057
FXUS66 KPQR 240511 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
1010 PM PDT TUE JUN 23 2026
UPDATED AVIATION DISCUSSION AND PQR WATCHES/WARNINGS/ADVISORIES.
SYNOPSIS
EXPECT ONE FINAL DAY OF ABNORMALLY WARM CONDITIONS
ON WEDNESDAY WHILE ONSHORE FLOW CONTINUES TO INCREASE EVENTUALLY
LEADING TO MORE SEASONABLE CONDITIONS FOR THURSDAY. A
SIGNIFICANT WEATHER PATTERN CHANGE IS STILL IN STORE THURSDAY
EVENING/NIGHT THROUGH SATURDAY AS COOLER AND WETTER CONDITIONS
TAKE HOLD; SLIGHT CHANCE (15-20%) FOR THUNDERSTORMS
FRIDAY/SATURDAY AFTERNOON AS WELL. CONDITIONS TREND DRIER
SUNDAY AND MONDAY, BUT WE'LL MAINTAIN SLIGHT CHANCES FOR LIGHT
RAIN SHOWERS ACROSS THE COAST RANGE AND CASCADES WHILE
TEMPERATURES REMAIN NEAR THE BELOW NORMAL ACROSS THE ENTIRE
REGION.
DISCUSSION...TODAY THROUGH MONDAY
THE UPPER-LEVEL RIDGE
PATTERN WHICH HAS BEEN DRIVING OUR WARMER THAN NORMAL CONDITIONS
CONTINUES TO BREAK DOWN AND SHIFT EASTWARD OPENING THE DOOR FOR
INCREASING ONSHORE FLOW HEADED INTO WEDNESDAY MORNING. IT'S
WORTH NOTING MODELS STILL SHOW A WEAK UPPER-TROUGH PASSING
THROUGH THE REGION DURING THE AFTERNOON. WITH THE LINGERING DRY
AIRMASS OVERHEAD, IT'S NOT EXPECTED TO BRING ANY SHOWER ACTIVITY
AND/OR PRECIPITATION WEST OF THE CASCADE CREST-LINE. WEDNESDAY
AFTERNOON HIGHS WILL STILL BE RATHER WARM ACROSS THE INLAND
VALLEYS BUT A COUPLE DEGREES COOLER THAN THE DAY PRIOR (TODAY).
TEMPERATURES CHANGES MORE NOTICEABLY COME THURSDAY AS ONSHORE
FLOW AT THE SURFACE AND WESTERLY FLOW ALOFT PUSH HIGH
TEMPERATURES INTO THE 70S TO NEAR 80 ACROSS THE INLAND VALLEYS
WITH UPPER 50S TO 60S ALONG THE COAST. THE COOLING TREND ONLY
CONTINUES INTO THE END OF THE WEEK.
A LARGE-SCALE PATTERN CHANGE TO COOLER AND WETTER CONDITIONS
REMAINS ON TRACK FOR THURSDAY NIGHT AND FRIDAY INTO THE WEEKEND
AS ENSEMBLE AND DETERMINISTIC GUIDANCE IS IN EXCELLENT
AGREEMENT DEPICTING AN UPPER-LEVEL LOW PRESSURE SYSTEM
PROGRESSING INTO THE PACIFIC NORTHWEST FROM THE GULF OF ALASKA.
MOST ENSEMBLE MEMBERS HAVE RAINFALL VIA A COLD-FRONTAL BOUNDARY
REACHING THE COAST BY LATE THURSDAY AFTERNOON/EVENING AND THEN
SPREADING INTO THE I-5 CORRIDOR BY LATER THURSDAY NIGHT INTO
FRIDAY MORNING. WE'LL REMAIN IN THIS COOLER AND WET PATTERN
THROUGH AT LEAST SATURDAY, BUT AT LEAST TOTAL RAIN AMOUNTS AT
THIS TIME APPEAR BENEFICIAL AND GENERALLY NON-IMPACTFUL.
LOOKING AT THE LATEST NBM, CHANCES FOR 48-HOUR RAIN AMOUNTS
EXCEEDING 0.50 INCH FROM 5 AM FRIDAY TO 5 AM SUNDAY HAVE
INCREASED WITH FORECAST CYCLE AND ARE AROUND 80-90% FOR THE
COAST AND COAST RANGE, 40-70% ALONG THE I-5 CORRIDOR, AND
GREATER THAN 95% ACROSS THE CASCADES DUE TO WESTERLY FLOW
BRINGING OROGRAPHIC ENHANCEMENT. WILL NOTE THAT THE WESTERN-MOST
PARTS OF THE WILLAMETTE VALLEY (INCLUDING MCMINNVILLE AND
CORVALLIS) ONLY HAVE A 30-40% CHANCE TO EXCEEDING 0.50 INCH
DURING THIS TIMEFRAME DUE TO POTENTIAL RAINSHADOWING FROM THE
COAST RANGE.
ON SATURDAY THE CORE OF THE UPPER-LEVEL LOW PRESSURE CENTERS
ITSELF RIGHT OVER-TOP THE PACIFIC NORTHWEST. TEMPERATURES WILL
FURTHER COOL ALOFT ALLOWING FOR INCREASING ATMOSPHERIC
INSTABILITY DURING THE DAYTIME HOURS AND FACILITATING CAPE
VALUES OF 100-300 J/KG LATE SATURDAY MORNING INTO THE AFTERNOON.
THIS INSTABILITY PLUS SUFFICIENT LIFT FROM THE LOW WILL SUPPORT
A SLIGHT CHANCE (15-24%) FOR THUNDERSTORMS ACROSS NORTHWEST
OREGON AND SOUTHWEST WASHINGTON. FOR NOW ANY CONVECTION APPEARS
RATHER WEAK AND UNORGANIZED (OUR TYPICAL POST-FRONTAL POP-UP
STORMS) WITH DETERMINISTIC GUIDANCE SUGGESTING ONLY 15-20 KNOTS
OF EFFECTIVE SHEAR - SEVERE THUNDERSTORMS ARE UNLIKELY (<5%).
ANY PASSING THUNDERSTORMS MAY PRODUCE LIGHTNING, BRIEF HEAVY
RAIN, ERRATIC WINDS, AND/OR SMALL HAIL. ALSO CAN'T RULE OUT A
A COLD AIR FUNNEL CLOUD OR TWO GIVEN THE TIME OF YEAR.
THE LATTER HALF OF THE WEEKEND INTO EARLY NEXT WEEK THE
MAJORITY OF ENSEMBLE MEMBERS ARE SHOWING THE BROADER UPPER-
LEVEL LOW FEATURE SHIFTING EASTWARD, RETURNING RELATIVELY DRIER
CONDITIONS AND A WARM-UP OF A FEW DEGREES. WILL STILL MAINTAIN
PRECIPITATION CHANCES ACROSS THE COAST RANGE AND CASCADES AS
WESTERLY FLOW CONTINUES TO SUPPORT OROGRAPHIC ENHANCEMENT OF
PRECIPITATION, HOWEVER, ANY ADDITIONAL RAIN AMOUNTS APPEAR
LIGHT. STILL, WE'LL HAVE TO KEEP AN EYE ON SUBTLE SHORTWAVE
FEATURES ROTATING INTO THE REGION NORTH TO SOUTH ON THE BACK
SIDE OF THE UPPER-LEVEL LOW WHICH MAY EXPAND THE COVERAGE OF
SHOWERS TEMPORARILY - LOW CONFIDENCE ON THE PLACEMENT/TIMING OF
THESE SMALLER SHORTWAVE FEATURES. WESTERLY WINDS THROUGHOUT
THIS COOL AND WET PATTERN WILL BE BREEZIEST ALONG THE CENTRAL
COLUMBIA RIVER GORGE AND ACROSS UPPER HOOD RIVER VALLEY, WITH
CHANCES FOR ISOLATED WIND GUSTS EXCEEDING 45 MPH AROUND 10-35%
FROM FRIDAY TO THE END OF THE WEEKEND. -99/10
AVIATION
MOSTLY CLEAR SKIES AND VFR CONDITIONS WILL CONTINUE
FOR INLAND TAF SITES THROUGH 06Z THURSDAY, WITH LIGHT AND VARIABLE
WINDS AROUND 5 KT OR LESS BECOMING NORTHERLY TO NORTHWESTERLY
AFTER 21Z WEDNESDAY, WITH GUSTS UP TO 15-20 KT EXPECTED BY LATE
WEDNESDAY AFTERNOON.
MEANWHILE, LOW MARINE STRATUS WITH CEILINGS AROUND 400-600 FT WILL
CONTINUE AT THE COAST TONIGHT AND TOMORROW. SIMILAR TO THE LAST
COUPLE OF DAYS, KONP WILL LIKELY FAIL TO CLEAR OUT TOMORROW
AFTERNOON. EVEN IF LOW CLOUDS DO CLEAR OUT AT KONP TOMORROW, IT
WOULD MOST LIKELY BE VERY SHORT-LIVED. MEANWHILE, THERE IS AN
80-90% CHANCE KAST WILL CLEAR OUT BY 17-18Z WEDNESDAY BEFORE LOW
STRATUS RETURNS TO THE TERMINAL AROUND 03Z THURSDAY.
KPDX AND APPROACHES...VFR CONDITIONS WILL CONTINUE THROUGH 06Z
THURSDAY WITH SCATTERED HIGH CLOUDS ABOVE 20 KFT FROM TIME TO
TIME. LIGHT AND VARIABLE WINDS AROUND 5 KT OR LESS TONIGHT WILL
BECOME NORTHWESTERLY WEDNESDAY AFTERNOON WITH GUSTS UP TO 20 KT
EXPECTED BY 00Z THURSDAY WITH AN INCOMING SEA BREEZE. -23
MARINE
HIGH PRESSURE WILL MAINTAIN NORTHWEST WINDS ACROSS THE
COASTAL WATERS THROUGH WEDNESDAY. WINDS ARE GENERALLY EXPECTED TO
REMAIN UNDER 20 KT. WEAKENING HIGH PRESSURE WILL GIVE WAY TO A
FRONTAL SYSTEM APPROACHING THE AREA ON THURSDAY. WINDS ARE
EXPECTED TO BACK WEST TO SOUTHWESTERLY BEFORE THE COLD FRONT
PUSHES ACROSS THE COASTAL WATERS LATE THURSDAY INTO FRIDAY.
SOUTHWEST WINDS ARE EXPECTED TO BE STRONGEST ACROSS THE INNER
COASTAL WATERS NORTH OF CAPE FOULWEATHER, BUT THERE IS ONLY AROUND
A 10-20% CHANCE OF WIND GUSTS EXCEEDING 21 KT AT ANY GIVEN HOUR
THROUGH FRIDAY MORNING. WEST TO NORTHWEST WINDS WILL PERSIST
BEHIND THE FRONT LATER FRIDAY AND INTO THE WEEKEND AS WEAK LOW
PRESSURE LINGERS NEAR VANCOUVER ISLAND. HIGH PRESSURE GRADUALLY
BUILDS ACROSS THE WATERS LATE WEEKEND. SEAS ARE EXPECTED TO
REMAIN LESS THAN 8 FT THROUGH FRIDAY. /DH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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