textproduct: Seattle/Tacoma

SYNOPSIS

Showers will taper off outside of convergence zone showers and thunderstorms today, with drier and warmer conditions settling into the region through the weekend and into early next week. Areas of Moderate (Orange) HeatRisk will expand across the lowlands by Sunday and continue into Monday with pockets of Major (Red) HeatRisk possible.

SHORT TERM /TONIGHT THROUGH THURSDAY NIGHT/

A frontal system moved across the region earlier today, leaving widespread breezy winds and light shower activity in its wake. A Puget Sound Convergence Zone is well underway this afternoon over Snohomish County, and has produced a few lightning strikes so far in heavier shower activity. While most other areas dry out, convergence zone activity is expected to persist overnight and will likely be stalled over Snohomish County due to breezy southwesterly winds.

Wednesday will kick off a warming and drying trend across western Washington as weak high pressure passes over the region and a high pressure ridge begins to build offshore. Wednesday morning will likely feature another round of marine stratus creeping inland, with sunny skies prevailing by the afternoon. The region will see some warming, though temperatures will still peak a few degrees below normal on Wednesday in the mid to upper 60s across the lowlands.

Northwesterly flow aloft will prevail on Thursday as the upper level ridge offshore to the south slowly amplifies northward. Despite a cool and cloudy morning, Thursday will bring additional warming with sunny skies in the afternoon. Highs will peak in the upper 60s to lower 70s. This will introduce widespread Minor (Yellow) HeatRisk across much of the lowlands.

LONG TERM /FRIDAY THROUGH TUESDAY/

A warming and drying trend will continue into the weekend as an upper level ridge continues to build offshore. A thermal trough moving up the coastline will reach western Washington by late Saturday, with easterly offshore flow developing as a result on Sunday and Monday. Temperatures Sunday are on track to peak in the upper 80s to lower 90s, with even warmer conditions south and east of the Puget Sound Monday with temperatures peaking in the low to mid 90s. This will introduce widespread Moderate (Orange) HeatRisk both days, with up to a 30% to 50% chance for Major (Red) HeatRisk near the metro areas on Monday. A few locations may even break daily temperature records on Sunday and Monday. Longer range models suggest a pattern change may be on track for the middle of next week, bringing an end to the incoming heat wave.

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AVIATION

A post-frontal convergence zone continues in Snohomish County this evening, wit a 20% chance of thunder remaining with this activity throughout the evening. Conditions with this convergence zone have dropped locally to MVFR/IFR at times, with cloud tops less than 20,000 ft. Showers in the southwest interior/coast have also resulted in brief drops to MVFR as they pass over the terminal. The shower activity will continue into early Wednesday morning. Breezy southwest winds also continue this afternoon, with sustained winds up to 20 kt and gusts up to 30 kt. Winds will taper down tonight into Wednesday to around 4-8 kt, with only the Strait of Juan de Fuca area remaining breezy part way into Wednesday. A few Puget Sound locations will see winds turn to the north late Wednesday afternoon (via diffluence from the strait). There remains a 40-60% of widespread MVFR ceilings redeveloping tonight and into Wednesday morning through 18-21Z (with the highest chance for LIFR/IFR conditions remain in the mountains).

KSEA...VFR through tonight, with convergence zone activity remaining north of the terminal. Will remain breezy through tonight with sustained winds 15-20 kt with gusts up to 30 kt diminishing to around 4-8 kt by Wednesday morning. Potential for north winds at around 5 kt or less after 00Z Thursday. MVFR probabilities increase to 40-60% around 10Z through 20Z, before scattering out.

HPR/Mazurkiewicz

MARINE

A strong onshore push in wake of a front that went through late last night/this morning continues. Showers will continue across a majority of the waters through the evening/Wednesday morning. The only threat for thunder remains in the north Puget Sound/water areas adjacent to Whidbey Island with a convergence zone continuing into the evening. Winds remain breezy across the interior waters, with Strait of Juan de Fuca winds continuing to remain the breeziest with gale gusts through this evening into tonight. Breezy southwest winds also continue in the Puget Sound, Admiralty Inlet, and Northern Inland Waters through tonight. Diurnal pushes through the Strait of Juan de Fuca will continue through the week, although probability has decreased with the potential for small craft winds. A thermal trough building along the coast this weekend/early next week may result in periods of offshore flow.

Seas at 6-8 ft today into Wednesday will decrease to 4-6 ft Thursday through the weekend/next week, with a brief increase to 6-8 ft seas Friday.

HPR

FIRE WEATHER

After some wetting rains, western Washington will see a warming and drying trend settle into the region through early next week. A thermal trough will develop offshore by late Saturday, causing winds to shift easterly offshore. This will allow fine fuels to cure, with RH dropping to near critical levels over the weekend. Larger fuels may also see drying with this heat wave. Fire weather concerns will remain elevated into the weekend and will peak on Monday, corresponding with the warmest expected day of the heat wave. The thermal trough will shift inland on Monday before potentially shifting eastward by Tuesday and allowing the region to see cooler temperatures.

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SEW WATCHES/WARNINGS/ADVISORIES

WA...None. PZ...Gale Warning until 5 AM PDT Wednesday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca.

Small Craft Advisory until 11 PM PDT this evening for Admiralty Inlet-Northern Inland Waters Including The San Juan Islands.

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