Area Forecast Discussion
Issued by NWS Seattle/Tacoma, WA
Issued by NWS Seattle/Tacoma, WA
115 FXUS66 KSEW 291037 AFDSEW Area Forecast Discussion National Weather Service Seattle WA 237 AM PST Sat Nov 29 2025 .SYNOPSIS... An overall cooler and drier trend will continue into next week, though a few weak disturbances moving across the area may bring some additional shower chances at times. A stronger system may approach western Washington late next week. && .SHORT TERM /TODAY THROUGH MONDAY/... An upper level ridge building into the northeastern Pacific this weekend will keep conditions rather calm across western Washington for the time of year. Overall, expect a cooler and drier trend through the short term, though weak disturbances will drop down into the area today and again on Monday under northwesterly flow aloft. The system today will primarily increase cloud cover across the area and will keep much of the area dry, however could see a few light showers pop up as it moves through- particularly over the mountains. Temperatures will cool a few degrees through the weekend, with afternoon highs generally expected to be in the mid to upper 40s across the interior and upper 40s to low 50s along the coast. Morning lows will be in the mid to upper 30s today but will fall within a few degrees of freezing and into the low to mid 30s Sunday and Monday. Another disturbance will then drop down into the area on Monday under the northwesterly flow aloft. At this time,the system does not look to be very impactful, but does looks to bring better chances for some more widespread light rain to the lowlands and light snow to the mountains. Most lowland locations will likely only see a few hundredths of an inch of rain and most spots across the mountains will likely only see 1-3 inches of snow Monday night into Tuesday. Light snow accumulations will also be possible at the passes. && .LONG TERM /TUESDAY THROUGH FRIDAY/... Precipitation will taper across the area throughout the day Tuesday. The pattern through the long term will be similar to that of the short term, with both ensembles and deterministic guidance suggesting the ridge of high pressure remaining situated over the northeastern Pacific through much of the week. A few weak disturbances may drop down into western Washington under the northerly flow aloft again Wednesday into Thursday, but expect any precipitation to remain mostly light. Highs will be in the mid to upper 40s and morning lows will be in the 30s. The pattern becomes more uncertain later in the week as model guidance suggests a wetter system making its way into the area as the ridge over the Pacific weakens. Ensembles hang onto the amplified ridge a little longer though, so will have to see how guidance resolves this scenario over the coming days. 14 && .AVIATION... North flow will increase today over western WA as the jet aloft gets sandwiched between an embedded trough to the east, and a ridge over the eastern Pacific Ocean moves onto land. Most terminals are reporting clear or high scattered clouds this morning with light or calm winds (out of a northeast or variable direction). Patchy/areas of mist and fog have begun to form from KCLS to KOLM to KTCM/KPLU areas of the south sound, and this is the favored area for development this morning. Outside of this area, the high clouds and drier offshore pattern is expected to prevent widespread low vis/cigs from forming (though a couple isolated patches cannot be ruled out). The trough/stationary front to the east will drop south today in east WA, but will be enough to produce a couple of light showers this afternoon and evening. The highest confidence for low cigs/vis down to IFR/LIFR for Saturday night/Sunday is the Chehalis Valley corridor up through the Kitsap (though there is some model discrepancies with how widespread coverage will be based on how much clearing takes place with calm winds again). KSEA...VFR is expected through the TAF period. Lower cigs/vis to the southwest is not expected to advance past the Tacoma area this morning. There is a 15% chance of a shower later this afternoon and evening, so will keep it as a vicinity shower for now due to low confidence in track. Low confidence in ceilings Sunday morning (given about 80-90% of clouds will clear out).in the week If ceilings do form, NBM gives highest odds for MVFR level decks in the morning. Winds: NE 4-8 kt. HPR && .MARINE... A ridge over the east Pacific will move inland today, with low pressure further inland moving through. Northeast winds will continue through Sunday with magnitudes remaining light. Seas will remain at 6 to 8 ft through next Tuesday. A system will sneak over the outer coastal waters then, with seas building back to 8 to 12 ft (higher seas in the outer coastal zones). A few gusty northwest winds to 25 kt are possible Tuesday with this system. Towards the end of next week, seas will return to 4 to 6 ft with light winds. HPR && .HYDROLOGY... River flooding is not expected over the next 7 days. && .SEW WATCHES/WARNINGS/ADVISORIES... WA...None. PZ...None. && $$