textproduct: Seattle/Tacoma

SYNOPSIS

A weak system will bring precipitation chances across northern portions of Western Washington. Warmer and drier conditions Friday into the weekend with high pressure settling over the region. Onshore flow returns next week for a return of closer to normal temperatures but continued dry conditions into next week.

SHORT TERM /TODAY THROUGH SATURDAY/

Mid and high clouds continue across portions of Western Washington this morning. An upper-level zonal pattern will remain over the region through Friday afternoon. A weak system system moving northeast into British Columbia will clip portions of northern Western Washington and bring the chance for light showers for the North Coast, Olympic Peninsula, and Whatcom County today into Friday. Today's high temperatures will be in the upper 50s to low 60s along the coast and mid to upper 60s. Warmer and drier conditions Friday into Saturday as surface high pressure builds over the region. High temperatures will warm into the low 60s along the coast and upper 60s to low 70s in the interior. Additionally, a thermal trough will build along the coast on Saturday, leading to surface winds to switch offshore. 29

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/

Ensemble guidance remains consistent with high pressure in place over the region with a thermal trough remaining over the area. This will bring light offshore flow to the region and maintain temperatures above normal on Sunday. With the thermal trough pushing eastward and a return to onshore flow, expect to see temperatures trend a few degrees cooler for the start of next week with increased morning clouds. Dry conditions are likely to continue through at least the middle of next week.

AVIATION

VFR with high clouds today. BCFG has been observed across a couple of inland terminals this morning but should subside by 16-17z. While winds will be light tonight, high clouds passing through should help limit fog development. A weak weather system moving into British Columbia could bring light rain showers near northernmost terminals (CLM & BLI) today. Calm to light northerly surface winds this morning. Surface winds will transition southerly late this evening.

KSEA...VFR conditions will prevail today with high clouds. Surface winds northwesterly at 5-6 kt or less. Winds will shift southerly late this evening around 07Z. 29

MARINE

High pressure returns to the waters this week. A passing front to the north may clip the waters, but won't do much to increase any marine weather concerns. A building thermal trough will bring northerly or offshore breezes over the weekend. Seas become a little steeper over the coastal waters as a result, but expect conditions to remain well short of steepness criteria for an advisory. Otherwise, the breakdown of the high pressure could bring a stronger westerly push late Monday through Strait of Juan de Fuca, and represents the next potential chance for advisory conditions.

FIRE WEATHER

Fire weather concerns remain minimal through the next few days. Developing high pressure aloft this weekend with a thermal trough building up the coastline will bring warm temperatures and light offshore flow. This could result in locations in the Cascades and adjacent valleys seeing minimum RH values approach 30% on Sunday. This will be short lived, with onshore flow returning early next week to boost humidity values and cool temperatures.

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...None.