Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA

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000 FXUS66 KSEW 051542 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 842 AM PDT Wed Aug 5 2020 .SYNOPSIS...High pressure aloft will weaken as a frontal system approaches the region. The front will bring some light rain to the area late tonight and Thursday morning. Weak troughing will persist over Western Washington into Saturday for generally dry but cooler conditions. High pressure will gradually rebuild early next week for a trend toward somewhat warmer conditions. && .SHORT TERM /TODAY THROUGH FRIDAY/...Stratus that pushed part way inland overnight is burning back to the coast this morning with plenty of sunshine over the interior. A weak frontal system will spread some high clouds into the area later this afternoon with some rain possible on the coast after midnight. Light rain will spread into the interior of Western Washington on Thursday morning, but amounts will be light. High temperatures on Thursday should be a good 8 to 12 degrees cooler than today. Weak upper troughing remains over the region Friday into Saturday, but it should be dry with night and morning clouds and temperatures near or a little below seasonal normals. No forecast updates planned this morning. The remainder of the previous discussion follows with updates to the marine and aviation discussions. 27 The model interpretation for Friday is still to trend drier with a return to seasonably normal temperatures, as low amplitude upper level ridging builds back into the area. Highs will be in the low to mid 70s with 60s along the coast. .LONG TERM /SATURDAY THROUGH TUESDAY/...Moving into the weekend, a clear pattern is lacking in the wake of the system that moves through on Thursday. Arguably quasi-zonal flow with a broadly unsettled pattern shaping up for Saturday, which is shaping up to be benign across western Washington. Highs will be in the mid to upper 70s, continuing into Sunday before the pattern starts hinting at rebuilding a more well defined ridge. A more well defined system looks to trek south from the Gulf of Alaska, but at this point, it does not appear to dive south enough into Washington. At this point in time, if the system just clips the area, that could lead to light shower activity in the northern parts of the CWA at best. Confidence in the exact extent of its southward movement is low and bears monitoring in future forecast iterations. For Tuesday, the pattern seems quiet again and temperatures warm a few degrees from Monday`s temperatures, although the models hint at yet another system in the first half of next week. While too early to speculate, more details will come into focus as the time frame of interest nears. Kristell && .AVIATION...Southwest flow aloft as an upper trough approaches the area today. Onshore flow will stratus clouds and the coast and into areas around the South Sound. VFR for most this morning with IFR along the coast and Southwest Interior. Patchy fog across the central Puget Sound near KPWT. VFR cigs by late this morning as clouds clear towards the coast. A cold front will bring rain tonight to the coast with low clouds and rain pushing into the interior areas early Thursday morning. South to southwest winds light this morning with 5 to 10 knot winds this afternoon into tonight. JD KSEA...VFR cigs. South to southwest winds light this morning to 10 knots this afternoon. JD && .MARINE...Onshore flow through this week. Small Craft Advisory winds for the Strait of Juan de Fuca through tonight. SCA winds tonight for the northern inland waters. Onshore flow will increasing Thursday as a cold front moves through the area. A second, weaker, front will diminish over the Coastal Waters Friday night. Onshore flow through the weekend Onshore flow will continue today. Highest wind and waves will be found through the Strait of Juan de Fuca - Small Craft Advisory winds are likely. Onshore flow will increase on Thursday as a cold front moves inland. A second, weaker, front will diminish over the Coastal Waters Friday night. Onshore flow will continue into the weekend. 33 && .HYDROLOGY...The daily hydrology discussion has ended until the start of the next rainy season; it will only be updated as needed until then. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 11 PM PDT this evening for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory from 5 AM early this morning to 11 PM PDT this evening for Northern Inland Waters Including The San Juan Islands. && $$ www.weather.gov/seattle

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