315
FXUS66 KPQR 210537 AAA
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
1038 PM PDT SAT JUN 20 2026
UPDATED AVIATION DISCUSSION
SYNOPSIS
WE'LL EMBARK ON A NOTICEABLE WARMING TREND THE NEXT
SEVERAL DAYS WITH HIGH TEMPERATURES PEAKING ACROSS THE REGION
ON MONDAY AND TUESDAY. WIDESPREAD MODERATE HEATRISK AND
LOCALIZED MAJOR HEATRISK FOR THE PORTLAND-VANCOUVER METRO AREA
IS ANTICIPATED. FAIRLY WARM OVERNIGHT TEMPERATURES FOR INTERIOR
VALLEYS WILL PROVIDE LIMITED OVERNIGHT RELIEF AS WELL,
ESPECIALLY IN URBAN AREAS. WITH THESE THINGS IN MIND, A HEAT
ADVISORY IS IN EFFECT FOR MANY OF THE INTERIOR VALLEYS AND
COLUMBIA RIVER GORGE MONDAY THROUGH TUESDAY. AT LEAST CONFIDENCE
IS INCREASING FOR COOLER TEMPERATURES AND EVEN RAINFALL CHANCES
(30-60%) BY LATE THURSDAY/FRIDAY.
DISCUSSION...TODAY THROUGH FRIDAY
STRONG ONSHORE FLOW REMAINS
IN PLACE THIS AFTERNOON AS MORNING CLOUDS HAVE TAKEN THEIR TIME
DISSIPATING. FORECAST HIGH TEMPERATURES TODAY WERE LOWERED
GENERALLY INTO LOW TO MID 70S ACROSS THE INLAND VALLEYS TO
COMPENSATE FOR THE MORE PERSISTENT CLOUD COVER. ALL IN ALL,
THESE CONDITIONS ARE RIGHT AROUND NORMAL FOR MID TO LATE JUNE
AND IT'S ONLY UP FROM HERE.
ON SUNDAY TEMPERATURES BEGIN TO REBOUND THANKS TO AN UPPER-LEVEL
RIDGE OF HIGH PRESSURE AMPLIFYING OVER THE EASTERN PACIFIC WITH
BUILDING HEIGHTS OVERHEAD. STILL, WE'LL MAINTAIN SOME DEGREE OF
ONSHORE FLOW WHICH KEEPS TEMPERATURES ACROSS WESTERN OREGON AND
SOUTHWEST WASHINGTON MORE MODERATED THAN THEY OTHERWISE WOULD
BE. EXPECT HIGHS IN THE LOW TO MID 80S ACROSS INTERIOR VALLEYS
SUNDAY AFTERNOON. THE HOTTEST DAYS OVER THE NEXT WEEK ARE STILL
EXPECTED MONDAY AND TUESDAY DURING WHICH THE VAST MAJORITY OF
ENSEMBLE MEMBERS SHOW THE RIDGE SLIDING RIGHT OVER-TOP THE
PACIFIC NORTHWEST. THERE IS HIGH CONFIDENCE (>90% CHANCE) FOR
HIGH TEMPERATURES EXCEEDING 90 DEGREES F ACROSS THE WILLAMETTE
VALLEY AND SOUTHWEST WASHINGTON LOWLANDS ON MONDAY AND TUESDAY
WITH A 10-30% CHANCE FOR TEMPERATURES EXCEEDING 100 DEGREES F
FROM SALEM TO PORTLAND-VANCOUVER ON MONDAY, INCREASING TO 30-50%
ON TUESDAY. OVERNIGHT LOWS WILL ALSO BE WARM (NEAR 60 TO MID
60S), ESPECIALLY FOR URBAN CENTERS AWAY FROM THE COAST.
OVERNIGHT LOWS NEAR OR ABOVE 65 DEGREES WOULD PROVIDE LIMITED
OVERNIGHT RELIEF FROM THE HEAT. AS A RESULT, THERE WILL BE
WIDESPREAD MODERATE HEATRISK ACROSS MUCH OF NORTHWEST OREGON AND
SOUTHWEST WASHINGTON DURING THIS PERIOD, WITH LOCALIZED MAJOR
HEATRISK ACROSS THE PORTLAND-VANCVOUER METRO AREA THROUGH THE
COLUMBIA RIVER GORGE DUE TO THE WARM OVERNIGHT TEMPERATURES. A
HEAT ADVISORY IS NOW IN EFFECT FOR MUCH OF THE THE SOUTHWESTERN
WASHINGTON LOWLANDS THROUGH INTERIOR VALLEYS OF WESTERN OREGON.
MAKE SURE TO PRACTICE HEAT SAFETY, INCLUDING STAYING HYDRATED,
WEARING LIGHT-COLORED AND LOOSE-FITTED CLOTHING, WEARING SUN
PROTECTION, AND TAKING FREQUENT BREAKS FROM THE HEAT. IF
POSSIBLE, SCHEDULE OUTDOOR PLANS DURING THE EARLY MORNING OR
LATE EVENING WHEN TEMPERATURES WILL BE LESS INTENSE.
ALL THAT SAID, THERE ARE A COUPLE FORECASTING PITFALLS WORTH
HIGHLIGHTING THAT MAY KEEP TEMPERATURES FOR SPOTS LIKE THE
PORTLAND METRO CLOSER TO THE MID 90S MONDAY AND TUESDAY COMPARED
TO NBM 5.0 (AND THE CURRENT FORECAST) WHICH PROJECTS HIGHS IN
THE MID TO UPPER 90S TO NEAR 100. THE FIRST OF THESE PITFALLS IS
SLIGHT HIGH BIAS OCCASIONALLY OBSERVED IN MID TO LONG TERM
TEMPERATURE PROJECTIONS WITH THE LATEST 5.0 VERSION OF THE NBM
AND A FEATURE WE CONTINUE TO ASSESS HERE LOCALLY SINCE THIS IS
ONLY OUR SECOND HEATWAVE LEANING ON 5.0 - WE'D LIKE TO HAVE A
MORE STATISTICALLY SOUND REASON TO MODIFY THE NBM 5.0 OUTPUT
BEYOND DAY ~3 AND WE'RE NOT QUITE WERE YET. WE'RE ALSO
MONITORING THE PLACEMENT AND STRENGTH OF A NEAR SURFACE THERMAL
TROUGH DURING THIS MON/TUE PERIOD WHICH IF CENTERED ALONG OR
JUST WEST OF THE COASTLINE HELPS TO SHIELD THE I-5 CORRIDOR FROM
ONSHORE INFLUENCE AND ENHANCES EASTERLY FLOW - TYPICALLY A
MESOSCALE FEATURE OBSERVED WHEN WE HAVE A SHOT AT HITTING THE
100 DEGREE MARK. EXPLORING THE LATEST DETERMINISTIC GUIDANCE
FROM THE GFS, NAM, ECMWF, ETC. SHOWS THE ROUGH AXIS OF THE
THERMAL TROUGH OSCILLATING FROM THE COAST RANGE INTO THE I-5
CORRIDOR (EVEN AS FAR EAST AS THE CASCADES FOOTHILLS) WHICH
WOULD ALLOW JUST ENOUGH NNW FLOW INTO THE INTERIOR VALLEYS TO
KEEP BOTH HIGH AND LOW TEMPERATURES 2-4 DEGREES COOLER THAN
CURRENTLY FORECAST. THE LACK OF MODEST EASTERLY FLOW NEAR THE
BOUNDARY LAYER OF THE ATMOSPHERE (850MB) ALSO BACKS THIS
ASSERTION, ESPECIALLY ON TUESDAY. WITH ALL THIS IN MIND, WOULD
ONLY GIVE MODERATE CONFIDENCE TO THE HIGH TEMPERATURES FORECAST
ON MONDAY AND TUESDAY, AND SHOULD THE TREND WITH THE THERMAL
TROUGH PLACEMENT HOLD, HIGHS MAY NEED TO BE DECREASED A FEW
DEGREES ALONG THE I-5 CORRIDOR MON/TUE COMPARED TO WHAT THE NBM
WOULD OTHERWISE SUGGEST. BUT EVEN IF TEMPERATURES ARE ONLY IN
THE MID 90S, IT'S STILL GOING TO BE ABNORMALLY WARM EARLY NEXT
WEEK.
THE RIDGE OF HIGH PRESSURE OVERHEAD BEGINS TO DRIFT TO OUR EAST
ON WEDNESDAY ALTHOUGH THERE STILL REMAINS FORECAST UNCERTAINTY
AS TO JUST HOW QUICKLY IT'LL PROGRESS. IT WOULD SEEM THE
MAJORITY OF ENSEMBLE MEMBERS 70% KICK IT WELL EAST OF THE
CASCADE CREST-LINE WHICH WOULD ALLOW FOR TEMPERATURES TO
DECREASE INTO THE UPPER 80S TO LOW 90S ACROSS THE INTERIOR
LOWLANDS, IF NOT FURTHER. THE LATEST NBM STILL GIVES A 20-40%
CHANCE FOR HIGHS TO EXCEED 95 DEGREES WEDNESDAY AFTERNOON. LATE
WEEK THERE'S NOW A GROWING NUMBER OF ENSEMBLE MEMBERS (60-70%)
DEPICTING A TROUGH OF LOW PRESSURE MOVING INTO THE PACIFIC
NORTHWEST WHICH WOULD INCREASE CHANCES FOR LIGHT RAINFALL AND
BELOW NORMAL TEMPERATURES. -99
AVIATION
NORTHWEST FLOW ALOFT CONTINUES WITH WEAK UPPER LEVEL
TROUGHING HELPING TO DEEPEN THE MARINE LAYER ALONG THE COAST.
MARINE STRATUS WITH MVFR CIGS IS EXPECTED TO PERSIST AT COASTAL
TERMINALS THROUGH AT LEAST 17-18Z SUNDAY. CIGS ARE EXPECTED TO
LIFT WITH IMPROVEMENT TO VFR BECOMING LIKELY (80-90% CHANCE) AFTER
18Z SUNDAY. STRATUS MAY PUSH INLAND OVERNIGHT, AS PROBS FOR MVFR
HAVE INCREASED TO AROUND 30-40% BETWEEN 10-18Z SUNDAY. OTHERWISE,
EXPECT PREDOMINATELY VFR CONDITIONS AT INLAND TERMINALS. NORTH TO
NORTHWEST WINDS CONTINUE, STRONGEST DURING THE AFTERNOON/EARLY
EVENING. /DH
KPDX AND APPROACHES...VFR CONDITIONS ARE LIKELY TO PERSIST THROUGH
THE TAF PERIOD, THOUGH CHANCES FOR MVFR STRATUS ARE INCREASING
(30-40%) FOR LATER TONIGHT, BETWEEN 11-17Z SUNDAY. NORTHWEST WINDS
AROUND 6-8 KT. /DH
MARINE
HIGH PRESSURE OFFSHORE HAS WEAKENED, RESULTING IN WEAKER
NORTHWESTERLY WINDS TONIGHT THROUGH SUNDAY MORNING. STEEP AND
CHOPPY SEAS AROUND 7 TO 9 FT CONTINUE TO SUBSIDE TOWARD 5 TO 7 FT
THROUGH SUNDAY. A SMALL CRAFT ADVISORY REMAINS IN EFFECT ACROSS
THE OUTER WATERS (BEYOND 10 NM OFFSHORE) UNTIL 11 PM TONIGHT. LATE
SUNDAY INTO EARLY NEXT WEEK, WIND GUSTS AROUND 20 TO 25 KT
RETURN, WHILE SEAS REMAIN AROUND 5 TO 7 FT. THERE IS ONLY A 10 TO
20 PERCENT CHANCE FOR SEAS TO EXCEED 7 FT FROM MONDAY TO
WEDNESDAY. ~12
PQR WATCHES/WARNINGS/ADVISORIES
OR...HEAT ADVISORY FROM 11 AM MONDAY TO 11 PM PDT TUESDAY FOR
ORZ108>123.
WA...HEAT ADVISORY FROM 11 AM MONDAY TO 11 PM PDT TUESDAY FOR
WAZ204>210.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR PZZ271>273.
SMALL CRAFT ADVISORY FROM 5 PM SUNDAY TO 2 PM PDT MONDAY FOR
PZZ272.
SMALL CRAFT ADVISORY FROM 2 PM SUNDAY TO 2 PM PDT MONDAY FOR
PZZ273.
WWW.WEATHER.GOV/PORTLAND
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