Surface high pressure over british columbia and east of the cascades will maintain offshore flow into early next week. Strong northeast fraser outflow winds will affect parts of the north interior tonight into sunday morning before easing. Drier air filtering into western washington will result in colder temperatures, especially monday and tuesday when lows should fall below freezing in most areas. A system arriving from the south may bring some light rain and snow wednesday and thursday with snow levels around 500 to 1000 feet. Low pressure will begin to shift east friday with a drying trend possible into next weekend.
Fraser outflow winds have developed across the north interior with the strongest gusts so far reaching up to 35 mph across western whatcom, the san juans, and western skagit counties. The bli-ywl gradient reached close to -14 mb this morning but has not shown any clear trend this afternoon. Model forecast gradients continue to run around nearly -5 mb too strong which was expected and accounted for in the forecast. A lull in pressure gradients was hinted at in the models and should strengthen a bit more tonight. This may still produce the advisory level wind gusts of 45 to 50 mph tonight before easing sometime sunday morning. Will keep the wind advisory in place for western whatcom, western skagit, and the san juans with marginal gusts up to 45 or 50 mph tonight. Tree limb damage and localized power outages are still possible. Winds elsewhere will become breezy out of the north or northeast.
A few snow showers have been noted in road report obs near the upper passes and also seen on area web cams. This activity remains near the crest and is not expected to accumulate or last much longer into the evening as drier air works into the area.
Winds will settle down sunday afternoon, and low dew point air will be in place across western washington sunday night through tuesday. Clear skies and light flow should allow for efficient radiational cooling with low temperatures falling below freezing across nearly the entire area monday and tuesday mornings. A few cold pocket locations like olympia and shelton could even dip into the upper teens with upper 20s to around 30 in the warmer metro areas. Highs will peak in the mid to upper 40s. Mercer
Global models show a system arriving on wednesday but there is little agreement on how much splitting the system will undergo or where the northern branch low will form. The ecmwf continues to be the wetter of the models with the closed upper low off the coast and moisture lifting north over the area. There could be some initial overrunning light snowfall if precipitation arrives in the morning, but more than likely just mixed rain/snow will transition to cold rain in the lowlands. Minor accumulation below an inch on hilltops is possible but probably is not in the cards below a few hundred feet. The gfs and canadian develop the upper low directly over the pacific northwest with less moisture to work with and precipitation would be more showery in this case. These models also show a more progressive pattern with the low shifting east and a faster drying trend wednesday night and thursday. Decided to go with the slower ecmwf and keep some chance pops into thursday. Most models show a period a drier weather friday into saturday, although timing of the next system is uncertain and could arrive by saturday. Given this is the day 6-7 period, it seems reasonable to maintain the dry forecast until there is a little more model agreement on timing of the next system. Mercer
Mercer
River flooding is not expected for the next 7 days.
Wa...wind advisory until noon pst sunday for san juan county-western skagit county-western whatcom county.
Pz...small craft advisory until noon pst monday 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-west entrance u.s. Waters strait of juan de fuca.
small craft advisory until midnight pst sunday night for east entrance u.s. Waters strait of juan de fuca.
small craft advisory from 10 am sunday to noon pst monday for northern inland waters including the san juan islands.
gale warning until 10 am pst sunday for northern inland waters including the san juan islands.
small craft advisory until 7 pm pst sunday for admiralty inlet- puget sound and hood canal.
A 1050 mb arctic high from north-central montana into alberta continues to spill into central british columbia is resulting in fraser outflow. Winds are near gale over the northern inland waters and are expected to increase to gale force by this evening as pressure gradients between the interior of bc and the northern inland waters tighten. Small craft advisory conditions are occurring over the remainder of the waters with the outflow and strong n/ne pressure gradients.
Winds will very slowly diminish sunday through tuesday as the arctic high pressure slides southeast into the central us and offshore pressure gradients relax. Albrecht
Moderate northerly flow aloft will become northwesterly tonight and sunday. Strong high pressure extending from the canadian prairies into central british columbia will give northeasterly low level flow through sunday. The air mass is dry and stable.
A few clouds with bases around fl050 persist this afternoon over the mountains. These clouds will dissipate this evening leaving mainly clear conditions later tonight through sunday. The air mass will remain dry and no fog is expected across the forecast area through at least sunday.
Northeast surface winds 20-30 kt with some gusts to 40 kt can be expected from the san juan islands northeastward through western whatcom county through sunday morning. Winds will slowly diminish sunday afternoon. Albrecht
Ksea...good vfr conditions. North winds 10-15 kt with occasional gusts to 20 kt will become 05008-13 kt this evening then shift back to northerly and increase to 11-15kt after 17z sunday. Albrecht