141
FXUS66 KPQR 021106
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
406 AM PDT WED SEP 2 2026
SYNOPSIS
AN UNUSUALLY STRONG SERIES OF SYSTEMS, BY EARLY
SEPTEMBER STANDARDS, TAKES AIM AT THE PACIFIC NORTHWEST OVER THE
NEXT 36-48 HOURS. THESE SYSTEMS LOOK TO BRING WIDESPREAD RAINFALL,
LOCALLY BREEZY/GUSTY WINDS, AND A 15-30% CHANCE FOR POP-UP
THUNDERSTORMS, WITH HIGHER CHANCES ON THURSDAY. CONDITIONS TREND
SLIGHTLY DRIER BY LATE THURSDAY/FRIDAY AND CONTINUE INTO THE
WEEKEND. HOWEVER, COOLER THAN NORMAL TEMPERATURES AND SHOWER
CHANCES PERSIST.
SHORT TERM...TODAY THROUGH THURSDAY NIGHT
TODAY IS SHAPING UP
TO BE MORE EVENTFUL FOR THE PAC NW AS A MUCH STRONGER UPPER
LEVEL LOW DROPS SOUTH ALONG THE WESTERN CANADA COAST. EARLY
MORNING OBSERVATIONS VIA RADAR SHOW PRECIPITATION WELL OFFSHORE
AND IS THE HARBINGER OF A COLD FRONT THAT IS SLOWLY MOVING
EASTWARD. EXPECT CONDITIONS TO BECOME MUCH WETTER, COOLER, AND
WINDIER AS THE DAY PROGRESSES ACROSS THE CWA. RAIN IS EXPECTED
TO REACH THE COAST EARLY THIS MORNING, REACHING THE INTERIOR
LOWLANDS AND CASCADES BY MID-MORNING. SOUTHERLY WINDS ALSO
INCREASE DURING THIS TIME WITH THE STRONGEST WINDS EXPECTED
ALONG THE COAST, MOST LIKELY BETWEEN 35-45 MPH BUT THERE IS A
15-30% CHANCE FOR ISOLATED GUSTS OF 50 MPH OR GREATER THROUGH
THIS AFTERNOON. WHILE WIND GUSTS ARE NOT EXPECTED TO REACH
WARNING CRITERIA ALONG THE COAST, THIS WILL BE THE STRONGEST
WINDS OBSERVED IN SEVERAL MONTHS SO IT IS POSSIBLE TREES OR
BRANCHES THAT HAVE WEAKENED OR DIED MAY COME LOSE WITH THESE
WINDS. INLAND GUSTS WILL PEAK AROUND 30 MPH WITH ISOLATED GUSTS
UP TO 40 MPH WITH LITTLE TO NO IMPACT EXPECTED, STILL VIGILANCE
SHOULD BE MAINTAINED.
THIS SYSTEM WILL BRING THE MOST SIGNIFICANT WIDESPREAD RAINFALL
SINCE THE SPRING WITH A 85-95% CHANCE FOR 48 HOUR RAINFALL TOTALS
OF AT LEAST 1 INCH BY FRIDAY MORNING. CHANCES FOR 2 INCHES OR
MORE DURING THE SAME TIME FRAME ARE 20-50% AND ARE CONFINED TO
THE COAST AND COAST RANGE ALONG WITH THE SOUTHWEST WA CASCADES.
THERE IS ALSO A SLIGHT CHANCE FOR EMBEDDED THUNDERSTORMS
TOMORROW AFTERNOON, MAINLY ACROSS THE COAST RANGE, WILLAMETTE
VALLEY AND PORTLAND METRO. DAYTIME HIGHS EXPECTED TO BE IN THE
LOW TO MID 60S FOR INLAND VALLEYS, MID 50S TO MID 60S FOR THE
COAST AND LOW TO UPPER 50S FOR THE HIGHER TERRAIN IN THE COAST
RANGE AND CASCADES.
THERE A RELATIVE LULL IN PRECIPITATION IS EXPECTED OVERNIGHT
WITH SCATTERED SHOWERS LINGERING. HOWEVER, WIDESPREAD PRECIPITATION
RETURNS THURSDAY MORNING AS THE SURFACE LOW CONTINUES TO SLOWLY
TRACK ALONG THE WA THEN OR COASTS. IN THE POST FRONTAL ENVIRONMENT,
SHOWER ACTIVITY WILL INCREASE ALONG WITH A BETTER CHANCE FOR
THUNDERSTORMS ACROSS THE ENTIRE AREA. CAPE IS EXPECTED TO BE
BETWEEN 150-250 J/KG DURING THE AFTERNOON ALONG WITH COOLER
TEMPERATURES IN THE UPPER LEVELS WILL SUPPORT A 20-30% CHANCE
FOR THUNDERSTORMS. THE OVERALL STORM ENVIRONMENT LOOKS TO FAVOR
POP-CORN STORMS THAT WILL BE CAPABLE OF SOME LIGHTNING, GUSTY
WINDS AND SMALL HAIL. IN ADDITION, COLD AIR ALOFT WILL ALSO PUT
INTO PLAY THE POTENTIAL DEVELOPMENT OF COLD CORE FUNNEL CLOUDS.
/42-19
LONG TERM...FRIDAY THROUGH WEDNESDAY
CHANCES FOR SHOWERS AND
THUNDERSTORMS CONTINUE FRIDAY AND THE WEEKEND AS THE
AFOREMENTIONED, UPPER LEVEL LOW WEAKENS BUT REMAINS OVER THE
REGION. CAPE WILL BE ON THE RELATIVELY LOWER SIDE, AROUND
100-200 J/KG EACH AFTERNOON FRIDAY THROUGH SUNDAY, WITH CIN
INCREASING EACH DAY. INCREASING CIN WILL LOWER THUNDERSTORM
CHANCES EACH AFTERNOON. TEMPERATURES TREND WARMER FRIDAY THROUGH
SUNDAY AS A SHORT-WAVE RIDGE QUICKLY BUILDS OVER THE REGION.
EXPECT DAYTIME HIGHS TO WARM INTO THE MID TO UPPER 70S BY THE
MIDDLE OF NEXT WEEK AS CLOUD COVER BECOMES MORE BROKEN AND LESS
OVERCAST. DRIER, MORE BENIGN CONDITIONS ARE EXPECTED TO RETURN
EARLY NEXT WEEK AS SHORTWAVE RIDGING DEVELOPS ACROSS THE PACNW.
/42-19
AVIATION...THROUGH 12Z THURSDAY
LARGELY VFR CONDITIONS
CONTINUE ACROSS THE AIRSPACE. HOWEVER, AN APPROACHING FRONTAL
SYSTEM WILL BRING WIDESPREAD RAIN AND VARIABLE FLIGHT CONDITIONS
THROUGH THE MAJORITY OF THE TAF PERIOD.
LIGHT RAIN EXPECTED TO START ALONG THE COAST AROUND 12Z-14Z
WEDNESDAY AND WILL BRING ABOUT MOSTLY MVFR CONDITIONS TO THE
COAST. THERE IS THE CHANCE THAT INTERMITTENT IFR CONDITIONS WILL
ALSO OCCUR AND THESE CONDITIONS ARE LIKELY TO COINCIDE WITH ANY
INCREASE IN PRECIPITATION RATE. IN ADDITION SOUTHERLY WINDS WILL
ALSO INCREASE WITH STARTING AROUND 13Z-15Z WEDNESDAY WITH GUSTS
APPROACHING 35 KT. MAX WIND GUSTS EXPECTED FROM 17Z-21Z WEDNESDAY.
FOR INLAND LOCATIONS EXPECT THE CURRENT VFR CONDITIONS TO BECOME A
MIXTURE OF VFR/MVFR AROUND 15Z-17Z WEDNESDAY WHICH WILL COINCIDE
WITH THE START OF PRECIPITATION. PERSISTENT SOUTHERLY WINDS ARE
ALSO EXPECTED WITH GUSTS APPROACHING 25 KT. MAX WIND GUSTS
EXPECTED FROM 18Z WEDNESDAY THROUGH 00Z THURSDAY.
ALSO, THERE IS A 15-25% CHANCE FOR THUNDERSTORMS ACROSS THE AIRSPACE
FROM 16Z WEDNESDAY THROUGH 03Z THURSDAY. ANY THUNDERSTORMS THAT
DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE LIGHTNING, SMALL HAIL
ALONG WITH GUSTY AND ERRATIC WINDS.
CONDITIONS MAY BEGIN TO IMPROVE AFTER 03Z THURSDAY AS STEADY RAIN
TRANSITIONS TO RAIN SHOWERS BEHIND THE FRONTAL BOUNDARY.
SOUTH/SOUTHWESTERLY WINDS 7-10 KTS WILL CONTINUE THROUGH THE
REMAINDER OF THE TAF PERIOD. ALSO, THE AIRSPACE WILL LIKELY
SETTLE INTO A LOW-END VFR/HIGH-END MVFR MIXTURE FOR THE REMAINDER
OF THE TAF PERIOD.
KPDX AND APPROACHES...VFR CONDITIONS WILL SLOWLY LOWER TOWARDS A
VFR/MVFR MIXTURE AS AN APPROACHING FRONTAL SYSTEM WILL BRING
WIDESPREAD PRECIPITATION, SOUTHERLY WINDS WITH GUSTS UP TO 25 KT.
PRECIPITATION AND THE MIXED FLIGHT CATEGORIES ARE EXPECTED TO
START AROUND 17Z WEDNESDAY AND PERSIST THROUGH AROUND 03Z
THURSDAY. 15-25% CHANCE FOR THUNDERSTORMS FROM 20Z WEDNESDAY
THROUGH 03Z THURSDAY. CONDITIONS MAY BEGIN TO IMPROVE AFTER 03Z
THURSDAY AS STEADY RAIN TRANSITIONS TO RAIN SHOWERS BEHIND THE
FRONTAL BOUNDARY. SOUTH/SOUTHWESTERLY WINDS 7-10 KTS ALONG WITH A
MIXTURE OF LOW- END VFR/HIGH-END MVFR CONDITIONS. /42
MARINE
AN ACTIVE WEATHER PATTERN CONTINUES THROUGH THE MIDDLE
OF THE WEEK AS A SERIES OF SYSTEMS MOVES INTO THE PAC NW. A BROAD
AREA OF LOW PRESSURE DROPPING FROM THE GULF OF ALASKA TOWARD THE
OREGON AND WASHINGTON COASTS WILL DRIVE A STRONG FRONTAL BOUNDARY
ACROSS ALL WATERS THROUGH THE LATE AFTERNOON, WHICH WILL RESULT IN
STRENGTHENING WINDS AND BUILDING SEAS ACROSS THE WATERS. SOUTH TO
SOUTHWEST WINDS WILL REACH 20-35 KT WITH FREQUENT GUSTS OF 40-45
KT EARLY THIS MORNING THROUGH THE LATE AFTERNOON. THE STRONGEST
GUSTS WILL MOST LIKELY OCCUR BETWEEN 8 AM AND NOON PDT BEYOND 30
NM FROM THE COAST, AND BETWEEN 10 AM AND 3 PM WITHIN 30 NM. WHILE
NOT EXPECTED TO BE PERSISTENT OR WIDESPREAD, THERE ARE 20-40%
CHANCES OF ISOLATED STORM-FORCE GUSTS WITHIN 20 NM AS THE FRONT
MOVES ONTO THE COAST LATE THIS MORNING/AFTERNOON. AS SUCH WILL
MAINTAIN THE CURRENT SUITE OF GALE WARNINGS ACROSS ALL WATERS
UNTIL AT LEAST 5 PM PDT TODAY.
SEAS REMAIN LARGELY WIND-DRIVEN, BUILDING TOWARDS TO 10-14 FT.
BEHIND THE FRONT, A FRESH WEST/NORTHWEST SWELL OF 7-9 FT WILL
ARRIVE, AND HELP TO MAINTAIN SEAS AROUND 9-11 FT THROUGH MUCH OF
THURSDAY. THESE STEEP SEAS MAY REQUIRE SMALL CRAFT OR HAZARDOUS
SEAS ALERTS IF CONFIDENCE IN THEIR TIMING, OCCURRENCE, AND
PERSISTENCE INCREASES. THERE WILL ALSO BE 15-30% CHANCES FOR
ISOLATED TO SCATTERED THUNDERSTORMS ON THURSDAY, WHICH WILL BE
CAPABLE OF PRODUCING GUSTY AND ERRATIC WINDS, SMALL HAIL, AND
LIGHTNING.
WHILE RELATIVELY ACTIVE WEATHER WITH LINGERING RAIN SHOWERS WILL
CONTINUE INTO THE WEEKEND, MARINE CONDITIONS WILL TEND TO SUBSIDE
AS WINDS AND SEAS EASE AFTER THURSDAY. FAIRLY BENIGN WINDS OF
5-15 KT AND SEAS OF 4-6 FT ARE EXPECTED BY THE WEEKEND AND INTO
EARLY NEXT WEEK. /42-36
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...GALE WARNING UNTIL 5 PM PDT THIS AFTERNOON FOR PZZ210-251>253-
271>273.
WWW.WEATHER.GOV/PORTLAND
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