textproduct: Seattle/Tacoma

SYNOPSIS

High pressure over the area today will shift east tonight. A front will move through the area Saturday. Post frontal convergence zone over mostly Snohomish county Saturday night will dissipate Sunday morning. Upper level ridge building offshore Sunday night will move over Western Washington Monday. The ridge will remain in place through Wednesday. Weak upper level trough with increasing low level onshore flow towards the end of next week.

SHORT TERM /TODAY THROUGH SUNDAY/

Satellite imagery shows stratus along the north coast with clear skies over the remainder of the area. Temperatures at 3 AM/10Z were in the 50s and lower 60s.

Today looks to be the warmest day since the 22nd with an upper level trough offshore pumping up a temporary ridge over Western Washington. Low level flow doesn't turn offshore keeping high temperatures from getting too warm. Highs in the lower to mid 70s on the coast and mid 70s to mid 80s inland.

Upper level ridge moving east tonight with upper level trough and associated front approaching the coast overnight. Rain reaching the coast early Saturday morning with a chance of rain west of Puget Sound and over the Northwest Interior around sunrise. Increasing clouds will keep lows in a narrow range, mid and upper 50s.

Upper level through and front moving through Western Washington Saturday afternoon. Westerly flow aloft will create a bit of a rain shadow over the Central Puget Sound with the lowest pops there ( around 30 percent ). Front weakening as it moves inland so will go with showers as the precipitation type in the afternoon with rain in the morning. Air mass slightly unstable with the front producing a small chance of thunderstorms in the North Cascades. Highs only in the 60s and lower 70s.

Front east of the Cascades Saturday night. Post frontal onshore flow in the lower levels with a convergence zone developing over Snohomish County. Pops confined to the convergence zone by late evening. Lows in the 50s.

Convergence zone dissipating Sunday morning. Low level onshore flow combined with weak trofiness aloft will keep skies mostly cloudy and high temperatures below normal, in the mid 60s to lower 70s. Felton

LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/

Upper level ridge building offshore Sunday night moving inland Monday. Ridge remaining over the area at least until Wednesday with 500 mb heights in the mid 580 dms. Thermally induced surface trough remaining inland with the low level flow never turning offshore for any length of time. Highs in the upper 60s to upper 70s Monday warming to the mid 70s to mid 80s for the interior by Wednesday. Highs on the coast Tuesday and Wednesday in the lower to mid 70s.

Upper level ridge moving east Thursday with a weak upper level trough moving over the area. Low level flow turning weakly onshore. Highs cooling a little with lower 70s to lower 80s inland and mid 60s to near 70 along the coast. Felton

AVIATION

Southwest flow aloft throughout the period with an upper-trough offshore in concert with an upper-ridge over the Intermountain West. Areas of IFR/LIFR stratus is developing along the immediate coast with patchy stratus across the interior as the morning progress. Any lingering ceilings should scatter by 16z with VFR areawide thereafter. Low-stratus looks to redevelop overnight Friday into Saturday morning as a front enters the region.

KSEA...Mostly clear skies throughout most of the period. Surface winds W/SW 7 knots or less veering northerly this evening, then becoming W/NW Friday afternoon. Winds generally ranging between the W and N between 5-10 kt, becoming more southerly early Saturday morning ahead of an approaching frontal boundary.

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MARINE

Surface high pressure today before a weak front enters the water tonight into Saturday. A SCA has been issued for the central/eastern strait for Friday afternoon through early Saturday morning. An additional SCA may be needed for the same locations Saturday evening as well once area waters are post-frontal. High pressure will rebuild over the coastal waters Sunday and remain in place through Monday. Light flow in the low-levels well into next week.

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FIRE WEATHER

Elevated fire weather concerns today with above normal temperatures and afternoon relative humidity values lowering to near 30 percent over the southern portion of the area as well as in the foothills.

Front Saturday bringing wetting rain to the north coast and North Cascades (with a chance of thunderstorms in the North Cascades). It will be windy with gusts near the crest in the 30-40 MPH range. However, with the wetter and cooler conditions, min RHs will not reach critical thresholds.

Warmer and drier weather early next week will keep the fire weather threat elevated, especially next Tuesday and Wednesday, where min RHs will dip into the 20s and 30s again. Felton/33

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory from 4 PM this afternoon to 4 AM PDT Saturday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca.