173 FXUS66 KSEW 210326 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 826 PM PDT Fri Aug 20 2021 .SYNOPSIS...A weak weather system will exit the area early Saturday morning. Another weak upper low will pass to the north on Sunday. Weak high pressure aloft will allow temperatures to warm to near normal the first half of next week. Another weak system could move through the area late in the week. && .SHORT TERM /TONIGHT THROUGH MONDAY/...An upper low pushing south through the area this evening will exit the area Saturday morning. A few isolated thunderstorms will continue in the North Cascades, especially near the crest. Elsewhere, a few areas of showers continue in western Whatcom County and stretching across the San Juan Islands and into the US 101 corridor on the northern Olympic Peninsula. The area near Sequim was briefly strong enough to bring around a half inch of rain in only 15 minutes, but these will continue to weaken and slowly move, limiting any significant impacts from this burst of rain. These shows will continue to rotate around the upper low before gradually subsiding late tonight. Otherwise the forecast remains on track this evening, with no additional updates other than to account for the ongoing radar trends. Remainder of previous short term discussion remains valid and follows below. Cullen A weak short wave upper ridge will cross the area on Saturday for a generally dry day with a mix of clouds and sunshine. Highs will be a few degrees below normal. A second upper low will brush the area to the northeast on Sunday, bringing another chance of showers. There might be a PSCZ Sunday morning as well. Highs will be slightly cooler than Saturday - mostly in the 60s. An upper ridge will start to build in from the west on Monday. This should bring a dry day with highs creeping up a few degrees but still a few degrees below normal. Schneider .LONG TERM /TUESDAY THROUGH FRIDAY/...No changes. Previous discussion follows. Upper heights will build a little over the area on Tuesday with temperatures warming to near normal. There isn't very good agreement in the models or even the ensembles after that although the details don't make much difference because it is such a nondescript pattern. Some variation of westerly flow aloft is likely with low level onshore flow and seasonable temperatures. It looks largely dry through the period although there might be a weak weather system late in the week. Schneider && .AVIATION...As of 0300 UTC some showers remain in the area, mostly over the Olympic Peninsula, the Cascade crest, as well as Whatcom County. The strength of these showers is expected to decrease through the rest of this evening. Mostly MVFR ceilings are expected through tonight, but there could be some localized pockets of IFR, particularly in areas of light rain showers. Ceilings are expected to improve to VFR for much of Western Washington by Saturday afternoon. With an onshore flow continuing, light west to southwest winds are expected tonight. These winds are expected to pick up to 7-10 knots around 0000 UTC Sunday. KSEA...MVFR ceilings expected to remain in place through the rest of the night. No rain is expected to move over the terminals tonight. Ceilings should improve to VFR between 1800-2000 UTC Saturday. Southwest winds will decrease slightly tonight but are expected to gradually increase to 7-10 knots by Saturday afternoon. Butwin && .MARINE...A weak low dropping south over the region this evening will continue to push away by early Saturday. High pressure returns offshore Saturday, with a stronger push of west winds through the Strait of Juan de Fuca Saturday evening. Expect low- end advisory winds possible through the central and eastern Strait. High pressure strengthens a bit into early next week, likely bringing a return of a typical late summer pattern featuring diurnally driven west winds through the Strait and breezy northwest winds and steeper seas over the coastal waters. Cullen && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$ www.weather.gov/seattle