Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
824 FXUS66 KSEW 162142 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 242 PM PDT Sun Jun 16 2024 .SYNOPSIS...An upper level trough over Western Washington will shift east of the area on Monday. High pressure aloft will gradually build through the week for a trend toward drier and warmer conditions. Another upper trough is expected to approach the region late next weekend for a cooling trend and a returning chance of showers to portions of the area. && .SHORT TERM /TONIGHT THROUGH WEDNESDAY/...Scattered showers continue across the area this afternoon as an upper trough over the area gradually shifts southeastward. The trough axis will be east of the Cascades on Monday, but continued weak troughing aloft will keep clouds and a chance of showers in the forecast. Heights continue to rise on Tuesday with onshore flow weakening. This will allow much of the area to clear out by Tuesday afternoon with temperatures bouncing back to near seasonal levels. Upper ridging centered well offshore continues to strengthen on Wednesday as 500 millibar heights approach 570 dam with 850 millibar temps approaching 14 C. With thermal troughing just to our south and only weak onshore flow, much of the interior of Western Washington should warm into the mid to upper 70s with 60s along the coast. .LONG TERM /THURSDAY THROUGH SUNDAY/...Low amplitude ridging continues to build across the area Thursday and Friday for continued dry and warmer conditions with portions of the interior from Seattle southward reaching near or above 80 degrees. Ensembles are in fairly good agreement that the ridge axis will shift east of the region early in the coming weekend as an upper trough deepens along the British Columbia coast. This will result in a cooling trend along with a returning chance for showers...especially over the Olympic Peninsula and across the North Interior. 27 && .AVIATION...Broad upper low over the Pac NW tonight with a cool and slightly unstable air mass over western Washington. Showers will mostly affect the mountains and South Sound this evening, with light rain persisting in the interior early Monday morning. The flow aloft is northerly. Drier conditions expected Monday afternoon as the upper trough departs east. 33 KSEA...Showers in the vicinity this afternoon and early evening. W/NW wind to 10 kt through 06z, becoming S. Low clouds, light rain and MVFR conditions early Monday. 33 && .MARINE...High pressure over the NE Pacific will maintain onshore flow over western WA this week. Highest wind and waves will be through the Strait of Juan de Fuca, mainly during the afternoon and evening hours. 33 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory from 5 PM this afternoon to 5 AM PDT Monday for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. && $$