textproduct: Seattle/Tacoma

SYNOPSIS

A weak front will reach the coast this morning and move through the interior this afternoon. Upper level trough arriving Sunday moving east late in the day. Upper level ridge building offshore Sunday night moving over Western Washington Monday. Temperatures warming Tuesday and Wednesday. Ridge weakening a little towards the end of the week for slightly cooler temperatures.

SHORT TERM /TODAY THROUGH MONDAY/

Satellite imagery shows weak cold front near 120W at 10Z this morning. Clouds out ahead of the front have reached the Cascades. Rain started along the north coast around 09Z but has not gotten much further inland. Temperatures were in the mid 50s to lower 60s.

Front reaching the coast this morning moving through the interior early this afternoon. Rain along the coast this morning. With the front weakening as it moves inland showers likely/chance of showers a few hours ahead, with and behind the front for the interior mid morning through early afternoon. Skies clearing late in the afternoon except over Snohomish county where a Puget Sound Convergence Zone will form behind the front. In addition to the precipitation breezy conditions developing with and just behind the front with gusts around 30 mph in most locations. Highs in the 60s and lower 70s.

Weak upper level trofiness behind the front tonight with showers becoming confined to the convergence zone by late evening. It's going to be a cool early August morning Sunday with the colder locations dropping into the 40s. For the remainder of the area lows in the lower to mid 50s.

Upper level trough moving into Western Washington Sunday. Trough coming down from the north so not much moisture with it. The little bit of lift it will provide could generate some showers mostly over the North Cascades. Convergence zone over Snohomish county dissipating late morning. Another cool day under mostly cloudy skies with highs again in the 60s and lower 70s.

Upper level trough moving east Sunday evening with an upper level ridge building offshore. Ridge moving towards Western Washington overnight. Clearing skies providing another cool morning with lows in the upper 40s to mid 50s.

Upper level ridge building Monday. High temperatures warming but still falling a couple of degree short of normal. Highs in the 70s.

For the first time since 2012 Seattle had below normal temperatures for the month of July. The average temperature for the month was 66.9 degrees. Normal is 67.1 degrees. There were 9 days with highs 80 degrees plus. For the last 9 years ( 2017-2025 ) Seattle has averaged 15 days in July with highs 80 degrees plus. The last year there was less than 10 80 degree plus days was 2016. It was also the coldest July in Seattle since 2016 where the average temperature was 66.8 degrees ( normal temperature for July in 2016 was 65.7 degrees so it was still an above normal month temperature wise ). Felton

LONG TERM /MONDAY NIGHT THROUGH FRIDAY/

Models showing good consistency with a flat upper level ridge over Western Washington at least through Wednesday. Some small differences showing up in the models beginning Thursday with some of the solutions weakening the ridge while other solutions keep the ridge in the middle to upper 580 dms. Much warmer Tuesday and Wednesday as the low level flow tries to turn offshore. Highs in the 70s on the coast and upper 70s to near 90 inland. With the stronger ridge solutions just introduced this model run will stay with the previous idea of a little cooler Thursday and Friday with highs near 70 coast and lower 70s to lower 80s inland.

Low level flow turning a little northerly Tuesday which could pull some smoke from the fires in British Columbia down over the area. Low level flow remaining northerly Wednesday before turning back to a more westerly direction Thursday. Felton

AVIATION

Southwesterly flow aloft becoming more westerly into Sunday morning as a weak front pushes through. MVFR cigs are pushing west to east - increasing in coverage this morning. This activity is slated to persist along with rain showers before conditions improve into the afternoon. Gusty post-frontal west to southwesterly surface winds (25-30 kt) are expected at times today and a convergence zone is expected to develop later this afternoon/evening over Snohomish County. Latest guidance suggests the convergence zone will remain near PAE. Surface winds will trend lighter overnight with marine stratus rebounding becoming more widespread into Sunday morning.

KSEA...Ceilings are lowering to MVFR this morning and will persist until 19-20z. Southwesterly surface winds will rise to 10 to 15 knots with gusts to 20-30 knots this afternoon. Winds will gradually decrease overnight into Sunday morning. MVFR stratus likely to redevelop into Sunday morning as well before scattering into the afternoon.

41

MARINE

A weak frontal system is pushing across area waters today. Increasing onshore flow will lead to small craft advisory westerly winds in the central/east strait much of today. Additionally, post- frontal onshore flow will lead to small craft advisory southwesterlies in Puget Sound/Hood Canal during today as well. High pressure will rebuild over the coastal waters Sunday and remain in place into early next week as thermally induced low pressure expands northward across the interior with light flow.

41

FIRE WEATHER

Good chance for wetting rains along the north coast and in the North Cascades today with the front. This along with cooler temperatures will help ease fire weather concerns. There is a slight chance of thunderstorms in the North Cascades but if one does occur it will be accompanied by rain. Another cool day Sunday will keep fire weather concerns at a minimum.

Warming temperatures Monday with elevated fire weather concerns beginning Tuesday with above normal temperatures and low level drying. Minimum relative humidity values again dropping into the 20s late in the afternoon over the southern portion of the area and the Cascade foothills both days. Elevated fire weather concerns could continue through the end of the week if the small cool down does not materialize. Felton

SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Small Craft Advisory until 10 PM PDT this evening for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 10 PM PDT this evening for Puget Sound and Hood Canal.