Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
816 FXUS66 KSEW 290247 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 747 PM PDT Fri Jun 28 2024 .SYNOPSIS...A weak shortwave will bring in increased cloud cover and light showers this evening. Another frontal system will cross western Washington on Saturday, bringing in another round of showers. Unsettled and cloudy weather will linger into Monday morning before high pressure offshore allows conditions to dry out and slowly warm up through the end of next week. && .SHORT TERM /TONIGHT THROUGH TUESDAY/...No major changes to the forecast have been made this evening. The rest of the previous discussion can be found below with an update to the aviation and marine sections. A front will swing through the region throughout the day Saturday, with additional light shower chances confined mainly to the Olympics and higher terrain in the North Cascades. While much of the lowlands will see little more than cloudy skies and some occasional sprinkles, the mountains will see light accumulations of a few hundredths. Temperatures will return to near normal for late June with highs in the mid 70s across the lowlands. Shower chances will taper off Sunday, leading us into a drier upcoming period with a ridge building offshore. High resolution models continue to hint at the possibility of convergence zone shower activity developing along the King/Snohomish County line, though the exact track and intensity of any convergence zone showers is uncertain. Cloudy skies with periodic breaks will persist for much of the region on Sunday as onshore flow continues. Northwest flow aloft will maintain somewhat cloudy skies on Monday, with a slight chance for showers lingering over the mountains. Otherwise, Monday will be the last day of spring-like weather ahead of a pattern change on tap for the rest of the week. .LONG TERM /WEDNESDAY THROUGH SATURDAY/...Models in good agreement with a warming, drying trend throughout next week as an upper level ridge shifts onshore Monday into Tuesday. A weak shortwave will influence the region Tuesday night into early Wednesday morning, with shower chances minimal and temperatures increasing several degrees above normal. The ridge axis will cross over the region on Thursday with high pressure dominating the weather pattern into next weekend. The warmest days will likely come late in the extended period as we`ll see a 50-60% chance of exceeding 80 degrees for the lowlands going into next weekend. Shepard/Lindeman && .AVIATION...Southwesterly flow aloft this evening into Saturday afternoon in advance of an incoming shortwave trough. Persistent onshore flow continues to result in most obs sites seeing surface winds mostly westerly or northwesterly with speeds generally ranging 4 to 8 kts. VFR conditions in place over W WA this evening with only mid to high level clouds in place over the area. Cigs in the majority of terminals will lower somewhat tonight, however all cigs are expected to remain VFR. Locations prone to low clouds may see some SCT clouds develop around 2000-3000 ft, but confidence is low they will be impactful. KSEA...VFR conditions throughout the TAF period, even though cigs may lower a little bit after 06Z. Winds this evening remaining northwesterly before becoming light and variable overnight. Westerly surface winds around 5 kts expected Saturday afternoon. 18 && .MARINE...A weak system will pass over the waters this weekend, but no hazards are expected with this push as wind speeds remain under any headline thresholds. Once this system passes through, pushes down the Strait will resume their daily pattern, however, again, wind speeds will remain below 20 kts. Seas of 3 to 5 feet will build to 4 to 6 feet Sunday through Tuesday before increasing again Wednesday and Thursday to to 6 to 8 feet. HPR/18 && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$