textproduct: Seattle/Tacoma

SYNOPSIS

An upper level low will spin multiple fronts crossing the region over the weekend. These fronts will bring several rounds of lowland rain, mountain snow and gusty winds through early next week. Temperatures will warm to near seasonal values this weekend onward. Active weather continues through the end of next week.

SHORT TERM /TODAY THROUGH MONDAY/

An upper level low will continue to meander over the coastal waters this morning. Recent radar imagery shows an approaching front just offshore. This front will continue to move onshore later this morning with widespread rain showers throughout the interior. High temps will stay in the upper 40s. Along with lowland rain, gradients will tighten, allowing easterly winds to become gusty. Easterly winds will be the strongest along the coast and in the Cascade foothills and valleys with gusts up to 40 to 45 mph at times this afternoon and evening. Snow levels will slowly rise to 2000 to 2500 feet by this afternoon with snowfall continuing in the mountains. Snowfall amounts look to remain under advisory thresholds at this time.

A secondary front will cross over western Washington on Sunday, for another round of lowland rain, mountain snow, and breezy winds. Winds will continue to be breezy in the Cascade gaps, and will be strong in the Northern Interior, San Juans, and Whidbey Island. Snow levels will be a touch higher, generally 3500-4000 feet, with snow continuing in the mountains.

Ensembles are in agreement that the offshore low will continue to meander offshore, with another shortwave entering the area on Monday, continuing the lowland rain and mountain snow pattern. High temperatures will warm slightly in the low 50s. '

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

Waves of precipitation look to continue throughout midweek with the pattern remaining active. High temperatures will continue to be in the lower 50s which is just around seasonal average. With precipitation continuing throughout much of the long term, there will be rises on area rivers, more notably on the Skokomish River. Along with potential river flooding, confidence is increasing on some more significant mountain snowfall, especially later on in the week.

28

AVIATION

Southwesterly flow will increase and turn southerly today as a broad upper level trough digs southward across the northeastern Pacific. Conditions remain VFR across all the area terminals early this morning. Though, expect ceilings to gradually lower towards MVFR along the coast over the next few hours as radar shows the initial band of precipitation moving into the central WA coast. Low level easterly flow will increase today, with gusty easterly surface winds expected near the coast and near gaps in the terrain. A few gusts to 20-25 kt could even make it into Puget Sound terminals at times.

Rain will spread inland to the interior terminals this morning and afternoon. Ceilings may be slow to drop below VFR for interior terminals though, with easterly flow downsloping from the Cascades and drying the lower levels of the atmosphere.

KSEA...VFR conditions will likely persist at the terminal today, with precipitation coverage expected to increase around 18Z. Ceilings will likely lower between 3500-4500 ft, but look to remain VFR through much of the day as easterly flow increases at the surface. Surface winds SE around 10-12 kt early this morning will shift more to the E/NE by late morning. A few gusts of 20-25 kt will be possible through the morning hours and again this evening.

14

MARINE

A series of low pressure systems rotating around the northeastern Pacific will swing multiple fronts across the area waters this weekend, which will bring periods of gales to the coastal waters and the Strait of Juan de Fuca. Strong winds will allow for seas to build across the coastal waters today into Sunday. The dominant wave group will be out of the south, with the outer coastal waters likely approaching 20-25 ft by late tonight.

An active pattern will continue into the early part of the week as another disturbance moves into the area waters on Monday. Though not as strong as the systems this weekend, this system will likely bringing additional headlines to the area waters for winds and seas. High pressure will then attempt to build into the coastal waters in its wake. Seas hovering around 10-12 ft on Monday will continue to subside towards 5-7 ft by midweek.

14

HYDROLOGY

No river flooding is expected over the next seven days but later next week chances increase significantly for flooding on the Skokomish River. Starting this weekend through next week there will be multiple rounds of widespread precipitation along with warming temperatures to raise the snow level. With the thin mountain snowpack and existence of low elevation snow, rain on snow could produce enough snow melt getting added to the otherwise unimpressive forecast precipitation amounts to result in flooding.

SEW WATCHES/WARNINGS/ADVISORIES

WA...Wind Advisory until 10 AM PST Sunday for Foothills and Valleys of Central King County-Foothills and Valleys of Pierce and Southern King Counties-Foothills and Valleys of Snohomish and Northern King Counties.

Wind Advisory from 7 AM this morning to 10 AM PST Sunday for Grays Harbor County Coast-Northern Washington Coast.

PZ...Small Craft Advisory from 4 PM this afternoon to 10 PM PST Sunday for Grays Harbor Bar.

Gale Warning until 4 PM PST Sunday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca-West Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory from 7 AM to 4 PM PST Sunday for Admiralty Inlet-Northern Inland Waters Including The San Juan Islands.

Gale Warning until 4 PM PST Sunday 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.