A cool upper level low over the area today will weaken tonight and shift east of the area on friday. Mostly dry conditions over the weekend with a weak upper level ridge over british columbia and northeasterly flow aloft over western washington. Next front arriving later monday with the trailing upper level trough over the area on tuesday.
Satellite imagery and doppler radar show band of showers along the coast just beginning to move into the interior at 3 am. Snow has already been reported with the showers along the coast and as far east as olympia. cloudy skies over the remainder of the area. Temperatures at 3 am/11z were in the upper 20s to mid 30s.
Showers moving northeast this morning reaching the puget sound area in time for the morning commute. Precipitation type with the showers will mostly be snow with temperatures in the mid 30s and dew points in the lower 30s. Heavier showers embedded in the band can drop a quick inch of snow with accumulations even on the road surfaces. Main band of showers will move into the cascades by 18z but doppler radar shows scattered shower activity behind the main band of showers. Have issued winter weather advisories for the north coast as well as the interior lowland zones from seattle south including the cascade foothills for the morning hours for the possibility of an inch or two of snow. Low level onshore flow increasing later this morning into this afternoon. This will raise the snow level up to around 1000 feet. Shower activity will decrease as well. Another cool march day in store with highs only in the lower 40s.
Upper level low moving over western washington overnight and weakening by morning. Low level onshore flow weakening with snow levels dropping back down under 500 feet by early friday morning. With the low weakening shower activity will become spotty and light overnight with the exception being a possible convergence zone over snohomish county. Lows friday morning will be in the upper 20s to mid 30s.
Upper level low slowly drifting east on friday with the flow aloft becoming northerly late in the day. With the low still hanging around will have to keep a chance of showers in the forecast. Snow levels will remain low, 500 feet or less for most of the day, with the lack of any onshore flow. Highs once again will only be in the lower to mid 40s.
Upper level low remaining over eastern washington friday night into saturday. Flow aloft becoming northeasterly as a weak upper level ridge builds into british columbia. Spotty showers will come to an end on saturday. Snow levels will remain low, less than 1000 feet, but significant accumulations are not expected. Lows friday night in the mid 20s to lower 30s. Highs on saturday in the 40s.
Extended models in good agreement with a dry day on sunday. Still some timing differences for the onset of the precipitation on monday but both the gfs and ecmwf are wet by monday night. Cool upper level trough moving through on tuesday. Both models have a ridge on wednesday with the ecmwf showing more amplitude to the ridge versus the gfs but even the gfs has a couple of dry days in the middle of next week. temperatures will remain below normal through the period. Felton
River flooding is not expected for the next 7 days.
Wa...winter weather advisory until noon pst today for bellevue and vicinity-east puget sound lowlands-seattle and vicinity- tacoma area.
winter weather advisory until 10 am pst this morning for hood canal area-lower chehalis valley area-north coast-southwest interior.
Pz...small craft advisory until 4 am pst friday 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.
Onshore flow will increase somewhat today as an area of low pressure moves onshore. Advisory level winds are expected over the outer coastal waters into tomorrow and perhaps in the central strait briefly this evening. Onshore flow will then weaken on friday. Weak offshore flow will return over the weekend before a frontal system brings advisory strength southerly winds to much of the waters on monday. 27
Southwesterly flow aloft will turn more westerly through the day as an upper level low over vancouver island moves weakens and moves east. Southerly surface winds expected through the period. precipitation along the coast will push east through the morning hours. Quick burst of snow is possible across the puget sound area from 12z-17z. Accumulations generally under an inch or two with more on grass than pavement. Spotty rain showers around during the afternoon and evening. Ceilings will continue to be mvfr/ifr through the morning. Cigs generally mvfr through the afternoon with times of vfr. Winds 5-15 knots.
Ksea...cigs generally mvfr through the morning hours, ifr possible between 12z-17z, mainly during times of precipitation. Snow likely between 12-15z as band of precipitation pushes through. accumulations generally under an inch or two, more on grass than pavement. Spotty rain showers otherwise through the day. Southerly surface winds 7-12 knots. Jd