839
FXUS66 KPQR 092058
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
158 PM PDT WED SEP 9 2026
SYNOPSIS
TEMPERATURES WILL GRADUALLY COOL EACH DAY THURSDAY
THROUGH THE WEEKEND AS ONSHORE FLOW STRENGTHENS AHEAD OF A LOW
PRESSURE SYSTEM SET TO BRING WIDESPREAD RAIN TO THE AREA ON SATURDAY.
SHOWERS DISSIPATE ON SUNDAY, WITH DRY AND MILD CONDITIONS EXPECTED
EARLY NEXT WEEK.
SHORT TERM...WEDNESDAY NIGHT THROUGH SATURDAY NIGHT
THE SHORT TERM
FORECAST IS HIGHLIGHTED BY A GRADUAL COOLING TREND WITH WIDESPREAD
RAIN ARRIVING ON SATURDAY. UP UNTIL SATURDAY, CONFIDENCE IS HIGH
CONDITIONS WILL STAY DRY. ALTHOUGH THURSDAY WILL BE RELATIVELY COOLER
COMPARED TO WEDNESDAY, TEMPERATURES WILL STILL BE SEASONABLY
WARM IN THE AFTERNOON WITH HIGHS RANGING BETWEEN 75-80 DEGREES FOR
MOST INLAND VALLEY LOCATIONS, EXCEPT 65-70 DEGREES AT THE COAST.
THE HREF ENSEMBLE MEAN FOR CLOUD COVER SUGGESTS A BAND OF MID TO HIGH
LEVEL CLOUDS WILL MOVE SOUTHWARD OVER SOUTHWEST WASHINGTON AND
NORTHWEST OREGON DURING THE LATE MORNING AND EARLY AFTERNOON HOURS.
MEANWHILE, LANE COUNTY SHOULD REMAIN MOSTLY SUNNY THROUGH THE DAY,
WHICH WILL RESULT IN SLIGHTLY WARMER TEMPERATURES IN THIS AREA
COMPARED TO LOCATIONS TO THE NORTH OF LANE COUNTY. SKIES ON FRIDAY
LOOK TO BE MOSTLY CLOUDY TO THE NORTH OF A LINE EXTENDING FROM
NEWPORT TO SALEM TO MOLALLA AND PARTLY CLOUDY TO MOSTLY CLEAR SOUTH
OF THAT LINE. TEMPERATURES ALOFT WILL BE SEVERAL DEGREES COOLER, WITH
HIGHS RUNNING 5-10 DEGREES BELOW AVERAGE FOR THIS TIME OF YEAR.
CLOUD COVER WILL INCREASE ACROSS ALL OF SOUTHWEST WASHINGTON AND
NORTHWEST OREGON FRIDAY NIGHT INTO SATURDAY AHEAD OF A LOW PRESSURE
SYSTEM THAT WILL BRING WIDESPREAD RAIN TO THE AREA BEGINNING SOMETIME
BETWEEN EARLY SATURDAY MORNING AND LATE SATURDAY AFTERNOON. DESPITE
THE MODEL TIMING DIFFERENCES, AROUND 95% OF MODEL ENSEMBLE GUIDANCE
FROM THE GEFS/GEPS/ENS SUGGESTS MEASURABLE RAIN WILL OCCUR WITH THIS
SYSTEM. AS SUCH, EXPECT A COOL AND WET DAY ON SATURDAY WITH
TEMPERATURES IN THE 60S AND TOTAL RAIN AMOUNTS RANGING BETWEEN
0.2-0.5 INCHES FOR MOST LOCATIONS, HIGHEST IN THE CASCADES IN COAST
RANGE. NOTE THIS IS NOT ENOUGH RAIN TO RESULT IN FLOODING IMPACTS.
SOME RAIN SHOWERS WILL LINGER INTO SATURDAY NIGHT, ESPECIALLY IN THE
CASCADES AND FOOTHILLS. NOTE THE NBM ALSO SUGGESTS THERE IS A 15-25%
CHANCE OF THUNDERSTORMS SATURDAY AFTERNOON, AND THE OVERALL SET-UP
SUGGESTS STRONGER CONVECTIVE CELLS COULD PRODUCE A COLD CORE FUNNEL
CLOUD. ROTATION WITH COLD CORE FUNNEL CLOUDS RARELY REACHES THE
GROUND OR CAUSES IMPACTS, BUT IT IS NOT IMPOSSIBLE. NOTE THESE ARE
NON-MESOCYCLONIC IN NATURE, AND CAN FORM WITHOUT STRONG DEEP-LAYER
WIND SHEAR IN PLACE. -23
LONG TERM...SUNDAY THROUGH TUESDAY NIGHT
THE LONG TERM FORECAST IS
HIGHLIGHTED BY MAINLY DRY CONDITIONS AND THE CONTINUATION OF BELOW
AVERAGE TEMPERATURES, ALBEIT A BIT WARMER THAN WHAT IS EXPECTED ON
SATURDAY. THE VAST MAJORITY (>90%) OF ENSEMBLE GUIDANCE SUGGESTS THE
UPPER LEVEL LOW OVER THE AREA ON SATURDAY WILL PUSH EASTWARD AND MOVE
TOWARDS THE NORTHERN PLAINS SUNDAY INTO EARLY NEXT WEEK. A WEAKER
SECONDARY TROUGH ON THE BACKSIDE OF THIS LOW LOOKS TO REMAIN OVER
OREGON AND WASHINGTON, HOWEVER IT IS UNCLEAR HOW DEEP THIS SECONDARY
TROUGH WILL BE. TOTAL MODEL SPREAD FOR TEMPERATURES ON THE NBM 1D
VIEWER RANGES IS FAIRLY LOW ON SUNDAY, WITH HIGHS MOST LIKELY RANGING
BETWEEN THE MID 60S AND LOWER 70S (80% CHANCE). ON MONDAY, SPREAD
RANGES FROM THE UPPER 60S TO AROUND 80 DEGREES, WITH LOW TO MID 70S
BEING THE MOST LIKELY OUTCOME. SPREAD INCREASES A BIT ON TUESDAY, AS
HIGHS COULD RANGE ANYWHERE FROM THE MID 60S TO THE MID 80S. OVERALL,
THERE ARE NO SIGNS OF ANY HIGH IMPACT WEATHER ON THE HORIZON. -23
AVIATION...THROUGH 18Z THURSDAY
HIGH PRESSURE OVER THE REGION
WILL CONTINUE TO SUPPORT WIDESPREAD VFR CONDITIONS ACROSS THE
AIRSPACE BENEATH LARGELY CLEAR SKIES. LIGHT NORTH/NORTHEAST FLOW
FOR INLAND LOCATIONS WITH NORTHERLY WINDS FOR THE COAST LESS THAN
10 KT THROUGH THE TAF PERIOD. EXPECT WIDESPREAD VFR UNDER MOSTLY
CLEAR SKIES FOR ALL INLAND LOCATIONS THROUGH THE TAF PERIOD.
COOL AND MOIST ONSHORE FLOW RETURNS AROUND 03Z-06Z THURSDAY, WHICH
WILL BRING MORE NORTH/NORTHWEST WINDS ACROSS THE AIRSPACE, BUT
STILL LESS THAN 10 KT. THIS PATTERN CHANGE WILL BRING THE RETURN
OF MVFR TO LIFR CONDITIONS TO THE COAST STARTING AROUND 06Z-09Z
THURSDAY. EXPECT THESE LOWERED FLIGHT CONDITIONS TO IMPACT KAST
FIRST, FOLLOWED BY KONP. ALSO, LOOK FOR PREDOMINATELY IFR/LIFR
CONDITIONS ALONG THE COAST STARTING AROUND 08Z THURSDAY FOR KAST
AND 13Z THURSDAY FOR KONP. ANY LOWERED FLIGHT CONDITIONS SHOULD
START TO IMPROVE AROUND 18Z THURSDAY.
KPDX AND APPROACHES...VFR UNDER MOSTLY CLEAR SKIES WITH LIGHT
NORTHERLY WINDS THROUGH THE TAF PERIOD PERIOD. /42
MARINE
HIGH PRESSURE OFFSHORE WILL MAINTAIN PREDOMINATELY
NORTHERLY WINDS ACROSS ALL WATERS THROUGH AT LEAST FRIDAY.
BREEZY NORTH WINDS CONTINUE WITH GUSTS UP TO 30 KT FROM LATE
TONIGHT THROUGH THURSDAY EVENING. THEREFORE, HAVE ISSUED A SMALL
CRAFT ADVISORY ACROSS ALL WATERS. SEAS 5 TO 8 FT THROUGH FRIDAY
WITH PERIOD OF 9 TO 11 SECONDS THROUGH AT LEAST THURSDAY NIGHT.
ANOTHER WEAKER SYSTEM IS EXPECTED TO APPROACH THE COASTAL WATERS
FROM THE NORTH LATE FRIDAY INTO SATURDAY. THIS WILL RESULT IN A
SOUTHERLY WIND SHIFT ALONG WITH SEAS SUBSIDING TOWARDS 4 TO 6 FT
AND GUSTS BELOW 20 KTS WITH THIS SYSTEM. /42
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 5 AM TO 8 PM PDT THURSDAY FOR
PZZ251>253-271>273.
WWW.WEATHER.GOV/PORTLAND
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