137
FXUS66 KPQR 161651 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PORTLAND OR
951 AM PDT TUE SEP 16 2025
UPDATED AVIATION DISCUSSION.
SYNOPSIS
DRY WEATHER WILL PREVAIL TODAY UNDER CLEAR SKIES AND
STRENGTHENING OFFSHORE FLOW. THIS WILL LEAD TO WARM TEMPERATURES
AND BREEZY TO LOCALLY STRONG EASTERLY WINDS THROUGH THE COLUMBIA
RIVER GORGE AND CASCADE GAPS THIS MORNING. ONSHORE FLOW RETURNS
MIDWEEK AS A WEAK FRONT BRUSHES THE COAST, WITH LIMITED
PRECIPITATION POTENTIAL. A BROADER TROUGH DIGGING INTO THE
REGION FROM THE NORTHEAST PACIFIC WILL BRING BETTER RAIN CHANCES
INTO THE WEEKEND, ESPECIALLY NEAR THE COAST AND ACROSS
SOUTHWEST WASHINGTON.
SHORT TERM...NOW THROUGH WEDNESDAY MORNING
CLEAR SKIES AND
DRY CONDITIONS ARE IN PLACE EARLY THIS MORNING, WITH MINIMUM
HUMIDITY LATE TODAY EXPECTED TO BOTTOM OUT IN THE 20-30% RANGE
ACROSS MUCH OF THE FORECAST AREA. OFFSHORE GRADIENTS HAVE
TIGHTENED OVERNIGHT, NOW PROJECTED AT -5 TO 6 MB TTD-DLS THROUGH
LATE MORNING. WINDS ARE ALREADY GUSTING 25-35 MPH IN THE
WESTERN GORGE AND CASCADE GAPS, WITH ISOLATED 40 MP GUSTS
OBSERVED. GUSTS WILL LIKELY PEAK FROM NOW UNTIL 10 AM, WITH A
40-60% PROBABILITY OF EXCEEDING 40 MPH MOSTLY IN THE CASCADE
LOCKS EASTWARD TOWARD THE HOOD RIVER VALLEY. WINDS WILL
GRADUALLY EASE THROUGH THE AFTERNOON, AND MOST LOCATIONS SHOULD
FALL BELOW 20 MPH BY LATE EVENING. TEMPERATURES RISE WELL ABOVE
SEASONABLE AVERAGES TODAY, WITH HIGHS REACHING THE UPPER 80S TO
NEAR 90 INLAND AND MID 70S AT THE COAST. NBM PROBABILITIES SHOW
A 70-90% CHANCE OF REACHING 85 DEGREES ACROSS INTERIOR VALLEYS,
AND A 10-30% CHANCE OF TOUCHING 90 DEGREES AT SELECT LOCATIONS.
WHILE OVERLAP OF STRONGER WINDS AND LOWEST DAYTIME HUMIDITIES
WILL BE LIMITED, FIRE WEATHER CONCERNS REMAIN ELEVATED TODAY.
FORTUNATELY, RECENT WIDESPREAD RAINFALL HAS REDUCED FUEL
RECEPTIVENESS, PREVENTING CONDITIONS FROM REACHING CRITICAL
THRESHOLDS.
LONG TERM...WEDNESDAY THROUGH SUNDAY
A WEAK FRONT BRUSHING
THE COAST WEDNESDAY WILL REINTRODUCE ONSHORE FLOW, THOUGH
PRECIPITATION POTENTIAL LOOKS MINIMAL. PROBABILITIES FOR
MEASURABLE RAINFALL ARE 10-20% ALONG THE COAST WEDNESDAY
MORNING, WITH DRY WEATHER FAVORED INLAND. TEMPERATURES REMAIN
OLD WITH HIGHS IN THE MID TO UPPER 70S INLAND AND MID 60S ALONG
THE COAST.
BY FRIDAY, ENSEMBLE GUIDANCE CONVERGES ON A GENERALLY DRY
PATTERN UNDER A NARROW RIDGE, KEEPING HIGHS IN THE UPPER 70S TO
NEAR 80 INLAND. A LARGER-SCALE TROUGH BEGINS TO DIG
SOUTHEASTWARD FROM THE GULF OF ALASKA INTO THE WEEKEND,
INCREASING RAIN POTENTIAL. PRECIPITATION CHANCES CLIMB TO
20-40% ACROSS THE FORECAST AREA SATURDAY THROUGH SUNDAY, WITH
HIGHER PROBABILITIES (50-70%) ALONG THE SOUTHWEST WASHINGTON
COAST AND NEAR ASTORIA SATURDAY NIGHT INTO SUNDAY. TEMPERATURES
COOL BACK INTO THE 70S INLAND AND LOW TO MID 60S ALONG THE COAST
UNDER THIS MORE UNSETTLED REGIME. ~HALL
AVIATION
CLEAR SKIES AND WIDESPREAD VFR FLIGHT CONDITIONS
PREVAIL THROUGH TUESDAY AS HIGH PRESSURE REMAINS IN PLACE ACROSS
THE REGION. LOW-LEVEL OFFSHORE FLOW CONTINUES THIS MORNING, BRINGING
GUSTY EASTERLY WINDS UP TO 30 KT AT KTTD AND GUSTS UP TO 20 KT AT
KPDX AND KHIO. EAST WINDS BEGIN GRADUALLY DECREASING AFTER 20Z
TUESDAY. OFFSHORE WINDS ALONG THE COAST TURN SOUTHERLY TO
SOUTHWESTERLY AFTER 18-21Z TUESDAY. WINDS ARE GENERALLY LIGHT AND
VARIABLE FROM KUAO TO KSLE TO KEUG.
PROBABILITIES FOR LIFR TO IFR CIGS BEGIN TO INCREASE ALONG THE
COAST LATE TONIGHT DUE TO THE RETURN OF ONSHORE FLOW. CHANCES
FOR CIGS BELOW 1000 FT INCREASE TO 60-80% AT KONP BETWEEN 06-09Z
WEDNESDAY. CHANCES REACH 50% AT KAST BY 09Z WEDNESDAY BEFORE
INCREASING TO 60% BY 18Z WEDNESDAY.
KPDX AND APPROACHES...CLEAR SKIES AND VFR FLIGHT CONDITIONS WILL
CONTINUE THROUGH 18Z WEDNESDAY. EAST WINDS AROUND 10-12 KT WITH
GUSTS UP TO 20-22 KT WILL CONTINUE THROUGH TODAY BEFORE EAST
WINDS GRADUALLY WEAKEN AFTER SUNSET. -TK
MARINE
WINDS WILL SHIFT FROM NORTHEAST TO EAST THIS MORNING,
WITH LOCALIZED WIND GUSTS UP TO 25 KT OVER THE INNER WATERS
DOWNWIND OF GAPS IN THE COASTAL TERRAIN AS WELL AS IN THE NORTHERN
HALF OF ZONES PZZ272 AND 252 OUT TO 60 NM. WINDS WILL QUICKLY
BECOME SOUTHERLY AND DECREASE THIS AFTERNOON AT AROUND 10 KT OR
LESS IN RESPONSE TO A SURFACE FRONT THAT WILL BE APPROACHING THE
COASTAL WATERS TUESDAY NIGHT INTO WEDNESDAY MORNING. NO IMPACTS
ARE EXPECTED WITH THIS FRONT AS IT WILL DECAY OVER THE WATERS.
HOWEVER, WINDS WILL QUICKLY SWITCH NORTHERLY AND INCREASE BEHIND
THIS FRONT WEDNESDAY EVENING INTO THURSDAY. WIDESPREAD SMALL
CRAFT ADVISORY LEVEL WIND GUSTS UP TO 25 KT LIKELY (90% CHANCE).
OCCASIONAL GUSTS UP TO 30 KT CANNOT BE RULED OUT OVER THE
SOUTHERN WATERS (50-70% CHANCE). -TK/HEC
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
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