Today will be sunny as dry offshore flow continues over the area. Moisture associated with a system moving into northern california will move into the area later wednesday through thursday morning. Temperatures will be cool enough that precipitation wednesday night into thursday morning may fall as snow, or a rain-snow mix, on higher hills. Showers with low snow levels will continue thursday into friday as an upper low remains in the area. Drying is expected for the weekend especially on sunday. Temperatures will remain below normal through the period.
Satellite imagery shows clear skies over western washington early this morning. With the clear skies temperatures have dropped below freezing in most locations. At 3 am/11z the colder spots are near 20 while easterly winds at sea-tac are keeping the temperature there in the mid 30s.
One more sunny day for western washington with a weak upper level low well to the northwest and the next system in the eastern pacific moving toward northern california. Surface gradients remaining offshore but temperatures aloft remain cold, 850 mb temps -3 to -7c. Expect another day of below normal high temperatures even with the sunshine. Highs in the 40s will be common. Today will be the 32nd day in a row with a below normal high in seattle. The last day with an above normal high temperature was february 1st.
Some changes in the pattern begin to develop tonight with the upper level low to the northwest moving south. This will turn the flow aloft southwesterly opening the door for the moisture associated with the system moving inland well to the south to reach the area. By late tonight there is a slight chance of showers over the extreme southern portion of the area. With the lack of cloud cover initially tonight temperatures will drop in the 20s and lower 30s before the cloud cover arrives. This will make the precipitation type snow in the locations with a slight chance of showers.
Upper level low continues to drift south and east on wednesday with the flow aloft becoming a little more southwesterly. This will push more moisture up into the area with the best chances for precipitation over the eastern portion of the area. Snow levels will start out low wednesday morning but with the low level flow turning onshore will rise to around 1000 feet in the afternoon. highs on wednesday once again in the 40s.
Low level onshore flow continuing wednesday night. This will keep the snow level off the surface and closer to 500 feet overnight into thursday morning. Upper level low over vancouver island by 12z thursday, close enough to keep showers in the forecast. precipitation amounts with the showers will not be much, a few hundredths at best so if any snow does fall on the higher hills snow amounts will be light. Lows will be mostly in the 30s.
Upper level low drifting down over western washington on thursday keeping a least a chance of showers in the forecast. Snow levels will slowly lift during the day ending up around 1000 feet in the afternoon. Highs will be in the mid 40s.
Extended models in good agreement with the upper level low hanging around on friday with a chance of showers with low snow levels continuing over the area.
Low level flow turning offshore again on saturday with the low level offshore flow continuing into sunday as the next system in the eastern pacific drops way south towards central california. dry north northeasterly flow aloft developing to go along with the low level offshore flow making for a dry forecast saturday night and sunday.
Some differences in the model solutions begin to appear on monday with the ecmwf slower with the approach of the next system versus the gfs. Both solutions are faster than the previous runs. For now will add some cloud cover to the forecast on monday but keep the forecast dry for now. High temperatures will continue to be below normal through the period, mostly in the 40s. We could see a few low 50s on sunday. Felton
River flooding is not expected for the next 7 days.
Wa...none. Pz...small craft advisory until 4 pm pst this afternoon for east entrance u.s. Waters strait of juan de fuca.
Offshore flow today will generally remain below 20 kt, except for advisory level northeast winds around the east entrance. Flow will change to onshore wednesday as a trough of low pressure over the coastal waters shifts inland. Onshore flow will weaken thursday into friday. The onshore gradient on wednesday night may be strong enough for small craft advisory winds over portions of the coastal waters, strait, and puget sound. Otherwise, winds are generally expected to be fairly light over the next 5 days. Offshore flow may redevelop later saturday as surface high pressure builds east of the cascades. Chb
Southwesterly flow aloft will continue with an upper level low near vancouver island. The air mass is dry and stable. vfr conditions will continue today with increasing high clouds tonight as a weather system moves mainly into oregon. Surface flow will be generally northeasterly with high pressure over eastern british columbia.
Ksea...discussion above applies. Northeasterly winds 5-10 kt. Chb