A cool upper level low over the area will shift south this afternoon. Snow or a mix at times may produce light accumulation from the central coast to the southwest interior/hood canal this morning. Rain and snow showers over the area gradually dissipate by midday. Mostly dry conditions over the weekend with a weak ridge of high pressure over the region. The next front arrives later monday and tuesday with breezy and wet conditions. Drier weather returns by the middle of next week.
The convergence zone which dropped 1 to 3 inches overnight across parts of western snohomish/skagit counties and whidbey island has mostly dissipated. Radar shows just a few lingering showers north of seattle but this activity is unorganized and not likely to result in an additional accumulations, thus this advisory was dropped for those areas.
A closed upper low over wa this morning is associated with a -38c cold pool aloft and a surface low feature just offshore. Latest msas analysis places a 1013 mb close surface low west of the central coast, which is generating a batch of instability showers moving into the southwest interior. 1000-850 mb thickness values near 1385m with steep lapse rates in the low levels and surface temperatures near freezing should keep showers in the form of snow for most the morning. Models differ on how quickly this activity shifts south, but given the upper low closing off over the area, showers may stick around through at least the morning commute. will need to monitor the progress of showers reaching inland but model precipitation amounts generally agree than light accumulations could reach up to the tacoma area but probably under an inch. A dusting of snow may reach the seattle metro area but most the showers will stay confined to the lower hood canal and sw interior to the central coast. The winter weather advisory was expanded to thurston and lewis counties with 1 to 2 inches of snow possible this morning in heavier showers. The low will drift south this afternoon and mixed rain/snow showers will gradually end.
High pressure is expected to build over the region this weekend with dry weather. There could be some patch fog, mainly in prone low lying valleys including olympia and shelton. Fog should not be widespread and temperatures will warm slightly during the day, but remain a bit chilly at night, near freezing in colder outlying areas. Mercer
The extended forecast closely followers the ecmwf solution which brings a decent consolidated front into the area monday night and pushing east tuesday with a transition to showers. This looks like a garden variety front and is progressive, so river flooding is not expected to be an issue. Temperatures will be a bit milder and snow levels will keep any snow limited to the passes. Precipitationamounts are not terribly impressive and suggest a few inches of snow possible, but may not reach advisory level.
The trailing trough will shift east on wednesday with a gradual drying trend. High pressure builds over the pacific northwest with possible undercutting of the high in split flow keeping systems to our south. The middle to later part of next week appear to look dry with partial sunshine. Mercer
Mercer
River flooding is not expected for the next 7 days.
Wa...winter weather advisory until 10 am pst this morning for central coast-hood canal area-lower chehalis valley area-southwest interior.
Pz...none.
A weak low pressure center off the central coast will move south today, with weak offshore flow developing. Moderate offshore flow will develop over the weekend as a deeper low far to the southwest moves into california. A front will move through the area monday and monday night, with small craft advisory strength winds likely over most waters. These winds will probably extend into tuesday. Westerly swells of 15 ft or so may reach the coast monday night and tuesday. 27
Weakening upper level low over the area this morning will shift east of the cascades this afternoon. Light flow aloft becoming north northeasterly this afternoon into tonight. Ceilings in the 1000-2000 foot range this morning with local ceilings below 1000 feet and visibility 1-3sm in light snow showers from about tacoma south and west and north of everett until 18z. Ceilings improving to 3000 to 4000 feet this afternoon and to aoa 5000 feet this evening.
Ksea...ceilings 1000-2000 feet this morning lifting to 3000-4000 feet this afternoon. Improving trend continuing tonight into saturday morning. Showers approaching the terminal from the southwest 14z-18z could briefly reach the terminal with the precipitation type being rain and snow mixed. No snow accumulations expected. Light southerly wind becoming northerly after 00z. Felton