045
FXUS66 KPQR 230554 AAB
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
953 PM PST Fri Nov 22 2024

...Updated aviation discussion...

.SYNOPSIS...Another round of rain showers and wind today,
windiest at the coast. Rain showers and mountain snow showers
over the weekend into early next week. Trending towards drier
weather later next week with seasonable temperatures.

&&

.DISCUSSION...Today through Thursday...Warm front is currently over
the Cascades as of 1:30 pm Fri, with most of the area seeing
post- frontal showery activity. Winds at the north coast are
currently seeing peak gusting up to 50-60 mph; for areas further
south, winds will be slowly decreasing as the low moves further
and further north towards Washington/Canada. Inland, the
central Willamette Valley saw peak gusts around noon of 35-45
mph winds; these too will be on the decline over the next few
hours. Main impacts from wind are broken tree branches and
perhaps some trees in soggy ground become uprooted, potentially
resulting in power outages and other damage. Any remaining rain
accumulations associated with this front will be fairly light;
around 0.10-0.20" for most areas, and around 0.5" for the
Cascades and Coast Range.

The possibility for coastal thunderstorms continues this afternoon
going through Sunday. Conditions still support a very low chance
(<5%) of some isolated waterspouts over the waters. Any heavier
thunderstorms still see the possibility of producing small hail and
bursts of heavier rain as well at the coast.

Snow levels are currently quite high (7000-8000 ft) following this
warm front, but will continue falling overnight tonight. Snow levels
likely fall to around 3000-3500 ft by Saturday morning. Snow amounts
during this time look to be around 1/2 foot at passes Friday night
to Sunday afternoon (48 hours), and closer to 1 ft for the volcano
peaks. At this time no winter headlines are expected.

The next wave of moisture from the parent low arrives Saturday in
the late afternoon, bringing another round of steadier rain to the
area.
Looking at 24 hr rainfall between 10am Sat and 10am Sun, only around
a 25% chance of exceeding 0.5" in the Willamette Valley. The coast
and Coast Range see slightly better rainfall, somewhere around 0.5-
1.5" of rain. Winds won`t be nearly as strong inland, with less than
10% chance of gusts over 25 mph anywhere inland. At the coast, gusts
right around 25-30 mph will be possible throughout Saturday night
and Sunday morning, decreasing afterwards.

Light weak showery activity continues through the beginning of next
week, without any particularly impactful weather expected. WPC
Cluster Analysis shows strong agreement (90%+) of upper level riding
moving in by Wednesday night, likely producing drier and warmer
weather. /JLiu

&&

.AVIATION...A shortwave from an exiting system will bring showers
and lower cigs from south to north tonight. Guidance suggests a 40-
60% chance for MVFR cigs at any given terminal beginning 10-12z Sat
and lasting through late Saturday morning. After 21z Sat, expect
improvement to predominately VFR thresholds but with lingering
showers as broad low pressure remains over the Pacific.
Expect southerly/southeasterly winds generally under 10 kt for
majority of terminals as pressure gradients weaken. However, could
see some gusts up to 20 kt around the KONP area Saturday afternoon.

PDX APPROACHES...VFR thresholds through most of the night, with a 40-
60% chance of cigs falling to high-end MVFR between 14-21z Sat with
an incoming shortwave. Will likely see improvement to low-end VFR
Saturday afternoon with lingering showers. Southeast winds generally
under 10 kt through the TAF period.     -Alviz

&&

.MARINE...A strong low pressure system centered around 100-150
miles offshore continues to bring steep and hazardous seas along
with strong southerly winds for the coastal waters. Buoy
observations from 1-2 PM Friday showed seas around 20 ft over the
northern waters and around 15 ft over the southern waters. Winds
were generally gusting between 35-45 kt with occasional storm force
wind gusts. Although seas and winds are elevated at the moment,
expect both seas and winds to begin rapidly decreasing Friday
evening through Friday night as the aforementioned low pressure
system continues moving northward towards Vancouver Island. By 10 PM
Friday, seas should range between 12 to 15 ft, highest over the
northern waters beyond 10 nm offshore. Winds will likely be gusting
between 20-30 kt at that time, with isolated gusts to 35 kt over the
northern waters. By sunrise on Saturday, seas should be around 10
feet with wind gusts under 30 kt.

Beyond Saturday, the weather pattern becomes relatively benign for
this time of year with no signs of significant winds or hazardous
seas. The only exception to that statement is Saturday night and
Sunday when a brief period of stronger winds is expected as a weak
small-scale surface low moves north over the coastal waters. There
is still some uncertainty regarding how strong winds will get with
this low, but as of right now it appears wind gusts up to 30-35 kt
are likely. However, cannot completely rule out gusts as high as 40
kt (30-40% chance). Given the short duration of these stronger
winds, seas are not expected to have enough time to build much
beyond 10-12 ft. The probability for seas over 12 ft is only around
10-20% at this time. -TK

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Gale Warning until 10 PM PST this evening for PZZ210-251-252-
     271-272.

     Hazardous Seas Warning until 4 AM PST Saturday for PZZ210-251-
     252-271-272.

     Hazardous Seas Warning until 4 AM PST Saturday for PZZ253-273.
&&

$$

www.weather.gov/portland

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