939
FXUS66 KPQR 032151
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
251 PM PDT WED JUN 3 2026
SYNOPSIS
A SHORTWAVE TROUGH EXITING THE REGION WILL MAINTAIN
ISOLATED SHOWERS ACROSS NORTHWEST OREGON AND SOUTHWEST
WASHINGTON THIS AFTERNOON. A DEEPER TROUGH SHIFTS SOUTHWARD INTO
THE REGION FRIDAY TO SATURDAY, INCREASING ONSHORE FLOW AND
RETURNING MORE WIDESPREAD CHANCES FOR PRECIPITATION. SLIGHT
CHANCES FOR THUNDERSTORMS FRIDAY AND SATURDAY AFTERNOON. DRIER
WEATHER RETURNS SUNDAY BEFORE ANOTHER TROUGH RETURNS CHANCES FOR
PRECIPITATION EARLY NEXT WEEK.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT
RADAR IMAGERY AS OF
EARLY WEDNESDAY AFTERNOON DEPICTS SCATTERED SHOWERS ACROSS
NORTHWEST OREGON AND SOUTHWEST WASHINGTON AS AN UPPER-LEVEL
SHORTWAVE TROUGH SWINGS THROUGH THE REGION. THIS TROUGH WILL
QUICKLY EXIT EASTWARD THIS AFTERNOON, LEADING TO DECREASING
SHOWERS THROUGH THIS EVENING. FOLLOWING THIS QUICK-MOVING
SYSTEM, DRY WEATHER AND SUNNY SKIES RETURN ON THURSDAY AS DRY
WESTERLY FLOW SETS UP OVER THE REGION. WESTERLY WINDS AT THE
SURFACE WILL GENERALLY BE LIGHT TOMORROW, EXCEPT FOR THE CENTRAL
COLUMBIA RIVER GORGE AND UPPER HOOD RIVER VALLEY WHERE WESTERLY
WINDS WILL BE BREEZIEST AND GUST UP TO 30 MPH.
ON FRIDAY, A COOLER AND WETTER PATTERN RETURNS AS A DEEPER
TROUGH DROPS APPROACHES THE PACIFIC NORTHWEST FROM THE GULF OF
ALASKA. AS THIS UPPER TROUGH MOVES IN, IT WILL PUSH A WEAK FRONT
INTO NORTHWEST OREGON AND SOUTHWEST WASHINGTON. THIS WILL RETURN
MORE WIDESPREAD CHANCES FOR PRECIPITATION, WITH THE HIGHEST
CHANCES OVER SOUTHWEST WASHINGTON AND THE NORTH OREGON COAST,
COAST RANGE, AND CASCADES. GIVEN THE SHOWERY NATURE OF THIS SYSTEM,
RAINFALL AMOUNTS WILL VARY ACROSS THE AREA AND THE HIGHEST
AMOUNTS WILL ULTIMATELY DEPEND ON WHERE SHOWERS SET-UP. OVERALL,
SHOWERS WILL BE NON-IMPACTFUL. CHANCES FOR 24 HOUR
PRECIPITATION EXCEEDING 0.25 INCH FROM 5 AM FRIDAY TO 5 AM
SATURDAY ARE AROUND 60-80% FROM TILLAMOOK TO THE SOUTH WA COAST,
50-70% ACROSS THE SOUTH WA AND NORTH OR CASCADES, 20-30% ACROSS
THE COWLITZ VALLEY, AND 5% OR LESS FOR THE WILLAMETTE VALLEY
AND UPPER HOOD RIVER VALLEY. GIVEN THE NORTHERN TRACK OF THIS
TROUGH, CHANCES FOR PRECIPITATION ARE HIGHEST AS YOU GO FURTHER
NORTH. IN ADDITION, THERE IS A 10-15% CHANCE FOR THUNDERSTORMS
ACROSS THESE AREAS AS INSTABILITY INCREASES DUE TO COLD AIR
ALOFT ALONG WITH SUFFICIENT LIFT FROM THE TROUGH. ANY PASSING
THUNDERSTORMS COULD PRODUCE LIGHTNING, BRIEF HEAVY RAIN, ERRATIC
WINDS, AND/OR SMALL HAIL.
ONSHORE FLOW WILL ALSO INCREASE AS THIS UPPER TROUGH MOVES IN.
WEST-SOUTHWESTERLY WINDS WON'T BE TOO IMPACTFUL ACROSS MOST
AREAS WITH GUSTS UP TO 20 MPH ALONG THE I-5 CORRIDOR, HOWEVER,
TYPICAL BREEZY SPOTS DURING ONSHORE FLOW LIKE THE CENTRAL GORGE
AND UPPER HOOD RIVER VALLEY COULD GUST UP TO 35-40 MPH. THERE IS
ALSO A 5-15% CHANCE FOR ISOLATED WIND GUSTS EXCEEDING 45 MPH
THROUGH THESE AREAS AS WELL, WITH HIGHER CHANCES (25-35%) FOR
HIGHER TERRAIN AND EXPOSED RIDGETOPS. -10
LONG TERM...SATURDAY THROUGH TUESDAY
THE VAST MAJORITY OF
ENSEMBLE MEMBERS ARE IN AGREEMENT THAT THE AFOREMENTIONED UPPER-
LEVEL TROUGH WILL SHIFT OVER THE PACIFIC NORTHWEST ON SATURDAY,
MAINTAINING RAIN SHOWERS ACROSS NORTHWEST OREGON AND SOUTHWEST
WASHINGTON THROUGH SATURDAY AFTERNOON. THERE STILL REMAINS SOME
UNCERTAINTY ON EXACT RAINFALL AMOUNTS DUE TO THE SHOWERY NATURE
OF THE PRECIPITATION. THIS TROUGH STILL MAINTAINS IT'S MORE
NORTHERLY TRACK WITH US SITTING ON THE SOUTHERN EDGE WHERE
THERE IS LESS MOISTURE. AT THE SAME TIME, WE ARE SITTING IN THE
RIGHT ENTRANCE REGION OF THE JET STREAK WHICH IS OFTEN
ASSOCIATED WITH MORE ENERGETIC WEATHER. COMBINE THIS WITH THE
DIVERGENT FLOW, RAIN, AND OROGRAPHIC EFFECTS, CANNOT RULE OUT
ANOTHER THREAT FOR THUNDERSTORMS IN THE AFTERNOON. OF THE TWO
DAYS (FRIDAY AND SATURDAY), SATURDAY IS THE MOST POTENT DAY WITH
CAPE EXCEEDING 150 J/KG IN SOME LOCATIONS. THEREFORE, THERE IS
A 15-30% CHANCE FOR THUNDERSTORMS SATURDAY AFTERNOON FROM SALEM
AND LINCOLN CITY NORTHWARD, WITH THE HIGHEST CHANCES ACROSS
SOUTHWEST WASHINGTON AND THE PORTLAND-VANCOUVER METRO AREA. THIS
WOULD AGAIN BRING THE THREAT FOR LIGHTNING, BRIEF HEAVY RAIN,
ERRATIC WINDS, AND/OR SMALL HAIL.
DRIER WEATHER BRIEFLY RETURNS ON SUNDAY AS A SHORTWAVE RIDGE
PASSES OVER THE PACIFIC NORTHWEST. BY MONDAY, ABOUT 75% OF
ENSEMBLE MEMBERS ARE SHOWING SOME SORT OF BROAD TROUGHING AND
BELOW-AVERAGE 500 MB HEIGHTS RETURNING TO THE AREA. WHILE THIS
WOULD RETURN WIDESPREAD CHANCES FOR PRECIPITATION AND COOLER
TEMPERATURES, THERE STILL REMAINS UNCERTAINTY ON THE EXACT
MAGNITUDE AND TRACK OF THIS TROUGH. THE OTHER 25% OF ENSEMBLE
MEMBERS SUGGEST ZONAL FLOW WITH DRY WEATHER ON MONDAY. GREATER
UNCERTAINTY FOLLOWS ON TUESDAY WITH EXACTLY HOW THIS TROUGH
EXITS THE AREA (IF IT DOES), BUT WE'LL STILL MAINTAIN CHANCES
FOR LIGHT, NON-IMPACT PRECIPITATION. -10/27
AVIATION
RADAR IMAGERY AT 21Z WEDNESDAY SHOWED ISOLATED LIGHT
RAIN SHOWERS BEGINNING TO DISSIPATE OVER THE AREA. EXPECT
PREDOMINATELY VFR CEILINGS AND VISIBILITIES TO CONTINUE THROUGH
THIS EVENING, ASIDE FROM IFR TO MVFR CONDITIONS AT KONP. CHANCES
FOR IFR TO MVFR CEILINGS INCREASE TONIGHT INTO EARLY TOMORROW
MORNING BOTH INLAND AND AT THE COAST. BY 12Z THURSDAY, CHANCES
FOR CEILINGS BELOW 3000 FT INCREASE TO 25-50% FOR INLAND TAF
SITES, EXCEPT 60-75% AT KSLE AND KEUG. CHANCES FOR CEILINGS
BELOW 3000 FT RANGE BETWEEN 75-95% AT KAST AND KONP BETWEEN 21Z
WEDNESDAY AND 12Z THURSDAY.
KPDX AND APPROACHES...ASIDE FROM A FEW SPRINKLES NOW THROUGH 00Z
THURSDAY, EXPECT MAINLY DRY CONDITIONS TO CONTINUE WITH VFR
CEILINGS/VISIBILITIES AND SOUTHWEST WINDS AROUND 5-10 KT. THERE
IS A 30-40% CHANCE FOR CEILINGS BELOW 3000 FT BETWEEN 08-17Z
THURSDAY AS LOWER CLOUDS FORMING ALONG THE CASCADE FOOTHILLS
ATTEMPT BACKBUILDING WESTWARD TOWARDS THE KPDX TERMINAL. -23
MARINE
BUOY OBSERVATIONS FROM EARLY TO MID WEDNESDAY
AFTERNOON SHOWED SEAS AROUND 5 TO 6 FT WITH SOUTHERLY WINDS
AROUND 10 TO 20 KT. WINDS WERE GUSTING AS HIGH AS 23 KT AT TIMES
AT BUOY 029, HOWEVER WIND GUSTS OF THIS MAGNITUDE ARE NOT
EXPECTED TO LAST LONG AND ARE MAINLY ASSOCIATED WITH AN ONGOING
FRONTAL PASSAGE.
AS THIS FRONT EXITS WEDNESDAY EVENING/NIGHT, WINDS WILL VEER TO
THE NORTHWEST WHILE WEAKENING IN STRENGTH. SEAS ARE EXPECTED TO
REMAIN AROUND 5 TO 6 FT AS A WESTERLY SWELL PERSISTS. SEAS THEN
BUILD TO 6-8 FT AT 11 TO 12 SECONDS LATE THURSDAY NIGHT INTO
FRIDAY MORNING AS A WEAK FRONTAL BOUNDARY APPROACHES THE WATER.
THIS FRONT WILL ALSO BRING INCREASING WESTERLY WINDS WITH GUSTS UP
TO 20 KT.
A SECONDARY FRONT ARRIVES ON SATURDAY, BRINGING A SHIFT TO
NORTHWEST WINDS. HOWEVER, WIND SPEEDS ARE NOT EXPECTED TO
INCREASE MUCH WITH THIS FRONTAL PASSAGE. THE TIME PERIOD WITH
HIGHEST WIND SPEEDS WILL LIKELY OCCUR ON MONDAY AS STRONGER
SYSTEM MOVES OVER THE WATERS, BRINGING SOUTH WINDS UP TO 20-25
KT AND SEAS APPROACHING 9-10 FT. -23
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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