textproduct: Seattle/Tacoma

SYNOPSIS

Upper level ridge centered offshore today will weaken tonight and Saturday as a system moves by to the north. The ridge will rebuild Sunday with the ridge axis moving over Western Washington Monday and Tuesday. Thermally induced surface trough developing along the coast Sunday night will remain over the area through Tuesday. Thermal trough moving east Tuesday night with the upper level ridge weakening Thursday. Upper level trough approaching the coast late Thursday.

SHORT TERM /TODAY THROUGH SUNDAY/

Satellite imagery shows high clouds over the southern portion of the area this morning with clear skies near the Canadian border. Temperatures at 3 am/10z were in the 50s and lower 60s except in the Seattle metro area where temperatures were in the mid 60s.

Upper level ridge centered offshore extending over the area today. Light northerly flow in the lower levels. Highs well above normal, in the upper 70s to upper 80s inland and upper 60s to mid 70s coast.

Upper level ridge weakening tonight and Saturday as a weather system moves through British Columbia. Low level flow going onshore tonight bringing cooler marine air into Western Washington. Lows tonight in the upper 40s to mid 50s. Highs Saturday in the lower to mid 70s inland and mid 60s coast.

Upper level ridge rebuilding Saturday night into Sunday. Low level onshore flow weakening Saturday night with the low level flow going northerly again Sunday. Highs rebounding into the mid 70s to mid 80s interior and upper 60s to mid 70s coast. Lows Saturday night in the upper 40s to mid 50s.

LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/

Thermally induced surface trough developing along the coast Sunday night. Upper level ridge offshore moving east with the ridge axis over Western Washington Monday. Increasing low level offshore flow pushing highs into the 80s to lower 90s inland and lower to mid 80s for the coast. Lows in the 50s.

Little change in the pattern Monday night into Tuesday with the thermally induced surface trough still in the area and the upper level ridge centered over Western Washington. Highs a couple of degrees warmer over the interior, 80s to mid 90s. Afternoon seabreezes along the coast with the thermally induced surface trough starting to move inland keeping highs in the upper 70s to mid 80s. Lows in the mid 50s to mid 60s. There is a chance for record breaking highs and record high minimum temperatures Tuesday.

Thermally induced trough moving east of the Cascades Tuesday night into Wednesday. Upper level ridge remaining over the area with 500 mb heights still in the mid 580 dms. Low level flow going onshore cooling highs over the interior 5 to 10 degrees versus Tuesday, in the mid 70s to mid 80s. Highs along the coast in the mid and upper 60s. Record high minimums again possible Tuesday night with lows in the mid 50s to lower 60s.

Upper level ridge weakening Wednesday night into Thursday with an upper level trough approaching the area late Thursday. By 06z Friday the trough axis will be near 130W. This forecast package only goes through Thursday so the forecast is still dry. If the pattern holds up there will be a chance of showers Friday. This would be the first rain in Western Washington in two weeks. Seattle last recorded measurable rain on June 9th.

With the well above normal high temperatures and warm low temperatures moderate HeatRisk across Western Washington Monday and Tuesday. If the forecast trend continues look for a heat advisory for Monday and Tuesday to be issued sometime over the weekend.

Seattle has a chance to reach 90 degrees Monday with a better chance Tuesday. It is rare for Seattle to have 2 90 degree plus days in June. In 81 years of records there have only been 10 years with two or more 90 degree plus days in June. The record for the month is 3 days in 1992, 1995 and the memorable heat dome of 2021. Felton

AVIATION

VFR conditions with mid to high clouds today. MVFR cigs still remain possible (30-50%) between 11z-19z for the coast. Conditions expected to rebound to VFR for the coast. Increased onshore flow evening/tonight will bring increased chances for widespread MVFR cigs. Highest chances (40-70%) are along the coast after 02z, with a slight chance (20%) of IFR cigs between 04z-10z. For interior terminals, changes range between 30-50% after 11z. Light to variable winds early this morning will increase this afternoon to 6-12 kt, with stronger speeds along the coastline. SW winds after 06z-08z Saturday.

KSEA...VFR conditions today with mid to high clouds. Onshore flow starting Friday evening will introduce the chances for MVFR cigs Saturday morning. Latest guidance has a 30-40% chance of MVFR cigs after 11z. Light N/NE winds early this morning will transition to W/NW this afternoon to 6-8 kt. Increasing SW winds after 06z-08z at 6-9 kt.

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MARINE

Broad high pressure over the offshore waters of the Pacific retreats to the west as a low pressure system moves through British Columbia today and Saturday, causing high pressure over Washington's waters to continue to weaken. Once the low pressure system pushes east, high pressure will quickly rebuild over area waters late Saturday evening and will strengthen through midweek.

Elevated winds and seas will continue for the coastal waters through Saturday morning and will begin to subside in the afternoon. Strong northerly flow will cause seas to build to 10-15 ft this evening through Saturday morning. As high pressure continues to strengthen over the waters early next week, increased northerly flow over the coastal waters will bring the chance of small craft winds Monday and Tuesday, with the latest probabilities around 50-80%. Diurnal pushes through the Strait of Juan de Fuca will also begin today and will continue into next week. Guidance suggests the best chance for small craft winds will be on Wednesday, with a 60-80% chance. In addition, guidance is highlighting a slight chance (15-35%) for gales.

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FIRE WEATHER

Elevated fire weather concerns today and again Monday and Tuesday with minimum relative humidity values dropping into the 30s. In some locations Monday and Tuesday, minimum RH values will be as low as the teens and 20s. Fuels will continue to dry and the atmosphere may become conditionally unstable with the surface thermal trough Monday and Tuesday. Fuels are getting close to critical levels. Even without hitting critical levels needed for red flag warnings to be issued, fine fuels like grass and brush will ignite quickly with it being so dry. Lets continue to be careful out there. Felton

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 1 PM this afternoon to 11 AM PDT Saturday 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 5 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.