Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
675 FXUS66 KSEW 081646 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 846 AM PST Fri Nov 8 2024 .SYNOPSIS...Quiet weather this afternoon before unsettled weather returns as a series of systems impacts the area starting tonight and into the weekend. Active weather will continue into next week, with lowland rain, mountain snow, chances of thunder, and breezy conditions. && .SHORT TERM /TODAY THROUGH SUNDAY/...Last dry day over the next 7. Not as cool this morning with temps mostly in the 40s. Expect highs this afternoon in the 50s with high clouds aloft. 33 Previous discussion...Recent satellite imagery shows high clouds over western Washington early this morning. Upper level ridging will gradually move eastward away from the region throughout the afternoon as upper level clouds continue to stream in ahead of an approaching frontal system offshore. One of the last overall drier days we will have in a while as high temperatures remain in the upper 50s and lower 60s this afternoon. The aforementioned frontal system will weaken and stall over the coast later this evening, slowly spreading precip over the area tonight and into Saturday. This system will be fairly weak in the series of systems that will cross W WA over in the next week. Precip totals are mostly around 0.30-0.75" with this frontal system. Snow levels will remain high, generally in the 5000-6000 feet, mainly limiting snow to the higher elevations. A, stronger deep upper level low will transverse through the area from British Columbia late Sunday into Monday, bringing increased moisture to the lowlands and the mountains, along with lower snow levels, and breezy conditions. .LONG TERM /MONDAY THROUGH THURSDAY/...The aforementioned strong deep upper low will push through W WA into Monday, where impulses of rain will persist. The bulk of the rain will be focused mainly in the Olympics, Cascades, and along the coast. Latest probabilistic guidance shows around 50 to 60% chance of 2 inches or more in those locations. Slight instability with this system also brings a chance of thunderstorms mainly along the coast late on Monday, along with locally breezy winds, with the highest winds near the coast and the North Interior. With multiple wet systems in a short amount of time, decent rainfall will lead to rising rivers across the area, especially the Skokomish River in Mason County. Refer to the .Hydrology section below for more information on possible river flooding. Another system will impact the area on Tuesday-Wednesday, with more lowland rain, and lower snow levels down to around 3500-4000 feet with accumulating snow at the higher peaks and near the passes likely. Active weather will continue through the long term period, with more bouts of rain for the lowlands and snow for the mountains. Mazurkiewicz && .AVIATION...Southwesterly flow aloft today ahead of an incoming upper level trough. Surface winds over the area generally southeasterly ranging 4-8 kts although getting some reports of southwesterlies at HQM and CLM. A weak disturbance offshore is spreading some mid-level clouds over the region, however mostly VFR conditions at current over the CWA. Only CLM seems to be experiencing fog issues, lowering their cigs down into IFR/LIFR territory. They should recover back to VFR conditions by early this afternoon. Remaining stations will remain VFR for much of the TAF period, even as rainfall from incoming weak front enters the area. That said, those locations prone to lower cigs may see MVFR conditions emerge late tonight/early Saturday morning due to the incoming precip. KSEA...VFR conditions prevail with increasing mid-level clouds through the day. Surface winds southerly at 4 to 8 kts through the day. A weak front arrives tonight, bringing rain to the terminal. This may allow cigs to dip occasionally into MVFR early Saturday morning. 18 && .MARINE...A warm front will move into the coastal waters and stall out, with only a few occasional gusts to 15-20 kt. The bigger impact may be seas, building to 9-10 ft over the outer coastal waters this morning. As a result, a small craft advisory remains in place for these zones. The next disturbance, a weak cold front, will push through the waters on Saturday. However, will see a much stronger frontal system that will bring a return of widespread advisory winds...with the potential for some gales. Current guidance suggests around a 40-50% chance over the coastal waters and around the eastern Strait of Juan de Fuca. Seas over the outer waters are likely to hover around 10 ft today and tonight as a northwest swell enters the waters. Seas will likely build back above 10 ft at times through the weekend. However, a much larger increase is expected around Monday as a stronger system approaches and brings a sharp increase in seas over the coastal waters to around 18 to 20 ft. MC/18 && .HYDROLOGY...A weakening frontal system will move through Western Washington later tonight and Saturday for increasing rain, although at this time QPF amounts are expected to remain lighter. A more significant chance of precipitation is expected Sunday through Monday, and again on Wednesday as an active weather pattern returns. At this time, the Skokomish River is the only river forecasted to rise into flood stage, and potentially moderate flood stage during the middle of next week. For other rivers, significant rises are expected and flooding could be possible, but at this time is not forecasted. Flooding extent will depend on rainfall rates, temperatures, as well as snow levels with precipitation that falls with each of these weather systems next week. We will continue to monitor river levels during this period. JD/Mazurkiewicz && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...Small Craft Advisory until 5 AM PST Saturday for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm-Coastal Waters From James Island To Point Grenville 10 To 60 Nm- Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm. && $$