SYNOPSIS
Very warm week ahead for Western Washington as an upper level ridge slowly drifts over the area. Temperatures will peak Sunday through Tuesday with highs over the interior in the mid 80s to near 100. The ridge will slowly exit to the east making for a gradual cooling trend in the middle of next week.

Key Messages,

* HEAT...Continued warming will lead to hot conditions beginning today. Temperatures peaking Monday and possibly into Tuesday for the interior in the upper 80s to near 100. Highs will be cooler along the coast. A Heat Advisory is in effect for the entire region beginning this afternoon, ending Sunday evening for the coast, Monday evening elsewhere. If the trend continues the heat advisory for the interior will be extended into Tuesday.

* FIRE WEATHER...Increasing dry and unstable conditions for this weekend has warranted the issuance of a Fire Weather Watch for the Cascades. These conditions could also extend into Monday and Tuesday. See the Fire Weather discussion below for details.

SHORT TERM /TODAY THROUGH SUNDAY/
Satellite imagery shows clear skies over Western Washington with an upper level ridge building well offshore. Temperatures at 3 am/10z were in the mid 50s to mid 60s.

Upper level ridge offshore continuing to build today through Saturday. Ridge axis near 130W this morning will drift east towards the coast but will still be offshore by 00z Sunday. 500 mb heights in the mid 580 to lower 590 dms. Low level flow remaining light northerly with the cross Cascade gradient remaining positive into Saturday afternoon. Winds above the surface to 850 mb also never turn easterly. Temperatures aloft warming with 850 mb temperatures in the plus 18C to plus 22C range late this afternoon. Little change in the temperatures aloft tonight and Saturday. High temperatures today warming by about 5 degrees across the area with 80s and lower 90s over the interior and upper 70s to mid 80s along the coast. Lows tonight in the mid 50s to lower 60s. Highs Saturday similar to today.

Upper level ridge drifting east Saturday night and Sunday with the ridge axis right off the coast by late Sunday afternoon. High temperatures warming over the interior slightly Sunday with 80s to mid 90s. Highs along the coast remaining in the upper 70s to mid 80s. Lows also slightly warmer Saturday night with upper 50s to mid 60s interior and mid to upper 50s coast.

LONG TERM /MONDAY THROUGH THURSDAY/
Extended model ensembles in good agreement trending towards slower eastward movement of the upper level ridge with the ridge axis not completely east of the area until Tuesday night. This scenario would make high temperatures Tuesday similar to Monday. 850 mb temperatures peaking in the plus 22C to plus 26C late Monday into Tuesday.
Surface thermally induced trough over Western Oregon moving into Western Washington Monday and Tuesday shifting east of the Cascades Tuesday night. Highs both days for the interior upper 80s to near 100. Thermally induced surface trough inland enough to keep highs along the coast in the 70s. Lows will start to get a little uncomfortable in the urban areas with mid 60s common. Lows in the remainder of the area in the mid 50s to lower 60s.

Very weak shortwave moving by well to the north Wednesday into Thursday. This combined with the upper level ridge axis to the east will induce a little low level onshore flow cooling high temperatures Wednesday and Thursday. With the shortwave well to the north the marine layer/onshore push will not be that strong.
High temperatures for the interior cooling into the mid 70s to upper 80s Wednesday with a couple more degrees of cooling Thursday. Highs along the coast lowering to the mid 60s to lower 70s. With the low level flow onshore low temperatures will return to a more comfortable 50s and lower 60s. Felton

AVIATION
High pressure and offshore flow will lead to a dry and stable air mass across western WA with VFR conditions for the TAF period.

KSEA...VFR and clear with north winds generally 6 to 12 kt.

15/Maz

MARINE
Light offshore flow through the weekend with a thermal trough along the coast. The flow will turn onshore Monday and Tuesday with stronger westerly pushes down the strait.

Seas generally 4 to 6 ft through the weekend and into early next week.

15

FIRE WEATHER
Strengthening upper level ridge settling over the region beginning today and continuing into the early next week.
Surface gradients light northerly through the weekend. High temperatures rising today through Sunday with the highs Sunday in the watch zones in the 80s and lower 90s. With the air mass drying out critical RH values are likely over the Cascades with possibly some isolated areas within the Olympic Mountain valleys over the weekend. The hot and dry setting will be enough to create elevated fire weather conditions especially with fuels expected to rapidly dry out in the next couple of days. The air mass will be unstable over the Cascades but the lack of moisture will keep the threat of convection minimal. The Fire Weather Watch for dry and unstable conditions remains in effect for fire weather zones 658 and 659 Saturday and Sunday.

Model trends are pushing back the improving fire weather conditions into Monday and possibly Tuesday. While RH recoveries will improve over the coastal fire zones beginning Monday with a thermally induced surface trough over the interior enhanced fire weather conditions could continue especially in the Cascades into Tuesday. Felton

CLIMATE
Record high temperatures for Seattle, Sunday 90 degrees (2010), Monday 95 degrees (2010), Tuesday 93 degrees (2010).
Record highs for Olympia 95 degrees each day (1953), (2010) and (1985). Record highs for Bellingham 88 Sunday and Monday (1953)
and (2010), Tuesday 85 degrees in 1979.

Record high low temperatures also possible for Seattle Sunday through Tuesday with the record 64 degrees Sunday (2014), 63 Monday (2010) and 63 Tuesday (2006). Felton

SEW WATCHES/WARNINGS/ADVISORIES
WA...Heat Advisory until 10 PM PDT Monday for Admiralty Inlet Area- Bellevue and Vicinity-Bremerton and Vicinity-East Puget Sound Lowlands-Eastern Strait of Juan de Fuca-Everett and Vicinity-Hood Canal Area-Lower Chehalis Valley Area- Olympics-San Juan County-Seattle and Vicinity-Southwest Interior-Tacoma Area-West Slopes North Cascades and Passes- West Slopes North Central Cascades and Passes-West Slopes South Central Cascades and Passes-Western Skagit County- Western Whatcom County.

Heat Advisory until 10 PM PDT Sunday for Central Coast-North Coast-Western Strait of Juan De Fuca.

Fire Weather Watch from Saturday morning through Sunday evening for West Slopes of the Central Cascades Generally above 1500 Feet-West Slopes of the North Cascades Generally above 1500 Feet.

PZ...None.