Littell, Washington Weather Forecast Discussion

382
FXUS66 KSEW 080346
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
846 PM PDT Sun Sep 7 2025
.SYNOPSIS...Cool, cloudy, and unsettled conditions will continue
across western Washington through the first half of the week, with
periods of showers and thunderstorms at times. A brief period of
drier conditions is possible towards the end of the week, with
another system bringing increasing rain chances by next weekend.
&&
.SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/...Dry conditions
this evening across the majority of Western Washington with a
few lingering showers dissipating over Whatcom County. Generally
drier conditions tonight into Monday morning with continued
stratus and mid to high clouds. No major updates this evening.
Previous discussion below.
An upper low pressure system will continue to slowly meander
inland through the short- term, maintaining cool and unsettled
conditions across western Washington. A shortwave in the
southerly flow aloft will ripple northward across western
Washington this afternoon, generating light showers and isolated
thunderstorm activity over the Cascades. The best chance for
thunderstorms remains over the North Cascades, where ensembles
show a 20% to 30% chance of thunderstorms through the evening
near the Cascade crest. However, with a marine layer stemming
all the way to the crest, the ample cloud cover and cooler
temperatures will make it difficult for storms to initiate. The
lowlands will likely see little more than cloudy skies this
afternoon, with temperatures on track to reach the 60s to low
70s.
Cloudy conditions will stick around into Monday, with another
round of marine stratus expanding inland in the morning and
eroding towards the coast by the afternoon. The low pressure
system will start to track inland over Oregon on Monday, with some
wrap around moisture favored to fire up shower and thunderstorm
activity Monday afternoon mainly south of the Puget Sound and over
the Cascades. The best chance for more widespread showers and
thunderstorms will be late Monday night into Tuesday as the low
continues to shift eastward and moisture continues to be advected
towards western Washington. Some uncertainty still exists over the
coverage and strength of precipitation Tuesday, but with
temperatures peaking in the 60s for most areas under cloudy skies,
instability may be fairly limited.
Cool and cloudy conditions will continue on into Wednesday as the
low slowly shifts eastward. More wrap around moisture will move
into western Washington, but resultant showers will likely be
confined to the Cascades with a few lightning strikes possible.
&&
.LONG TERM /WEDNESDAY THROUGH SUNDAY/...The slow moving upper low
will continue to creep eastward on Thursday and Friday, with high
pressure building in behind. Ensembles continue to favor drying
across the lowlands on Thursday and Friday, with potential for
lingering showers once again over the Cascades. This will allow
temperatures to warm up several degrees, returning to near normal
for the middle of September. Highs will likely rebound to the mid
70s across the lowlands and the mid 60s along the coast.
Forecast models continue to hint at a pattern change heading into
next weekend, bringing increasing chances for more widespread
precipitation and slightly cooler temperatures on Saturday and
Sunday. The latest ensemble guidance shows potential for up to
half an inch of rain across the lowlands next weekend, and up to
an inch or more of rain over the mountains.
15
&&
.AVIATION...A broad upper trough remains centered offshore with
an upper ridge over the Rockies producing light southerly flow aloft
over Western Washington. The air mass is moist west of the Cascades
with multiple cloud layers and a few showers. Mostly VFR ceilings
this evening aside from low MVFR stratus over KCLM. Area ceilings are
expected to deteriorate tonight to low MVFR or occasional IFR once
again on Monday morning. VFR ceilings return by Monday
afternoon.
KSEA...VFR ceilings so far this evening with limited shower
activity. Ceilings will fall back to low MVFR or tempo IFR late
tonight into Monday morning but improvement to VFR will be met by
the afternoon. Surface winds will be S/SW 8 knots or less.
27/McMillian
&&
.MARINE...A weak surface ridge over the coastal and offshore waters
will be replaced by a weak low today. This general pattern will
persist through the first half of this week before a stronger
surface ridge rebuilds offshore around mid-week.
Seas 2 to 4 ft through at least Tuesday night, increasing to 4 to 6
ft by Wednesday.
18/27
&&
.FIRE WEATHER...As an upper level trough slowly inches eastward
over the area, we will see renewed chances for thunderstorms,
with the highest chances (15-25%) over the Cascades. The day
with the highest chances will be Tuesday, but the threat will be
possible each day through Wednesday. The primary threats from
any thunderstorms will be gusty winds, brief heavy downpours,
and lightning. Luckily, increased moisture, cloud cover, and
more seasonal temperatures across the area will help to
alleviate significant fire weather impacts.
Looking forward, Thursday has the best chance to be the driest day
of the week, with more chances for cooler and showery weather going
into next weekend.
JD/62
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$

NWS SEW Office Area Forecast Discussion