textproduct: Seattle/Tacoma

SYNOPSIS

Warm and dry conditions with high clouds and hazy skies continue tonight and into Wednesday. Chances for showers and thunderstorms arrive Wednesday night and into Thursday. An upper level trough moves over Western Washington with low level onshore flow Friday through the first part of next week for a round of seasonable temperatures and some additional chances for showers.

SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/

Satellite imagery continues to show high clouds and some upper level smoke. With that, temperatures have warmed into the {FILL IN}. High temperatures remain on track to reach the upper 80s to mid 90s, with 70s to near 80 along the immediate coastlines. Low temperatures in the low to mid 60s will provide minimal relief overnight. Highs look to get a little warmer on Wednesday, with much of the interior in the 90s, pushing 100 in favored places such as the Southwest Interior and the Cascade Valleys. Luckily, stronger onshore flow is on track to arrive Wednesday night into Thursday. Areas along the Olympic Peninsula will see a return to low temperatures in the upper 50s to near 60 Wednesday night, through elsewhere low to mid 60s remain. The amount of cooling will depend on the cloud cover and the strength of the onshore flow, but the Olympic Peninsula looks to cool into the 70s on Thursday, with low to mid 80s expected across the interior. This will put an end to the Major HeatRisk (and thus the Heat Advisory), with most places retuning to Minor, through the metro area and northward will continue to flirt with Moderate HeatRisk.

Outside of temperatures, conditions look to become more become more active Wednesday night as a trough offshore beings to pull in moisture from Oregon, for chances of showers and thunderstorms. The best chances for thunderstorms Wednesday night will be across the southern Washington Cascades and portions of southwest Washington. Showers and storms are expected to drift from south to north overnight with chances for storms continuing across the area Thursday morning. Thunderstorms should depart the area Thursday afternoon. The greatest uncertainty is the coverage of thunderstorms through this time period. Even with a mix of wet and dry thunderstorms, new fire starts will be possible with lightning strikes. A Fire Weather Watch has been issued for portions of southwest WA and the southern Cascades from Wednesday evening through Thursday afternoon.

Smoke continues to linger across the area, primarily aloft, through may be more noticeable across Whatcom and Skagit counties, as well as higher elevations in the Cascades. Stronger onshore flow Wednesday night into Thursday will help to push the smoke east of the Cascades.

LONG TERM /FRIDAY THROUGH TUESDAY/

Drier conditions are expected on Friday before the low pressure system offshore will finally moves inland and traverses the region Saturday. Additional systems Sunday and into early next week will continue to keep chances for showers in the forecast. Temperatures return to more seasonable conditions with highs in the mid 60s to mid 70s and lows in the 50s.

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AVIATION

High pressure across the region maintaining VFR conditions area-wide this afternoon. Some passing high clouds remain, as well as lingering low clouds offshore to the west of KHQM. Embedded wildfire smoke aloft across portions of the region continues to limit both horizontal and slant-range visibility through early Wednesday, but begins to clear through the day tomorrow. Around a 50-60% chance of IFR returning to the immediate coast, including KHQM, late tonight through early Wednesday morning.

KSEA...VFR conditions continue with variable high clouds with some entrained smoke above the surface. No significant ceiling/visibility issues expected through the period. Northerly surface winds this afternoon and evening, easing overnight.

MARINE

Strong high pressure remains offshore with a thermal trough along the WA coast. Overall winds are generally light across the coastal waters with seas under 6 ft. The thermal trough will shift inland Wednesday and Thursday with stronger onshore pushes expected through the strait of Juan de Fuca which may warrant headlines. West to southwest winds and seas below 6 ft look to persist across the coastal waters Thursday and beyond.

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FIRE WEATHER

Elevated fire weather concerns continue into Wednesday due to very warm and dry conditions. Minimum relative humidities will fall as low as 20% to 30% again on Wednesday, with drier locations across the southern Puget Sound potentially bottoming out in the teens. There is a chance of thunderstorms coming in from the south late Wednesday night into early Thursday which, given the warm and dry conditions, could cause additional ignitions from lightning. A Fire Weather Watch is in effect for the southern Cascades and South Sound areas from Wednesday night through Thursday afternoon. Even with Onshore flow will increase later Thursday bringing cooler temperatures and better overnight RH recoveries through the weekend into the first part of next week easing fire weather concerns.

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SEW WATCHES/WARNINGS/ADVISORIES

WA...Air Quality Alert until 9 AM PDT Wednesday for Cascades of Whatcom and Skagit Counties-Foothills and Valleys of the North Cascades-Lowlands of Western Skagit and Northwestern Snohomish Counties-Lowlands of Western Whatcom County.

Fire Weather Watch from Wednesday afternoon through Thursday afternoon for Black Hills and Southwest Interior Lowlands- West Slopes of the Central Cascades Generally above 1500 Feet.

Heat Advisory until 11 PM PDT Wednesday for City of Seattle- Downtown Everett / Marysville Area-Eastern Kitsap County- Eastern Strait of Juan de Fuca-Eastside-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-Foothills and Valleys of Thurston and Lewis Counties-Foothills and Valleys of the North Cascades-Foothills of the Western and Southern Olympic Peninsula-Lake Crescent Area Including US 101-Lowlands of Lewis and Southern Thurston Counties-Lowlands of Pierce and Southern King Counties- Lowlands of Western Skagit and Northwestern Snohomish Counties-Lowlands of Western Whatcom County-Middle Chehalis River Valley-Northern Hood Canal-Olympia and Southern Puget Sound-Port Townsend Area-Shoreline / Lynnwood / South Everett Area-Southern Hood Canal.

PZ...None.