A dry upper low off the washington coast will shift inland tuesday and dissipate. Cool offshore flow and lack of clouds will allow morning low temperatures to dip into the upper teens and 20s monday and tuesday. Shower chances will return around wednesday through the end of the week as an upper trough reaches western washington. Low snow levels may produce a mix of rain and snow down to 500 feet at times. Dry and milder weather is possible next weekend.
Offshore flow has turned more easterly this afternoon and fraser outflow winds will diminish shortly with the bli-ywl at -10 mb and easing. Surface high pressure building east of the cascades is causing a modest rise in the easterly cross cascade gradient, now close to -7 mb sea-eat. However, easterly gap flow should not strengthen much and any breezy winds are likely to stay localized to the upper passes.
Much drier air is in place across western washington with dew points currently in the teens across much of the area. An upper low drifting west off the washington coast will be moisture starved and is not expected to have much if any affect on clouds or temperatures. With partial clearing tonight, strong radiational cooling is likely given the low dew points and lack of surface flow. Late night and morning temperatures will fall into the 20s across much of the lowlands with upper teens in the typical cold pockets. The good news is the dry air should prevent fog or freezing fog and ice should not cause much impact on travel. motorists should still use caution, especially near any sources of water run off that would freeze at night. Highs will reach the mid to upper 40s with some sunshine in the forecast through tuesday.
Models continue to have difficulty with the evolution of the next low pressure system that may reach the area wednesday. The gfs is sticking by a solution that takes most of the energy and moisture inland to our south on wednesday. An upper low offshore is forecast by the ecmwf to lift moisture northward across the area wednesday which is the preferred solution for now. Cold dry air may allow some light snow to fall at the onset, but steadier light precipitation may not begin until midday and would likely just be a mix of rain and snow with no accumulation expected. Southerly gradients develop rather quickly, so mostly cold rain is expected by wednesday night, though a mix or wet snow could fall on higher hills above 500 feet. Mercer
Both the gfs and ecmwf maintain upper level low pressure over the region, though the extent of split flow is different between the models. The flow will still be southerly, so the impressive -38c cold pool aloft may still result in just mixed rain and snow in the lowlands. Some snow could fall in the foothills and higher hilltops above 500 feet later thursday into friday, but the lack of moisture and light precipitation should not produce much if any accumulation. However, the mountains will probably pick up a few inches.
Models continue to struggle with the pattern going into next weekend but there seems to be a trend toward a drier split flow pattern that keeps systems to our north and south. Kept the forecast dry for now until there is better agreement. Temperatures should warm slightly and low temperatures will not be nearly as cold, only dropping to near or just below freezing. A system could approach by sunday or wait until monday. Mercer
River flooding is not expected for the next 7 days.
Wa...none. Pz...small craft advisory until 10 am pst monday for coastal waters from point grenville to cape shoalwater 10 to 60 nm.
small craft advisory until 4 pm 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-northern inland waters including the san juan islands-west entrance u.s. Waters strait of juan de fuca.
Strong high pressure from alberta into montana will weaken and move slowly southeast through tuesday. Offshore flow will continue through wednesday but will gradually weaken with time. Small craft advisories remain in effect for the northern inland waters, the western two-thirds of the strait of juan de fuca, the outer coastal waters, and the northern two thirds of the inner coastal waters. All advisories are expected to come to an end monday afternoon.
A weak trough of low pressure will develop over the coastal waters on wednesday. This will give light southerly flow to the inland waters mid week. Albrecht
Northwesterly flow aloft will become more westerly overnight into monday morning as an upper level low develops west of vancouver island. Northeast to east flow at the surface will continue as high pressure remains over central british columbia and a weak trough of low pressure sits over the coastal waters. the air mass is dry and stable.
Vfr conditions prevail and will continue through monday. Expect only a few high clouds at times. Albrecht
Ksea...good vfr conditions. Winds east to northeast 8-12 kt. Albrecht