822
FXUS66 KPQR 230449
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
949 PM PDT TUE APR 22 2025
UPDATED AVIATION DISCUSSION
SYNOPSIS
DRY WEATHER WITH CLEAR SKIES THROUGH THURSDAY AS
HIGH PRESSURE BUILDS OVER THE REGION. PATTERN CHANGE RETURNS
THURSDAY NIGHT INTO FRIDAY AS AN APPROACHING SYSTEM RETURNS
COOLER AND WETTER WEATHER HEADING INTO THE WEEKEND.
SHORT TERM...NOW THROUGH THURSDAY NIGHT
HIGH PRESSURE WILL
MAINTAIN DRY WEATHER WITH CLEAR SKIES ACROSS NORTHWEST OREGON
AND SOUTHWEST WASHINGTON THROUGH THURSDAY. ZONAL FLOW ALOFT WILL
TURN NORTHERLY TODAY INTO WEDNESDAY AS AN UPPER LEVEL RIDGE
OVER THE NORTHEAST PACIFIC SHIFTS INTO THE PACIFIC NORTHWEST.
EXPECT AFTERNOON HIGHS TO GRADUALLY WARM UP THE NEXT COUPLE
DAYS, WITH THURSDAY BEING THE WARMEST DAY. HIGHS ARE FORECAST IN
THE UPPER 60S TO LOW 70S ON WEDNESDAY FOR INTERIOR VALLEYS, AND
MID TO UPPER 70S ON THURSDAY. CAN'T RULE OUT REACHING 80
DEGREES IN THE GREATER PORTLAND/VANCOUVER METRO AREA (NBM
GUIDANCE SUGGESTS A 30-50% PROBABILITY OF EXCEEDING 80 DEGREES).
ALTHOUGH NIGHTS WILL BE CLEAR, FROST THREAT IS NOT EXPECTED AS
LOWS ARE FORECAST IN THE UPPER 30S TO LOW 40S WEST OF THE HIGH
CASCADES. WINDS THROUGHOUT THE NEXT COUPLE DAYS WILL GENERALLY
BE LIGHT AND NORTH-NORTHWESTERLY, WITH GUSTS TO 20-25 MPH ALONG
THE COAST TODAY AND WEDNESDAY AFTERNOON.
THURSDAY NIGHT, THE NEXT UPPER LEVEL TROUGH WILL APPROACH THE
PACIFIC NORTHWEST, TURNING FLOW ALOFT MORE SOUTHERLY TO
SOUTHEASTERLY. THIS KIND OF PATTERN TYPICALLY HELPS ADVECT MORE
MOISTURE FROM THE SOUTH AS WELL AS INSTABILITY AS COLDER AIR
FILTERS IN ALOFT. THIS IS THE KIND OF PATTERN THAT COULD LEAD TO
ELEVATED THUNDERSTORMS, ESPECIALLY IN THE LINN AND LANE COUNTY
CASCADES. AS OF NOW, IT'S MAINLY THE NAM MODEL SHOWING 700-300
MB MUCAPE VALUES OF 100-150 J/KG THURSDAY EVENING. THE OTHER
GLOBAL MODELS AREN'T QUITE SHOWING MUCAPE VALUES OF THIS
MAGNITUDE YET, SO DECIDED TO ONLY INCREASE THUNDER PROBABILITIES
SLIGHTLY FROM NBM IN THE LINN/LANE COUNTY CASCADES TO AROUND
10-15% THURSDAY EVENING. -ALVIZ
LONG TERM...FRIDAY TO MONDAY
FRIDAY MARKS A PATTERN CHANGE
TO COOLER AND WETTER WEATHER. THE MAJORITY OF ENSEMBLE MEMBERS
FROM THE GEFS, EPS, AND GEPS ARE IN AGREEMENT OF AN UPPER LEVEL
TROUGH TOWARD NORTHERN CALIFORNIA. AS THIS TROUGH MOVES INTO
CALIFORNIA, THIS WILL BRING SHOWERS INTO NORTHWEST OREGON AND
SOUTHWEST WASHINGTON FROM THE SOUTH/SOUTHEAST AS MOISTURE WRAPS
AROUND THE LOW. PROBABILITIES FOR 24 HOUR RAINFALL EXCEEDING
0.25 INCH FROM 5 AM FRIDAY TO 5 AM SATURDAY ARE AROUND 15-35%
ALONG THE COAST AND WILLAMETTE VALLEY, AND 40-70% ACROSS THE
COAST RANGE AND CASCADES. HIGHS WILL ALSO DROP INTO THE UPPER
50S TO LOW 60S FOR MOST AREAS WEST OF THE CASCADES. EXPECT A
COOL WEEKEND WITH LINGERING SHOWERS ON SATURDAY AS THE
AFOREMENTIONED LOW TRACKS EASTWARD INTO THE INTERMOUNTAIN WEST.
BY SUNDAY-MONDAY, PRECIPITATION CHANCES DECREASE AS THE MAJORITY
OF ENSEMBLE MEMBERS SUGGEST HIGH PRESSURE RE-BUILDING OVER THE
AREA AND RETURNING DRIER WEATHER. -ALVIZ
AVIATION
EXPECT VFR CONDITIONS TO PREVAIL THROUGH THE PERIOD AT
MOST TERMINAL ACROSS NW OREGON AND SW WASHINGTON. MOSTLY CLEAR
SKIES WILL BE MAINTAINED TONIGHT AND WEDNESDAY, HOWEVER, WE'LL
NEED TO WATCH FOR A WEAK PUSH OF COASTAL STRATUS LATE OVERNIGHT
INTO THE SUNRISE HOURS. AN EASTERLY COMPONENT TO THE LOW LEVEL
FLOW SHOULD KEEP IT MAINLY OFFSHORE, ALTHOUGH THE LATEST GUIDANCE
INDICATES IT MAY (50-60% CHANCE) SHIFT INTO OR NEAR KAST AROUND
~13-16Z RESULTING IN MVFR TO HIGH END IFR CIGS SHOULD THIS OCCUR.
WINDS STAY GENERALLY LESS THAN 10 KTS THROUGH THE TAF PERIOD FOR
MOST AREAS. GUSTS AROUND 20 KT POSSIBLE ALONG THE COAST,
ESPECIALLY AT KONP WEDNESDAY AFTERNOON.
PDX AND APPROACHES...VFR CONDITIONS CONTINUE THROUGH THE TAF
PERIOD. NW-NNE WINDS STAY LESS THAN 10-15 KTS TONIGHT INTO
WEDNESDAY MORNING AND AFTERNOON. -SCHULDT
MARINE
STRONG HIGH PRESSURE OFFSHORE ALONG WITH A SURFACE
LEVEL THERMAL TROUGH DEVELOPING AND STRENGTHENING OVER THE
SOUTHERN AND CENTRAL OREGON COAST WILL MAINTAIN NORTHERLY WINDS
ACROSS ALL WATERS THROUGH THE MIDDLE OF THE WEEK. AS THE THERMAL
TROUGH STRENGTHENS OVER THE COAST, THESE WINDS ARE EXPECTED TO
SPREAD NORTH ALONG THE NORTHERN OREGON AND SOUTHERN WASHINGTON
COASTAL WATERS, WITH GUSTS 25-30 KTS POSSIBLE AT TIMES. A SMALL
CRAFT ADVISORY REMAINS IN EFFECT FOR ZONES (EXCEPT THE COLUMBIA
RIVER BAR) UNTIL 11 PM WEDNESDAY. STRONGEST WINDS ARE EXPECTED
TO EBB AND FLOW DIURNALLY, STRONGEST IN THE LATE AFTERNOON TO
OVERNIGHT HOURS, BACKING OFF IN THE MORNING HOURS. WINDS MAY
DROP BELOW SMALL CRAFT ADVISORY CRITERIA DURING THE OVERNIGHT
HOURS BEFORE INCREASING DURING THE DAY. HAVE DECIDED TO EXTEND
THE ADVISORY FOR ALL ZONES INSTEAD OF BREAKING UP TIMEFRAME
GIVEN THE SHORT LULL. SEAS ARE EXPECTED TO PERSIST AROUND 6 TO 8
FT AROUND 10 SECONDS THROUGH THE MIDDLE OF THE WEEK. -BATZ
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT WEDNESDAY FOR PZZ251>253-
271>273.
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