textproduct: Seattle/Tacoma

SYNOPSIS

Showers and thunderstorms will continue over the mountains this afternoon and Friday afternoon under the influence of an upper level trough. Southwest flow aloft will develop over the weekend, bringing some warming ahead of another weak trough at the beginning of next week that will likely bring slightly cooler and unsettled conditions.

SHORT TERM /TONIGHT THROUGH SATURDAY NIGHT/

Convection continues over the northern Cascades this evening. Expect thunderstorm activity to continue subsiding into tonight. Otherwise no major updates to the forecast. Refer to an updated aviation discussion.

An upper level trough will remain in place over western Washington into friday. This trough will help the air mass become unstable this afternoon and evening over the Cascades and the Olympics, especially the higher terrain. We'll continue to see chances for scattered convection this afternoon and evening, primarily for areas in the Cascades and Olympics. In any thunderstorm that develops, we could see the potential for abundant lightning, erratic wind gusts up to 40 mph, and localized wetting rains that could produce and elevated risk of burn scar debris flows. Additionally, a Red Flag Warning remains in effect this evening for those aforementioned areas. For more information about fire wx conditions, see the .FIRE WEATHER section down below.

Generally, we'll see high temperatures this afternoon in the upper 70s to lower 80s in spots with a mix of sun and haze. Onshore flow will continue tonight and into Friday morning, with a shallow marine layer moving inland by the morning. High temperatures on Friday will be slightly cooler, in the upper 70s for most locations. The atmosphere will continue to remain unstable Friday afternoon - which will lead to another chance of scattered thunderstorms, primarily in the Cascades and Olympics. A Fire Weather Watch is in effect for those areas - primarily for lightning and gusty outflow winds.

Weak ridging will influence the area heading into Saturday, which will lead to generally warm and dry conditions. A few showers may still be possible in the Cascades, but overall a typical summer day with high temperatures in the low 80s.

LONG TERM /SUNDAY THROUGH THURSDAY/

Warm and dry conditions continuing on Sunday with high temperatures in the lower 80s. Upper level troughing looks to maintain influence over the area through midweek, allowing for onshore flow in variable strengths throughout the week. Unsettled and cooler conditions through the remainder of the week, with high temperatures in the mid 70s.

Mazurkiewicz

AVIATION

Interior terminals VFR this evening and IFR/LIFR along the coast. Thunderstorm activity continues for the Cascades this evening, but is expected to stay away from the main terminals. Additionally, smoke from fires will primarily remain elevated over the terminals, but areas near fires will see poor surface visibilities. Another marine push is expected for Friday morning. Slight increase in probabilities for IFR/LIFR conditions. IFR probabilities currently around 40-60% and LIFR around 20-40%. Some areas of fog can't be ruled out within the marine push. Improvement to VFR expected for interior terminals after 17z. Calm to light northwest winds tonight will increase out of the west/southwest on Friday to 5-10 kt.

KSEA...VFR conditions this evening. Probabilities for IFR/LIFR conditions have trended slightly upwards. Latest probabilities hint at a 30-50% chance for IFR cigs and 20-40% chance for LIFR cigs between 13z-15z. Improvement to VFR i the afternoon. Light northwest winds will shift southwesterly Friday morning, increasing to 4-7 kt.

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MARINE

High pressure remains in the northeast Pacific through Friday. An upper level low will cut southward over the waters this weekend which will push the high towards the south. The high pressure will rebuild again over the coastal waters early next week. Main concern remains the diurnal westerly pushes through the Strait of Juan de Fuca, with probabilities for winds and/or gusts over 20 kt remaining low until Friday and Saturday evening.

Seas next 7 days will remain at 3-6 ft.

HPR

FIRE WEATHER

Fire weather concerns remain elevated to critical at times through Friday night. Air mass has already became unstable over the higher terrain this afternoon and will continue through the early evening hours with chances of thunderstorms and showers likely, primarily in the Cascades and Olympics. A Red Flag Warning is in effect through 9PM. In any thunderstorm that develops, we could see the potential for abundant lightning, erratic wind gusts up to 40 mph, and localized wetting rains. Additionally, A Fire Weather Watch has been issued for Friday afternoon and evening, for another round of convection across the Cascades and Olympics - primarily for lightning and gusty outflow winds.

Upper level trough replaced by an upper level ridge over the weekend lessening but not eliminating the chances for convection over the mountains especially the Cascades. Another upper level trough moving into the area next week will once again increase fire weather concerns.

Felton/Mazurkiewicz

SEW WATCHES/WARNINGS/ADVISORIES

WA...Fire Weather Watch from Friday afternoon through Friday evening for East Portion of the Olympic Mountains-West Portion of the Olympic Mountains-West Slopes of the Central Cascades Generally above 1500 Feet-West Slopes of the North Cascades Generally above 1500 Feet.

PZ...None.