361
FXUS66 KPQR 242122
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
222 PM PDT THU SEP 24 2026
SYNOPSIS
AN EARLY-SEASON FRONTAL SYSTEM WILL BRING WIDESPREAD
RAIN AND GUSTY WINDS TO THE REGION THIS EVENING THROUGH MUCH OF
FRIDAY. THE PROGRESSIVE PATTERN WILL SEE DRY WEATHER QUICKLY
RETURN LATE FRIDAY THROUGH THE WEEKEND, BEFORE CHANCES FOR
RAIN INCREASE AGAIN EARLY NEXT WEEK.
SHORT TERM...NOW THROUGH FRIDAY NIGHT
AN AREA OF SURFACE LOW
PRESSURE CURRENTLY LOCATED NEAR 44N/130W, OR ROUGHLY 300 MILES
WEST OF FLORENCE, IS EXPECTED TO TRACK TO THE NORTHEAST BEFORE
MOVING ONSHORE SOMEWHERE NEAR THE MOUTH OF THE COLUMBIA RIVER
FRIDAY MORNING. A WEAK WARM FRONTAL BOUNDARY LIFTED NORTHWARD
EARLIER TODAY, BRINGING LIGHT RAIN SHOWERS TO THE SOUTH
WASHINGTON AND FAR NORTH OREGON COASTS, WHILE THE ASSOCIATED
COLD FRONTAL BOUNDARY CURRENTLY SITS SOME 20-60 MILES OFFSHORE.
THIS FRONT WILL BRING STEADY RAIN TO THE COAST LATER THIS
AFTERNOON, BEGINNING BETWEEN 4-6 PM PDT, BEFORE PUSHING INLAND
TO THE I-5 CORRIDOR BY 7-10 PM PDT THIS EVENING. THERE IS A
15-20% CHANCE FOR AN ISOLATED EMBEDDED THUNDERSTORM WITHIN THE
COLD FRONT ALONG THE OREGON COAST AND WESTERN SLOPES OF THE
COAST RANGE THIS AFTERNOON BEFORE CHANCES DECREASE AFTER SUNSET.
WINDS BLOWING OUT OF THE SOUTH WILL INCREASE AT PRECIPITATION
ONSET, REACHING 20-30 MPH ALONG THE COAST AND 15-25 MPH INLAND.
WINDS GUSTS WILL BE HIGHER, AT LEAST UP TO 40-45 AT THE COAST
AND 35-40 MPH INLAND.
STEADY RAIN WILL TRANSITION TO ON-AND-OFF RAIN SHOWERS BEHIND
THE COLD FRONT BY 10 PM-12 AM PDT THIS EVENING AT THE COAST AND
1-3 AM PDT FRIDAY ALONG I-5. COOLER AIR IN PLACE ALOFT NEAR THE
LOW CENTER WILL SUPPORT SUFFICIENT INSTABILITY TO MAINTAIN RAIN
SHOWERS INTO THE DAY FRIDAY, WHEN DAYTIME SURFACE HEATING WILL
ACT TO FURTHER INCREASE INSTABILITY AND GENERATE 15-20% CHANCES
FOR THUNDER ANYWHERE BETWEEN THE COAST AND THE CASCADE CREST. AN
ISOLATED COLD CORE FUNNEL ALSO CANNOT BE RULED OUT, MOST LIKELY
ALONG THE COAST, BUT IMPACTS AT THE GROUND FROM THESE FEATURES
ARE UNLIKELY. AS THE SURFACE LOW NEARS THE COAST FRIDAY
MORNING, WINDS WILL SHIFT OUT OF THE SOUTHWEST TO WEST AND
STEADILY WEAKEN THROUGH MUCH OF THE DAY WEST OF THE CASCADES,
HOWEVER TO THE EAST OF THE CREST WITHIN THE HOOD RIVER VALLEY,
DOWNSLOPE ACCELERATION ON EAST- FACING SLOPES WILL SEE STRONG
WINDS PROLONGED THROUGH FRIDAY AFTERNOON. A WIND ADVISORY HAS
BEEN ISSUED FROM 8 AM THROUGH 8 PM PDT FRIDAY IN THE UPPER HOOD
RIVER VALLEY, PARTICULARLY FOR AREAS WEST OF OREGON ROUTE 281,
WHERE WIND GUSTS HAVE THE HIGHEST CHANCE OF EXCEEDING 50 MPH.
WHILE THESE FORECAST WINDS MAY BE LOWER THAN TYPICAL WINTERTIME
WIND STORMS, THE EARLY SEASON NATURE OF THIS SYSTEM MAY FAVOR
TREE DAMAGE AT LOWER WIND SPEEDS AS FULL LEAF COVER ACTS TO
INCREASE DRAG ON TREE LIMBS.
WHILE WIDESPREAD IMPACTS FROM WINDS ARE NOT ANTICIPATED, SOME
AREAS OF LOCALLY STRONGER WINDS MAY RESULT IN POCKETS OF TREE OR
LIMB DAMAGE WHICH COULD IN TURN YIELD DOWNED POWER LINES AND
OUTAGES. WHILE LIMITED INSTABILITY WILL CAP THUNDERSTORM
INTENSITY, THE AVAILABILITY OF HIGHER MOMENTUM AIR AT LOW
ALTITUDES WILL MAKE ANY THUNDERSTORM OR HEAVY RAIN SHOWER
CAPABLE OF PRODUCING GUSTY OUTFLOW THROUGH FRIDAY AFTERNOON,
WHICH MAY ALSO SUPPORT LOCAL AREAS OF WIND DAMAGE. RAINFALL
AMOUNTS REMAIN UNLIKELY TO CAUSE IMPACTS, WITH ANNUAL MINIMUM
STREAMFLOWS ABLE TO HANDLE RUNOFF WITHOUT FLOODING CONCERNS.
RAIN SHOWERS WILL END ACROSS MOST AREAS WEST OF THE CASCADES BY
FRIDAY AFTERNOON, AND IN THE CASCADES BY MIDNIGHT FRIDAY NIGHT.
PROGRESSIVE SHORTWAVE RIDGING WILL THEN FAVOR RAPID DRYING
THROUGH FRIDAY NIGHT. TEMPERATURES WILL REMAIN BELOW AVERAGE
DURING THIS PERIOD, WITH AFTERNOON HIGHS ONLY IN THE UPPER 50S
TO LOW 60S ACROSS THE REGION ON FRIDAY. COOLER AIR BEHIND THE
FRONTAL BOUNDARY WILL SEE OVERNIGHT LOWS FALL INTO THE 40S
THROUGH FRIDAY NIGHT, AND PERHAPS TO THE UPPER 30S IN THE HOOD
RIVER VALLEY. THERE IS A 10-15% CHANCE OF LOW TEMPERATURES BELOW
37 DEGREES IN THE ODELL AREA, AND 40-60% CHANCES FARTHER UP THE
VALLEY NEAR DEE AND PARKDALE. FROST ADVISORIES MAY BE NEEDED IN
THESE AREAS IF CONFIDENCE IN FROST IMPACTS INCREASE. -36
LONG TERM...SATURDAY THROUGH THURSDAY
THE PROGRESSIVE PATTERN
ALOFT WILL SEE UPPER-LEVEL RIDGING AND SURFACE HIGH PRESSURE
SUPPORT DRY WEATHER THROUGH THE WEEKEND, ALTHOUGH MODERATING
TEMPERATURES ARE STILL LIKELY TO REMAIN BELOW SEASONAL NORMS.
COOL OVERNIGHT LOWS MAY FAVOR FURTHER CHANCES FOR FROST IN THE
UPPER HOOD RIVER VALLEY, WITH DECREASING CONFIDENCE AFTER
SATURDAY MORNING. THE MAJORITY OF LONG-RANGE ENSEMBLE MEMBERS
FAVOR TROUGHING TO RETURN TO THE PACIFIC NORTHWEST EARLY NEXT
WEEK, ALTHOUGH THERE REMAINS MUCH SPREAD IN ITS INTENSITY AND
LOCATION. CHANCES FOR RAINFALL THEREFORE INCREASE AGAIN TO
20-40% MONDAY THROUGH WEDNESDAY, GENERALLY HIGHER TO THE NORTH
AND WITHIN AREAS OF TERRAIN. -36
AVIATION...THROUGH 00Z FRIDAY
SATELLITE IMAGERY AND TERMINAL
OBSERVATIONS AS OF LATE THURSDAY MORNING DEPICTS WIDESPREAD HIGH
CLOUDS AHEAD OF THE NEXT SYSTEM. RADAR ALSO SHOWS RAIN
APPROACHING KAST AS A WEAK SHORTWAVE AHEAD OF THE NEXT SYSTEM
PASSES THROUGH. THIS EVENING, AN APPROACHING FRONTAL SYSTEM WILL
BRING WIDESPREAD RAIN TO THE COAST BEGINNING 00-02Z FRI,
SPREADING INTO THE WILLAMETTE VALLEY BY 02-04Z FRI. WILL SEE
MORE MODERATE RAIN AS THE FRONT MOVES INLAND, RESULTING IN
POTENTIAL VIS REDUCTIONS TO 4-5SM BETWEEN 03-06Z FRI ALONG THE
COAST AND 06-09Z FRI FOR VALLEY TERMINALS. BY THIS TIME, THERE
IS HIGH CONFIDENCE FOR CIGS DROPPING TO IFR/MVFR ALONG THE
COAST. BY 09-10Z FRI, RAIN WILL TRANSITION INTO ON-AND-OFF
SHOWERS, AND IT WILL BE THEN THAT WE SEE HIGH CONFIDENCE FOR
CIGS DROPPING TO MVFR ACROSS MOST OF THE VALLEY. WILL ALSO SEE
WINDS INCREASING THIS EVENING AND TURNING MORE SOUTHERLY TO
SOUTHWESTERLY. THE BREEZIEST WINDS ARE EXPECTED BEHIND THE FRONT
AFTER 10-12Z FRI, WHEN WE COULD SEE GUSTS TO 30-40 KT ALONG THE
COAST AND 20-30 KT ACROSS THE WILLAMETTE VALLEY THROUGH THE END
OF THE TAF PERIOD.
BY FRIDAY AFTERNOON, INCREASING INSTABILITY WILL RESULT IN
A 10-20% CHANCE FOR THUNDERSTORMS. ANY PASSING THUNDERSTORMS MAY
PRODUCE LIGHTNING, HEAVY RAIN LEADING TO VIS REDUCTIONS, GUSTY
AND ERRATIC WINDS, AND SMALL HAIL.
KPDX AND APPROACHES...VFR CONDITIONS WITH HIGH CLOUDS THROUGH
THIS AFTERNOON. THIS EVENING, CIGS DROP TO LOW-END VFR WITH
RETURN OF RAIN AS THE FRONT APPROACHES. AS THE FRONT MOVES
THROUGH LATE THIS EVENING, WILL SEE MODERATE RAIN WITH POTENTIAL
VIS REDUCTIONS TO 4-5SM. POST-FRONTAL CONDITIONS WITH MVFR CIGS
AFTER 10-12Z FRI. SOUTHERLY TO SOUTHWESTERLY WINDS UNDER 10 KT
THROUGH THIS EVENING, INCREASING TO 10-15 KT WITH GUSTS TO 25-30
KT AFTER 10-12Z FRI. -10
MARINE
A STRONG LOW PRESSURE SYSTEM WILL MOVE OVER THE
COASTAL WATERS TONIGHT INTO FRIDAY, BRINGING RAPIDLY
INCREASING WINDS AND SEAS ALONG WITH WIDESPREAD RAIN. GALE
WARNINGS ARE IN EFFECT BEGINNING 5 PM THURSDAY FOR THE WATERS
SOUTH OF CAPE FOULWEATHER, AND 11 PM THURSDAY FOR THE WATERS
NORTH OF CAPE FOULWEATHER INCLUDING THE COLUMBIA RIVER BAR.
THESE GALE WARNINGS ARE FOLLOWED BY HAZARDOUS SEAS WARNINGS THAT
LAST THROUGH FRIDAY AFTERNOON/EVENING.
GIVEN THAT THE LOW PRESSURE SYSTEM WILL BE COMING FROM THE
SOUTHWEST, WILL SEE WINDS RAMP UP ACROSS THE SOUTHERN WATERS AT
FIRST, THEN GRADUALLY INCREASE TOWARDS THE NORTHERN WATERS
HEADING INTO TONIGHT. EXPECT WIDESPREAD WIND GUSTS AS HIGH AS
40-45 KT WITH A 30-50% CHANCE FOR BRIEF AND ISOLATED STORM-FORCE
WIND GUSTS TO 50-55 KT. EXPECT STEEP AND CHOPPY SEAS THAT ARE
WIND-DRIVEN. SEAS BUILD TO AROUND 9-11 FT AT 10 SEC TONIGHT INTO
EARLY FRIDAY MORNING, PEAKING LATE MORNING AROUND 15-17 FT FOR
THE WATERS BEYOND 10 NM, AND PEAKING EARLY AFTERNOON AROUND
14-16 FT FOR THE INNER WATERS UP TO 10 NM OFFSHORE. SEAS WILL
GRADUALLY SUBSIDE FRIDAY AFTERNOON AS WINDS QUICKLY WEAKEN. BY
LATE FRIDAY EVENING, SEAS FALL TO AROUND 7-9 FT AT 9 SECONDS.
NORTHERLY WINDS INCREASE OVER THE WEEKEND, STRONGEST SATURDAY
AFTERNOON AND EVENING WHEN WIND GUSTS INCREASE TO 20-25 KT. -10
PQR WATCHES/WARNINGS/ADVISORIES
OR...WIND ADVISORY FROM 8 AM TO 8 PM PDT FRIDAY FOR ORZ121.
WA...NONE.
PZ...GALE WARNING FROM 11 PM THIS EVENING TO 2 PM PDT FRIDAY FOR
PZZ210-251-252-271-272.
HAZARDOUS SEAS WARNING FROM 2 PM TO 8 PM PDT FRIDAY FOR PZZ210-
251-252-271-272.
GALE WARNING FROM 5 PM THIS AFTERNOON TO 11 AM PDT FRIDAY FOR
PZZ253-273.
HAZARDOUS SEAS WARNING FROM 11 AM TO 5 PM PDT FRIDAY FOR
PZZ253-273.
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