND
FOOTHILLS ONLY REACHES 10-15 MPH. THE LIGHT OFFSHORE FLOW AT NIGHT
WILL ALSO SUPPORT DRY MID-LEVELS, WHICH WILL ALLOW EFFICIENT
RADIATIVE COOLING AND MORNING LOW TEMPERATURES FALLING TO THE UPPER
40S TO LOW 50S.
WHILE NOT AS WIDESPREAD AS RECENT MORNINGS, SOME AREAS OF FOG OR
LOW CLOUDS MAY DEVELOP ALONG THE COAST OR IN SHELTERED VALLEYS.
BY THURSDAY NIGHT, HIGH CLOUD COVER WILL BEGIN TO INCREASE
AHEAD OF AN APPROACHING WEATHER SYSTEM. DH/36
LONG TERM...FRIDAY THROUGH TUESDAY NIGHT
AN UPPER LEVEL TROUGH
OVER THE GULF OF ALASKA WILL BEGIN PUSHING INTO THE PACIFIC NW ON
FRIDAY, BRINGING AN INITIAL ROUND OF LIGHT RAIN ASSOCIATED WITH A
WEAK COLD FRONT DROPPING SOUTH OVER THE AREA. RAIN LIKELY BEGINS
EARLY FRIDAY ALONG THE COAST BEFORE REACHING INLAND TO THE I-5
CORRIDOR BY THE AFTERNOON TO EARLY EVENING. THIS WILL FAVOR
ACCUMULATIONS ALONG THE NORTH OREGON AND SOUTH WASHINGTON COAST AS
WELL AS IN THE CASCADES AND WESTERN FOOTHILLS THROUGH THE DAY ON
FRIDAY, WHILE AREAS ALONG THE CENTRAL OREGON COAST AND WITHIN THE
WILLAMETTE VALLEY MAY TEND TO STAY DRY. AVERAGE FORECAST RAIN TOTALS
DURING THIS PERIOD ARE 0.10-0.15 INCHES NORTH OF TILLAMOOK HEAD AND
IN THE MOUNT ST.HELENS AREA, WITH LOWER AMOUNTS OF 0.05-0.1 INCHES
ELSEWHERE IN THE LOWER COLUMBIA AND COWLITZ VALLEYS, ALONG THE COAST
FROM TILLAMOOK HEAD TO LINCOLN CITY, AND IN THE NORTH OREGON AND
SOUTH WASHINGTON CASCADES.
AS THE TROUGH MOVES INLAND, A SECOND SHORTWAVE IMPULSE MOVING SOUTH
ON ITS WESTERN FLANK ON SATURDAY WILL SEE THE TROUGH ELONGATE AND
EVENTUALLY PINCH OFF INTO A CLOSED UPPER LOW WHICH WILL SETTLE SOUTH
OVER CALIFORNIA BY EARLY NEXT WEEK. THIS FEATURE WILL RESULT IN
ANOTHER CHANCE FOR LIGHT RAIN ON SATURDAY AFTERNOON, WITH MORE
WIDESPREAD POTENTIAL FOR UP TO 0.1 INCHES OF RAIN, ESPECIALLY TO THE
NORTH OF US-20, BEFORE TRENDING DRIER BY SATURDAY EVENING AND NIGHT.
ALL TOLD, THE CHANCES FOR 0.25 INCHES OF RAIN IN 48 HOURS REACH ONLY
30-50% IN THE WETTEST AREAS NORTH OF TILLAMOOK HEAD AND IN THE
CASCADES AT FOOTHILLS NORTH OF OR-22. ELSEWHERE, THOSE CHANCES ARE 5-
15% FROM LINCOLN CITY TO TILLAMOOK HEAD AND ALONG I-5 NORTH OF
SALEM, AND 5% OR LESS SOUTH OF LINCOLN CITY AND SALEM.
AS THE INITIAL FRONT MOVES INLAND FRIDAY EVENING THOUGH FRIDAY
NIGHT, PEAK GUSTS OUT OF THE WEST IN THE CASCADES, COLUMBIA
RIVER GORGE, AND HOOD RIVER VALLEY COULD REACH 30-40 MPH. BEHIND
THE BOUNDARY AND AS THE CORE OF COOLER AIR ALOFT MOVES OVERHEAD,
TEMPERATURES WILL QUICKLY FALL BACK TOWARD SEASONAL NORMS IN THE
UPPER 50S AND 60S FRIDAY THROUGH THE WEEKEND. OVERNIGHT LOWS
WILL SIMILARLY TREND COOLER, ESPECIALLY SATURDAY AND SUNDAY NIGHTS
WHEN THERE ARE 80% OR GREATER CHANCES FOR FROST IN THE UPPER HOOD
RIVER VALLEY, AND 20-50% CHANCES IN CASCADE VALLEYS, NORTH OREGON
COAST RANGE VALLEYS, THE UPPER COWLITZ VALLEY, AND THE WILLAMETTE
VALLEY SOUTH OF SALEM. CHANCES FOR A TRUE FREEZE ARE 40-60% IN THE
UPPER HOOD RIVER VALLEY NEAR PARKDALE AND DEE, AND 20-40% ALONG OR-
58 BETWEEN EUGENE AND OAKRIDGE. THOSE WITH AGRICULTURAL INTERESTS OR
HOME GROWERS WITH SENSITIVE OUTDOOR PLANTS SHOULD CONTINUE TO
MONITOR THE FORECAST THIS WEEK.
BY EARLY NEXT WEEK AS THE CLOSED LOW DRIFTS TO THE SOUTH, UPPER
HEIGHTS MAY BRIEFLY RISE AS RIDGING REDEVELOPS OVERHEAD. THIS
WILL FAVOR A MODEST WARMING TREND MONDAY INTO TUESDAY. THERE IS
MUCH LOWER CONFIDENCE IN THE EVOLUTION OF THE LARGE-SCALE
PATTERN BY THE MIDDLE OF NEXT WEEK, BUT THERE ARE LOW CHANCES
FOR ANOTHER TROUGH TO BRING ADDITIONAL RAIN. DH/36
AVIATION...THROUGH 00Z FRIDAY
VFR CONDITIONS ARE IN PLACE
ACROSS THE REGION THANKS TO HIGH PRESSURE REMAINING OVERHEAD.
WHILE CONFIDENCE IS HIGH VFR CIGS/VIS PERSIST THROUGH THE EVENING,
WE'LL ONCE AGAIN HAVE TO BE ON THE LOOKOUT FOR PATCHY FOG/LOW
CLOUD FORMATION NEAR SUNRISE THURSDAY MORNING, ALTHOUGH CONTINUED
WEAK OFFSHORE FLOW AND A SLIGHTLY DRIER AIRMASS SHOULD FURTHER
LIMIT THE PROLIFERATION OF LIFR/IFR CONDITIONS. CHANCES FOR IFR
VIS/CIGS AT THE COAST PEAK AROUND 35-45% COME 12-15Z THUR WITH
15-25% CHANCES FOR SIMILAR CONDITIONS AT INLAND TERMINALS (30-40%
CHANCE AT KEUG). GIVEN THE LATEST HRRR, WOULD LEAN TOWARDS HIGH
PROBABILITY OF FOG IN AT LEAST THE VICINITY OF KEUG. ANY FOG/LOW
STRATUS LAYER THURSDAY MORNING WILL BE SHALLOW, QUICKLY
DISSIPATING BY 17-18Z. WINDS PEAK LATE THIS AFTERNOON ALONG THE
COAST WITH GUSTS AROUND 20 KNOTS BEFORE DECREASING THIS EVENING.
KPDX AND APPROACHES...VFR CONDITIONS CONTINUE THROUGH THIS EVENING
AND MOST OF THE OVERNIGHT HOURS. COME THE SUNRISE HOURS WE'LL
ONCE AGAIN HAVE TO WATCH FOR PATCHY FOG FORMATION NEAR THE
TERMINAL (12-15Z TIME PERIOD), HOWEVER, CHANCES FOR DEGRADED
CONDITIONS CURRENTLY SIT AT AROUND ~20%.-99
MARINE
HIGH PRESSURE AT THE SURFACE WILL CONTINUE TO LINGER
OVER THE EASTERN PACIFIC THE REST OF TODAY THROUGH THURSDAY
FACILITATING PEAK AFTERNOON/EVENING WIND GUSTS OF 20-25 KNOTS. AS
A RESULT, SMALL CRAFT ADVISORIES REMAIN IN EFFECT THROUGH THIS
EVENING AND THEN AGAIN THURSDAY MID AFTERNOON/EVENING FOR THE
WATERS SOUTH OF CAPE FALCON. DURING THIS TIME PERIOD, ANTICIPATE
SEAS AROUND 6-9 FT WITH AN UNDERLYING LONG PERIOD WEST-NORTHWEST
SWELL. HIGH PRESSURE ALOFT WILL ALSO SUPPORT AREAS OF DENSE FOG
DEVELOPING NIGHTLY THROUGH THE MORNING HOURS AS CLOUD BASES ARE
COMPRESSED DOWN TO THE SURFACE.
COME FRIDAY EXPECT THE DEVELOPMENT OF MORE ACTIVE MARINE
CONDITIONS AS TROUGHING OVER THE GULF OF ALASKA PUSHING SOUTHWARD
GENERATES A REINFORCING NORTHWEST SWELL IN ADDITION TO THE
ARRIVAL OF A FRONTAL BOUNDARY. WINDS OUT OF THE NORTHWEST
ASSOCIATED WITH A COLD FRONT WILL INCREASE ON FRIDAY INTO FRIDAY
EVENING AS SEAS PEAK AT 8-12 FT BY FRIDAY NIGHT AND SATURDAY. AT
LEAST THIS RISE IN SEAS IS FAIRLY SHORT LIVED. SUNDAY WINDS EASE
AND VEER OUT OF THE NORTH TO NORTH-NORTHEAST WHILE SEAS FALL BACK
TO THE 5-7 FT RANGE FOR THE EARLY TO MIDDLE PORTION OF NEXT WEEK.
-99/36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 2 AM PDT THURSDAY FOR PZZ210-251>253.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT THURSDAY FOR PZZ271>273.
WWW.WEATHER.GOV/PORTLAND
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