Ajlune, Washington Weather Forecast Discussion

870
FXUS66 KSEW 230304
AFDSEW
Area Forecast Discussion
National Weather Service Seattle WA
804 PM PDT Mon Sep 22 2025
.SYNOPSIS...Conditions will trend drier and warmer across
Western Washington for the first half of the week. Smoke or haze
may creep into western Washington during this time frame.
Warmest days look to be Tuesday and Wednesday, with typical late
September weather with near normal temperatures and potential
for precipitation Friday and especially into the weekend.
&&
.SHORT TERM /TONIGHT THROUGH THURSDAY/...Clear skies overnight
with lows in the mid 40s to lower 50s. No updates from the
previous forecast tonight. 33
Previous discussion...Fog and low clouds have retreated leaving
mostly clear conditions across western Washington this afternoon.
A ridge of high pressure will continue to build into the region
over the next 24 hours allowing temperatures to warm back into the
70s across much of the lowlands for Tuesday. A wave will keep the
ridge from building further on Wednesday, allowing for similar
conditions. Flow during this timeframe will be weak offshore,
allowing haze/smoke from fires in the Cascades to creep west
toward the Puget Sound lowlands as well as smoke from fires in the
Cascades to move near the coast.
.LONG TERM /FRIDAY THROUGH MONDAY/...By late Wednesday or
Thursday there is good ensemble agreement in the 500mb flow
becoming more zonal, turning the flow onshore, bringing
temperatures down, and opening the door for weather systems.
There is decent agreement that a relatively weak wave will
traverse the region in the Thursday time frame, but little to no
precipitation is expected.
Ensemble guidance begins to diverge over the weekend and the
latest cluster guidance continues to remain split nearly evenly
between a relatively wet vs dry start to the weekend. That
said, nearly all clusters indicate at least some rainfall by
late Sunday or Monday across the region. Temperatures look to
remain at or slightly above normal for late September/early
October. -Wolcott-
&&
.AVIATION...Westerly flow aloft as a ridge slowly builds over
western Washington, with light northerly flow in the lower levels.
VFR conditions continue this evening. Marine stratus will likely
bring LIFR/IFR to areas along the coast and potentially as far as
KOLM early Tuesday morning, but with light winds and general drying
throughout the area, the marine layer will likely remain out of the
interior. Terminals that receive the marine air will clear by 18Z.
Winds Tuesday will be light out of the north 4-6 kt.
KSEA...VFR conditions throughout the TAF period. Northerly surface
winds this evening remain around 5 to 7 knots will continue
overnight, nudging gently to the NE at times - before turning
solidly more N early Tuesday morning.
Mazurkiewicz/HPR
&&
.MARINE...A surface high pressure will build over the coastal
waters this afternoon along with a thermally induced low pressure
expanding northward along the coast. Flow will slightly turn
offshore through Tuesday but remain light. Onshore flow will
resume around Wednesday with a frontal system passing by to the
north.
Coastal seas generally 5 to 7 feet through the first half of the
week, increasing slowly to 6 to 8 feet by midweek then subsiding
back down to 5 to 7 by the end of the week.
Mazurkiewicz
&&
.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...None.
&&
$$

NWS SEW Office Area Forecast Discussion