textproduct: Seattle/Tacoma

SYNOPSIS

Active weather pattern for the next week. System dissipating over Western Washington this morning with another one brushing the area tonight. Stronger system later Saturday into Sunday morning could produce windy conditions for parts of the area. Possible break Monday before additional systems reach Western Washington in the middle of next week.

SHORT TERM /TODAY THROUGH SUNDAY/

Widespread clouds this morning across Western Washington. Another round of light precipitation will lift northwards through today. No major forecast updates, previous discussion below:

Satellite imagery shows cloudy skies over Western Washington this morning. Doppler radar has echoes over mostly the eastern half of the area. Light flow in the lower levels with some reduced visibilities, 3 to 5 miles, in light rain and fog. Temperatures at 3 am/11z were in the lower to mid 40s.

System dissipating over Western Washington this morning. Easterly gradients across the Cascades weakening but shallow layer of cool air near the pass surfaces remaining intact. Have extended the Winter Weather Advisory for freezing rain in the passes until noon. Could see a tenth of an inch or less of ice accumulation. Just a chance of rain this afternoon for the area. Highs near 50.

Large upper level low remaining off the Northern California coast tonight. Another system spinning out of the low brushing Western Washington this evening for another round of light precipitation. South southwesterly flow aloft with snow levels above the passes, 5500 to 6500 feet, overnight. With the low so far to the southwest no winds to speak of with this feature as well. Temperatures will only drop a few degrees with lows in the lower to mid 40s.

Low moving north Saturday and weakening into an open trough. Another system spinning out of the low approaching the area with rain at times throughout the day. Highs in the lower to mid 50s.

Surface low associated with the trough moving northeast Saturday night into Sunday morning. The models are having a hard time latching on to a solution for the path of this feature. Yesterday the ECMWF had the low moving inland Sunday morning while the GFS kept the surface low offshore along 127W. The 00z runs have flop flopped with the ECMWF keeping the low offshore while the GFS moves the low inland Sunday morning. Ensemble means on both models have wind gusts in the 25 to 35 mph range late Saturday night into Sunday morning with just a small number of solutions ( 10% or less ) indicating wind advisory speeds. Associated front moving southwest to northeast and stalling over the area for another round of rain Saturday night into Sunday. Snow levels dropping to near 3500 feet Sunday with snow on the higher passes. Lows Saturday night in the lower to mid 40s. Highs Sunday near 50.

Coastal Flood warning in effect along the Pacific coast this morning. Better chance for more widespread coastal flooding ( along the Pacific as well as the interior waters ) Saturday and Sunday with lower pressure over the area and windier conditions producing higher waves. Felton

LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/

Extended models in pretty good agreement on the overall pattern with a weak trough moving through Sunday night into Monday followed by a very temporary ridge. Flow aloft switching with systems moving into the area from the northwest instead of the southwest beginning Tuesday. System Tuesday night into Wednesday producing another round of breezy conditions with the ECMWF ensemble mean gusts near 40 mph. With the storm track out of the northwest snow levels will be lower with all of the passes seeing snow beginning Tuesday. Temperatures near normal with highs in the mid 40s and lows in the mid 30s.

AVIATION

Light west to southwest flow aloft will turn southerly and increase late tonight as an upper level trough west of Northern California begins to lift northward toward the Pacific Northwest. A mix of MVFR and IFR/LIFR ceilings this morning with surface visibilities reduced to 3-5SM in light showers and/or drizzle. Marginal improvement to MVFR this afternoon for most areas as precipitation diminishes. Another round of rain expected this evening into the overnight hours. Light winds today generally 5 kt or less, with the exception of the coast.

KSEA...IFR ceilings this morning in light showers and/or drizzle. will improve to MVFR this afternoon. Conditions will improve to MVFR this afternoon as showers diminish. However, another round of rain expected this evening after 00Z. E/NE surface winds today generally 5 kt or less, shifting SE early Saturday morning. 27/29

MARINE

High pressure east of the Cascades with a strong surface low well offshore giving low level easterly flow to the waters. System spinning out of the low moving through tonight into Saturday. A stronger frontal system associated with a 985 mb low just offshore will move through the waters later Saturday into Sunday morning. Possible break Monday before before the pattern becomes active again in the middle of next week.

Gale watch has been issued for all the waters Saturday night into Sunday morning as a surface low moves inland to the north Sunday morning. Small craft advisory winds are possible over the coastal waters next week as additional systems reach the area.

Seas 4 to 6 feet today building to 6 to 9 feet Saturday and to 10 to 15 feet Sunday. Seas subsiding under 10 feet Monday before building back into the 10 to 14 foot range later Tuesday. Felton

HYDROLOGY

Multiple frontal systems will move through Western Washington into next week. The Skokomish River, starting from elevated levels, is forecast to approach flood stage Sunday before slowly receding next week. No additional river flooding is expected the next 7 days.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Winter Weather Advisory until noon PST today for Cascades of Pierce and Lewis Counties-Cascades of Snohomish and Northern King Counties-Cascades of Southern King County.

Coastal Flood Watch from Saturday morning through Saturday afternoon for Grays Harbor County Coast-Northern Washington Coast.

Coastal Flood Warning until 1 PM PST this afternoon for Grays Harbor County Coast.

PZ...Gale Watch from Saturday evening through Sunday morning 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-West Entrance U.S. Waters Strait Of Juan De Fuca.

Gale Watch from late Saturday night through Sunday morning for Admiralty Inlet-East Entrance U.S. Waters Strait Of Juan De Fuca-Northern Inland Waters Including The San Juan Islands-Puget Sound and Hood Canal.

Small Craft Advisory from 6 AM to 6 PM PST Saturday 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.