073
FXUS66 KSEW 112119
AFDSEW

Area Forecast Discussion
National Weather Service Seattle WA
219 PM PDT Sat May 11 2024

.SYNOPSIS...Upper level ridging will start to weaken into Sunday,
although still providing warm and dry conditions across western
Washington. A weak system will move across the area Sunday night
into Monday with a touch cooler temperatures. High pressure looks
to build back into the area Tuesday into Thursday with warm
conditions. Unsettled weather looks to make a return by the
weekend.

&&

.SHORT TERM /TONIGHT THROUGH TUESDAY/...Recent satellite imagery
shows another beautiful day across western Washington. Upper level
ridging will start to weaken over our area into Sunday, with high
temperatures in the interior this afternoon topping out to
generally around 80 degrees. The transition to onshore flow this
afternoon will help the coastal locations cool down, with high
temperatures there this afternoon to be in the low to mid 60s.

As the upper level ridge weakens tonight, skies will remain mostly
clear throughout most of the interior, with the possibility for
some patchy stratus along the coast. It will be another good
night for viewing conditions for the Aurora Borealis, especially for
interior locations. Refer to spaceweather.gov for more space
weather information, including tonight potential for viewing.

The aforementioned ridge will start to move eastward on Sunday and
flatten, weakening the thermal trough along the coast. This will
likely lead to slightly cooler temperatures across the area
tomorrow, along with increasing onshore flow, afternoon high
temperatures can be expected to generally be around the low to mid
70s.

A weak system will cross into our area Sunday night into Monday,
bringing a chance of showers across most of the region, with the
most likely areas to receive any precip would be the Olympics and
the Cascades. Increased cloud cover on Monday will bring temps
down to around normal, in the mid 60s. High pressure looks to
rebuild back in the area on Tuesday, for slightly warmer temps
in the low 70s for the interior, and mid 60s for the coast.

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...Ensemble guidance in
good agreement for a high pressure to build through Wednesday for
dry and warm conditions, with high temperatures not warming up
too much, staying in the low to mid 70s. Confidence is still
somewhat low looking at the end of next week, with the ECMWF
ensemble highlighting and unsettled pattern Friday and into
Saturday which would bring increased precipitation chances -
meanwhile, the GFS ensemble decides it wants another weekend or
dry and warm conditions over western Washington. Cluster analysis
also favors the ECMWF solution a bit which would bring unsettled
weather into next weekend, but nonetheless, temperatures look to
remain around seasonal normals, but could change if ridging does
develop.

Mazurkiewicz

&&

.AVIATION...An upper ridge remains in control with westerly flow
aloft, but weakens today. Low level onshore flow will increase today
as thermally induced low pressure shifts eastward, with a passing
upper level disturbance allowing for the return of some IFR ceilings
to return to the coastal areas. Not a sufficiently strong push to
reach into much of the interior with continued VFR conditions under
clear skies for most terminals.

KSEA...Northerly winds around 7-9 kt through evening with VFR
conditions under mostly clear skies. Any inland push of stratus
likely too weak to bring much into to south Sound or closer to the
terminal area - around than a 15% chance at best. Winds likely a bit
variable as they go light overnight, but predominantly northwest
winds expected Sunday once winds increase mid-morning onward.
Cullen

&&

.MARINE...Thermal low pressure located near the coast will
shift onshore this afternoon before pushing east of the Cascades
overnight, bringing an increase in onshore flow. The strongest winds
(that is, most consistently around 20-25 kt) will remain over the
outer coastal waters, but with frequent gusts to 25 kt over all of
the coastal zones, as well as in the central and eastern Strait of
Juan de Fuca, have maintained the existing advisories. Over the
coastal waters, the seas will remain rather choppy and approaching
if not meeting steepness criteria, as well, further supporting the
maintaining of the advisories. Elsewhere, with a weak front dropping
north of the area Sunday night and Monday, expect the onshore flow
to further increase. Have upgraded the gale watch to a warning for
the central and eastern Strait for late Sunday as a result.
Additional frontal systems will continue to cross the waters through
much of next week, with winds periodically building to near advisory
thresholds. Meanwhile, seas over the coastal waters will build a bit
with each passing system and remain generally short period, around 7
to 9 seconds, through the middle of next week.   Cullen

&&

.HYDROLOGY...The daily hydrology discussion has ended until the
start of the next rainy season; it will only be updated as needed.

&&

.SEW WATCHES/WARNINGS/ADVISORIES...
WA...None.
PZ...Small Craft Advisory from 4 PM this afternoon to 3 AM PDT Sunday
     for Central U.S. Waters Strait Of Juan De Fuca-East
     Entrance U.S. Waters Strait Of Juan De Fuca.

     Gale Watch from Sunday morning through Monday morning for
     Central U.S. Waters Strait Of Juan De Fuca-East Entrance
     U.S. Waters Strait Of Juan De Fuca.

     Small Craft Advisory from 5 PM this afternoon to 11 PM PDT
     Sunday for Coastal Waters From Cape Flattery To James
     Island Out 10 Nm-Coastal Waters From James Island To Point
     Grenville Out 10 Nm-Coastal Waters From Point Grenville To
     Cape Shoalwater Out 10 Nm.

     Small Craft Advisory until 3 AM PDT Monday for Coastal Waters
     From Cape Flattery To James Island 10 To 60 Nm-Coastal
     Waters From James Island To Point Grenville 10 To 60 Nm-
     Coastal Waters From Point Grenville To Cape Shoalwater 10
     To 60 Nm.

&&

$$