Dry conditions and clear skies are expected to continue through monday morning as high pressure aloft remains over western washington. Temperatures will dip to near or just below freezing, with highs reaching the 40s to around 50 today and monday. The next front will arrive monday afternoon with rain and snow above 1000 to 2000 feet into tuesday with breezy winds. Snow accumulation in the passes may cause slick pass conditions and possible delays monday night into tuesday, check road conditions at 5-1-1 before departing. Drier weather will return by late wednesday into next weekend with temperatures near or slightly above average.
Goes-17 fog/stratus imagery and obs indicate mostly clear skies across western washington this morning. Temperatures are generally in the 20s with low 30s around the warmer seattle metro area. Dew point and temperature spreads show drier air has settled over the area but typical colder pockets are still getting periods of freezing fog. The kitsap, parts of hood canal, and parts of the southwest interior are the areas that may still see some isolated or patchy freezing fog, dissipating by mid morning. Otherwise, sunshine will prevail today with slightly warmer highs reaching the mid 40s to the lower 50s.
High clouds could begin to reach the area early monday morning and could keeps lows from dipping quite as cold, but many areas should still reach freezing. Southerly flow will increase ahead of an approaching front with at least filtered sunshine allowing for a bit more warming with more spots reaching the low 50s. Models remain in good agreement that rain will reach the coast midday and quickly spread inland later in the afternoon and evening. Forecast gradients are not especially strong, but mixing and some instability along the front should give some breezy winds to much of western washington and even parts of greater puget sound, especially behind the front. A wind advisory could be needed for marginal wind gusts to 45 mph, mainly tacoma northward and near the coastlines.
Snow levels start off low monday evening, around 1000 feet but rise to at least 2000 feet monday night as steadier precipitation reaching the cascades. The system is progressive, but most models still produce up to 1 inch of liquid on the higher south facing slopes of the volcanos, and maybe half that in the passes. This could translate to advisory level snow amounts with 6+ inches possible in the cascade passes and possibly near a foot at ski resorts or higher elevations above 6000 feet.
Snow levels fall with the upper trough and much colder air aloft moving over the area tuesday into early wednesday before shifting east. Snow levels still look to remain high enough to keep precipitation as rain at sea-level with maybe some periods of mixed rain/snow with no accumulation on the higher hill tops around 500 to 1000 feet. The puget sound convergence zone is expected to become active late tuesday in typical north king to snohomish county corridor. As the flow aloft turns northwesterly late tuesday night and wednesday morning, the flow will favor pushing the convergence zone south over the seattle to tacoma areas. If precipitation is heavy enough for a long enough period of time, snow levels could be dragged artificially down to the hilltops. But temperatures still look marginal to supports hilltop snow and accumulation outside of a dusting on grassy surfaces is not expected. There is a chance the convergence zone could reach stevens pass initially and then snoqualmie pass by early wednesday morning. This could enhance snow amounts by a couple inches if it sets up just perfectly.
Showers will decrease across most areas early wednesday, but rain and snow above 1000-2000 feet could linger with the convergence zone over king/pierce counties. The band should weaken and dissipate by wednesday evening.
High pressure will build thursday through the weekend with a return to dry conditions. High temperatures will be noticeably milder, with 50s and possibly the first highs reaching 60 by friday or saturday. Lows will be in the 30s to around 40, with cold pockets reaching near freezing but not as cold as recent mornings. Sunshine is expected to prevail through the period, though some high clouds could clip the area at times as weak systems pass north of the area. Mercer
A front monday night and tuesday will bring precipitation to the cascades and olympics, but low snow levels and the quick passage of the system should not cause any rivers to flood. Flooding is not expected for the next 7 days.
Wa...none. Pz...small craft advisory for hazardous seas until 1 am pdt monday 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.
small craft advisory for hazardous seas from 11 am this morning to 1 am pdt monday 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.
gale watch from monday morning through late monday night for 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-northern inland waters including the san juan islands.
Light northeast to east flow will continue through today. The only advisories will be for the coastal waters where a westerly 10-11 ft swell at 16-18 seconds will move through the offshore waters later this morning and into the nearshore coastal waters this afternoon and evening.
A front will reach the area monday afternoon and night and move inland tuesday morning. Expect small craft advisory southerly winds to develop ahead of the front starting monday morning and continuing until the front passes when winds will turn west to northwesterly. There are indications that gale force winds may occur over the northern two thirds of the coastal waters and over the northern inland waters as strong flow aloft with the front interacts with the olympics. Hence a gale watch has been issued for those areas monday through monday night.
Strong northwesterly winds are expected across most of the waters on tuesday behind the front and as high pressure offshore approaches the waters. Then winds will diminish on wednesday as high pressure moves into the waters. Albrecht
An upper level ridge will continue to build over western washington today and remain the dominant influence across the region through tonight. This will keep terminals dry and mostly vfr throughout the day, with the exception of terminals in the southwest interior, where patchy areas of freezing fog and stratus remain possible through 18z. The airmass is mainly dry and stable. Northeast flow aloft will start to shift to the north-northwest early this evening.
Ksea...clear skies. Ne winds around 5-10 kts, shifting to the north-northwest this afternoon. Sb