textproduct: Seattle/Tacoma

SYNOPSIS

Showers continue tonight into tomorrow as low pressure moves through the area. Winds and seas will slowly ease tonight into Saturday. Overnight lows over the weekend may be enough for localized frost and freeze potential. The next front to impact the area looks to arrive late Tuesday into Wednesday for more rain and breezy winds.

SHORT TERM /TONIGHT THROUGH SUNDAY NIGHT/

Rain has mostly ended across western Washington with the exception of a post-frontal convergence zone centered over Seattle and extending east into the Cascades. This feature will slowly shift south and eastward and weaken this evening as the winds slowly ease. Winds across the area remain in the 10-20 mph range with gusts between 20-35 mph. Winds are peaking now and will slowly ease this evening. High temperatures today in the upper 50s to low 60s will cool into the upper 30s to mid 40s.

Another weak low pressure system will move across the area on Saturday, keeping chances for scattered showers in the forecast through tomorrow afternoon. High temperatures remain seasonably cool, into the mid to upper 50s. Skies look to clear out Saturday evening. As the low moves south, offshore flow will begin to pick up Saturday evening with breezy northeasterly winds from western Whatcom county and through the San Juans with gusts up to around 25 mph. Elsewhere, across southwestern Washington, clear skies and mostly light winds Saturday night will promote efficient cooling, with lows reaching from the mid 40s in the metro area to mid 30s in the sheltered valley locations. Our first frost advisory for the season has been issued for portions of the SW WA Cascades and the middle Chehalis river valley. The upper reaches near Olympia and Chehalis could potentially get fog, so there is greater uncertainty there. The winds would be the limiting factor for the foothills and valleys farther north into King and Snohomish counties, but trends will have to be monitored for expansion of the frost advisory.

Sunday looks to be drier and sunnier as high pressure builds back in over the area. Breezy north/northeasterly winds look to continue with gusts up to 20 mph, especially over the waters. Highs in the upper 50s to low 60s. Cool conditions continue Sunday night with the potential for more frost.

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LONG TERM /MONDAY THROUGH FRIDAY/

Ensembles continue to highlight drier but cooler conditions into Monday. Morning lows Monday will likely reflect the previous couple of nights, in the mid to upper 30s for most areas. Could see potentially another round of frost and freeze potential, particularly in the Cascade valley and southwest interior locations. Otherwise, Monday will be mostly dry with high temperatures in the low 60s. A weak system looks to cross over the area Tuesday into Wednesday for a round of light rain. Beyond the middle of the week, there is uncertainty in the pattern but generally, guidance indicates that a return to high pressure and mild conditions is favored.

Mazurkiewicz

AVIATION

Southwesterly flow aloft becoming northwesterly this afternoon as a frontal system leaves the area. A mixed bag of conditions early this afternoon as a convergence zone continues over Snohomish and King counties. Conditions maintaining MVFR/IFR this afternoon and in areas within the convergence zone will continue to see deteriorated conditions (likely PAE, SEA). Conditions will see improvement later this afternoon with ceilings lifting to VFR lasting into overnight. Southerly winds will slowly shift to the north for terminals KSEA northward, while areas south of KSEA will continue to see S/SW winds, remaining around 8 to 12 knots. MVFR likely to return Saturday morning for most areas.

KSEA...MVFR conditions this afternoon with S/SW 9 to 14 knots. Will continue to see periodic gusts up to 20 knots this afternoon, with winds easing past 00z. Winds will turn N/NE at times throughout the afternoon due to a convergence zone near the terminal that will start to dissipate by this evening. Additionally, conditions will gradually return to VFR around 21z-00z and continue through the evening. MVFR conditions look to return Saturday morning 12z-17z along with southerly winds.

Mazurkiewicz

MARINE

Strong onshore flow continues this evening behind a frontal passage that occurred early this morning. Small Craft Advisories remain in effect most of the interior waters except Puget Sound, and the Central/Eastern Strait of Juan de Fuca where Gale Warnings remain in effect. Winds through the interior waters are peaking now and will ease below thresholds this evening.

Over the coastal waters, Small Craft Advisories continue through mid-day Saturday. Winds will slowly ease overnight into Saturday morning, but seas look to remain above 10 feet through mid-day Saturday. Seas will remain choppy and locally-wind driven with the dominant period being in the 8-10 second range.

A weak low pressure system will move through on Saturday, behind which winds will turn offshore Saturday evening. Winds will briefly be enhanced slightly in the Northern Inland Waters near the San Juans and off the coast in the central and southern coastal waters zones, with potential for wind gusts to approach Small Craft criteria overnight into early Sunday morning.

Winds ease next week as high pressure builds back in from well offshore. The next low pressure system look to move across the area Tuesday night into Wednesday, but there remains some uncertainty in timing as this is later than previously forecast.

After Saturday, seas look to remain in the 5-8 ft range Sunday through the first part of next week.

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SEW WATCHES/WARNINGS/ADVISORIES

WA...Frost Advisory from midnight Saturday night to 8 AM PDT Sunday for Foothills and Valleys of Pierce and Southern King Counties-Foothills and Valleys of Thurston and Lewis Counties-Middle Chehalis River Valley.

PZ...Small Craft Advisory until 5 AM PDT Saturday for Grays Harbor Bar.

Small Craft Advisory until 8 PM PDT this evening for Admiralty Inlet-West Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Warning until 11 PM PDT this evening for Central U.S. Waters Strait Of Juan De Fuca-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-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.

Small Craft Advisory from 11 PM this evening to 6 PM PDT Saturday 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.