175
FXUS66 KPQR 051656 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
956 AM PDT FRI JUN 5 2026
UPDATED AVIATION DISCUSSION
SYNOPSIS
A FAIRLY PROGRESSIVE UPPER-LEVEL WEATHER PATTERN
REMAINS IN PLACE AS A SERIES OF WEAK FRONTAL SYSTEMS PARADE INTO
THE PACIFIC NORTHWEST THROUGH THE EARLY TO MIDDLE PORTION OF
NEXT WEEK. THIS'LL KEEP TEMPERATURES GENERALLY BELOW NORMAL WITH
ON/OFF SHOWER AND WEAK T-STORM CHANCES AT TIMES, ESPECIALLY AT
THE COAST AND ACROSS OUR ELEVATED TERRAIN FEATURES. HOWEVER,
THESE CONDITIONS WON'T LAST IN PERPETUITY AS A GROWING NUMBER OF
MODELS DEPICT A RIDGE OF HIGH PRESSURE BUILDING OVERHEAD
TOWARDS THE END OF NEXT WEEK - WELCOME NEWS FOR THOSE CRAVING
SOME WARMING/DRIER WEATHER.
SHORT TERM...NOW THROUGH SUNDAY
EARLY THIS MORNING
SATELLITE OBSERVATIONS DEPICTS CLOUD COVER INCREASING ACROSS
WESTERN OREGON AND SOUTHWEST WASHINGTON AS A WEAK FRONTAL SYSTEM
BEGINS TO WORK ITS WAY INTO THE REGION. AS A RESULT, EXPECT A
RETURN OF PRECIPITATION CHANCES ALTHOUGH IMPACTS APPEAR RATHER
BENIGN OVERALL WITH THE BEST SHOT FOR RAIN SHOWER ACTIVITY OVER
SOUTHWEST WASHINGTON AND THE NORTH OREGON COAST, COAST RANGE,
AND CASCADES, WHILE MOST INTERIOR VALLEYS ROUGHLY SOUTH OF
PORTLAND REMAIN DRY. GIVEN THE SHOWERY NATURE OF THIS SYSTEM,
RAINFALL AMOUNTS TODAY WILL VARY ACROSS THE AREA AND THE HIGHEST
AMOUNTS WILL ULTIMATELY DEPEND ON WHERE SHOWERS SET-UP. MOST
LOCATIONS SHOULD SEE LESS THAN 0.10" OF AN INCH OF RAINFALL INTO
THIS EVENING. IN ADDITION, THERE IS A 10-15% CHANCE FOR
ISOLATED THUNDERSTORMS ACROSS SOUTHWEST WASHINGTON FRIDAY
AFTERNOON DUE TO INCREASING INSTABILITY FROM COLD AIR ALOFT
ALONG WITH SUFFICIENT LIFT FROM THE INCOMING TROUGH.
THEN ON SATURDAY, AN UPPER TROUGH WHICH HAS BEEN DROPPING
SOUTHWARD FROM THE GULF OF ALASKA WILL MOVE INLAND BRINGING
MORE WIDESPREAD CHANCES FOR RAINFALL ACROSS NORTHWEST OREGON
AND SOUTHWEST WASHINGTON. AT THE SAME TIME, COOLING TEMPERATURES
ALOFT WILL FURTHER INCREASE INSTABILITY WITH CAPE VALUES AS
HIGH AS 150-350 J/KG LEADING TO A 15-25% CHANCE FOR
THUNDERSTORMS, MAINLY FROM PACIFIC CITY AND THE CENTRAL
WILLAMETTE VALLEY NORTHWARD WITH THE HIGHEST CHANCES (20-25%)
ACROSS SOUTHWEST WASHINGTON. HOWEVER, A LACK OF VERTICAL WIND
SHEAR (EFFECTIVE SHEAR VALUES NEAR ~15 KNOTS) LEAVES MUCH TO BE
DESIRED IN REGARD TO UPDRAFT ORGANIZATION, SO OUR STORM-MODE
LIKELY REMAINS IN THE WEAKER POP-UP/SINGLE CELL CATEGORY. THESE
POP-UP STORMS WITH A QUICK LIFE-CYCLE ARE FAIRLY NORMAL FOR THIS
TYPE OF POST-FRONTAL CONVECTION REGIME AND DISTINCTLY DIFFERENT
FROM OUR SOUTHERLY FLOW MONSOONAL BASED THUNDERSTORM SET-UPS
WHICH WE CAN ALSO SEE THIS TIME OF YEAR - ACTIVITY ASSOCIATED
WITH THE LATTER CASE TYPICALLY CARRIES A GREATER THREAT OF
LIGHTNING/IMPACTS. THE PERIOD OF WATCH FOR STRONGER SHOWERS AND
WEAK T-STORMS WILL BE MIDDAY THROUGH THE AFTERNOON HOURS (11
AM-5 PM SATURDAY) WHEN INSTABILITY DUE TO DAYTIME HEATING IS
THE GREATEST. ANY PASSING THUNDERSTORMS ON BOTH FRIDAY AND
SATURDAY MAY PRODUCE LIGHTNING, BRIEF HEAVY RAIN, ERRATIC GUSTY
WINDS, AND/OR SMALL HAIL.
INCREASING ONSHORE FLOW WILL KEEP WESTERLY WINDS BREEZY THROUGH
THE CENTRAL COLUMBIA GORGE AND UPPER HOOD RIVER VALLEY THROUGH
SATURDAY WITH GUSTS GENERALLY BETWEEN 25-35 MPH. THAT SAID,
THERE IS ALSO A 10-20% CHANCE FOR ISOLATED WIND GUSTS OF 40-45
MPH THROUGH THESE AREAS AS WELL, MAINLY FOR HIGHER TERRAIN AND
EXPOSED RIDGETOPS. IF THE LOW SHIFTS ANY FURTHER NORTH, THESE
WINDS WOULD END UP WEAKER.
COME SATURDAY EVENING INTO EARLY SUNDAY MORNING, DETERMINISTIC
AND ENSEMBLE MODELS ARE IN GOOD AGREEMENT SHIFTING THE AXIS OF
THE UPPER-LEVEL TROUGH HELPING TO DRIVE OUR SHOWER ACTIVITY
FURTHER EAST ALLOWING FOR A WEAK TRANSITORY RIDGE OF HIGH
PRESSURE TO PASS OVERHEAD. SO FOR THOSE WITH SUNDAY PLANS
CONFIDENCE IS MODERATE TO HIGH DRIER WEATHER RETURNS, ALBEIT
BRIEFLY. TEMPERATURES INCREASE DAY TO DAY AS WELL WITH HIGHS
GENERALLY IN THE UPPER 60S TO NEAR 70 ACROSS THE INLAND VALLEYS.
-99/10
LONG TERM...MONDAY THROUGH THURSDAY
AFTER OUR ONE DAY OF NEAR
NORMAL AND MOSTLY DRY JUNE WEATHER ON SUNDAY, THE VAST MAJORITY
OF DETERMINISTIC AND ENSEMBLE MODELS DEPICT BROAD TROUGHING AND
BELOW-AVERAGE 500 MB HEIGHTS RETURNING TO THE AREA FOR MONDAY.
WHILE MODELS CAPTURE THE PROGRESSION OF THE OVERALL TROUGH
FEATURE EARLY NEXT WEEK, THERE STILL REMAINS SOME UNCERTAINTY
IN THE EXACT AMPLITUDE AND TRACK OF THIS SYSTEM WHICH WOULD
MODULATE PRECIPITATION AMOUNTS AND PLACEMENT, ESPECIALLY ACROSS
THE INLAND VALLEYS. ALL IN ALL, AROUND ~75-80% OF ENSEMBLE
MEMBERS KEEP SOME SORT OF TROUGHING AND THE ASSOCIATED
COOLER/WETTER CONDITIONS OVER THE PACIFIC NORTHWEST THROUGH
TUESDAY AND WEDNESDAY. DURING THIS PERIOD, THE NBM PROJECTS
CHANCES TO EXCEED 1 INCH OF LIQUID PRECIPITATION IN 48 HOURS
BETWEEN 5 AM MONDAY TO 5 AM WEDNESDAY AT AROUND 50-55% ACROSS
THE WEST SLOPES OF THE CASCADES AND ADJACENT FOOTHILLS, AND
15-25% IN THE COAST RANGE/WILLAPA HILLS. LESS THAN A 15% CHANCE
ELSEWHERE. BY THURSDAY THERE IS GREATER UNCERTAINTY AS ENSEMBLE
GUIDANCE IS HALF AND HALF ON WHETHER OR NOT TROUGHING LINGERS
OVERHEAD OR EXITS THE AREA TO THE EAST. EITHER WAY, ANY
PRECIPITATION THAT FALLS WILL LIKELY BE LIGHT AND NON-IMPACTFUL
BY THIS POINT. THEN THERE IS GROWING CONSENSUS AMONG ENSEMBLE
MEMBERS (~55-65%) FOR A RIDGE OF HIGH PRESSURE OVER THE EASTERN
PACIFIC TO BEGIN SHIFTING INTO THE PACIFIC NORTHWEST AROUND FRIDAY
WHICH WOULD LEAD TO COMPLETELY DRY WEATHER AND A NOTICEABLE
WARMING TREND TO END NEXT WEEK. THIS SCENARIO IS ALSO BEING
DEPICTED BY AI BASED MODEL GUIDANCE AS WELL ADDING SOME
ADDITIONAL CONFIDENCE TO AN EVENTUAL WARM-UP AT THE END OF THE
FORECAST PERIOD. -99/10
AVIATION
EXPECT GENERALLY VFR CONDITIONS ACROSS THE AIRSPACE AS
A TROUGH, CURRENTLY OVER THE GULF OF ALASKA SLOWLY DRIFTS
SOUTHEASTWARD TOWARDS. CURRENT SURFACE OBSERVATIONS SHOW CLOUD
DECKS ACROSS THE AIRSPACE AROUND FL035-FL060. A SERIES OF WEAK
FRONTS, ASSOCIATED WITH THE ALASKAN LOW, WILL SLOWLY PUSH INLAND
THROUGH THE DAY. THIS WILL RESULT IN BRIEF SHOWERS IMPACTING
LOCATIONS NORTH OF KONP ALONG THE COAST AND KSLE FOR INLAND
LOCATIONS. THESE SHOWERS LOOK TO BE LIGHT WITH MINIMAL IMPACTS,
BUT CANNOT RULE OUT BRIEF PERIODS OF MVFR CONDITIONS WHICH WILL BE
ASSOCIATED WITH SAID SHOWERS. SOUTHWEST TO WEST WINDS BETWEEN
5-10 KT AT MOST SITES.
IT'S WORTH QUICKLY NOTING THERE'LL BE A 15% CHANCE FOR
THUNDERSTORMS THIS AFTERNOON MAINLY FOR KAST AND THE PORTLAND
METRO TERMINALS WITH LIMITED, IF ANY IMPACTS.
KPDX AND APPROACHES...VFR CONDITIONS WITH CIGS BETWEEN
FL035-FL060. LIGHT SHOWERS POSSIBLE THROUGH THE TAF PERIOD WHICH
COULD RESULT IN BRIEF PERIODS OF MVFR CONDITIONS. /42
MARINE
OVERALL FAIRLY BENIGN CONDITIONS ARE EXPECTED THROUGH
THE WEEKEND INTO NEXT WEEK WHILE SEVERAL WEAK FRONTAL SYSTEMS
MOVE THROUGH THE REGION. THIS FIRST OF THESE FRONTAL SYSTEMS
ARRIVING TODAY ALLOW SEAS TO BUILD INTO THE 6-8 FT RANGE AT
10-11 SECONDS WITH WESTERLY WINDS GENERALLY GUSTING IN THE 13-18
KNOT RANGE, HIGHEST ACROSS THE OUTER WATERS. THEN A SECONDARY
FRONT ARRIVES ON SATURDAY, BRINGING A SHIFT TO NORTHWEST WINDS
IN THE AFTERNOON AND EVENING HOURS. WINDS ONLY INCREASE
MARGINALLY WITH ONLY A 15-35% CHANCE FOR SMALL CRAFT ADVISORY
WIND GUSTS - HIGHEST PROBABILITIES ACROSS THE OUTER WATERS.
AFTER A LULL DURING THE DAY ON SUNDAY, WINDS LIKELY INCREASE YET
AGAIN ON MONDAY AS A COMPARATIVELY STRONGER SYSTEM MOVES OVER
THE WATERS, BRINGING SOUTH WIND GUSTS UP TO 20-25 KT AND SEAS
APPROACHING 6-8 FT. CONDITIONS THEN GRADUALLY CALM INTO THE
MIDDLE THE OF THE WEEK AS A RIDGE OF HIGH PRESSURE ATTEMPTS TO
BUILD OVERHEAD AND NORTHWESTERLY WINDS RETURN WHILE SEAS HOLD
AROUND 5-6FT AROUND 9-10 SECONDS. -99
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
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