Maple Valley, WA Weather

Synopsis

High pressure aloft will provide another day of dry conditions for Western Washington today. An area of low pressure moving southward from the British Columbia coast will bring some rain to the region later Saturday into the early portion of next week. Drier conditions are expected to return by the middle of next week as the low pressure system moves eastward.

Short Term

No major updates to the forecast have been made this morning. See below for an updated aviation discussion.

High pressure aloft will briefly rebuild into Western Washington today for a dry day ahead and near seasonal temperatures. An area of low pressure sliding south from the British Columbia coast is still slated to begin to affect the area later Saturday into Sunday. Models still remain at odds with respect to its track, but there's enough consensus to warrant likely to categorical PoPs for the coast and Olympic Peninsula Saturday night into Sunday. Some QPF is expected to make it into Puget Sound on Sunday, but present thinking is that it will remain rather light. Temperatures through the short term period will hover within a couple degrees of normal for the final week of October.

Long Term

Upper troughing remains over the Pacific Northwest Sunday night into Monday for a lingering chance of precip...mostly focused on the southern half of the CWA. The upper trough is expected to shift eastward on Tuesday, but confidence in the forecast trails off by the middle of the coming week as ensembles begin to diverge somewhat from what they featured just a day ago. The GFS suite of solutions have a stronger influence of upper troughing over the region while the ECMWF height anomalies would keep broad upper troughing just offshore of California. To be clear, neither of these is a particularly wet scenario for Western Washington, but it lends enough uncertainty to retain some generic low chance PoPs for much of the CWA...and that's exactly what the NBM is using in the forecast. Temperatures are expected to remain generally seasonal, but chances for some sub-freezing overnight lows in the Southwest Interior and outlying areas increase toward the middle/later portion of next week.

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Aviation

Generally low end VFR to MVFR in mid level clouds, which are slowly beginning to scatter out this morning with widespread VFR expected by the afternoon. Northwesterly flow aloft in the wake of an exiting trough expected to remain that way throughout the day and into Saturday. Surface winds at all terminals light and variable this morning with northerly winds expected to develop by this afternoon with speeds ranging 4-8 kts. Light and variable winds expected again tonight.

KSEA...Cigs hovering right around 3000 feet this morning should scatter out by 18z, revealing clear skies. Increasing high clouds later tonight expected to hinder chances of degraded ceilings developing overnight into Saturday morning. Surface winds generally light at the terminal this morning becoming northerly 5 to 10 kt in the afternoon, and light and variable overnight.

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