Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
604 FXUS66 KSEW 250339 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 839 PM PDT Mon Jun 24 2024 .UPDATE...Mostly clear conditions this evening other than some high clouds as well as dissipating lower clouds over the Olympics. High clouds at times tonight with perhaps isolated areas of patchy fog. No major forecast updates this evening. && .SYNOPSIS...High pressure aloft continues to build over the region, maintaining warmer and dry conditions through Tuesday. The next upper trough crosses the area Wednesday and Thursday bringing a return of showers and cooler temperatures. Expect a similar pattern late in the week with a brief warm up alternating with weak passing disturbances. && .SHORT TERM /TONIGHT THROUGH FRIDAY/...Lower level clouds continue to gradually scatter across the area this afternoon, with patches of clouds most prominent near the higher terrain. This has led to temperatures warming closer to seasonally normal values this afternoon. With heights continuing to rise and with increasingly clear skies, expect that Tuesday will be the warmest day of the week for most. Expect widespread 70s through the interior and local 80s in the warmest spots. Meanwhile, low-level flow remains onshore and an afternoon sea breeze will prevent a more significant warming for the areas closest to the coastline. HeatRisk remains in the minor category for nearly all of the area, with only a few pockets of moderate (orange). A shift in the pattern Wednesday and lingering into Thursday as the ridge breaks down and shifts eastward. Expect the next upper trough to spread widespread cloud cover and a fair amount of moisture (especially for late June) across western Washington. Continue to see some increased instability that may allow for the a few isolated thunderstorms near the Cascade crest (especially in the North Cascades) during the afternoon Wednesday. Stronger onshore flow as the trough slides east likely induces a Puget Sound Convergence Zone on Thursday. .LONG TERM /SATURDAY THROUGH TUESDAY/...Ensemble guidance in the extended continues to favor rather unremarkable pattern with largely zonal flow with some chances (20-30%) on either side suggesting weak ridging or a few passing weak troughs through the region. On the whole, expect this to maintain temperatures generally somewhat close to normal and at least some showers chances at times for the weekend and the start of next week. && .AVIATION...Zonal flow aloft becoming more southerly into Tuesday morning as a weak upper level ridge traverses the area. Light onshore flow will continue in the low levels. Conditions have rebounded to VFR as of this evening for all area terminals and will persist through the remainder of the night. A few areas of patchy fog will be possible for areas along the coast and southwest interior Tuesday morning, but expect most sites to mostly remain VFR. KSEA...VFR conditions through the TAF period. Winds currently between 7-12 kt. Winds will ease overnight into Tuesday, persisting at 4-7 kt. && .MARINE...High pressure over the coastal waters will interact with lower pressure inland through Tuesday, promoting relatively calm conditions and onshore flow across the region. The strongest winds will be along the Strait of Juan de Fuca, where diurnal westerly pushes look likely over the next few days and could result in Small Craft headlines at times. A frontal system will then move across the area waters on Wednesday, bringing breezy southerly winds to the waters. High pressure will build back into the coastal waters Thursday, with additional systems moving into the area waters over the weekend. Seas generally persisting at 6-8 ft this afternoon. Expect seas to gradually subside back towards 4-6 ft tonight into Tuesday and persist at this range over the next several days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$