textproduct: Seattle/Tacoma

SYNOPSIS

Onshore flow today with showers mainly in the interior and Cascades. Cool, wet and windy conditions Tuesday into Wednesday with heavy snow possible in the Cascades. Drier weather is in store Thursday into the weekend with high pressure.

SHORT TERM /TODAY THROUGH WEDNESDAY/

Onshore flow continues today with showers mainly in the interior and Cascades, especially King and Snohomish counties due to low level convergence. Up in the mountains, snow levels will hover around 5000 ft then lower to around 4000 ft this afternoon.

Cool, wet and windy conditions are favored Tuesday and Wednesday as a deep upper low spins down B.C. and into WA. Snow levels will start around 3500 on Tuesday but fall to around 1500 on Wednesday with snow in the Cascades and all passes. Periods of heavy snow is possible - a Winter Storm Watch is in effect. Expect windy conditions on Tuesday with S/SW winds gusting to 20-30 mph (peaking Tuesday evening). Temperatures will track below average both days with lows in the 30s and highs in the 40s to around 50. The air mass is slightly unstable on Wednesday with the cool low overhead and there is also a slight chance of thunderstorms. Precipitation tapers off Wednesday night as the low exits east. 33

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

Western WA is under dry northerly flow Thursday and Friday as high pressure forms offshore. Low temperatures will remain cool and in the 30s with freezing temperatures (frost) possible around the south sound both mornings. Highs will reach the mid 50s. The ridge slides inland over the weekend for warmer conditions and highs in the interior in the lower 60s. An upper low slowly tracks south through the offshore waters on Sunday with a chance of showers over western WA. 33

AVIATION

North to northwesterly flow aloft as weak troughiness remains over western Washington. Conditions uniformly MVFR across much of the interior early this morning with some localized IFR. MVFR conditions will likely continue throughout the morning and the first half of the afternoon. Could see conditions pop back and forth from MVFR/VFR throughout the late afternoon. Latest guidance has conditions falling back down to MVFR later in the evening (30-40%) for most terminals in the interior. S/SW winds 8 to 12 knots this morning with a few gusts up to 20 kts possible at times this afternoon as onshore flow continues.

KSEA...Consolidated MVFR conditions at the terminal early this morning. These conditions are slated to remain throughout much of the morning and afternoon, with some guidance suggesting a 30% chance of VFR later in the afternoon. Conditions will then lower to MVFR once again in the evening and in the overnight hours. Southwesterly winds 8 to 12 knots with the potential for some gusts up to 20 kts this morning. Winds look to remain above 10 knots throughout the afternoon.

Mazurkiewicz

MARINE

Surface high pressure developing offshore in the northeastern Pacific. Onshore flow continues over the area waters as well for the small craft advisory in the Strait of Juan De Fuca for enhanced westerlies. A stronger frontal system will approach the area waters late Tuesday into Wednesday for breezy conditions and elevated seas. A small craft advisory has been issued for all of the coastal water zones starting early Tuesday as S/SW winds increase ahead of the front. More widespread headlines are likely for the interior waters as we get closer, along with the potential for some gale strength winds especially in the Strait.

Coastal seas 6 to 8 feet throughout the remainder of today, with seas increasing upward to 9 to 12 feet by Tuesday afternoon. Seas look to remain above 10 feet through Thursday before decreasing by Friday to 3 to 5 feet.

Mazurkiewicz

HYDROLOGY

No river flooding the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Winter Storm Watch from Tuesday morning through Wednesday evening for Cascades of Pierce and Lewis Counties- Cascades of Snohomish and Northern King Counties-Cascades of Southern King County-Cascades of Whatcom and Skagit Counties.

PZ...Small Craft Advisory until 5 AM PDT Tuesday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 5 AM Tuesday to 5 AM PDT Wednesday for 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-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.