textproduct: Seattle/Tacoma

SYNOPSIS

Widespread showers continues across Western Washington as an in a cool and somewhat unstable air mass. A series of disturbances will cross the next few days, with the strongest of which bringing unseasonably cool conditions for the start of the weekend. High pressure returns for the start of next week for a drier pattern, though it may remain weak enough to limit the extent of warming.

SHORT TERM /TONIGHT THROUGH FRIDAY NIGHT/

Cool, cloudy, and showery conditions continue across Western Washington today. As onshore flow increases, we'll see a weak Puget Sound Convergence Zone likely develop across Snohomish County in the evening and some lingering gusty winds in the interior, but neither should be particularly long-lived. Expect a brief break early Thursday, but the next impulse will again spread some showers and clouds as a weak front passes through.

The next upper disturbance crosses the region into Friday, and will bring some additional instability. Expect more widespread showers and perhaps enough support for a thunderstorm or two with marginally sufficient instability. One caveat could be that additional cloud cover would limit any additional surface based support from diurnal heating. Nevertheless, widespread showers and cooler temperatures are expected Friday with daytime highs topping out in the 50s.

LONG TERM /SATURDAY THROUGH WEDNESDAY/

As the deeper upper trough arrives in the region Saturday, we'll have continued showers across the region. Steepening lapse rates due to the cooling aloft, and perhaps paired with a little bit of clearing in the clouds, could yield another day of the potential for isolated thunderstorm. This chance would be highest nearest the Cascades and in a potential PSCZ that develops later Saturday. With this colder air mass moving into place, we'll see notably colder conditions in the mountains. While the chances for any snow accumulating remain quite low, those heading to the mountains for any recreation should be prepared for notably colder temperatures - especially given the recent warmer weather and lack of significant snow that makes some of the higher elevations more accessible than they might otherwise be in mid-May.

Ensemble guidance continues to support general high pressure pattern returning to the northeastern Pacific, which should bring temperatures a bit closer to seasonal normals by the end of the weekend into early next week. It may be far enough away to leave the door open for a weak disturbance around Monday to increase clouds a bit, but generally dry conditions remain favored for the start of next week with temperatures returning into the 60s.

AVIATION

Southerly flow turning westerly this afternoon as a post frontal airmass settles over the region. Mixed bag of conditions this afternoon across many terminals as localized showers bring a mix of MVFR/IFR to some terminals, with other terminals seeing VFR. Will continue to see unsettled conditions throughout the afternoon, with rain showers dissipating by the evening conditions will start to improve towards VFR by the overnight hours. Breezy southwesterly winds with gusts up to 25 kts this afternoon will gradually taper down tonight, with S/SW wings of 10 to 15 kts.

KSEA...A mix of MVFR to VFR conditions this afternoon as showers remain near the terminal. Showers will decrease this evening leading to a rebound to VFR conditions, likely around 00-03z. Breezy SW winds 10 to 15 kts with gusts up to 25 kts will continue this afternoon and into the early part of the evening. Gusts will start to subside but sustained winds will remain around 10 to 15 kts.

Mazurkiewicz

MARINE

Onshore flow will continue this afternoon as a trough remains offshore. A Gale Warning continues through the Strait of Juan De Fuca this evening for gusts up to 35 kts. Throughout this push down the Strait of Juan De Fuca, some winds will spillover into the Northern Interior Waters, where a Small Craft Advisory will remain thus evening. Winds will subside by Thursday morning. Onshore flow will continue through the Strait of Juan De Fuca through the end of the week with more pushes through the Strait over the weekend. A system will pass over the area on Sunday for an increase of winds over the coastal waters.

Coastal seas 5 to 7 feet this afternoon will subside generally around 3 to 5 feet on Thursday. Seas will then rebuild towards 7 to 9 feet late Friday and into Saturday.

Mazurkiewicz

HYDROLOGY

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

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Gale Warning until 11 PM PDT this evening for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 11 PM PDT this evening for Northern Inland Waters Including The San Juan Islands.