FXUS66 KMFR 250600 AFDMFR Area Forecast Discussion National Weather Service Medford OR 1000 PM PST Sun Nov 24 2024 .UPDATE...Updated Aviation discussion. && .DISCUSSION...Main update for this evening was to extend the Wind Advisory until 10 pm tonight for the Shasta Valley. Gusty winds are generally easing west of the Cascades, but gusts to 45 mph in the Shasta Valley will persist for a few more hours. Low pressure lingering offshore is maintaining southerly flow over the region, and shortwaves rotating around the base of this low are bringing additional rain and snow to the area. A Winter Storm Warning remains in effect through tonight for elevations above 4000 ft in the Mt Shasta area. Snow has been falling down around 3500 ft in the Mt Shasta City region. We'll continue to monitor in case we need to include this area in any winter headlines. Unsettled weather will continue through Tuesday before this persistent offshore trough finally moves east of the region. For more details, see the previous discussion below. /BR-y && .AVIATION...25/06Z TAFS...Gusty south to southeast winds have eased in the Rogue Valley late this evening. Low-level wind shear is still a concern for North Bend overnight into early Monday morning, since surface winds are comparatively lower than wind speeds just above the ground (2000 feet). Winds at that level are in the 30-40kt range. This risk subsides later Monday morning as winds aloft ease. Low-level turbulence can be expected near and west of the Cascades, especially in the vicinity of terrain. An occluded front near the coast will bring some precipitation inland tonight, with the focus near the coast to the Umpqua Divide over to the Cascades as well as in the vicinity of Mt. Shasta. There is a risk of thunderstorms over the marine waters and along the immediate coast. Overall, ceilings are a mix of VFR/MVFR with the lowest ceilings in areas of rain/snow. Snow falling near Mount Shasta will bring IFR and perhaps even LIFR at times there. The southeast winds lasted long enough here in the Rogue Valley this afternoon/evening that fog potential here is much less likely, especially since dew points have dropped to the low 30s. Even if there is some clearing and winds decouple from the boundary layer, fog formation potential is unlikely. Other valleys that didn't get the wind could have patchy fog and/or low clouds toward morning. A secondary front will push onshore Monday with light precip, mixed MVFR/VFR ceilings and higher terrain obscurations. Local IFR/LIFR is possible in heavier precip. -Spilde && .MARINE...Updated 830 PM PST Sunday, November 24, 2024...Low pressure moved past North Bend in the last hour or so, with gales moving north through the waters. The gale warning was extended to 9 pm, but this will end as the low moves northward and onshore. We still expect some showers and even isolated thunderstorms over the coastal waters tonight into Monday. Any of the heavier showers/thunderstorms could produce gusty winds in excess of 34 kt, but overall, wind speeds should back off to 20-30kt. Another reason for extending the gale through 9 pm was the sea state. Still some very steep seas out there this evening with 10-11 ft, 8 sec at Buoys 15 and 27 at 8 pm. These should lower to small craft conditions (near or below 10 feet) late this evening and overnight. The sea state improves Monday, even as an upper level low remains over head. Conditions will further improve through the week as high pressure builds. -Spilde && .PREV DISCUSSION... /Issued 502 PM PST Sun Nov 24 2024/ DISCUSSION...A low pressure system lingering over the Pacific continues to dictate conditions over northern California and southern California. Southerly flow aloft will bring more showers over Curry County ranges, western Siskiyou County, and the Mount Shasta region. Snow levels lingering at 4000 to 5000 feet will allow for snow showers to continue over nigher terrain in these areas. Southerly flow is also bringing gusty winds into the Shasta Valley and the southern Rogue Valley. Wind Advisories remain in place for the Shasta and southern Rogue Valley through 8 PM tonight. A Winter Storm Warning continues for areas around Mount Shasta above 4000 feet through Tuesday at 4 AM. Upper level pressure will move eastward, passing over the area through Monday and Tuesday. Broadly, this will bring increased shower chances across the area. Snow showers will continue over those higher elevation areas around Mount Shasta and could develop over the Cascades on Monday as winds aloft become more westerly. Moderate to heavy snow is possible around Crater Lake, including parts of highways 230 and 62. Current forecast snowfall amounts are borderline for Advisory thresholds in these areas and lower in other parts of the Cascades. A Winter Weather Advisory will not be issued as of this moment, but additional data could change that. Showers and winds taper off through the day Tuesday, with a dry period in the forecast from Tuesday evening through the weekend under an upper level ridge. Daytime temperatures do not look to substantially change, but drier conditions and clear skies will allow for cooler nights across the area. For Tuesday night through Saturday night, the Oregon coast is forecast to have lows in the mid 30s to low 40s. West side valleys will be in the mid 20s to mid 30s, and areas east of the Cascades will be in the low to high tens. Sunday afternoon and beyond is where confidence starts to falter. Both ECMWF and GFS long term ensemble outcomes start to show varying possibilities for Sunday afternoon and beyond, with some staying dry and others with varying precipitation. At this point, even these varying possibilities do not look impactful. Meteogram guidance for Crater Lake snowfall reflects similar possibilities, with no truly organized signals for heavy snowfall at this point. -TAD && .MFR WATCHES/WARNINGS/ADVISORIES... OR...CA...Wind Advisory until 10 PM PST this evening for CAZ081. Winter Storm Warning until 4 AM PST Tuesday for CAZ082. PACIFIC COASTAL WATERS...Gale Warning until 9 PM PST this evening for PZZ350-356-370-376. Small Craft Advisory until 7 AM PST Tuesday for PZZ350-356-370- 376. && $$