Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
241 FXUS66 KSEW 031001 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 201 AM PST Sun Nov 3 2024 .SYNOPSIS...Unsettled weather conditions will linger over the weekend with showers continuing, especially in the Cascades. A stronger frontal system will arrive on Monday for more rain, widespread breezy to locally windy conditions, mountain snow and high surf conditions. Drier weather is possible by midweek. && .SHORT TERM /TODAY THROUGH TUESDAY/...Western WA is under NW flow today with a strong ridge offshore and troughing over the Intermountain West. On radar, lingering showers over the region with a weak ripple in the flow. Light snow showers still expected in the Cascades this morning with snow levels around 3500-4000` - a Winter Weather Advisory remains in effect. Expect drier weather by the afternoon with temps in the 50s. A stronger Pacific frontal system will reach WA on Monday for more rain, wind, mountain snow and high seas. Classic baroclinic leaf pattern spotted in the satellite imagery offshore with rapid cyclogenesis and deepening over the next 24 hours. Much of western WA will be breezy to windy through the day with highest winds over the coast and north interior. Winds switch to westerly Monday afternoon and evening with a strong push through the Strait of Juan de Fuca. Meanwhile, up in the Cascades, strong/westerly upslope winds will help generate snow showers in a cool air mass (snow levels around 3500-4000`). There`s potential for periods of heavy snow in the north and central Cascades and a Winter Storm Watch is in effect. As for rainfall, we`re looking at another inch for the coast and around 0.25-0.50" in the interior with the wettest period during the morning hours. And lastly, high seas, as mentioned below in the marine section, with swells reaching 18-22 ft. Showers lingering into Tuesday with onshore flow and light warm frontal precip but overall the weather will be quieter compared to Monday. 33 .LONG TERM /WEDNESDAY THROUGH SATURDAY/...High pressure brings drier weather from Wednesday through the end of the week as moisture is deflected north into B.C. Temperatures will be cooler, though, with lows dipping into the 30s Wednesday and Thursday mornings. The ridge shows signs of weakening/flattening toward the weekend with rain returning to western WA. 33 && .AVIATION...Northwesterly flow will persist aloft as a series of upper level troughs move over the region. Rain shower coverage has decreased over the area, and should remain isolated throughout the day today. Ceilings are primarily MVFR across western Washington, with periods of IFR under isolated showers. Ceilings should remain MVFR and slowly rise to VFR, first this morning along the coast, then through the interior late morning into early this afternoon. Lower ceilings and rain will begin appear towards the end of the TAF period as a cold front begins to approach the region. Winds will generally persist from the south at 4-8 kt, though will begin to increase to 8 to 15 kt at the end of the TAF period. The exception is KCLM and KHQM, where winds will transition to more westerly. KSEA...MVFR ceilings will continue through this morning, rising to VFR early this afternoon, around 21Z, and remain VFR through most of the TAF period. Today should be mostly dry, but a few isolated showers are possible around the terminal. Winds will generally persist out of the south at 4-8 kts and will begin to increase around 12Z Monday as the next system approaches the area. LH && .MARINE...A weak cold front is currently moving through western Washington this morning, bringing with it breezy northwesterly winds across the coastal waters to 20-25 kt this morning. As the front moves through the area, a push of westerlies down the Strait of Juan de Fuca will follow behind the frontal passage, bringing periods of small craft advisory winds to the Central and East Entrance to the Strait of Juan de Fuca, as well as Admiralty Inlet. Winds will subside late this morning. A break in windy conditions across the area waters this afternoon will be brief before the next system approaches the area late tonight into Monday. Gale force winds are likely across the coastal waters as well as through the Strait of Juan de Fuca as a cold front passes through the area, for which Gale Watches have been issued. A brief period of gale force winds are possible through the Northern Interior Waters as well, but look to a brief period Monday morning as the front moves through. Winds will likely reach small craft advisory levels through Admiralty Inlet, Puget Sound, and Hood Canal as well on Monday. Guidance continues to indicate the potential for gusts to reach storm force (up to 50 kt) through the Central Strait of Juan de Fuca Monday afternoon and evening. High pressure will build back into the area on Tuesday will allow for winds to gradually ease across the area waters. High pressure then looks to persist into Wednesday, though a weakening warm front may skirt the coastal waters as it approaches British Columbia. High pressure will then remain situated over the coastal waters through Thursday before a weakening system approaches the region on Friday into next weekend. Seas 8 to 12 ft early this morning will continue to rise up to 14 to 18 ft through the day as long period swell generated by a low pressure system in the Gulf of Alaska moves into the coastal waters. The dominant period of these waves will be around 19-20 seconds. Seas then look to rapidly rise again on Monday morning up to 18 to 22 ft as the strong cold front approaches the area. Seas will then start to gradually subside on Tuesday, though likely not subsiding below 10 feet until early Wednesday. Seas will then hover between 5- 8 ft through the remainder of the week. LH && .SEW WATCHES/WARNINGS/ADVISORIES... WA...Winter Storm Watch from late tonight through Tuesday morning for West Slopes North Cascades and Passes-West Slopes North Central Cascades and Passes. Winter Weather Advisory until 10 AM PDT this morning for West Slopes North Central Cascades and Passes-West Slopes South Central Cascades and Passes. PZ...Small Craft Advisory from 4 AM early this morning to 10 PM PDT this evening for Grays Harbor Bar-West Entrance U.S. Waters Strait Of Juan De Fuca. Gale Watch from late tonight through Monday evening for West Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory until 10 AM PDT this morning for Admiralty Inlet-Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Gale Watch from Monday morning through late Monday night for Central U.S. Waters Strait Of Juan De Fuca-East Entrance U.S. Waters Strait Of Juan De Fuca. Small Craft Advisory until 10 PM PDT this evening for Coastal Waters From Cape Flattery To James Island Out 10 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm- Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm. Gale Watch from late tonight through Monday evening for Coastal Waters From Cape Flattery To James Island 10 To 60 Nm- Coastal Waters From Cape Flattery To James Island Out 10 Nm- Coastal Waters From James Island To Point Grenville 10 To 60 Nm-Coastal Waters From James Island To Point Grenville Out 10 Nm-Coastal Waters From Point Grenville To Cape Shoalwater 10 To 60 Nm-Coastal Waters From Point Grenville To Cape Shoalwater Out 10 Nm. Small Craft Advisory until 10 PM PDT this evening 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. && $$