971
FXUS66 KPQR 100406 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE PORTLAND OR
906 PM PDT TUE SEP 9 2025
UPDATED SHORT TERM AND AVIATION DISCUSSIONS
SYNOPSIS
SHOWERS AND THUNDERSTORMS CONTINUE THIS AFTERNOON
AND EVENING, MAINLY FOCUSED OVER THE SOUTHERN WILLAMETTE VALLEY
AND OREGON CASCADES WHERE ACTIVITY OCCURRED YESTERDAY. AREAS
THAT STAYED DRY ON MONDAY ARE LIKELY TO STAY DRY TODAY. THUNDER
CHANCES PERSIST INTO WEDNESDAY, PRIMARILY ALONG THE CASCADES,
BEFORE CONDITIONS TREND WARMER AND DRIER LATE THIS WEEK.
CONFIDENCE HAS DROPPED FOR WIDESPREAD RAIN LATE IN THE WEEKEND,
THOUGH IT STILL REMAINS A POSSIBILITY.
SHORT TERM...NOW THROUGH THURSDAY NIGHT
EVENING
UPDATE...SHOWERS WILL CONTINUE TO DISSIPATE OVER THE NEXT FEW
HOURS. MOST OF THE PRECIPITATION TODAY WAS WITHIN THE OR AND WA
CASCADES, THE OR CASCADE FOOTHILLS AND AREAS SOUTH OF SALEM, OR.
GIVEN THE SHOWERY NATURE OF THE PRECIPITATION THIS AFTERNOON,
THERE IS A WIDE SPREAD OF REPORTED TOTALS, IN ADDITION MOST
LOCATIONS THAT DID RECEIVE PRECIPITATION DO NOT HAVE REMOTE
SENSING PLATFORMS. STILL, THE REPORTS THAT WE CAN SEE SPREAD
FROM 0.01 INCHES TO 0.10 INCHES. THE HIGHEST PRECIPITATION TOTAL
SO FAR WAS 0.86 INCHES AT KCVO WHICH DID HAVE A THUNDERSTORM
PASS OVER THE AIRPORT.
PREVIOUS DISCUSSION FOLLOWS...THUNDERSTORM CHANCES APPEAR
WEAKER ON WEDNESDAY AND MORE CONFINED TO THE OREGON CASCADE
CRESTS ITSELF. FORECAST SOUNDINGS SHOW REDUCED CAPE AND A
SOMEWHAT STRONGER INVERSION, WHICH SHOULD LIMIT BOTH UPDRAFT
STRENGTH AND STORM COVERAGE. STILL, A FEW ISOLATED STORMS CANNOT
BE RULED OUT, ESPECIALLY DURING PEAK HEATING HOURS. BY
THURSDAY, SHOWER ACTIVITY BECOMES INCREASINGLY CONFINED TO THE
HIGH CASCADES BEFORE TAPERING OFF ALTOGETHER THURSDAY NIGHT AS A
SHORTWAVE RIDGE APPROACHES THE COAST.
LONG TERM...FRIDAY THROUGH MONDAY NIGHT
A MORE STABLE PATTERN
ARRIVES FRIDAY AND SATURDAY AS A SHORTWAVE RIDGE BUILDS
OVERHEAD. DRY CONDITIONS AND WARMER AFTERNOONS ARE EXPECTED,
WITH INLAND HIGHS CLIMBING INTO THE UPPER 70S TO NEAR 80, AND
COASTAL HIGHS IN THE 60S.
FORECAST CONFIDENCE DECREASES LATE SATURDAY INTO SUNDAY AS
ENSEMBLE SOLUTIONS DIVERGE ON THE TRACK OF THE NEXT UPPER
TROUGH. SOME KEEP THE SYSTEM INTACT, FAVORING WIDESPREAD RAIN,
WHILE MOST OF THE OTHER MODELS SPLIT IT SOUTH INTO NORTHERN
CALIFORNIA AND LEAVE OUR REGION A BIT DRIER. CURRENT CHANCES FOR
AT LEAST A QUARTER INCH OF RAIN STAND NEAR 40-50% FOR SATURDAY
AND 40-60% FOR SUNDAY FOR MUCH OF NORTHWEST OREGON AND SOUTHWEST
WASHINGTON, HIGHEST ALONG THE OREGON CASCADES. TEMPERATURES
SUNDAY WILL HINGE ON RAINFALL COVERAGE - LOW TO MID 70S IF WET,
UPPER 70S TO LOW 80S IF DRY. UNCERTAINTY LINGERS INTO EARLY
NEXT WEEK WITH LOW-END (20-30%) SHOWER CHANCES CONTINUING
THROUGH MONDAY AND HIGHS RANGING FROM THE 60S AT THE COAST TO
THE 70S INLAND. ~HALL
AVIATION
AN UPPER LEVEL LOW PRESSURE SYSTEM CONTINUES TO DRIFT
SLOWLY NORTH OVER THE PACNW. THIS BROUGHT SCATTERED SHOWERS AND
THUNDERSTORMS ACROSS THE CASCADES AND CASCADE FOOTHILLS, WHICH
CONTINUE TO SLOWLY DISSIPATE OVER THE NEXT FEW HOURS. AS HIGHER
PRESSURE ALOFT BUILDS OVER THE AIRSPACE TONIGHT, COMBINING THAT
WITH MOISTENING CONDITIONS WILL SUPPORT A MORE ROBUST MARINE
LAYER WITH MVFR/IFR (50-70% PROBABILITY) CONDITIONS DEVELOPING
ALONG THE COAST AND LOW-END VFR/HIGH-END MVFR CONDITIONS (40-60%
PROBABILITY) FOR INLAND LOCATIONS. EXPECT COASTAL IMPACT
STARTING BETWEEN 04Z-08Z WED AND INLAND IMPACTS STARTING AROUND
10Z-12Z WED. THESE LOWERED FLIGHT CONDITIONS ARE EXPECTED TO
PERSIST THROUGH AT LEAST 22Z WED THROUGH 00Z THUR WITH
CONDITIONS EXPECTED TO IMPROVE.
IT SHOULD BE NOTED THAT SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO RETURN AROUND 16Z-18Z WED WITH A 15-25% PROBABILITY FOR
THUNDERSTORMS ALONG THE CASCADES. CURRENTLY, PRECIPITATION
LOOKS TO IMPACT INLAND LOCATIONS AND AREAS SOUTH OF KONP.
KPDX AND APPROACHES...PREDOMINATELY VFR. THERE IS A 40-60%
PROBABILITY FOR LOW-END VFR/HIGH-END MVFR CONDITIONS STARTING
AROUND 10Z-12Z WED. LOWERED FLIGHT CONDITIONS ARE EXPECTED TO
PERSIST THROUGH AT LEAST 22Z WED THROUGH 00Z THUR WITH
CONDITIONS EXPECTED TO IMPROVE. /42
MARINE
HIGH PRESSURE OVER THE WATERS WILL MAINTAIN NORTHERLY
TO NORTHWESTERLY WINDS WITH GUSTS LESS THAN 15 KT THROUGH
FRIDAY. SEAS REMAIN AROUND 2-4 FT AT 10-12 SEC THROUGH
WEDNESDAY, BUILDING TO 5-7 FT AT 11-12 SEC BY FRIDAY WITH A
WEST-NORTHWESTERLY SWELL.
HEADING INTO THE WEEKEND, GUIDANCE IS SUGGESTING ANOTHER LOW
PRESSURE SYSTEM APPROACHING THE PACIFIC NORTHWEST. A FRONT
ASSOCIATED WITH THIS LOW WILL WEAKEN AS IT MOVES ACROSS THE WATERS
SATURDAY AND SUNDAY. THE WINDS WILL SHIFT SOUTHERLY AHEAD OF THE
FRONT ON SATURDAY, THEN NORTHERLY WITH AND BEHIND THE FRONT ON
SUNDAY. PROBABILITIES FOR WIND GUSTS OF 21 KT OR GREATER (SMALL
CRAFT CONDITIONS) ACROSS THE WATERS SATURDAY RANGE FROM 30-50%,
HIGHEST ACROSS THE OUTER WATERS. PROBABILITIES INCREASE SUNDAY TO
50-70% FOR ALL MARINE ZONES. GIVEN THE LEAD TIME WILL HOLD OFF ON
ISSUING ANY PRODUCTS BUT THIS WILL BE SOMETHING TO KEEP IN MIND
FOR THE COMING WEEKEND. SEAS ARE FORECAST AROUND 5-7 FEET AT
10-12 SEC THROUGH THE WEEKEND. -BATZ/ALVIZ
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...NONE.
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