Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
726 FXUS66 KSEW 301647 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 847 AM PST Sun Nov 30 2025 .SYNOPSIS... Overall, a cooler and drier pattern is expected to persist across western Washington through the first half of the week with ridging offshore, though a weak disturbance moving across the region Monday night into Tuesday will bring some showers to the area. A change to a wetter pattern is likely late in the week as the ridge weakens and opens the door for stronger and wetter systems to approach western Washington. && .SHORT TERM /TODAY THROUGH TUESDAY/... Dry conditions are expected across western Washington today as a ridge of high pressure continues to build into the area from the northeastern Pacific. Clearing overnight has allowed for some fog development across portions of the South Sound and East Puget Sound lowlands, which has brought some visibilities down to 1 mile or less in spots. The areas of fog remain rather shallow however, so expect fog to dissipate by the mid to late morning hours today to make way for some sun. In addition to fog, it will also be a chilly start to the morning as clearing has allowed for temperatures to cool to near freezing in spots, especially across portions of the southern Sound away from the water and along the Chehalis Valley. Afternoon highs today will be in the mid to upper 40s across the area. Another chilly and foggy start is likely for portions of western Washington on Monday morning, especially across the southern Sound and Chehalis Valley. A weak disturbance will then drop down into the area under the northwesterly flow aloft Monday night into Tuesday, bringing chances of light rain to the lowlands and snow to the mountains. At this time, this system does not look to be very impactful to the area, with most spots across the lowlands only expected to receive a couple hundredths to around a tenth of an inch of rain. Light snow accumulations are expected for the mountains, mainly between 1-3 inches, with only some light snow (roughly around an inch or less) expected at the passes. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Conditions will dry out again Tuesday night into Wednesday as the ridge of high pressure over the northeastern Pacific builds back into the region. The pattern then becomes a bit more uncertain heading into the second half of the week as ensemble clusters remain split on the degree of ridging over the northeastern Pacific. The majority of the GEFS members hint at the ridge weakening, allowing for wetter systems to move into western Washington, while the majority of the ENS members suggest somewhat drier solutions with more of an amplified ridge persisting over the Pacific. Will need to see how guidance resolves the scenarios over the coming days, but the current forecast from Thursday onward generally trends towards the wetter solutions at this time. Temperatures look to warm the second half of the week, from lows in the 30s and highs in the 40s on Wednesday and Thursday to lows in the 40s and highs in the 50s by Friday and Saturday. 14 && .AVIATION... An upper level ridge just offshore will begin to move inland today into Monday. The northerly flow aloft will weaken and become westerly Monday. The shallow radiational fog has formed in many of the low lying areas this morning should lift relatively quickly this morning. Ceilings will remain clear through the remainder of the day, with ceilings filling in Monday morning (most will see VFR decks between 3,000 - 10,000 ft but again probabilities remain medium for additional radiational fog or low ceilings in the morning in the same spots as this morning and potentially up through metro Seattle). Very light 3-6 kt or calm winds out of the east/northeast are expected across most terminals. KSEA... Shallow fog to the east of the terminal along the Green River will clear by late morning, and is not expected to affect the terminal. Lower confidence in fog forming Monday morning with most guidance keeping the odds below 40%. High clouds advecting into the area may help hinder development. Winds will remain light north/east 3-5 kt. HPR/Cook && .MARINE... High pressure will move inland next few days under a ridge coming ashore. Conditions are expected to remain calm through Tuesday with seas at 4 to 6 ft and calm or light offshore winds. A weak front will skirt the outer coastal waters Tuesday and Wednesday. At this time, the best chance of winds exceeding 20 kt remains in the outer coastal waters Tuesday. Seas will build back up to 9 to 12 ft Tuesday through Wednesday, then decrease back down to 4 to 6 ft with light winds Thursday with another system potentially passing through next weekend. This system may bring winds exceeding 20 kt to the Strait of Juan de Fuca, as well as 9-12 ft seas going into next weekend. HPR && .HYDROLOGY... River flooding is not expected over the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$