FXUS66 KPQR 290900 AFDPQR Area Forecast Discussion National Weather Service Portland OR 200 AM PDT Sat Mar 29 2025 .SYNOPSIS...Active weather will continue today, with cool, near normal temperatures and persistent showers. Saturday night into Sunday a brief break in the precipitation as well as a slight warming trend is expected as a shortwave ridge quickly moves across the forecast area. By thee start of the upcoming week, a broad area of low pressure will bring a return of cooler temperatures, rain and Cascade snow by late Sunday night/Monday and these conditions look to persist through the upcoming week. && .DISCUSSION...Today through Friday...The trailing end of the low pressure system will finally be pushed out through this afternoon. The low will be replaced by a shortwave ridge which will quickly be replaced by another low pressure system by Sunday evening/Monday. What this means is that light showers will continue to dissipate through the afternoon, with dry and warmer weather is expected by tonight. Sunday will start off as slightly warmer and drier than the previous few days, but this will be short lived as the next major low will bring another round of cooler temperatures and widespread showers across the forecast area through all of next week. The system on Sunday night/Monday is a rather broad, vertically stacked low, with the surface low expected to be around 985 mb and centered around 45.75N/136.40W on Monday. This low will slowly weaken and travel southeastward through the upcoming week, with models showing landfall in-between Florence, OR and the OR/CA border. As this low moves southeastward, it will send multiple fronts across the region. This will result in south/southeasterly flow, that along with moderate warming and a moisture latent atmosphere will result in around a 10-20% probability for thunderstorms come Monday afternoon and continue through the late Monday evening. Cool and moist conditions will continue as the low continues to trudge southeastward and will bring widespread precipitation along with 850 mb temperatures dipping down towards -1C to -4C. This will result in a lowering of snow levels and the combination of lowering snow levels and precipitation could easily bring 6-11 inches of new snow to the Cascades. Current guidance is showing 6-11 inches or so, every 24 hours stating on Monday and continuing through Thursday for elevations above 2500-3000 ft. The current track of the low the focus of the snow will be more towards the Lane and Linn County Cascades. There is also a 10-20% probability of elevations above 5000 ft seeing snow accumulation around 10-12 inches for the same region. Overall, expect daytime highs to be near normal (50s and 60s) for the forecast area, with Sunday expected to be the warmest through the upcoming week. Saturday into Sunday evening will be dry, but precipitation returns by the start of next week. Also, cooler temperatures are on deck for the start of next week and that could bring Advisory level snowfall (6-11 inches) to the Oregon Cascades Monday through Thursday. Early ensemble guidance shows snow levels falling to around 2000-3500 ft, and mountain snow can be expected at times throughout next week. Currently evaluating potential for Winter Weather Advisory-level snow in the mountains with the initial front, particularly in the Lane County Cascades. We will continue to monitor model output as this is still 3 to 5 days out and could easily change. /42 && .AVIATION...Northwest flow aloft with light southerly surface winds on Saturday, with both shifting northerly after 21z Saturday - 00z Sunday. Scattered showers continue across the region through Saturday, dissipating over the interior lowlands by 18-21z Saturday and across the coast and high terrain by 00-03z Sunday. Expecting mainly VFR conditions through the TAF period for most terminals except for a 70-90% chance of MVFR cigs and vsbys along the coast through around 18z Saturday. Heavier showers could temporarily lower cigs and vsbys to MVFR. Additionally, there is around a 20-40% chance of MVFR cigs within the Willamette Valley and around a 50-70% chance from KPDX northward from 10-18z Saturday. However, if the BKN/OVC mid to high level cloud deck clears by 10-14z inland, then probabilities will increase for MVFR conditions. -HEC PDX AND APPROACHES...Scattered rain showers through 00z Sunday with conditions predominately VFR through the period. There is around a 40-60% chance of MVFR cigs 11-18z Saturday. South to southwest winds less than 10 kts shifting northerly after 00z Sunday. -HEC && .MARINE...The surface trough pushed inland late Friday night, and winds and waves are weakening on the back side of this trough. Southwest winds will continue weakening through Saturday as weak high pressure moves over the waters. Winds turn offshore late Saturday into Sunday morning with locally breezy winds through coastal gaps. Winds then turn southerly by Sunday afternoon and increase through Sunday night as another frontal system approaches. There is about a 40-60% chance of low- end gale force wind gusts for Sunday night into Monday morning. More uncertainty into early next week as to where the surface low tracks, but confidence is high for at least Small Craft wind gusts over 21 kts. Seas have fallen to around 9 to 11 feet at 10 to 11 seconds, and will remain here through Saturday morning. A Small Craft Advisory is in effect through 11 AM Saturday. Seas should continue to subside through the weekend, falling to around 5 to 6 ft on Sunday. Seas will build again into the low teens late Sunday night into early next week in response to the approaching weather system and increasing southwesterly winds. -DH/HEC && .PQR WATCHES/WARNINGS/ADVISORIES... OR...None. WA...None. PZ...Small Craft Advisory until 8 AM PDT this morning for PZZ210. Small Craft Advisory until 11 AM PDT this morning for PZZ251>253- 271>273. && $$ www.weather.gov/portland Interact with us via social media: www.facebook.com/NWSPortland x.com/NWSPortland