Washington State Forecast Discussion

Western Washington


790
FXUS66 KSEW 051044
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
344 AM PDT Sun May 5 2024

.SYNOPSIS...Cool and unsettled conditions continue across the
region early this week. A shift in the pattern toward midweek with
bring about dry conditions and steadily warming temperatures
through the second half of the week.

&&

.SHORT TERM /TODAY THROUGH TUESDAY/...A mild start to the day
across the region with temperatures generally in the lower 50s at
this hour and rather damp with low stratus or fog present through
the interior this morning. Shower activity has diminished a bit as
the low begins to drift away, but some moisture does continue to
wrap around and move across the southern portions of the area
(generally from Olympia southward). Expect some showers to
continue this morning with an increase later in the day as
stronger onshore flow develops as the next trough approaches.
Expect primarily rain through the interior, though some light snow
will be possible above around 4500 feet and especially in the
higher Cascade elevations.

A stronger upper level trough approaches and moves into the region
on Monday. As cooler air aloft pushes into the region, steepening
lapse rates will increase the potential for isolated thunderstorms
through the day on Monday. Strong onshore flow will develop with
a Puget Sound Convergence Zone likely to develop into the
afternoon and evening. While snow levels will dip a bit closer to
the Cascade passes, the most significant threat for strong showers
will be under the PSCZ, especially if it's able to push into the
mountains.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Ensemble guidance
continues to depict high confidence in a shift to a much warmer
pattern through the second half of the week as a strong ridge
builds over the western U.S. starting around midweek. Still some
variations evident in the clusters of ensemble members with
respect to where the ridge axis sets up and just how strong it is,
but confidence is high in seeing temperatures climb to at least
10 to 15 degrees above normal by the late stages of the week for
much of the lowlands. Current forecast from the NBM suggest a run
into the lower to mid 80s is possible for the warmest spots
Saturday. While the precise temperature forecast will fluctuate a
bit in the coming days, it's worth noting that this will be a
significant warm up and coupled with the calendar turning to May,
many folks may be out around area water. Keep in mind that local
waters are still quite cool and be sure to adhere to safety
practices if you're out in or around the water later this week.
Cullen

&&

.AVIATION...Upper level low over Southeast oregon moving east
today. Frontal system spinning out of upper level low in the Gulf
of Alaska moving into the area tonight and Monday morning. Light
and variable flow aloft becoming westerly this afternoon. Flow
aloft increasing tonight into MOnday. In the lower levels onshore
gradients into Monday.

Widespread LIFR or IFR ceilings between Everett and Olympia this
morning with local visibility 3-5sm in fog or light drizzle. MVFR
ceilings over the remainder of the area except for VFR ceilings
near the Canadian border. Slow improvement late morning into the
afternoon hours with MVFR ceilings mostly locations after 21z.

KSEA...LIFR ceilings with visibility 3-5sm at times through 18z.
Ceilings lifting to IFR and then MVFR 18z-22z. MVFR ceilings
continuing into Monday morning. Southerly winds 6 to 10 knots
increasing to 10 to 15 knots with gusts 20 to 25 knots after 21z.
Felton

&&

.MARINE...A frontal system will move across the waters
tonight into Monday morning. High pressure will build back over
the area Monday night and Tuesday with the ridge remaining in
place Wednesday and Thursday.

Small craft advisory winds continuing in the Central Strait of
Juan de Fuca through at least Monday. Small craft advisory winds
for the Eastern Strait today into tonight. Winds in the Eastern
Strait easing late tonight then increasing again back up to small
craft advisory speeds Monday afternoon. Small craft advisory
winds in the Puget Sound and Hood Canal beginning this afternoon
and continuing through Monday.

Seas building to near 10 feet Monday night and remaining near 10
feet Tuesday. Felton

&&

.HYDROLOGY...No river flooding is expected through the next seven days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 2 PM PDT this afternoon for Central
U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 5 AM PDT early this morning for East
Entrance U.S. Waters Strait Of Juan De Fuca.

&&