618
FXUS66 KPQR 031531 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
830 AM PDT MON AUG 3 2026
UPDATED FIRE WEATHER DISCUSSION AND PQR WATCHES/WARNINGS/ADVISORIES.
SYNOPSIS
EXPECT A RAPID TRANSITION TO HOT AND DRY CONDITIONS
WITH INCREASING WILDFIRE SMOKE TODAY INTO TUESDAY AS OFFSHORE
FLOW TAKES HOLD ACROSS THE REGION. HIGH TEMPERATURES FOR MOST
INLAND VALLEY LOCATIONS PEAK BETWEEN 94-100 DEGREES BY TUESDAY
AND WEDNESDAY, AND POTENTIALLY INTO THURSDAY AS WELL. THIS
RESULTS IN WIDESPREAD MODERATE TO LOCALLY MAJOR HEATRISK
IMPACTS. AT LEAST CONDITIONS BEGIN TO TREND COOLER FRIDAY WITH
THE RETURN OF ONSHORE FLOW WHICH WILL ALSO HELP PUSH ANY WILDFIRE
SMOKE BACK EAST OF THE CASCADES. FIRE WEATHER CONCERNS REMAIN
IN THE FORECAST MONDAY, TUESDAY, AND POTENTIALLY WEDNESDAY FOR
SELECT AREAS AS WINDS INCREASE AND RELATIVE HUMIDITY VALUES
DEGRADE.
SHORT TERM...NOW THROUGH WEDNESDAY NIGHT
A RIDGE OF HIGH
PRESSURE BEGINS TO AMPLIFY OVER THE EASTERN PACIFIC TODAY
HELPING TO FACILITATE A QUICK WARMING AND DRYING TREND TO START
THE WEEK. BOTH DETERMINISTIC AND ENSEMBLE MODELS REMAIN IN GOOD
AGREEMENT FOR HIGHS IN THE MID TO UPPER 80S OVER INLAND VALLEYS
TODAY BEFORE REACHING INTO THE 94-100 DEGREE RANGE ON TUESDAY
AND WEDNESDAY. THIS WILL RESULT IN WIDESPREAD MODERATE TO
LOCALLY MAJOR HEATRISK AND BRING AN INCREASING RISK FOR HEAT-
RELATED ILLNESSES FOR THOSE WHO DO NOT HAVE ACCESS TO AIR
CONDITIONING. TAKE PRECAUTION IF YOU PLAN TO SPEND EXTENDED
PERIODS OF TIME OUTDOORS. TRIPLE DIGIT TEMPERATURES ARE IN PLAY
FOR MANY LOCATIONS WITH THE NBM PROBABILITY FOR HIGH
TEMPERATURES OF 100 DEGREES OR WARMER PEAKING ON WEDNESDAY; A
40-55% CHANCE FOR INLAND VALLEYS. HOWEVER, THESE PROBABILITIES
MAY BE OVERDONE DUE TO SMOKE DRIFTING OVERHEAD FROM REGIONAL
FIRES, THERE IS MORE ON THIS BELOW. ALONG THE COAST , HIGHS WILL
GENERALLY BE IN THE 70S TO LOW 80S GIVEN LIGHT ONSHORE WINDS
DURING THE AFTERNOON FOLLOWING OFFSHORE WINDS IN THE MORNING
HOURS, EXCEPT 80S TO NEAR 90 FOR INLAND COASTAL COMMUNITIES SUCH
AS TILLAMOOK AND POSSIBLY ASTORIA WHERE OFFSHORE WINDS WILL
LAST A BIT LONGER. IF OFFSHORE WINDS MANAGE TO LINGER INTO THE
MID AFTERNOON HOURS AT TILLAMOOK AND ASTORIA DUE TO A DELAYED
PROGRESSION OF THE NEAR SURFACE THERMAL TROUGH, HIGHS IN THE LOW
TO MID 90S WOULD BE POSSIBLE. THE BEST SHOT OF THIS HAPPENING
IS ON TUESDAY.
ONCE POINT OF SIGNIFICANT FORECAST UNCERTAINTY, PARTICULARLY FOR
OUR INLAND AREAS, IS THE IMPACT OF INCREASING WILDFIRE SMOKE
AND THUS MUTED DAYTIME HEATING WHICH ARE NOT TAKEN INTO ACCOUNT
BY MOST MODELS. AS WEAK ONSHORE WINDS TRANSITION TO OFFSHORE
WINDS THIS MORNING, WILDFIRE SMOKE BEGINS TO INFILTRATE WEST OF
THE CASCADES, LIKELY BEGINNING ALOFT AT FIRST. EVEN WITH PLENTY
OF SUNSHINE, THE INCREASING SMOKE AND HAZE MAY INHIBIT HIGH
TEMPERATURES BY APPROXIMATELY 1-4 DEGREES BELOW WHAT IS
FORECAST. THIS WILL BE HIGHLY DEPENDENT ON FIRE BEHAVIOR TO OUR
EAST AND EXACTLY WHERE THE THICKEST PLUMES ARE PRESENT.
EXPLORING THE RRFS MODEL WHICH DOES ATTEMPT TO RESOLVE THE
ATMOSPHERIC EVOLUTION OF SMOKE, THE COLUMBIA RIVER GORGE, UPPER
HOOD RIVER VALLEY, AND NORTH OR CASCADES AND ADJACENT FOOTHILLS
HAVE THE BEST CHANCE FOR RELATIVELY DENSER WILDFIRE SMOKE
ASSOCIATED WITH A SMOKE PLUME BLOWING WESTWARD FROM THE ONGOING
GRASSHOPPER FIRE BURNING IN THE MT. HOOD NATIONAL FOREST. THESE
LOCATIONS REMAIN OUT OF THE HEAT ADVISORY WHICH IS IN EFFECT FOR
THE WILLAMETTE VALLEY, PORTLAND/VANCOUVER METRO, COWLITZ
VALLEY, LOWER COLUMBIA, SOUTH WA CASCADES, AND OREGON COAST
RANGE LOWLANDS. WHILE THIS HEAT ADVISORY SPANS NOON PDT TUESDAY
THROUGH 11 PM PDT WEDNESDAY, THERE IS A CHANCE IT MAY NEED TO BE
EXTENDED THROUGH THURSDAY DEPENDING ON HOW MODEL GUIDANCE
TRENDS AND HOW DENSE WILDFIRE SMOKE BECOMES. DEGRADED AIR
QUALITY WILL ALSO BE A CONCERN IN AREAS WITH DENSER SMOKE NEAR
THE SURFACE. FOR UPDATES REGARDING THE AIR QUALITY FORECAST AND
ANY AIR QUALITY ADVISORIES THAT ARE IN EFFECT, PLEASE VISIT THE
OREGON SMOKE BLOG AT OREGONSMOKE.ORG AND THE WASHINGTON SMOKE
BLOG AT WASMOKE.BLOGSPOT.COM.
HELPING TO AID THE THE UPCOMING HEAT, A THERMALLY INDUCED
SURFACE TROUGH WILL SURGE NORTHWARD FROM SOUTHWEST OREGON TODAY
USHERING IN A PERIOD OF INCREASING WINDS, INDUCING OFFSHORE
FLOW LOWERING RELATIVE HUMIDITY VALUES, AND THUS LEADING TO
NOTEWORTHY FIRE WEATHER CONCERNS. MODEL GUIDANCE HAS MAINTAINED
DECENT AGREEMENT REGARDING THE TIMING AND EVOLUTION OF THIS
SURFACE TROUGH AND WIND SPEEDS. FOR DETAILS REGARDING FIRE
WEATHER CONCERNS INTO THE MIDDLE OF THE WEEK, PLEASE REFER TO
THE FIRE WEATHER DISCUSSION BELOW. -99/23
LONG TERM...THURSDAY THROUGH SUNDAY
WHILE THE FIRST HALF OF
THE WEEK IS MARKED BY A SHARP WARMING TREND, LATE WEEK INTO THE
WEEKEND IS HIGHLIGHTED BY A GRADUAL GLIDE-PATH OF MODERATING
TEMPERATURES AND DECREASING WILDFIRE SMOKE WEST OF THE CASCADES.
IT APPEARS THURSDAY WILL BE A TRANSITION DAY AS THE AXIS OF THE
UPPER-LEVEL TROUGH FINALLY PASSES OVERHEAD WEST TO EAST HELPING
TO KICK THE THERMALLY INDUCED SURFACE THERMAL TROUGH EAST OF
THE CASCADE CRESTS. THIS BRINGS A RETURN OF WEAK ONSHORE FLOW,
ALTHOUGH IT MAY TAKE UNTIL THE NEXT DAY (FRIDAY) TO SEE MORE
APPRECIABLE IMPROVEMENT IN DAYTIME HIGH TEMPERATURES ACROSS THE
INLAND VALLEYS. THE PATTERN PROGRESSION WILL ALSO ALLOW
WILDFIRE SMOKE TO START TO SLOWLY DECREASE FROM WEST TO EAST.
THEN ONSHORE FLOW IS EXPECTED TO STRENGTHEN MORE CONSIDERABLY
FRIDAY INTO WEEKEND, BRINGING MORE SEASONABLE TEMPERATURES BACK
INTO THE 80S BY SATURDAY. ONSHORE FLOW SHOULD BE STRONG ENOUGH
TO FLUSH ANY LINGERING SMOKE AND HAZE EAST OF THE CASCADES.
DESPITE THE INCREASING ONSHORE FLOW, DRY WEATHER IS EXPECTED TO
CONTINUE THROUGH THE END OF THE WEEKEND WITH NO SIGNS OF ANY
PRECIPITATION IN THE NEAR FUTURE. -99/23
AVIATION...THROUGH 12Z TUE
CURRENT OBSERVATIONS DEPICT
WIDESPREAD VFR CONDITIONS ACROSS THE AREA, LIKELY PERSISTING
THROUGH THE TAF PERIOD AS SKIES REMAIN MOSTLY CLEAR AND MARINE
STRATUS HOLDS JUST OFFSHORE. THAT SAID, THERE IS A 25-35% CHANCE
COASTAL TERMINALS (MAINLY KAST) SEE BRIEF MVFR CIGS BETWEEN
13-17Z. WINDS REMAIN OUT OF THE NORTH TO NORTHEAST TODAY WITH
GUSTS UP TO 15-25 KNOTS POSSIBLE ALONG THE COAST AND I-5 CORRIDOR
THIS AFTERNOON INTO THE EVENING. ALOFT, AN EASTERLY WIND SHIFT
WILL ALSO STEER SMOKE FROM WILDFIRES ON THE EAST SIDE OF THE
CASCADES TO THE WEST SIDE. GIVEN THE LATEST GUIDANCE, SMOKE
REMAINS IN THE INLAND TAFS FROM LATE MORNING/AFTERNOON ONWARD
WHERE CONCENTRATIONS WILL BE MORE NOTICEABLE - ONLY MODERATE
CONFIDENCE REGARDING TIMING HOWEVER.
KPDX AND APPROACHES...VFR CONDITIONS ARE EXPECTED TO CONTINUE
LOCALLY. NORTHERLY WINDS AROUND 5-10 KNOTS THIS MORNING INCREASE
LATE MORNING/MIDDAY WITH OCCASIONAL GUSTS AROUND 20 KNOTS POSSIBLE
THROUGH THE AFTERNOON INTO THE EARLY EVENING. -99
MARINE
AN UPPER-LEVEL RIDGE OF HIGH PRESSURE BUILDING OFF THE
COAST CONTINUES TO DRIVE NORTHERLY WINDS ACROSS THE WATERS TODAY
WITH HIGH CONFIDENCE IN GUSTS GREATER THAN 21 KNOTS, ESPECIALLY
THIS AFTERNOON INTO THE EVENING HOURS. A SMALL CRAFT ADVISORY
REMAINS IN EFFECT FOR THE INNER AND OUTER WATERS INTO THE MIDDLE
OF THE WEEK, INCLUDING THE COLUMBIA RIVER BAR ALTHOUGH FOR A MORE
TARGETED TIMEFRAME THERE - 1PM TODAY THROUGH 1AM TUESDAY. COME
THURSDAY INTO FRIDAY THESE WINDS BEGINS TO DECREASE AND GAIN A
SLIGHT WESTERLY COMPONENT, LIKELY LIMITING ANY FURTHER MARGINAL
SMALL CRAFT CONDITIONS TO THE OUTER WATERS THROUGH THE FIRST
HALF OF THE WEEKEND. EXPECT FAIRLY SIMILAR WAVE HEIGHTS DAY TO
DAY AS THEY HOLD AROUND 4-8 FT AT 7-9 SECONDS. -99
FIRE WEATHER...TODAY THROUGH THURSDAY
CRITICAL FIRE WEATHER
CONDITIONS ARE EXPECTED THIS AFTERNOON AND EVENING OVER THE
CENTRAL/SOUTHERN WILLAMETTE VALLEY MAINLY TO THE SOUTH OF SALEM THIS
AFTERNOON AND EVENING DUE TO BREEZY NORTH WINDS WITH GUSTS UP TO
APPROXIMATELY 25 MPH COMBINED WITH LOW RELATIVE HUMIDITY VALUES DOWN
TO 20-25%. A FEW MAX GUSTS UPWARDS OF 28 MPH ARE POSSIBLE. THIS MEANS
ANY NEW OR EXISTING FIRES IN THIS AREA COULD EXHIBIT RAPID FIRE
SPREAD. AS SUCH, A RED FLAG WARNING REMAINS IN EFFECT FOR FIRE
WEATHER ZONE 685. ALTHOUGH WIND SPEEDS ARE NOT FORECAST TO BE QUITE
AS STRONG TO THE NORTH OF SALEM, CONDITIONS WILL STILL BE DRY AND
BREEZY ENOUGH FOR ELEVATED FIRE WEATHER CONCERNS. WE HAVE A
DEVELOPING THERMALLY INDUCED SURFACE TROUGH CAUSING THESE
WINDS AS IT LIFTS NORTHWARD INTO THE REGION. WHILE WINDS AT THE
SURFACE HAVE A LARGE NORTHERLY COMPONENT TODAY, EASTERLY WINDS
WILL BE DEVELOPING ALOFT AROUND 3000-6000 FT THIS MORNING.
THESE EASTERLY WINDS WILL BRING IN DRIER AIR FROM EAST OF THE
CASCADES AND THE DOWNSLOPING ACTION WILL INCREASE COMPRESSIONAL
WARMING AND DRYING IN THE LOWER ELEVATIONS AND IN THE WILLAMETTE
VALLEY. COMBINE THIS WITH DAYTIME HEATING AND A DEEP LAYER OF
DRY AIR, WE WILL SEE RELATIVE HUMIDITY DROP WITHIN THE INTERIOR
LOWLANDS AS LOW AS 18-25%.
TONIGHT INTO TUESDAY, THE SURFACE THERMAL TROUGH IS EXPECTED TO
AMPLIFY WHILE THE AXIS OF THIS FEATURE SHIFTS TOWARDS THE
OREGON COAST. THIS WILL FURTHER INCREASE EASTERLY WINDS IN THE
COLUMBIA RIVER GORGE AND CASCADES, IN ADDITION TO A LOWERING
SUBSIDENCE INVERSION WITH SHARP OVERNIGHT THERMAL BELTS/POOR
OVERNIGHT HUMIDITY RECOVERIES, PARTICULARLY IN THE CASCADES.
EASTERLY WINDS ON TUESDAY ARE EXPECTED TO BE STRONGEST IN THE
WESTERN GORGE WITH GUSTS UP TO 30-40 MPH IN THE MOST WIND-PRONE
LOCATIONS. GIVEN THE LOW RELATIVE HUMIDITY VALUES IN PLACE AT
THAT TIME, CRITICAL FIRE WEATHER CONDITIONS CAPABLE OF RAPID
FIRE SPREAD WILL BE POSSIBLE. CONDITIONS THEN REMAIN DRY AND WINDY IN
THE WESTERN GORGE AS EASTERLY WINDS CONTINUE TUESDAY NIGHT THROUGH
WEDNESDAY EVENING. WINDS IN THE GORGE WILL BE STRONGEST TUESDAY
MORNING THROUGH EARLY TUESDAY AFTERNOON, AND AGAIN TUESDAY NIGHT
THROUGH EARLY WEDNESDAY AFTERNOON. RELATIVE HUMIDITY VALUES WILL BE
LOWEST TUESDAY AFTERNOON AND WEDNESDAY AFTERNOON, DOWN TO 15-20%.
POOR OVERNIGHT HUMIDITY RECOVERIES ARE EXPECTED TUESDAY NIGHT WITH
MAXIMUM RELATIVE HUMIDITY VALUES RANGING BETWEEN 35-45%. THEREFORE, A
RED FLAG WARNING HAS BEEN ISSUED FOR THE WESTERN GORGE, FIRE WEATHER
ZONE 636, FROM 11 AM PDT TUESDAY THROUGH 8 PM PDT WEDNESDAY. THE REST
OF THE CASCADES WILL HAVE RELATIVELY WEAKER EASTERLY WINDS WITH GUSTS
GENERALLY IN THE 15-25 MPH RANGE. ONE EXCEPTION WOULD BE ON EXPOSED
RIDGETOPS AND WEST-EAST ORIENTED VALLEYS WHERE SLIGHTLY HIGHER WIND
GUSTS ARE LIKELY. NEVERTHELESS, ELEVATED FIRE WEATHER CONCERNS STILL
EXIST IN THESE AREAS, AS WELL AS IN THE PORTLAND METRO AND WILLAMETTE
VALLEY WHERE NNE TO NE WINDS ARE EXPECTED TO GUST UP TO APPROXIMATELY
15-20 MPH IN THE AFTERNOON. AGAIN EXPECT POOR RIDGETOP RELATIVE
HUMIDITY RECOVERIES IN THE CASCADES AND ROAST RANGE TUESDAY NIGHT.
FIRE WEATHER CONCERNS DECREASE MORE CONSIDERABLY BY THURSDAY, WITH
ONE POTENTIAL EXCEPTION. THURSDAY IS WHEN WE TRANSITION TO ONSHORE
FLOW, WHICH WILL BRING BREEZY WESTERLY WINDS IN THE CENTRAL GORGE AND
HOOD RIVER AREA. GIVEN CONDITIONS WILL STILL BE DRY, ELEVATED FIRE
WEATHER CONCERNS WILL REMAIN IN PLACE. -23/99
PQR WATCHES/WARNINGS/ADVISORIES
OR...HEAT ADVISORY FROM NOON TUESDAY TO 11 PM PDT WEDNESDAY FOR
ORZ104-105-108>118.
RED FLAG WARNING FROM 1 PM THIS AFTERNOON TO 8 PM PDT THIS
EVENING FOR ORZ685.
WA...HEAT ADVISORY FROM NOON TUESDAY TO 11 PM PDT WEDNESDAY FOR
WAZ204>208.
RED FLAG WARNING FROM 11 AM TUESDAY TO 8 PM PDT WEDNESDAY FOR
WAZ636.
PZ...SMALL CRAFT ADVISORY FROM 1 PM THIS AFTERNOON TO 1 AM PDT
TUESDAY FOR PZZ210.
SMALL CRAFT ADVISORY UNTIL 5 AM PDT WEDNESDAY FOR PZZ251>253-
271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page