Mc Chord Air Force Base, Washington Weather Forecast Discussion

173
FXUS66 KSEW 032207
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
307 PM PDT Fri Oct 3 2025
.SYNOPSIS...Light showers will make a return tonight into Saturday
before high pressure brings more warming and drying to western
Washington through the middle of next week. Chances for more
widespread precipitation increase into next weekend.
&&
.SHORT TERM /TONIGHT THROUGH MONDAY/...Dry conditions will persist
across western Washington through the afternoon today as
northwest flow develops aloft. Cloud cover will continue to
increase throughout the day as the next weather system approaches,
with seasonable conditions and temperatures in the 60s across the
lowlands.
A weak frontal system will cross the region this evening,
spreading light showers inland into the early morning hours
Saturday. Northerly flow will develop behind, bringing
temperatures down a few degrees below normal. Isolated shower
activity may linger into Saturday afternoon, but much of the
region will see little more than cloudy skies through the
remainder of the day.
By Sunday, an upper level ridge of high pressure will amplify over
the northern Pacific and start to build inland towards the Pacific
Northwest. This will kick off a warming and drying trend into
Monday, with mild temperatures and mostly clear skies on Sunday
and Monday.
.LONG TERM /TUESDAY THROUGH FRIDAY/...Models show good agreement
over the upper ridge axis shifting inland on Tuesday, maintaining
warm and dry conditions across western Washington. Temperatures
are on track to reach the low to mid 70s across the interior
lowlands, roughly 5 to 10 degrees above normal for early October.
By the middle of next week, forecast models begin to show
different solutions. A cutoff low is expected to develop along the
western US coast, but a large degree of uncertainty remains over
the track of this low pressure system. While some models show the
low moving south and stalling offshore, keeping western Washington
dry, other models bring widespread precipitation into the Pacific
Northwest as early as Wednesday. A chance of precipitation is
maintained through the extended forecast, though significant
rainfall is not expected across western Washington at this time.
15
&&
.AVIATION...Stratus has finally mostly eroded across western
Washington, and we have now mostly transitioned to a fair weather
Cu field. Most locations are VFR [or on their way to becoming VFR
soon]. A weakening cold front is beginning to approach the area
from the northwest. This will usher in mid to high level clouds
this evening. Ceilings will then slowly lower overnight, becoming
mostly MVFR to IFR area-wide by Saturday morning. Given the
sufficient moisture in the low-levels, models are indicating that
locally lower ceilings to LIFR and areas of fog will be a threat
once again by tomorrow morning. Expect a similar trend on Saturday
morning, a slow rise in ceilings, lifting and scattering through
much of the day with a return to VFR conditions not expected until
Saturday afternoon (21Z Sat or shortly thereafter). Winds look to
remain light overnight tonight, becoming northerly around 6 kt or
less on Saturday.
KSEA...VFR conditions this afternoon with a low-based cumulus deck
around the terminal. Expect clouds to move in this evening and
slowly lower throughout the day dropping all the way down the IFR
(30-50% chc.) or LIFR (25-35% chc.) by Saturday morning. Areas of
fog are possible once again with limitations to visibility after
06-09Z. The lowest conditions will persist through around 16-18Z
before clouds and fog slowly rise and scatter through the rest of
the morning. VFR conditions will be slow to return Saturday
afternoon. Wind speeds remain 6 kt or less through the period. SW
winds will slowly veer to become N/NE then light and variable
tonight then remaining N tomorrow.
62
&&
.MARINE...A weakening low pressure system currently centered
offshore of southwest WA will continue to dissipate as it moves
southward. Another front is beginning to move in from British
Columbia but is quickly weakening as it does so, passing over the
area tonight into Saturday morning. High pressure will quickly
take its place over the coastal waters Saturday night through the
first part of next week. Troughing along the coastline will help
turn the winds offshore, with north to northeast winds over the
coastal waters. Through there remains some uncertainty, a frontal
system looks to approach the coastal waters by Tuesday night,
bringing with it increasing northwesterly winds that have a 30-50%
chance of exceeding 21 kt.
Seas will remain around 4-6 ft through the weekend. Seas will
build Tuesday to 6-8 ft.
62
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$

NWS SEW Office Area Forecast Discussion