000 FXUS66 KSEW 172320 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 320 PM PST Mon Jan 17 2022 .SYNOPSIS...Upper level trough moving down from the northwest reaching Western Washington later tonight into Tuesday. Weak upper level ridge building offshore Tuesday night dissipating Wednesday. Warm front moving into Western Washington Wednesday night with the trailing cold front moving through Thursday. Upper level ridge building Friday and remaining over the area into the first part of next week. && .SHORT TERM /TONIGHT THROUGH THURSDAY/...Satellite imagery shows a little bit of clearing this afternoon with clouds associated with an approaching upper level trough already moving into Northwest Washington. Doppler radar has a line of showers from about Quillayute to Bellingham. Temperatures at 2 pm/22z were in the 40s. Weak upper level trough embedded in the northwesterly flow aloft moving down over Western Washington late tonight into Tuesday morning. Shower activity associated with the trough already over Northwest Washington will spread down over the entire area overnight. Snow levels remaining above the passes. Lows tonight in the lower to mid 40s. Upper level trough moving through the area Tuesday morning with shower activity decreasing in the afternoon. Possible weak convergence zone near the east Entrance of the Strait of Juan de Fuca behind the trough passage later Tuesday morning into the afternoon hours. Highs mostly in the upper 40s. Weak upper level ridge building offshore Tuesday night. Could have a few residual showers lingering around Tuesday evening but for the most part this period looks fairly dry. Middle and high level clouds out ahead of an approaching warm front streaming through the top of the ridge keeping skies mostly cloudy. Lows near 40. Warm front fighting its way through the upper level ridge offshore Wednesday with rain out ahead of the front reaching the coast in the afternoon with a chance of rain inland. Highs near 50. Warm front moving over Western Washington Wednesday night with the trailing cold front arriving Thursday morning. This time frame will have the heaviest precipitation in the next week but not enough to cause any flooding on the area rivers. Snow levels will remain above the passes. Lows in the mid 40s and highs in the lower 50s. .LONG TERM /FRIDAY THROUGH MONDAY/...Models and ensembles still in good agreement with an upper level ridge building Friday and remaining over the area through the weekend. This is the strongest ridge we have seen for awhile with 500 mb heights getting into the 580 dms. Surface gradients and low level flow remaining light which combined with the decent inversion as a result of the ridge and the low level moisture present over the area to produce areas of night and morning fog. Blend high temperatures starting to trend down a little and are slightly below normal meaning the solutions are slowly trending towards more fog over the weekend. Some of the ensemble solutions starting to break down the ridge Monday with an upper level trough moving into the top of the ridge. A majority of the solutions keep the ridge intact for another night and morning low clouds and fog with some afternoon sunshine day Monday. Felton && .AVIATION...An upper trough will slide north of the area with west flow over the area. VFR cigs for most this afternoon with areas of IFR/MVFR. VFR mainly into this evening with MVFR/IFR along the coast. Rain will increase over the area tonight into Tuesday. MVFR/IFR cigs tonight into Tuesday with the light rain. Winds will be light southerly tonight. KSEA...VFR cigs this afternoon with MVFR cigs tonight and increasing rain chances, mainly into early Tuesday. IFR will be possible Tuesday morning. Winds will be light southerly through tonight. JD && .MARINE...A weak weather system will move across the area tonight and through Tuesday. A stronger weather system will move across the area later Wednesday and Thursday for increasing winds. Small Craft Advisory winds for most areas with this weather system. A ridge will build into the area later in the week with northerly, offshore flow through the area. JD && .HYDROLOGY...No river flooding expected in the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$ www.weather.gov/seattle
NWS SEW Office Area Forecast Discussion
Discussion Script by Ken True at Saratoga Weather - WFO Script by SE Lincoln Weather
