Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
644 FXUS66 KSEW 270325 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 825 PM PDT Wed Jun 26 2024 .SYNOPSIS...A passing upper level trough will keep widespread showers and isolated thunderstorms in the forecast into Thursday. Warmer and drier conditions set in for Friday into early Saturday, but another disturbance will bring showers again late Saturday into Sunday. The pattern remains unsettled, keeping some shower chances into early next week. && .SHORT TERM /TONIGHT THROUGH SUNDAY/...Shower activity is ongoing largely east of Puget Sound this evening, with only isolated showers moving onshore. Expect this activity to continue through the evening hours as a front and associated low pressure center move closer to the region. Showers likely continue through much of Thursday along with abundant cloud cover as the upper trough shifts eastward through the region. These showers will be most widespread in the mountains as well as in a continuing convergence zone. No major changes have been made this evening and the rest of the previous discussion will follow. High pressure returns to the region on Friday in between weather systems, which should bring increasingly dry conditions as well as slightly warmer temperatures. This then likely continues into at least early Saturday before the next disturbance approaches with additional cloud cover late in the day. .LONG TERM /MONDAY THROUGH THURSDAY/...The next disturbance in this series is likely to arrive late Saturday into Sunday, once again spreading increasing precipitation and cooler conditions across western Washington. Stronger onshore flow behind the front may again develop a PSCZ by Sunday evening, and there`s at least some (10-15%) chance of thunderstorms (especially closer to the Cascades). Confidence in the forecast decreases toward the middle of next week with ensemble guidance suggesting perhaps a weak disturbance or two but otherwise fairly zonal flow early next week that will maintain temperatures generally near normal and perhaps some showers at times. Cullen && .AVIATION...South-southwesterly flow aloft this evening will transition to more west/northwesterly on Thursday morning as an upper level low makes its way eastward across Washington. Radar shows rain showers making their way inland. Thunderstorms remain possible across portions of the Cascades this evening but the threat is greatly waning with loss of diurnal heating. Expect ceilings across the interior to gradually lower to more widespread MVFR tonight, likely near 06Z. A few localized pockets of IFR to LIFR will be possible for terminals in heavier showers. Expect MVFR ceilings to continue across the region through the overnight hours and through Thursday morning with showers persisting in the region. High-res guidance hints the development of a convergence zone across northern King and Snohomish counties on Thursday, so could see lower ceilings persist for northern interior terminals through much of the day. Winds remain breezy out of the S/SW this evening, generally persisting at around 12-17 knots, with gusts to 20-25 knots at times. Winds will ease towards 5-10 knots overnight between 04Z-06Z and increase again towards 8-12 knots between 12-15Z Thursday. KSEA...VFR conditions with breezy S/SW winds at the terminal. Gusts around 20 to 25 knots will be possible at times into this evening before winds ease overnight. S/SW winds increase towards 8-12 knots by mid morning Thursday. Ceilings expected to lower to MVFR between 04-07Z. Showers will be possible through Thursday morning. Brief IFR conditions will be possible should any heavier showers pass over the terminal. 14/McMillian && .MARINE...An exiting frontal system will keep increased winds in place over area waters this evening...with speeds in Admiralty Inlet, Puget Sound and the Central and Eastern Strait maintaining SCA criteria through 9 PM and 11 PM PDT respectively. That said, inherited headlines look good and will go unaltered for the evening forecast update. Speeds ease overnight for interior waters, however northwesterlies over the coastal waters will see speeds there increase early Thursday morning. This will also result in a westerly push through the Strait once again, where SCA wind speeds look to make a return late Thursday afternoon into Thursday night. Will opt not to hoist a headline for this yet so as to allow later shifts to gauge run-to-run model consistency. Otherwise, with weak high pressure in place for the late week period, no other significant activity is expected. Additional systems look to push through the area waters through the weekend and into the first part of next week. Seas 3 to 5 feet and expected to remain that way through Friday before increasing to 4 to 6 feet this weekend and into the start of next week. 18 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 11 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 9 PM PDT this evening for Admiralty Inlet-Puget Sound and Hood Canal. && $$