895
FXUS66 KPQR 021854 AAB
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1153 AM PDT SUN AUG 2 2026
UPDATED FORECAST DISCUSSION, FIRE WEATHER DISCUSSION, AND PQR
WATCHES/WARNINGS/ADVISORIES.
SYNOPSIS
ENJOY ONE FINAL DAY OF BELOW NORMAL TEMPERATURES
BEFORE CONDITIONS RAPIDLY WARM/DRY MONDAY INTO THE MIDDLE OF THE
WEEK. COMPARED TO PRIOR FORECASTS, HEAT RELATED IMPACTS HAVE
EMBARKED ON A RATHER STARK UPWARD TRAJECTORY AS HIGHS ARE NOW
FORECAST TO REACH INTO THE MID TO UPPER 90S ACROSS THE INLAND
VALLEYS AND 70S/80S AT THE COAST TUESDAY/WEDNESDAY. THIS WILL
RESULT IN MODERATE TO LOCALLY MAJOR HEATRISK ACROSS THE REGION.
OFFSHORE EASTERLY WINDS HELP TO INCREASE WILDFIRE SMOKE WEST OF
THE CASCADES ON MONDAY AND TUESDAY AS WELL. CONDITIONS SLOWLY
MODERATE LATE WEEK INTO THE WEEKEND.
UPDATE...TUESDAY THROUGH WEDNESDAY
A HEAT ADVISORY HAS BEEN ISSUED
FROM NOON PDT TUESDAY THROUGH 11 PM PDT WEDNESDAY FOR THE WILLAMETTE
VALLEY, GREATER PORTLAND/VANCOUVER METRO, LOWER COLUMBIA, COWLITZ
VALLEY, SOUTH WA CASCADES, AND THE OREGON COAST RANGE LOWLANDS. THIS
WAS IN RESPONSE TO ANOTHER UPTICK IN FORECAST HIGH TEMPERATURES ON
BOTH DAYS, WITH HIGH TEMPERATURES NOW EXPECTED TO TOP OUT BETWEEN
95-100 DEGREES IN THE AFOREMENTIONED AREAS. MORNING LOW TEMPERATURES
SHOULD GENERALLY RANGE BETWEEN 60-65 DEGREES. AS SUCH, THERE IS A
WIDESPREAD MODERATE HEATRISK WITH LOCALLY MAJOR HEATRISK IN THE
FORECAST. THIS MEANS THERE WILL BE AN INCREASED RISK OF HEAT-RELATED
ILLNESSES. IN ADDITION, WILDFIRE SMOKE IS EXPECTED TO INCREASE WEST
OF THE CASCADES EARLY IN THE WEEK, WHICH MAY LIMIT HIGH TEMPERATURES
BY APPROXIMATELY 1-3 DEGREES. HOWEVER, TEMPERATURES WILL STILL BE HOT
ENOUGH TO BRING AN INCREASED RISK OF HEAT-RELATED ILLNESSES EVEN IF
TEMPERATURES ARE DAMPENED A FEW DEGREES FROM SMOKE. FIRE WEATHER
CONCERNS HAVE ALSO INCREASED ON MONDAY AND TUESDAY, WHICH ARE
DISCUSSED BELOW IN THE FIRE WEATHER DISCUSSION. -23
SHORT TERM...TODAY THROUGH WEDNESDAY
THE PACIFIC NORTHWEST
REMAINS UNDER THE INFLUENCE OF A LARGE SCALE UPPER-LEVEL TROUGH
SITTING TO OUR NORTH TODAY KEEPING TEMPERATURES SLIGHTLY BELOW
AVERAGE WITH HIGHS IN THE 70S, EXCEPT 60S AT THE COAST. OVERALL
CONDITIONS SHOULD STAY MOSTLY DRY, ALTHOUGH THERE IS A 5-10%
CHANCE FOR LIGHT RAIN OR DRIZZLE ALONG THE SOUTH WA/NORTH OR
COAST AND COAST RANGE THIS MORNING GIVEN CONDITIONS WILL BE NEAR
SATURATION IN THE LOWEST 1 KM OF THE ATMOSPHERE AND THERE WILL
BE AT LEAST SOME WEAK FORCING FOR ASCENT AHEAD OF AN INCOMING
EMBEDDED SHORTWAVE TROUGH THAT IS ON TRACK TO PUSH THROUGH
WESTERN WA LATER TODAY.
AT THIS POINT CONFIDENCE IS HIGH CONDITIONS BEGIN A RATHER SHARP
WARMING AND DRYING TREND ON MONDAY AS AN UPPER LEVEL RIDGE
BEGINS TO AMPLIFY OVER THE EASTERN PACIFIC. MODEL GUIDANCE IS
IN GOOD AGREEMENT FOR DAYTIME TEMPERATURES INLAND TO JUMP 9-12
DEGREES DAY TO DAY, PUSHING HIGHS INTO THE MID TO UPPER 80S
MONDAY AFTERNOON. THE DEVELOPMENT OF BREEZY NORTH WINDS ARE
ALSO EXPECTED MONDAY AFTERNOON AND EVENING AS A THERMALLY
INDUCED SURFACE TROUGH BUILDS NORTHWARD INTO THE AREA. THIS WILL
BRING ELEVATED FIRE WEATHER CONCERNS GIVEN THE DRY CONDITIONS
THAT WILL BE IN PLACE, MAINLY IN THE CENTRAL AND SOUTHERN
WILLAMETTE VALLEY. SEE THE FIRE WEATHER SECTION BELOW FOR MORE
DETAILS. IT CERTAINLY WORTH HIGHLIGHTING WINDS FROM THIS POINT
ONWARD GAIN AN EASTERLY COMPONENT AND TURN MORE OFFSHORE IN THE
CASCADES, WHICH WILL ALLOW AT LEAST SOME WILDFIRE SMOKE TO BEGIN
PUSHING WESTWARD ONTO THE WEST SLOPES OF THE CASCADES AND INTO
THE FOOTHILLS/WILLAMETTE VALLEY AND COLUMBIA RIVER GORGE.
COME TUESDAY MODELS ARE IN GOOD AGREEMENT THIS EASTERLY
COMPONENT TO THE LOW TO MID LEVEL FLOW BEGINS TO PEAK THANKS TO
THE AXIS OF THE NEAR SURFACE THERMAL TROUGH SHIFTING TOWARDS THE
COASTLINE TO START THE DAY WHILE THE RIDGE OF HIGH PRESSURE
OFFSHORE NUDGES EVER-CLOSER TO THE PACIFIC NORTHWEST. ANTICIPATE
EASTERLY WINDS TO DEVELOP TUESDAY MORNING THROUGH THE COLUMBIA
GORGE AND CASCADE GAPS, ALTHOUGH LOCALIZED GUSTS GENERALLY STAY
IN THE 20-35 MPH RANGE FOR OUR MOST WIND-PRONE LOCATIONS (GUSTS
CLOSER TO 15-25 MPH FAR EAST PORTLAND METRO). WE'LL NEED TO
WATCH CLOSELY HOW FUTURE HIGH-RESOLUTION MODEL RUNS RESOLVE
THESE WINDS AS THIS CAN BE A CRITICAL FIRE WEATHER PATTERN THIS
TIME OF YEAR. AT LEAST WE CAN TAKE SOME SOLACE IN THE PRECEDING
COOLER CONDITIONS COUPLED WITH HIGHER RHS TODAY (SUNDAY) HELPING
TO TEMPER SOME OF THE POTENTIAL FIRE RELATED CONCERNS WITH THIS
PATTERN AT LEAST INITIALLY. ALL THIS BEING SAID, THE LOW-LEVEL
FLOW PATTERN IS DEFINITELY CONDUCIVE TO HOT CONDITIONS AS AIR
DESCENDING OFF THE CASCADES COMPRESSES AND WARMS BY THE TIME IT
GETS TO THE BASE OF THE FOOTHILLS. JUST HOW FAR THIS WARMER AIR
IS ABLE TO NAVIGATE WESTWARD WILL DEPEND ON THE PROGRESSION OF
THE THERMAL TROUGH THROUGH THE DAY. FOR NOW THOUGH IT APPEARS TO
STAY NEAR THE COAST/COAST RANGE LONG ENOUGH TO LAUNCH THE
INLAND VALLEYS INTO AT LEAST THE MID TO THE UPPER 90S COUPLED
WITH 70S TO 80S ALONG THE COAST. THE ONE FEATURE WHICH
INTRODUCES SOME UNCERTAINTY REGARDING TEMPERATURES TUESDAY (AND
WEDNESDAY AS WELL) IS WILDFIRE SMOKE GETTING TRANSPORTED INTO
THE AREA FROM EAST OF THE CASCADE CRESTS AS IT WOULD WORK
AGAINST WHAT WOULD OTHERWISE BE EFFICIENT DAYTIME INSOLATION.
THE RIDGE AXIS FINALLY TRACKS OVERHEAD ON WEDNESDAY
WITH MODELS NOW SHOWING THIS FEATURE ACTUALLY STRENGTHENING AS
IT MOVES EASTWARD. AS A RESULT, THIS CHANGE HAS LEAD TO AN
APPRECIABLE INCREASE IN FORECASTED DAYTIME HIGH TEMPERATURES
WEDNESDAY COMPARED TO WHERE THINGS STOOD 24HRS AGO. AND IT
WASN'T JUST A SMALL SUBSET OF MODELS PLAYING CATCH-UP EITHER,
THERE WAS A WHOLESALE RISE ACROSS ALMOST THE ENTIRE MODELING
SPACE. CONFIDENCE IS NOW MODERATE MAXIMUM TEMPERATURES PUSH
INTO THE MID TO UPPER 90S YET AGAIN ACROSS THE INLAND VALLEYS
WEDNESDAY WITH SLIGHTLY MORE ONSHORE FLOW WEST OF THE COAST
RANGE HELPING THOSE LOCATIONS MODERATE BACK INTO THE UPPER 60S
TO 70S. GIVEN THE FORECAST, HEATRISK IS NOW MODERATE TO LOCALLY
MAJOR ACROSS THE WILLAMETTE VALLEY, PORTLAND METRO, AND
SOUTHWEST WASHINGTON TUESDAY AND WEDNESDAY. PROBABILITIES FOR
MAJOR HEATRISK HAVE JUMPED TOO, RANGING BETWEEN 20-50%% FOR MOST
INLAND VALLEY LOCATIONS, HIGHEST IN THE PORTLAND METRO.
OVERNIGHT TEMPERATURES FOR THE LATTER AREA INTO THE COLUMBIA
GORGE AND ALONG THE BASE OF THE CASCADE FOOTHILLS MAY ONLY DROP
INTO THE LOW TO MID 60S TUESDAY NIGHT AND WEDNESDAY NIGHT
LIMITING POTENTIAL RELIEF. SHOULD THE CURRENT FORECAST HOLD,
HEAT RELATED HIGHLIGHTS MAY BE NECESSARY DURING THE TUESDAY AND
WEDNESDAY TIME PERIOD. IF YOU PLAN ON SPENDING TIME OUTDOORS
KEEP IN MIND THE INCREASED RISK FOR HEAT-RELATED ILLNESSES EARLY
TO MID-WEEK. -99
LONG TERM...THURSDAY THROUGH SATURDAY
MODEL UNCERTAINTY HAS
INCREASED LATE WEEK, PARTICULARLY ON THURSDAY, THANKS IN-PART
TO DETERMINISTIC AND ENSEMBLE GUIDANCE DEVIATING ON JUST HOW
QUICKLY THE RIDGE OF HIGH PRESSURE MOVES EASTWARD. A FASTER
PROGRESSION WOULD LEAD TO MORE NOTICEABLE MODERATION ON
THURSDAY, HOWEVER, GUIDANCE HAS BEEN TRENDING TOWARDS A SLOWER
AND THUS WARMER SCENARIO WHICH LEAVES THE INFLUENCE OF THE
RIDGE OVERHEAD A TOUCH LONGER. OF PARTICULAR NOTE IS THE
DIFFERENCE IN PROJECTED HIGH TEMPERATURES ON THURSDAY BETWEEN
LONGSTANDING NUMERICAL ENSEMBLE MODELING SYSTEMS AND THEIR
NEWER AI BASED COUNTERPARTS. THE LATTER AI ENSEMBLES (ECMWF
AIFS, AIGEFS) LEAN TOWARDS A SLOWLY (WARMER) SOLUTION COMPARED
TO THE FORMER WHICH HAS INCREASING ONSHORE INFLUENCE RESULTING
IN A ROUGHLY 3-6 DEGREE DISCREPANCY (LOW 90S VS MID TO UPPER 90S
INLAND). IT'LL BE INTERESTING TO SEE WHICH OF THESE SYSTEMS END
UP WINNING OUT IN THE END BUT THE FORECAST REFLECTS THE MORE
"OPTIMISTIC" NUMERICAL MODELING AT THE MOMENT. SHOULD THE
CURRENT TREND OF MODEL RUN TO RUN TEMPERATURES INCREASES
CONTINUE, HIGH TEMPERATURES ON THURSDAY MAY NEED TO BE BOOSTED
FURTHER, THUS EXTENDING HEAT IMPACTS. FORTUNATELY, THERE APPEARS
TO BE MORE CONSENSUS FOR TEMPERATURES TO MODERATE BACK TOWARDS
NORMAL FRIDAY INTO THE WEEKEND AS WEAK ONSHORE INFLUENCE
RETURNS. THE INCREASING ONSHORE FLOW WILL ALSO HELP CLEAR OUT
ANY SMOKE AND HAZE LINGERING IN THE AREA AS WELL, A NICE ADDED
BONUS. -99
AVIATION...THROUGH 18Z MON
WIDESPREAD VFR CONDITIONS WILL
CONTINUE THROUGH THE PERIOD FOR MOST TERMINALS. THE ONLY EXCEPTION
IS FOR SOME COASTAL TERMINALS (KAST AND KTMK), WHERE MARINE STRATUS
WILL PUSH INTO THE COAST AROUND 11-12Z MON AND MAINTAIN MVFR
CONDITIONS THROUGH AT LEAST 18Z MON (20-50% CHANCE OF MVFR, 10-20%
CHANCE OF IFR). OTHERWISE, EXPECT NORTHERLY WINDS TO INCREASE THIS
AFTERNOON AND EVENING AT MANY TERMINALS, TO AROUND 12-17 KT WITH
GUSTS UP TO 20-25 KT.
KPDX AND APPROACHES...VFR THROUGH THE TAF PERIOD. NORTH TO
NORTHWESTERLY WINDS AROUND 10-15 KT WITH GUSTS UP TO 20 KT IN THE
LATE AFTERNOON. ~12
MARINE
BEHIND THE FRONTAL BOUNDARY WHICH PASSED OVERHEAD
YESTERDAY (SATURDAY) NORTHERLY FLOW BEGINS TO INCREASE IN
EARNEST ACROSS THE COAST WATERS TODAY, ESPECIALLY THIS
AFTERNOON. CHANCES FOR MAXIMUM WIND GUSTS OF AT LEAST 21 KNOTS
REMAIN AROUND 85-95%+ FROM THIS LATE AFTERNOON AND EVENING
THROUGH THE MIDDLE OF THE WEEK WITH THE HIGHEST RELATIVE
PROBABILITIES ACROSS THE OUTER WATERS. THUS, A SMALL CRAFT
ADVISORY REMAINS IN EFFECT STARTING THIS AFTERNOON ACROSS THE
INNER AND OUTER WATERS INCLUDING THE COLUMBIA RIVER BAR. IT
STILL APPEARS THE SMALL CRAFT WIND CONCERNS SHIFT MORESO TO THE
OUTER WATERS ON WEDNESDAY THROUGH THE END OF THE WEEK. EXPECT
WAVE HEIGHTS THROUGH THE WEEK TO HOLD AROUND 4-8 FT AT 7-9
SECONDS. -99/12
FIRE WEATHER...MONDAY THROUGH WEDNESDAY
THERE REMAIN
ELEVATED FIRE WEATHER CONCERNS IN PORTIONS OF THE WILLAMETTE
VALLEY ON MONDAY AND TUESDAY DURING THE AFTERNOON AND EVENING
HOURS DUE TO BREEZY NORTH-NORTHEAST WINDS AND LOW HUMIDITY.
CONFIDENCE HAS INCREASED FOR CRITICAL FIRE WEATHER CONDITIONS MONDAY
AFTERNOON AND EVENING IN THE SOUTHERN WILLAMETTE VALLEY AS WINDS ARE
NOW EXPECTED TO GUST UP TO 25 MPH WITH RELATIVE HUMIDITY VALUES
LOWERING INTO THE 20-25% RANGE. THEREFORE, A RED FLAG WARNING HAS
BEEN ISSUED FOR FIRE WEATHER ZONE 685 FROM 1 TO 8 PM PDT MONDAY.
CONFIDENCE HAS ALSO INCREASED FOR HOT, DRY, AND WINDY CONDITIONS IN
THE WESTERN COLUMBIA RIVER GORGE ON TUESDAY AS OFFSHORE WINDS
DEVELOP. EASTERLY WINDS MAY GUST AS HIGH AS 40 MPH ON TUESDAY WHILE
RELATIVE HUMIDITY VALUES FALL AS LOW AS 15-20%. THEREFORE, A FIRE
WEATHER WATCH HAS BEEN ISSUED FOR FIRE WEATHER ZONE 636 TUESDAY
AFTERNOON AND EVENING. DETAILS FOR BOTH MONDAY AND TUESDAY ARE
DISCUSSED BELOW.
THE OUTCOME REMAINS HIGHLY DEPENDENT ON THE EVOLUTION OF A
SURFACE THERMAL TROUGH THAT WILL BEGIN LIFTING NORTHWARD INTO
WESTERN OREGON MONDAY INTO TUESDAY. TYPICALLY IT BUILDS OVERHEAD
FROM SOUTHWESTERN OREGON (DRY NORTHERLY WINDS WHEN THIS OCCURS)
THEN IT MODULATES DIURNALLY BACK-AND-FORTH FROM THE COAST/COAST
RANGE (AM) TOWARDS I-5 AND/OR THE CASCADES (PM) HELPING TO
INFLUENCE THE MAGNITUDE AND PLACEMENT OF OFFSHORE FLOW. MODELS
INDICATE IT'LL DEVELOP ALONG THE SOUTH OREGON COAST MONDAY
MORNING BEFORE MOVING INLAND AND FURTHER TO THE NORTH IN THE
AFTERNOON. THIS PROGRESSION WOULD CAUSE NORTHERLY WINDS TO
AMPLIFY IN THE WILLAMETTE VALLEY, AND INCREASE EASTERLY WINDS
ALOFT AROUND 5000 FT, INCLUDING IN THE HIGH CASCADES. THESE
EASTERLY WINDS WILL BRING IN DRIER AIR FROM EAST OF THE CASCADES
AND THE DOWNSLOPING ACTION WILL INCREASE 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 ON MONDAY TO
AS LOW AS 20-25%. AS THE THERMAL TROUGH BUILDS INTO THE AREA, WINDS
ARE EXPECTED TO GUST UPWARDS OF 20 MPH OVER THE CENTRAL WILLAMETTE
VALLEY AND UP TO 25 MPH IN THE SOUTHERN WILLAMETTE VALLEY, INCLUDING
THE EUGENE AREA. THE SLIGHTLY STRONGER WINDS IN THE SOUTH VALLEY IS
DUE TO MORE OF A CHANNELING/FETCH COMPONENT AND A TIGHTER NORTH-SOUTH
PRESSURE GRADIENT. THESE DRY AND BREEZY CONDITIONS WILL LEAD TO
CRITICAL FIRE WEATHER CONCERNS AS THEY OVERLAP MID INTO
THE EARLY EVENING ON MONDAY. TUESDAY WILL BE EVEN DRIER WITH HUMIDITY
VALUES WELL BELOW CRITICAL THRESHOLDS, HOWEVER NORTHERLY WINDS WILL
BE TRENDING WEAKER AND ARE NOT EXPECTED TO MEET CRITERIA FOR A RED
FLAG WARNING AT THIS TIME.
OUR ATTENTION ALSO TURNS TO THE WESTERN COLUMBIA RIVER GORGE
TUESDAY WHERE OFFSHORE EASTERLY WINDS APPEAR INCREASINGLY LIKELY
TO START THE MORNING, CONTINUING THROUGH THE DAY WHILE RELATIVE
HUMIDITY VALUES DEGRADE. LOCALIZED GUSTS FOR PLACES LIKE
CORBETT AND THREE CORNER ROCK GENERALLY STAY IN THE 25-40 MPH
RANGE, CLOSER TO 15-25 MPH FAR EAST PORTLAND METRO. WHILE THE NEAR
SURFACE THERMAL TROUGH DRIVING THESE WINDS WEAKENS BY WEDNESDAY
MORNING, PERSISTENT OFFSHORE WINDS REMAIN PRESENT. LASTLY, THE
PATTERN FAVORS POOR RELATIVE HUMIDITY RECOVERIES FOR MID TO UPPER
SLOPE LOCATIONS IN THE CASCADES, CASCADE FOOTHILLS, AND PORTIONS OF
THE COAST RANGE STARTING MONDAY NIGHT THROUGH THE MIDDLE OF THE WEEK.
-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 TO 8 PM PDT MONDAY FOR ORZ685.
WA...HEAT ADVISORY FROM NOON TUESDAY TO 11 PM PDT WEDNESDAY FOR
WAZ204>208.
FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY
EVENING FOR WAZ636.
PZ...SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 2 AM PDT
MONDAY FOR PZZ210.
SMALL CRAFT ADVISORY FROM 5 PM THIS AFTERNOON TO 5 AM PDT
TUESDAY FOR PZZ251-252-271-272.
SMALL CRAFT ADVISORY FROM 2 PM THIS AFTERNOON TO 5 AM PDT
TUESDAY FOR PZZ253-273.
WWW.WEATHER.GOV/PORTLAND
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