textproduct: Seattle/Tacoma

SYNOPSIS

A stronger, more fall-like system will move through the region this evening into Friday, bringing more widespread rain and some gusty winds to western Washington. Drier conditions are expected this weekend, however additional chances of precipitation will likely return to the area by early next week.

SHORT TERM /TODAY THROUGH SATURDAY/

No major updates have been made this morning. Please see below for the previous discussion, with an updated aviation and marine section.

A frontal system will move across western Washington this evening into Friday, bringing widespread rain to the area, along with some gusty winds along the coast and the Strait of Juan De Fuca. Rain will start to spread along the coast and Olympics this afternoon, with most of the rain reaching interior portions of western Washington by this evening. Most lowland locations will receive between half an inch to an inch of rainfall, with the Olympics and Cascades likely to receive between an inch and an inch and a half of rain. High temperatures will cool with most locations seeing upper 50s, and low 60s.

As the upper trough moves through the region Friday, rain will transition more to showers. Winds will increase across the area on Friday as the parent surface low approaches the coast. At this time, much uncertainty exists, as wind strength is dependent on the track of the surface low. The most likely scenario at this time shows wind gusts generally around 30 to 45 mph along the coast Friday morning, with areas along the Strait of Juan De Fuca also seeing gusts generally 35 to 45 mph Friday evening. If the surface low tracks southward, a small chance (10%) exists of gusts reaching 55 mph along Grays Harbor county.

Additionally, the airmass will be unstable in a post- frontal environment, leading to a slight chance of thunderstorms becoming possible across most of the area Friday afternoon and evening. Snow levels will lower to 6000 to 7000 feet by late Friday, which could bring the first dusting of snow to the higher elevations of the Olympics and Cascades.

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/

Conditions look to dry out over the weekend with weak upper level ridging across the area, meanwhile temperatures will remain in the low 60s across the area. Ensembles continue to highlight unsettled weather through the first half of next week, with chances of rain returning along with cooler temperatures.

Mazurkiewicz

AVIATION

Most all terminals remain VFR under a high level cloud deck across the area this morning. These ceilings will gradually lower into the afternoon and evening as a low pressure system pushes through tonight into tomorrow. This system will bring rain across the area this evening along the coast and pushing inland overnight into early Friday. Ceilings will lower to MVFR to IFR, with periods of LIFR possible in the heaviest rain along the coast, beginning after around 03-06Z tonight and will persist through the end of the TAF period. There will be a slight (15-25%) chance of thunderstorms on the back end of the system, mainly Friday morning along the coast and Friday afternoon through the interior.

Winds this morning N 5 kt or less will increase up to 5-8 kt this afternoon before easing tonight. Winds will increase along the coast after around 12Z Friday morning, then across the interior after 18Z Friday. Gusts up to 15-25 kt possible along the coast through 18Z Fri.

KSEA... VFR conditions continue through tonight with high clouds slowly lowering. Rain arrives at the terminal after 00Z this evening and will continue through the TAF period. Ceilings and visibilities likely deteriorate to MVFR after around 09Z with the precipitation. North winds will continue today at 5-10 kt through this evening. Winds turn to the south Friday morning and increase during the day with gusts up to 20-25 kt after around 18Z Fri.

HPR/62

MARINE

High pressure will briefly build back over the coastal waters today behind a weak front that moved through yesterday. A stronger low pressure system remains on track to move across the waters tonight into Friday. There remains some uncertainty in the exact low track, but it currently looks to make landfall somewhere between far northwest OR and southwest WA. The greatest likelihood of gale gusts (over 34 kt) remains the southern coastal waters and the central/east sections of the Strait of Juan de Fuca, where a gale watch has been issued for Friday. There remains a low (15-35%) chance of gusts of up to 40 kt along the southern coastal waters. There still remains a high likelihood of winds/gusts between 20-30 kt with this system across the remainder of the coastal and interior waters, which will meet Small Craft Advisory criteria. Additionally, there is a 15-20% chance of thunderstorms in the southern coastal waters with the precipitation moving through Friday morning.

Expect conditions to ease over the weekend into next week with no significant impacts with a weak system passing through Sunday. High pressure will rebuild over the coastal waters Monday before a stronger system looks to move through on Tuesday for another round of increasing winds.

Seas will build to 5-8 ft Thursday, and increase to 9-12 ft Friday with the system moving through, before dropping back to 4-6 ft this weekend, and 6-8 ft midweek next week.

HPR/62

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Gale Watch from Friday morning through late Friday night for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Watch from this evening through Friday evening for Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.