398
FXUS66 KPQR 271104
AFDPQR
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PORTLAND OR
404 AM PDT TUE OCT 27 2026
SYNOPSIS
SEASONABLY COOL AND SHOWERY CONDITIONS CONTINUE
THROUGH THE WORKWEEK AS REPEATED WEATHER SYSTEMS SUPPORT
PERSISTENT CHANCES FOR RAIN. A DRYING TREND BEGINNING FRIDAY MAY
BRING BETTER TRICK-OR-TREATING CONDITIONS BY LATE SATURDAY.
A MORE ACTIVE PATTERN LOOKS TO RETURN BY THE START OF NEXT WEEK
AS A BROAD AREA OF LOW PRESSURE MOVES SOUTHWARD OUR OF THE GULF
OF ALASKA.
SHORT TERM...TODAY THROUGH WEDNESDAY NIGHT
WHILE THE LOW THAT
BROUGHT THE REGION WIDESPREAD RAINFALL HAS NOW MOVED WELL EAST
OF THE CASCADES THIS MORNING. SCATTERED TO NUMEROUS RAIN SHOWERS
REMAIN IN THE FORECAST THROUGH AT LEAST WEDNESDAY NIGHT AS AN
UPPER LEVEL SHORTWAVE TROUGH IS SLOWLY PUSHED THROUGH THE
REGION. WHILE CAMS ARE SUGGESTING AT A BRIEF REDUCTION IN
SHOWER COVERAGE THROUGH THE AFTERNOON, MOST PLACES WILL STILL
SEE SOME SHOWER ACTIVITY. OBSERVED 48-HOUR RAINFALL TOTALS
THROUGH EARLY TUESDAY MORNING GENERALLY SHOW 0.75-1.30 INCHES
ACROSS THE CWA. ADDITIONAL RAINFALL OF 0.15-0.75 INCHES IS MOST
LIKELY THROUGH TUESDAY, WITH UP TO 1 INCH IN FAVORED TERRAIN.
WHILE WEDNESDAY IS LOOKING TO BE RELATIVELY DRIER THAN THE PAST
48 HOURS, SHOWERS REMAIN IN THE FORECAST WITH ADDITIONAL
PRECIPITATION AMOUNTS OF 0.10-0.50 INCHES WITH UP TO 0.75
INCHES IN FAVORED TERRAIN.
IN ADDITION TO THE PRECIPITATION, 850 MB TEMPERATURES WILL
CONTINUE TO FALL TOWARDS 0C TO -1C THROUGH WEDNESDAY NIGHT. THIS
WILL RESULT IN SNOW LEVELS AROUND 5000 FT TODAY CONTINUING TO
FALL TOWARDS 4000-4500 FT BY WEDNESDAY MORNING, ALLOWING FOR
LIGHT SNOW ACCUMULATIONS AT PASS LEVEL. CHANCES FOR 1 INCH OF
SNOW AT SANTIAM AND WILLAMETTE PASSES THROUGH TONIGHT REMAIN
70-80%, WITH ONLY 10% CHANCE AT PASSES NEAR MT. HOOD. AS FOR
WEDNESDAY, CHANCES FOR 1 INCH OF SNOW AT SANTIAM AND WILLAMETTE
PASSES ARE AROUND 70-85%, WITH A 30-40% CHANCE AT PASSES NEAR
MT. HOOD. SEASONABLE TEMPERATURES CONTINUE ACROSS THE REGION
WITH AFTERNOON HIGHS IN THE 50S AND EARLY MORNING LOWS IN THE
UPPER 30S TO MID 40S THROUGH THE MIDDLE OF THE WEEK. /42
THOSE PLANNING TRAVEL THROUGH THE CASCADES SHOULD PREPARE FOR
WINTER DRIVING CONDITIONS.
LONG TERM...THURSDAY THROUGH MONDAY
ANOTHER, BROADER CLOSED
UPPER LOW AND ITS ASSOCIATED SURFACE LOW WILL DROP SOUTH FROM
THE GULF OF ALASKA OVER VANCOUVER ISLAND AND INTO THE PACIFIC
NORTHWEST WEDNESDAY NIGHT INTO THURSDAY. THIS WILL BRING ANOTHER
ROUND OF PRECIPITATION TO THE REGION THROUGH FRIDAY. 850 MB
TEMPERATURES WILL CONTINUE TO SLOWLY FALL TOWARDS -1C TO -2C
THUS BRINGING SNOW LEVELS FURTHER DOWN TOWARDS 3000-3500 FT BY
THURSDAY. WHILE COOLER TEMPERATURES REMAIN IN THE FORECAST, QPF
HAS DECREASED SHARPLY WITH THE THURSDAY SYSTEM. CURRENTLY, THE
ENSEMBLES ARE SUPPORTING A 40-60% CHANCE FOR AN ADDITIONAL INCH
OF SNOW FOR THE CASCADE PASSES. FOR LOWER ELEVATIONS, ANOTHER
0.10-0.25 INCHES OF RAIN IS MOST LIKELY ACROSS THE CWA.
FROM FRIDAY THROUGH THE WEEKEND, WPC 500 MB CLUSTERS SUPPORT A
BROAD LOW REMAINING OFFSHORE OF THE PAC NW, WHILE WEAK RIDGING
LOOKS TO DEVELOP OVER THE GREAT BASIN. THIS LOOKS TO BRING SOME
DRIER AIR INTO THE REGION, WHICH IS CUTTING THE OVERALL QPF FOR
THE LATTER PART OF THIS WEEK AND INTO THE WEEKEND. HOWEVER,
15-30% POPS REMAIN IN THE FORECAST. WHILE A DRYING AND CLEARING
TREND IS EXPECTED FOR THE END OF THE WEEK AND WEEKEND, THERE
CONTINUES TO BE A SLIGHT CHANCE FOR LINGERING RAIN SHOWERS
FRIDAY AND SATURDAY. SO, FOR ALL THOSE HALLOWEEN TRICK-OR-
TREATERS JUST BE AWARE THAT SOME VERY LIGHT RAIN COULD IMPACT
ANY FESTIVITIES. GIVEN THE CLEARING TREND ALONG WITH THE INFLUX
OF COOLER TEMPERATURES EXPECT OVERNIGHT LOWS IN THE UPPER 20S
TO MID 30S MOST LIKELY FOR MOST INLAND VALLEYS THROUGH THE
WEEKEND AND INTO EARLY NEXT WEEK. /42
AVIATION...THROUGH 12Z WEDNESDAY
MOIST, WESTERLY FLOW ALOFT
CONTINUES AS AN UPPER LEVEL TROUGH MOVES OVER THE REGION. THIS
WILL MAINTAIN SHOWERS ACROSS THE AIRSPACE ALONG WITH A MIXTURE OF
VFR TO MVFR CONDITIONS. BRIEF PERIODS OF IFR/LIFR CONDITIONS WILL
ALSO BE POSSIBLE, THOUGH GENERALLY JUST A 10-20% CHANCE AT ANY GIVEN
HOUR THROUGH THE TAF PERIOD. CONDITIONS ARE LIKELY TO IMPROVE AFTER
18Z-21Z TUESDAY AS SHOWERS DECREASE AND CIGS LIFT TOWARD VFR. WINDS
GENERALLY REMAIN WEST TO SOUTHWEST AT 5-10 KT. AFTER 02Z WEDNESDAY,
WINDS ARE EXPECTED TO INCREASE ALONG THE COAST WITH GUSTS UP TO
20 KT THROUGH THE REMAINDER OF THE TAF PERIOD.
KPDX AND APPROACHES...SHOWERS EXPECTED TO CONTINUE ALONG WITH A
MIXTURE OF VFR TO MVFR CONDITIONS. 10-20% CHANCE FOR INTERMITTENT
IFR/LIFR CONDITIONS AT ANY GIVEN HOUR THROUGH THE TAF PERIOD. AFTER
18Z-21Z TUESDAY CONDITIONS LIKELY TO IMPROVE AS SHOWERS DECREASE
AND CIGS LIFT TOWARD VFR. WEST TO SOUTHWEST WINDS 5-10 KT. /42
MARINE
A SURFACE LOW PRESSURE SYSTEM WILL MOVE THROUGH ALL
WATERS TODAY BRINGING ELEVATED WINDS WITH GUSTS APPROACHING 25-30
KTS AND SEAS BUILDING TOWARDS 7-10 FT AT 8-10 SECONDS. AS SUCH,
HAVE ISSUED A SERIES OF SMALL CRAFT ADVISORIES FOR ALL WATERS AND
THE COLUMBIA RIVER BAR THROUGH AT EARLY WEDNESDAY MORNING. CONDITIONS
WILL SLOWLY SUBSIDE AFTER WEDNESDAY WITH GUSTS BELOW 15 KT AND
SEAS SUBSIDING TOWARDS 4-6 FT AT 10-12 SECONDS THROUGH THE WEEKEND.
LOOKING TOWARDS THE START OF NEXT WEEK, ANOTHER LOW PRESSURE SYSTEM
FROM THE GULF OF ALASKA LOOKS TO BRING BUILDING SEAS AND WINDS THAT
COULD RESULT IN SMALL CRAFT CONDITIONS FOR THE START OF NEXT WEEK.
/42
PQR WATCHES/WARNINGS/ADVISORIES
OR...NONE.
WA...NONE.
PZ...SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 11 AM PDT
WEDNESDAY FOR PZZ210-251-252.
SMALL CRAFT ADVISORY FROM 8 AM THIS MORNING TO 8 AM PDT
WEDNESDAY FOR PZZ253.
SMALL CRAFT ADVISORY FROM 5 AM EARLY THIS MORNING TO 5 PM PDT
WEDNESDAY FOR PZZ271-272.
SMALL CRAFT ADVISORY FROM 5 AM EARLY THIS MORNING TO 8 AM PDT
WEDNESDAY FOR PZZ273.
WWW.WEATHER.GOV/PORTLAND
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