textproduct: Seattle/Tacoma

SYNOPSIS

Weak system moving through today. Upper level ridge offshore rebuilds tonight and moves inland. The ridge will be east of the Cascades Tuesday. A series of weather systems will move through Western Washington Tuesday night through the weekend.

SHORT TERM /TODAY THROUGH WEDNESDAY/

No major forecast updates this morning, updated aviation discussion below.

Satellite imagery shows dissipating system moving into Southwest Washington this morning. Just middle and high level clouds with this feature. ASOS sites still reporting clear so clouds are above 12,000 feet. The cloud cover has limited the fog coverage with just patchy freezing fog over the South Puget Sound. Temperatures at 3 am/11z were in the 20s and lower 30s.

Dissipating front falling apart over Western Washington today. Middle and high level clouds over the area for a partly sunny/mostly cloudy forecast. Highs in the mid to upper 40s.

Upper level ridge offshore rebuilding this afternoon and moving inland tonight. Cloud cover thinning a little allowing some places to fall below freezing again Tuesday morning. Lows in the upper 20s to mid 30s.

Upper level ridge axis east of the Cascades Tuesday. Southwesterly flow aloft on the backside of the ridge will spread more middle and high level clouds into the area making for another partly sunny/mostly cloudy forecast. Frontal system approaching Tuesday afternoon. Front east of 130W by 00z Wednesday but rain still offshore late in the afternoon. Highs near 50.

Front splitting and weakening as it moves into Western Washington Tuesday night into Wednesday morning but not enough to prevent a little rain over the area. Looks like the rain will hold off in the Seattle area until after midnight. Another dry day Tuesday will tie the record long January dry streak in Seattle at 15 days. Chances of breaking the record not very good at all as the flow aloft consolidates over the Eastern Pacific and another system moves into Western Washington Wednesday night. Rain out ahead of this front reaching the coast midday with the rain spreading inland in the afternoon. Snow levels up around 5000 feet but easterly gradients across the Cascades could trap some cold air near the surface especially in the lower passes ( Stevens and Snoqualmie ) bringing up the possibility of freezing rain in the passes Wednesday. Cloudy skies will make for the warmest morning in awhile with lows in the upper 30s to mid 40s. Highs Wednesday near 50.

As mentioned above the record January dry streak for Seattle is 15 days ( January 16-30, 1963 ). This streak has 4 days with a trace including 3 days with snow flurries. The current 13 day dry streak with zero precipitation, not even a trace, is the longest one on record in Seattle. There have been two 12 day streaks with zero precipitation in January in Seattle, January 11-22, 2013 and January 19-30, 1945. Felton

LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/

Model solutions continuing to trend wetter in the extended. Upper level ridge well to the east with southwesterly flow aloft over Western Washington. Back to our regularly scheduled programming for late January with another system Thursday followed by a front stalling over the area Friday. Large deep upper level trough developing between 140W and 150W Friday into Saturday. This will stall the next frontal system offshore Saturday and pump up a temporary upper level ridge. The ridge does not last long with the front arriving Sunday. Snow levels with the southwesterly flow aloft remaining between 5000 and 6000 feet for the most part. Highs in the lower to mid 50s and lows in the lower to mid 40s. Felton

AVIATION

An upper level shortwave will move into the region and weaken this morning as a transient upper ridge builds back into the Pacific Northwest. West-southwest flow aloft continues through today. VFR mid and high clouds will continue at times across the interior through tonight. Periodic MVFR stratus will exist along the coast into this evening. Light E/SE surface winds.

KSEA...VFR through the TAF period with mid to high clouds. Light S/SE surface winds, mainly below 6 kts. JD

MARINE

High pressure will weaken across the waters today with a frontal system expected to move across the area on Tuesday. As a result, southerly winds will increase across the coastal waters this evening into Tuesday morning, with gusts expected to reach small craft strength at times. Winds will increase even more during the day on Tuesday, with gusts to gale likely for the coastal waters. For this reason, a Gale Watch was issued for the outer Coastal Waters for Tuesday. Latest probabilistic guidance also indicates about a 40-60 percent chance of gale gusts developing across the eastern Strait of Juan de Fuca and the Northern Inland Waters by Tuesday afternoon.

The pattern then remains active through the remainder of the week as additional systems move into the area waters and likely bring additional rounds of headlines at times.

Seas will persist between 3-6 ft today, before building to 11-15 ft on Tuesday. Seas will continue to build towards 18-20 ft Wednesday into Thursday before subsiding towards 10-15 ft. Seas will remain elevated, but generally within the 10-15 ft range heading into next weekend as additional systems move across the northeastern Pacific.

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HYDROLOGY

Forecast precipitation amounts increasing over the last couple of model runs with snow levels rising to near 6000 feet in the Olympics by Thursday. Precipitation amounts over the south slopes of the Olympics Thursday into Saturday morning in the 3 to 5 inch range with a few 6 inch bullseyes. This amount of rain will push the Skokomish River in Mason county near flood stage Friday and Saturday. No river flooding on the remainder of the rivers in the next 7 days. Felton

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 4 PM this afternoon to 10 PM PST Tuesday for Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm.

Small Craft Advisory from 4 PM this afternoon to 4 AM PST Tuesday 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.

Gale Watch from late tonight through Tuesday evening 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.