Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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FXUS66 KSEW 281616
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
916 AM PDT Thu Mar 28 2024

.SYNOPSIS...Low pressure spinning off the coast will maintain
scattered showers and isolated thunderstorms today. Showers will
gradually subside through the day Friday giving way warmer and
drier conditions as high pressure builds into the area, resulting
in above normal temperatures by Sunday and Monday. A cold front
is poised to move southward across the Pacific Northwest Tuesday,
bringing a return to a cooler and wetter pattern into the middle
part of next week.

&&

.SHORT TERM /TODAY THROUGH SATURDAY/...Scattered showers and
isolated thunderstorms will continue across western Washington
through the day today as a low pressure system continues to spin
offshore and eject shortwave perturbations across the region.
The overall forecast remains on track this morning, with radar
showing the heaviest shower activity moving along the coast as of
16Z. The previous discussion follows below, with updates made to
the aviation and marine sections below. 14

A vertically-stacked and occluded low pressure center continues
to spin just west of 130 W offshore with yesterday`s occluded
front having stalled over eastern Washington. A surface trough
will pivot onshore later this afternoon amidst several shortwave
perturbations and vorticity maxima pivoting around the occluded
upper low. These will maintain scattered and disorganized showers
with isolated thunderstorms through much of the day, largely
similar to those observed yesterday. Hazards from these will once
again include small hail/graupel, brief heavy downpours, gusty
winds, and dangerous cloud-to-ground lightning. Remember, when
thunder roars, go indoors!

Similar temperatures today as to yesterday with highs in the low
to mid 50s. Snow levels today will hover around 3000 to 3500 feet
with light snow accumulations of 1-3 inches at the Cascade Passes
will be possible. Total rainfall amounts today will be on the
lighter side - generally a quarter of an inch or less across the
lowlands, with 1 to 2 inches across the southern Olympics.

Meanwhile, a stronger shortwave trough will pivot southward
through the longwave trough over the eastern Pacific, prompting
cyclogenesis of a new surface low, which will overtake the current
one, pulling the focus for scattered showers and thunderstorms
south of the area through the day Friday as the only remaining
focus for showers isolates to the Cascades and Olympics. High
temperatures begin rising Friday as mid-level heights rise with
mid to upper 50s forecast.

Upper-level ridging will build south and east across the Pacific
Northwest on Saturday with pleasant conditions featuring clear
skies and highs in upper 50s to near 60.

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...Warm and dry weather
will continue Sunday into Monday, with the high temperatures
peaking Monday as the upper-level ridge axis moves overhead. Snow
levels also rise closer to 7000 feet by late Monday. While
forecast highs aren`t nearing any record highs Monday, the
forecast doesn`t look to be a joke of any sorts for April Fools`
Day with a high likelihood for max temperatures above 60 Monday
for the interior and Puget Sound lowlands.

The upper-level ridge begins to flatten into Tuesday as the upper
low previously along the coast cuts off over the Desert Southwest.
While some disagreement continues over how cutoff this low will
become and how long it will linger to our south, better agreement
appears to exist in the amplification of a new developing trough
across British Columbia into the Pacific Northwest by Wednesday.
At the surface, a cold front looks to slide southward across the
region Tuesday into Tuesday night, ushering in a return to cooler
and wetter weather by Wednesday.

Davis

&&

.AVIATION...Southwesterly flow aloft continues as an upper low
meanders just offshore. Mostly VFR this morning along with shower
activity. As showers continue throughout the day, can expect locally
lower ceilings and vsbys at times, especially as heavier showers
pass through. VFR will likely dominate through the day but may lower
to MVFR briefly with showers.

KSEA...VFR this morning along with shower activity. VFR will likely
rebound and persist, with brief drops to MVFR likely at times
throughout the day under heavier precipitation. S/SE winds 5 to 10
knots thru the morning, with gusts up to 20 kts possible around 20z
onward.

Mazurkiewicz/McMillian

&&

.MARINE...A surface low continues to meander offshore, with
gales over the coastal waters this morning. Elevated S/SE winds will
continue throughout majority of the day, with small craft advisories
still in place for the Eastern Entrance of the Strait, Admiralty
Inlet, and the Northern Inland Waters. Winds over these areas will
likely remain at small craft advisory threshold until Friday, before
the surface low drifts southward, which will let winds over the
waters ease into the weekend.

High pressure looks to return into the weekend, with both winds
and seas easing, headlines will be allowed to expire.

Combined seas this morning around 12 to 15 feet and will generally
maintain that height through the day. Seas look to drop below 10
feet Friday morning, and continue to lower to around 3 to 6 feet for
the weekend.

Mazurkiewicz/McMillian

&&

.HYDROLOGY...No river flooding is forecast over the next 7 days.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory until 11 AM PDT Friday for Grays Harbor Bar.

     Small Craft Advisory until 5 AM PDT Friday for West Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory until 8 AM PDT Friday for Admiralty Inlet-
     East Entrance U.S. Waters Strait Of Juan De Fuca-Northern
     Inland Waters Including The San Juan Islands.

     Gale Warning until 11 AM PDT this morning for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From Cape Flattery To James Island Out 10 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 Nm-
     Coastal Waters From James Island To Point Grenville Out 10
     Nm-Coastal Waters From Point Grenville To Cape Shoalwater
     10 To 60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater Out 10 Nm.

     Small Craft Advisory until 11 AM PDT Friday for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From Cape Flattery To James Island Out 10 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 Nm-
     Coastal Waters From James Island To Point Grenville Out 10
     Nm-Coastal Waters From Point Grenville To Cape Shoalwater
     10 To 60 Nm-Coastal Waters From Point Grenville To Cape
     Shoalwater Out 10 Nm.

&&

$$


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