Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
691 FXUS66 KSEW 212101 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 201 PM PDT Fri Jun 21 2024 .SYNOPSIS...After a warm day today, onshore flow will increase over the weekend allowing for slight cooling Saturday and much more cooling on Sunday. Showers will also return by Sunday. While temperatures will rebound slightly early next week, temperatures will remain mild with occasional chances for precipitation. && .SHORT TERM /TONIGHT THROUGH MONDAY/...Outside of some thin cirrus and some stratus along the immediate Pacific Coast, mostly clear skies are present across the region this afternoon. As of 2pm, temperatures were largely around 80 degrees in the interior lowlands (cooler near waterways, and warmer across the SW interior). Temperatures will likely rise another 2-4 degrees this afternoon. This will result in HeatRisk levels mainly in the minor/yellow category with some spots in the urban area cresting in the moderate/orange category. The heat will be relatively short lived as onshore flow increases over the weekend. Highs on Saturday will be 2-5 degrees cooler than the highs today, while Sunday will see more significant cooling with temperatures in the 60s. Areas of precipitation and breezy conditions will accompany these cooler temperatures on Sunday, with gusts of 20-25mph during the day. Weak ridging tries to build in again Monday into Tuesday allowing a rebound in temperatures back to near to above normal. .LONG TERM /TUESDAY THROUGH FRIDAY/...After another mild and likely pleasant day on Tuesday, the door will remain open for additional weak systems to roll through the region next week. This will keep temperatures in check and bring an occasional chance of precipitation to the region. At this time no significant weather hazards are anticipated. -Wolcott- && .AVIATION...High pressure remains in place over the region, moving east through Saturday. Continued westerly flow aloft with light flow in the lower levels becoming onshore tonight into Saturday. This will maintain VFR conditions under generally clear skies for much of the area through evening, but low stratus offshore will return to the coastline up the lower Chehalis this evening. The stratus is unlikely to make it to KSHN/KOLM tonight. Northerly winds this afternoon will become light and see a switch to southerly, mostly after 09z-12z Saturday. Some mid level clouds increase through the day Saturday. KSEA...VFR conditions continue under generally skies through the period. Expect north surface winds decreasing late evening and becoming southerly by 12z Saturday. && .MARINE...High pressure over the coastal waters with lower pressure inland today. Winds relatively light over most waters, but expect a westerly push through the Strait of Juan de Fuca this evening. The current advisory is unchanged. Meanwhile, seas over the coastal waters remain rather steep as a short-period wave group dominates. A passing disturbance Saturday will bring a stronger push of west winds through the Strait tomorrow evening. While guidance does suggest this will be stronger than today`s winds, the likelihood of widespread gales through the Strait remains lower (closer to 50%). As a result, have maintained the current gale watch and will wait until a future update to make the determination of SCA or gale warning for this upgrade. Looking ahead to next week, high pressure remains situated over the waters with no significant winds expected at this time. Seas will build closer to 8 feet by Monday morning, though, as a larger west wave group arrives. Seas then subside through the remainder of the forecast period. Cullen && .FIRE WEATHER...Temperatures will be warm through Saturday, with many locations in the Cascade foothills and high ridges achieving relative humidity values of 15 to 25 percent. This drier pattern will be short lived as onshore flow and a weak weather system returns on Sunday and brings up the relative humidity values. Unsettled weather is expected late next week as the offshore low pressure system remains in the area. This will be evaluated by early next week for any potential for lightning or additional rainfall. Kristell $$ .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 5 AM PDT Saturday for Central U.S. Waters Strait Of Juan De Fuca- East Entrance U.S. Waters Strait Of Juan De Fuca. Gale Watch from Saturday evening through late Saturday night for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$