331
FXUS66 KPQR 031734 AAA
AFDPQR
AREA FORECAST DISCUSSION...UPDATE
NATIONAL WEATHER SERVICE PORTLAND OR
1034 AM PDT THU SEP 3 2026
UPDATED AVIATION DISCUSSION
SYNOPSIS
ANOTHER FRONTAL SYSTEM WILL BRING WIDESPREAD RAIN,
BREEZY WINDS FROM THE SOUTH, AND A 20-30% CHANCE FOR THUNDERSTORMS
TODAY. ANY PASSING THUNDERSTORMS MAY PRODUCE LIGHTNING, HEAVY
RAIN, GUSTY ERRATIC WINDS, SMALL HAIL, AND/OR A FUNNEL CLOUD.
CHANCES FOR LINGERING SHOWERS CONTINUE THROUGH THE WEEKEND WITH
COOLER THAN AVERAGE TEMPERATURES. DRIER CONDITIONS EARLY NEXT
WEEK.
SHORT TERM...TODAY THROUGH FRIDAY NIGHT
OBSERVATIONS OVER THE
PAST 24 HOURS SHOW RAINFALL TOTALS ACROSS THE FORECAST AREAS
AROUND 0.30 TO 0.75 INCHES, WITH HIGHER ELEVATIONS PICKING UP
0.75 TO 1.25 INCHES. CURRENT RADAR OBSERVATIONS THIS MORNING
SHOWS MORE SHOWERS STREAMING INTO THE AREA. SO, IT LOOKS LIKE
OUR REGION IS IN STORE FOR ANOTHER ROUND OF WIDESPREAD SHOWERS
TODAY, WITH SIMILAR 24 HOUR RAINFALL TOTALS EXPECTED.
THE UPPER-LEVEL LOW WHICH BROUGHT THE RAIN YESTERDAY WILL MOVE
OVERHEAD OF THE PACIFIC NORTHWEST. THIS WILL LEAD TO COOLER
TEMPERATURES ALOFT AND A GENERAL INCREASE IN OVERALL ATMOSPHERIC
INSTABILITY. MODEL GUIDANCE IS SHOWING CAPE VALUES ANYWHERE
BETWEEN 100-500 J/KG ACROSS THE REGION. THIS INSTABILITY, ALONG
WITH GOOD LIFT AND MOISTURE FROM THE OVERALL UPPER-LEVEL LOW,
WILL SUPPORT A 20-30% CHANCE FOR THUNDERSTORMS STARTING LATE
THIS MORNING THROUGH AT LEAST TONIGHT. MODEL SOUNDINGS ARE
SHOWING MINIMAL SHEAR ACROSS THE REGION. THIS MEANS THAT LONG
LIVED CELLS ARE NOT LIKELY, WHICH MEANS THAT "STORM MODE" FOR
TODAY WILL LIKELY TAKE THE FORM OF "POP-CORN" SHOWERS AND
THUNDERSTORMS. IF A THUNDERSTORM DOES PASS OVER AN AREA, IT MAY
PRODUCE LIGHTNING, HEAVY DOWNPOURS, GUSTY AND ERRATIC WINDS,
SMALL HAIL, AND/OR A FUNNEL CLOUD. GIVEN THAT EVEN COOLER AIR
ALOFT IS EXPECTED TODAY, AN ISOLATED COLD-CORE FUNNEL CLOUD
CAN'T BE RULED OUT (5-10% CHANCE). BY FRIDAY, THE UPPER-LEVEL
LOW CONTINUES TO SIT OVERHEAD, MAINTAINING CHANCES FOR LINGERING
SHOWERS AND ANOTHER 15-20% CHANCE FOR AFTERNOON THUNDERSTORMS.
THESE SYSTEMS WILL CONTINUE TO BRING THE FIRST SUBSTANTIAL
RAINFALL OF THE SEASON. MODELS ARE STILL CALLING FOR 48 HOUR
TOTALS (WED MORNING-FRI MORNING) EXCEEDING AT LEAST 1 INCH OF
RAINFALL. WHILE THIS WET WEATHER WON'T BE A "FIRE SEASON
ENDER," IT WILL DEFINITELY SLOW DOWN FIRE SEASON. /42-10
LONG TERM...SATURDAY THROUGH WEDNESDAY
OVER THE WEEKEND, THE
MAJORITY OF ENSEMBLE MEMBERS CONTINUE TO SHOW BROAD UPPER-LEVEL
TROUGHING OVER THE PACIFIC NORTHWEST. HOWEVER, THERE IS UNCERTAINTY
WITH WHETHER OR NOT WE REMAIN DRY OR CONTINUE WITH LINGERING
SHOWERS. WHILE 75% OF ENSEMBLE MEMBERS SUGGEST SHOWERS CONTINUING
OVER THE REGION SATURDAY-SUNDAY, THE OTHER 25% KEEP US DRY.
WHAT WE CAN SAY WITH HIGHER CONFIDENCE IS THAT THIS UPPER-LEVEL
LOW WILL MAINTAIN BELOW-AVERAGE 500 MB HEIGHTS AND KEEP HIGH
TEMPERATURES SLIGHTLY COOLER THAN AVERAGE FOR THIS TIME OF YEAR.
EARLY NEXT WEEK, THE MAJORITY OF ENSEMBLE MEMBERS SHOW THE
UPPER LOW WEAKENING AND BEGINNING TO MOVE EASTWARD. THIS WOULD
FAVOR DRIER CONDITIONS, BUT THERE REMAINS UNCERTAINTY WITH HOW
MUCH HIGH PRESSURE WILL RE-BUILD OVER OUR AREA, AND HOW WARM/DRY
WE GET. /42-10
AVIATION...THROUGH 18Z FRIDAY
MOIST, SOUTHWEST FLOW ALOFT WILL
PERSIST TODAY AS A LOW PRESSURE SYSTEM MOVES TOWARD THE OREGON
COAST. THIS SYSTEM WILL MAINTAIN WIDESPREAD RAIN SHOWERS ACROSS
THE AREA WITH AROUND A 15-30% CHANCE OF THUNDERSTORMS THROUGH THIS
AFTERNOON, HIGHEST CHANCES ALONG THE COAST. PREDOMINATELY VFR
CONDITIONS ARE EXPECTED TO PREVAIL, EXCEPT WITH THE HEAVIER
SHOWERS WHICH ARE LIKELY TO PRODUCE BRIEF PERIODS OF MVFR TO IFR
REDUCTIONS IN VISIBILITY AND CIGS. RAIN IS EXPECTED TO GRADUALLY
TAPER OFF FROM NORTH TO SOUTH THROUGH THIS EVENING. PROBABILITIES
FOR WIDESPREAD MVFR OR WORSE REMAINS RELATIVELY LOW AT AROUND 20%
OR LESS, EXCEPT AT KONP WHERE PROBS ARE CLOSER TO AROUND 30-40%.
GENERALLY EXPECTED SOUTH TO SOUTHEASTERLY WINDS WITH BRIEF GUSTS
POSSIBLE UP TO 20 KT. ANY THUNDERSTORMS THAT DO DEVELOP WILL HAVE
THE POTENTIAL TO PRODUCE LIGHTNING AND GUSTY/ERRATIC WINDS.
KPDX AND APPROACHES...PREDOMINATELY VFR EXPECTED WITH BRIEF AND
INTERMITTENT MVFR CONDITIONS POSSIBLE WITH HEAVIER SHOWERS.
GENERALLY LESS THAN A 20% CHANCE FOR MVFR AT ANY GIVEN HOUR
THROUGH THE PERIOD. THERE IS ALSO AROUND A 10-20% CHANCE FOR
THUNDERSTORMS THROUGH THIS AFTERNOON. SOUTH TO SOUTHEAST WINDS
AROUND 5-10 KT EXPECTED TO EASE AFTER 02Z FRIDAY. /DH
MARINE
CURRENT OBSERVATIONS SHOW SEAS AROUND 9-11 FT AT 8-10
SECONDS WITH SOUTHERLY GUSTS UP TO 30 KT. THESE CONDITIONS ARE
EXPECTED TO CONTINUE THROUGH TONIGHT AS A FRESH WEST/NORTHWEST
SWELL OVERNIGHT INTO THURSDAY MAINTAINS CONDITIONS. DUE TO THE
CONTINUED SEA STATE AND BREEZY WINDS, A SMALL CRAFT ADVISORY IS IN
EFFECT THROUGH AT LEAST TONIGHT. THERE'LL ALSO BE 15-30% CHANCE
FOR THUNDERSTORMS THROUGH THURSDAY WITH THE BEST RELATIVE CHANCES
THURSDAY AFTERNOON. ANY OF THESE STORMS WILL BE CAPABLE OF PRODUCING
GUSTY/ERRATIC WINDS, SMALL HAIL, AND LIGHTNING.
WHILE RELATIVELY ACTIVE WEATHER WITH LINGERING RAIN SHOWERS WILL
CONTINUE INTO THE WEEKEND, MARINE CONDITIONS WILL SUBSIDE BY
FRIDAY WITH SEAS HOLDING IN THE 4-6 FT RANGE BY FRIDAY AFTERNOON.
SIMILAR CONDITIONS PERSIST INTO EARLY NEXT WEEK WHILE WINDS
OCCASIONALLY GUST TO 15-20 KNOTS.
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY UNTIL 11 PM PDT THIS EVENING FOR PZZ210-
251>253-271>273.
WWW.WEATHER.GOV/PORTLAND
INTERACT WITH US VIA SOCIAL MEDIA:
WWW.FACEBOOK.COM/NWSPORTLAND
X.COM/NWSPORTLAND
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