Keizer, Oregon 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

790
FXUS66 KPQR 220414 AAA
AFDPQR

Area Forecast Discussion...UPDATED
National Weather Service Portland OR
914 PM PDT Wed May 21 2025

Updated Aviation Discussion

.SYNOPSIS...Expect cooler and showery conditions to persist
through Thursday before drier weather returns by the weekend.
Temperatures trend warmer through the weekend as well, peaking
on Sunday.

&&

.SHORT TERM...Tonight through Friday...A weak transitory ridge
of high pressure which facilitated dry and fairly calm weather
today will give way to yet another shortwave trough progressing
west to east across the region tonight into Thursday morning.
Expect light shower activity to return as a result, peaking
early Thursday morning, before gradually decreasing Thursday
midday/afternoon. Overall, not much rainfall is anticipated
tonight through Thursday night with the NBM only suggesting only
a 5-10% chance for rainfall to exceed 0.25" along the I-5
corridor; better chances (40-60%) comparatively to hit this
wetting rain threshold(0.25") in the Cascades. That said at this
point in the year and additional rainfall is welcome. With a
added cloud cover and westerly flow, high temperatures look to
remain near to slightly below normal on Thursday as well,
holding in the 60s across the lower elevations. Upper-level
heights begin to build again on Friday as dry weather returns to
the region along with a slight increase in temperatures.

.LONG TERM...Friday Night through Tuesday...Both deterministic
and ensemble models are generally in agreement that shortwave
ridging will build into the Pacific Northwest Saturday into
Sunday leading to the area drying out further and temperatures
embarking on a noticeable warming to well above average by
Sunday. The NBM currently shows a 60-80% chance for high
temperatures to meet or exceed 80 degrees Sunday afternoon Salem
northward through the Portland Metro and Longview/Kelso.

Uncertainty in the upper level pattern does grow early next
week. The main area of uncertainty revolves around how long the
shortwave ridging persists over the region and when the next
shortwave trough slides into the Pacific Northwest from the
west. The current forecast is very middle of the road, but know
there is ~25% chance temperatures in the 80s will persist into
early next week and there is a ~20% chance that temperatures
hold in the 60s - more than likely the lower elevations will end
up somewhere in the middle (70s). We`ll also have to watch for
the possibility of convection, mainly in the Cascades, late
Sunday and/or Monday as this transition occurs due to the warm
preceding temperatures and potential negative tilt of the
incoming trough. Otherwise, ensembles favor a somewhat more
active pattern Tuesday into the middle of next week with broad
southwesterly flow aloft. -Schuldt

&&

.AVIATION...Predominately VFR with scattered to broken mid level
cloud cover across the area as weak high pressure moves east over
the Cascades through the overnight hours. Winds increase out of
the NW this afternoon, to around 10-15 kt at coastal sites, but
generally remaining below 10 kt inland. As the high pressure moves
eastward, an arriving disturbance will bring an increasing
probability to rain showers and periods of lowered flight
conditions starting around 06Z Thursday. From around 06Z through
15Z expect showers along with a 10-25% probability for
intermittent MVFR conditions. Around 18Z to 20Z Thursday expect
widespread VFR conditions to return and persist through the
remainder of the TAF period.

PDX AND APPROACHES...Predominately VFR conditions expected
through the TAF period with increasing mid to high clouds.
Northwest winds around 7-9 kt, becoming light overnight. Rain
chances increase after 06Z Thursday, but VFR likely to persist
through at least 15Z Thursday. Afterwards, around a 20%
probability for intermittent MVFR conditions from 06Z Thursday
through 15Z Thursday. /42

&&

.MARINE...Northerly breezes this afternoon expected to increase
enough to issue a Small Craft Advisory across the coastal waters,
with highest gusts up to 25 kt along the nearshore waters. Inland
daytime heating will drive the diurnal strengthening of the
coastal pressure gradient. By midnight, winds are expected to ease
and remain below 15 kt through Friday. Weak high pressure will
persist offshore through Saturday.

Meanwhile, seas around 6 to 7 ft will continue to gradually
subside through Thursday as a mid period swell decays below 5 ft.
Conditions remain on the quiet side Friday into the weekend as
benign onshore flow returns, yielding mainly light breezes and
seas below 5 ft. /DH

&&

.PQR WATCHES/WARNINGS/ADVISORIES...

OR...None.
WA...None.
PZ...Small Craft Advisory until midnight PDT tonight for PZZ251>253-
 271>273.

&&

$$

www.weather.gov/portland

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