506
FXUS66 KPQR 252129
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
229 PM PDT THU JUN 25 2026
SYNOPSIS
COOLER AND WETTER CONDITIONS ARE EXPECTED MOVING
INTO THE WEEKEND AS A SIGNIFICANT PATTERN CHANGE TAKES HOLD
WHILE LEAVING OUR PREVIOUSLY WARM/HOT CONDITIONS IN THE REAR-
VIEW MIRROR FOR THE FORESEEABLE FUTURE. AFTER SEVERAL ROUNDS OF
WIDESPREAD SHOWER ACTIVITY AND A 10-20% CHANCE FOR
THUNDERSTORMS SATURDAY AFTERNOON, CONDITIONS TREND A LITTLE
DRIER AND SLIGHTLY WARMER SUNDAY THROUGH EARLY NEXT WEEK.
HOWEVER, REGIONALLY WE'LL STILL MAINTAIN SLIGHT CHANCES FOR RAIN
SHOWERS MAINLY ACROSS TERRAIN FEATURES LIKE THE COAST RANGE AND
CASCADES.
DISCUSSION...TODAY THROUGH WEDNESDAY
MID TO HIGH CLOUD COVER
CONTINUES TO STREAM INTO THE PACIFIC NORTHWEST THIS AFTERNOON
THANKS TO AN APPROACHING LOW PRESSURE SYSTEM USHERING IN A
PERIOD OF COOLER AND SHOWERY CONDITIONS. WHILE MOST THE REGION
REMAINS DRY FOR THE NEXT FEW HOURS, A COLD-FRONTAL BOUNDARY
LIKELY BRINGS RAIN TO THE COAST BY THE LATE AFTERNOON/EVENING
HOURS BEFORE IT QUICKLY SPREADS EASTWARD INTO THE I-5 CORRIDOR
AND THEN THE CASCADES TONIGHT. WE'LL EXPERIENCE COOLER THAN
NORMAL TEMPERATURES AND SHOWER CHANCES THROUGH AT LEAST SATURDAY
INTO EARLY SUNDAY ALTHOUGH RAINFALL AMOUNTS APPEAR BENEFICIAL
AND GENERALLY NON-IMPACTFUL AT THIS TIME. LOOKING AT THE LATEST
NBM, CHANCES FOR 48-HOUR RAINFALL AMOUNTS EXCEEDING 1 INCH FROM
5 PM TODAY TO 5 PM SATURDAY ARE AROUND 30-55% FOR THE COAST AND
COAST RANGE, 5-10% ALONG THE I-5 CORRIDOR, AND 60-80% OR HIGHER
ACROSS THE CASCADES DUE TO WESTERLY FLOW BRINGING OROGRAPHIC
ENHANCEMENT. IT'S ALSO WORTH QUICKLY NOTING SNOW-LEVELS (THAT'S
NOT A TERM WE'VE USED IN A AWHILE) BOTTOM OUT AROUND 5000-6000FT
ON SATURDAY SO THOSE IN THE HIGHER ELEVATIONS OF THE CASCADES
HAVE A SHOT AT SEEING SOME WET SNOW IN THE AIR - MINIMAL IMPACTS.
WE CONTINUE TO MONITOR THE POTENTIAL FOR WEAK THUNDERSTORMS THE
NEXT SEVERAL DAYS AS THE UPPER-LEVEL LOW PRESSURE ORIGINATING
FROM THE GULF OF ALASKA TRACKS OVERHEAD. THE LATEST GUIDANCE
HAS BACKED OFF ON T-STORM CHANCES FRIDAY AFTERNOON (<10% CHANCE)
DUE IN-PART TO A LACK OF CONVECTIVE DEPTH THAT DOES NOT APPEAR
CONDUCIVE TO ELECTRIFICATION. WHILE MODELS DEPICT 50-200 J/KG
OF CAPE, DETERMINISTIC MODEL SOUNDINGS CONFINE THIS INSTABILITY
AROUND AND BELOW 0C. YOU GENERALLY NEED INSTABILITY TO EXTEND
WELL INTO THE -10C TO -25C MIX PHASED REGION OF THE ATMOSPHERE
TO PRODUCE LIGHTNING, AND IT APPEARS WE WON'T MEET THAT
REQUIREMENT ON FRIDAY. THE SHALLOW NATURE OF THE CONVECTION MAY
END UP BEING AN ISSUE ON SATURDAY AS WELL BUT THERE'S AT LEAST
A MODEL OR TWO SUGGESTING SLIGHTLY HIGHER CONVECTIVE DEPTH
COMPARATIVELY, ESPECIALLY RIGHT UNDER THE CORE OF THE LOW
PASSING OVERHEAD DURING THE AFTERNOON HOURS, SO THE 15-20%
CHANCE FOR THUNDERSTORMS REMAINS. HIGH RESOLUTION GUIDANCE
DURING THIS PERIOD SUGGESTS EFFECTIVE SHEAR REMAINS BELOW 20-25
KT TOO, THEREFORE, CHANCES FOR ANY THUNDERSTORMS BECOMING SEVERE
ARE VERY LOW (<5%). OTHERWISE, ANY STRONG SHOWER OR PASSING
WEAK THUNDERSTORM MAY PRODUCE BRIEF HEAVY RAIN, GUSTY AND
ERRATIC WINDS, AND A LIGHTNING STRIKE OR TWO. ALSO CAN'T RULE
OUT AN ISOLATED COLD AIR FUNNEL CLOUD GIVEN THE TIME OF YEAR,
ESPECIALLY ON SATURDAY.
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 AND LINGERING ALONG THE
INTERIOR MOUNTAIN WEST, RETURNING RELATIVELY DRIER CONDITIONS
AND A WARM-UP OF A FEW DEGREES TO OUR AREA. THIS WILL PUT HIGH
TEMPERATURES JUST BELOW THE SEASONAL NORMALS WITH LOW 70S FOR
THE INTERIOR LOWLANDS AND UPPER 50S TO LOW 60S FOR THE COAST).
WILL STILL MAINTAIN PRECIPITATION CHANCES ACROSS THE COAST RANGE
AND CASCADES AS WESTERLY FLOW CONTINUES TO SUPPORT OROGRAPHIC
ENHANCEMENT OF PRECIPITATION, THOUGH ANY ADDITIONAL RAIN AMOUNTS
APPEAR VERY LIGHT. STILL, WE'LL HAVE TO KEEP AN EYE ON SUBTLE
SHORTWAVE FEATURES (LIKE LATE ON SUNDAY) ROTATING INTO THE
REGION NORTH TO SOUTH ON THE BACK SIDE OF THE UPPER-LEVEL LOW
WHICH MAY EXPAND THE COVERAGE OF SHOWERS TEMPORARILY. THERE'S
ONLY LOW TO MODERATE CONFIDENCE ON THE PLACEMENT/TIMING OF
THESE SMALLER SHORTWAVE FEATURES. ENSEMBLE MEMBERS THEN SUGGEST
ANOTHER UPPER-LEVEL TROUGH DROPPING DOWN INTO THE AREA ON
WEDNESDAY INTO THURSDAY, HOWEVER, THERE IS ALSO VERY HIGH
UNCERTAINTY WITH HOW MUCH PRECIPITATION WE GET, IF ANY. WESTERLY
WINDS THROUGHOUT THE WEEK 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 THROUGH EARLY NEXT WEEK, WITH THE HIGHEST CHANCES
FROM SUNDAY TO TUESDAY. -99/10
AVIATION
MOIST, WEST TO SOUTHWESTERLY FLOW ALOFT IS SPREADING
MID-LEVEL CLOUDS ACROSS THE REGION THIS AFTERNOON. EXPECT CIGS TO
CONTINUE TO LOWER AS A FRONTAL SYSTEM APPROACHES THE AREA. AS OF
21Z, MARINE STRATUS AT THE COAST AS GENERALLY LIFTED TO MVFR,
THOUGH CIGS AT KONP MAY CONTINUE TO FLUCTUATE BETWEEN LOW-END
MVFR AND IFR THROUGH THIS EVENING, AS GUIDANCE SUGGESTS THERE IS
AROUND A 70% CHANCE OF IFR CONDITIONS THROUGH 06Z FRIDAY. FOR
INLAND TERMINALS, PREDOMINATELY VFR CONDITIONS ARE FAVORED THROUGH
05-07Z FRIDAY. LIGHT RAIN IS EXPECTED TO GRADUALLY SPREAD INLAND
BY 03-04Z THIS EVENING, WITH CHANCES FOR MVFR CIGS INCREASING TO
AROUND 60-80% AFTER 06-08Z FRIDAY. WINDS ARE EXPECTED TO BECOME
SOUTHWESTERLY WITH GUSTS UP TO 20-25 KT ALONG THE COAST OVERNIGHT.
KPDX AND APPROACHES...VFR CONDITIONS CONTINUE INTO THE EVENING AS
CIGS GRADUALLY LOWER. CIGS ARE EXPECTED TO FALL TO LOWER-END VFR
AS THE FRONTAL SYSTEM MOVES IN AND BRINGS RAIN BY 03-04Z FRIDAY.
AFTER 06Z FRIDAY, CHANCES FOR MVFR CIGS INCREASE TO AROUND
60-80%. /DH
MARINE
EXPECT INCREASING SOUTH TO SOUTHWESTERLY WINDS ACROSS
THE COASTAL WATERS THROUGH TONIGHT AS AN OCCLUDING FRONT
APPROACHES THE AREA. STRONGEST WINDS WITH GUSTS TO AROUND 25 KT
ARE EXPECTED ACROSS THE INNER COASTAL WATERS NORTH OF CAPE
FOULWEATHER AND UP TO 10-20 NM OFFSHORE. LATEST MODEL GUIDANCE
SUGGESTS WINDS INCREASE SLIGHTLY EARLIER, SO HAVE ADJUSTED THE
SMALL CRAFT ADVISORY TO BEGIN AT 9 PM THIS EVENING. STILL EXPECT
WINDS TO EASE BELOW SCA THRESHOLDS BY 5 AM FRIDAY AS WINDS TURN
MORE WESTERLY AS THE FRONT PUSHES ONSHORE.
WEST TO NORTHWEST WINDS WILL PERSIST BEHIND THE FRONT LATER
FRIDAY AND INTO SATURDAY AS WEAK LOW PRESSURE NEAR VANCOUVER
ISLAND SLIDES SOUTH NEAR THE WASHINGTON COAST. HIGH PRESSURE
GRADUALLY BUILDS ACROSS THE WATERS SUNDAY INTO EARLY NEXT WEEK.
SEAS AROUND 4 TO 5 FT THIS AFTERNOON BUILD TO AROUND 7 TO 9 FT
THIS WEEKEND AS A WEST-NORTHWESTERLY SWELL MOVES THROUGH THE
WATERS. /DH
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 5 AM PDT FRIDAY
FOR PZZ210-251-252.
WWW.WEATHER.GOV/PORTLAND
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