textproduct: Seattle/Tacoma

SYNOPSIS

Upper level low over the area will move east today. Weak upper level ridge trying to build tonight and Friday with a system moving by to the north Friday. Upper level ridge strengthening Friday night and remaining in place into early next week. Upper level trough moving by to the north Tuesday with an upper level low approaching the Oregon coast.

SHORT TERM /TODAY THROUGH SATURDAY/

The latest forecast remains on track this morning with no updates. Upper level low slowly moving east today. Moisture wrapping around the low moving into Western Washington keeping showers in the forecast. Snow levels 2500 to 3000 feet for snow in all the passes except Snoqualmie. An additional 4 to 8 inches of snow possible today in the Cascades with most of the snow coming in the morning. The advisory will remain in effect through 11 am. Convergence zone over Island County will drift east and dissipate this morning. Highs in the lower to mid 50s.

Low well to the east tonight with the upper level flow becoming northwesterly. Upper level ridge trying to build into the area. Showers coming to an end in the lowlands but lingering in the mountains in the evening hours. Plenty of moisture left over Western Washington keeping skies mostly cloudy. This will prevent lows from getting too cold Friday morning. The colder locations will be in the mid 30s while a majority of the area will be a couple of degrees either side of 40.

Weak system riding over the flat upper level ridge Friday for a chance of showers along the coast and over the northern portions. Mostly cloudy for the remainder of the area. Highs warming up getting closer to normal, in the mid 50s.

Upper level ridge strengthening Friday night and Saturday with the ridge axis right along the coast. Clearing skies will allow temperatures to drop into the 30s Saturday morning. Warming trend continuing with highs in the upper 50s to mid 60s.

Felton

LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/

Upper level ridge remaining over Western Washington into Monday. Low level offshore flow Sunday becoming light Monday. Trough riding by to the north Tuesday with an upper level low approaching the Oregon coast from the southwest. Slight chance moisture spinning out of this low makes it to Western Washington. A little bit better chance of showers Wednesday as the low moves closer to the coast.

Warming trend through the weekend peaking Monday with highs in the 60s and lower 70s. The forecast high of 67 degrees Monday in Seattle would be the warmest day since October 7th. Highs cooling Tuesday and Wednesday back mostly into the mid and upper 50s. Lows in the lower to mid 40s cooling to the mid 30s to lower 40s Wednesday morning.

AVIATION

An upper level trough will shift east of the region today with north to northwest flow aloft over Western Washington as weak upper level ridging offshore begins to rebuild into the area late today. Low level onshore flow will lead to some convergence zone activity into midday. Widespread MVFR ceilings and pockets of IFR are expected to gradually lift to low end VFR late this afternoon into the evening for most areas. Residual low level moisture will lead to areas of MVFR ceilings across the region again on Friday morning.

KSEA...MVFR ceilings are expected to persist through at least 22Z with some limited improvement thereafter to low end VFR thresholds between 035-050. Surface winds S/SW 8 to 12 knots.

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MARINE

Onshore low will gradually relax tonight as surface ridging over the coastal and offshore waters shifts into the interior of Western Washington. A weak front will clip the coastal waters on Friday, but is not expected to generate much in the way of impacts. A ridge will strengthen over area waters over the weekend with the flow turning northerly or weakly offshore as thermally induced low pressure expands northward along the Oregon coast. Onshore flow returns early next week as another frontal system passes north of the waters. This may generate a strong westerly push in the Strait of Juan de Fuca Monday night into Tuesday.

Seas will straddle the 10 foot mark today before subsiding back into single digits Friday into the early portion of next week.

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HYDROLOGY

No river flooding in the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Winter Weather Advisory until 11 AM PDT this morning 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 PM PDT this afternoon 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-Grays Harbor Bar.

Small Craft Advisory until 11 AM PDT this morning for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.