Cornelius Post Office Oregon Weather Forecast Discussion

928
FXUS66 KPQR 140355 AAB
AFDPQR
Area Forecast Discussion...UPDATED
National Weather Service Portland OR
855 PM PDT Mon Oct 13 2025
Updated short term, aviation, and marine discussions. Updated PQR
WATCHES/WARNINGS/ADVISORIES.
.SYNOPSIS...A low pressure system has dropped south of the area,
allowing for mostly sunny skies and increasing offshore flow this
afternoon. A broad upper level ridge slides over the region Tuesday
through the end of the week, supporting mostly dry conditions and
seasonable temperatures through Saturday. A weak front brings
increasing clouds and a chance for very light rain late Thursday
into Friday. The next Pacific frontal system is very likely to push
across the area later this weekend, with potential for more
substantial rainfall amounts.
&&
.UPDATE...Tonight and Tuesday night...Nudged the low temperature
forecast towards the NBM 10th percentile by 33% for wind sheltered
inland valley locations tonight and Tuesday night, as these areas
will see excellent radiational cooling both nights and will likely
cool a few degrees below the deterministic NBM. This lowered
temperatures a few degrees, bottoming out around 33-36 degrees both
nights. As such, frost is likely both tonight and Tuesday night in
wind sheltered valleys away from urban cores. It appears frost will
be more widespread Tuesday night due to calmer winds at all
locations. In addition, sub-freezing temperatures as cold as 28-32
degrees are still likely over the Upper Hood River Valley tonight and
Tuesday night from Odell to Parkdale. A Freeze Warning remains in
effect for this zone tonight. Have also issued a Freeze Watch for
this zone Tuesday night. -23
&&
.DISCUSSION...Tonight through Sunday...Relatively quiet weather
expected these next few days, with mostly sunny skies and seasonable
fall-like temperatures. An upper level trough over much of the
western US continues to dig south with an upper level low over
southern Oregon dropping into central California on Tuesday. This
will bring offshore flow with east to northeast winds across the
area through Tuesday night. East winds strongest out of the Columbia
River Gorge through this evening with gusts up to 30 mph possible.
Clear skies tonight will allow for optimal conditions for
radiational cooling, but only in areas sheltered from the east
winds. Therefore, Frost Advisories have been issued for temperatures
falling below 38 degrees overnight across much of the southern
Willamette Valley, as well as parts of the Tualatin Valley, and
northern Clark County in Washington. Not all locations within the
advisory will see temperatures that cold, but still a good idea to
cover or move sensitive plants indoor. A Freeze Warning remains in
effect for the Upper Hood River Valley where overnight temperatures
are likely to drop to around 28-32 degrees. Elsewhere, east winds
will maintain slightly warmer temperatures overnight.
By early Wednesday, the upper low shifts east across the Great
Basin, allowing for more north to northwesterly flow across the
region. Weak upper level ridging begins to nudge over the Pacific NW
by the middle of the week. This ridge is expected to flatten out
through the end of the week, and will likely allow a weak front to
push across the area late Thursday into Friday. Not much rain is
expected with this front as there is generally less than a 20%
chance of a tenth inch of precipitation. Mainly, increasing clouds
will bring slightly cooler afternoon temperatures on Thursday.
Generally expect highs this week to remain fairly seasonable, with
temperatures ranging from the upper 50s to mid-60s.
There is relatively good model and ensemble agreement for a frontal
system to push across the region sometime later Saturday or Sunday,
with a decent amount of rainfall possible. Probabilities for 1.0
inch of rainfall through Sunday night are 50-70% along the coast and
around 20-30% inland.
&&
.AVIATION...VFR conditions will continue across the area through
06z Wednesday. East to northeast winds have generally fallen
below 10 kt as of 04z Tuesday, and should remain below 10 kt
tonight. Winds will increase from the northeast again late Tuesday
morning with wind gusts increasing to 15-20 kt for inland TAF
sites.
KPDX AND APPROACHES...VFR conditions expected through the TAF
period. East to northwest winds have fallen to around 5 kt as of
04z Tuesday, and should turn to the north around 06-08z. Winds
become northeasterly again late Tuesday morning around 7-10 kt
with gust up to 15-20 kt. -23
&&
.MARINE...Low pressure continues to drop southward, supporting
northeast flow through Tuesday. Winds 15-20 kt with gusts to 25 kt
will slowly weaken overnight as the pressure gradient loosens.
Winds and seas have fallen below small craft advisory criteria
over the northern waters as expected Monday evening. While small
craft advisory level conditions continue over the central and
southern inner waters, still expecting conditions to improve for
these marine zones after 11 PM Monday. The central and southern
outer waters hang on to gusty northeast winds through Tuesday
afternoon. Winds turn northwesterly on Wednesday to around 10 kt.
Seas 9-10 feet at 10 seconds will continue to drop overnight to
around 7-8 feet at 9 seconds. Seas continue to drop to 4-5 feet at
8 seconds on Wednesday, persisting through Friday.
While the weather pattern remains a bit uncertain for this
upcoming weekend, model guidance for wave heights has come into
slightly better agreement. On Saturday, there is moderate to high
confidence for seas around 8 to 10 ft. The latter half of the
weekend into early next week shows a large range for potential
wave heights. The high end scenario (10% chance) pushes waves to
18-20 feet while the low end scenario (10% chance) is closer to
10-12 feet. -19/23
&&
.PQR WATCHES/WARNINGS/ADVISORIES...
OR...Frost Advisory from midnight tonight to 9 AM PDT Tuesday for
     ORZ104-108-109-116>118-124-125.
Freeze Warning from midnight tonight to 9 AM PDT Tuesday for
     ORZ121.
Freeze Watch from late Tuesday night through Wednesday morning
     for ORZ121.
WA...Frost Advisory from midnight tonight to 9 AM PDT Tuesday for
     WAZ204>206-208.
PZ...Small Craft Advisory until 11 PM PDT this evening for
     PZZ252-253.
Small Craft Advisory until 5 PM PDT Tuesday for PZZ272-273.
&&
$$
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NWS PQR Office Area Forecast Discussion