textproduct: Medford

DISCUSSION

A few light showers, mainly over the higher terrain from the Coast Range to the Cascades, have popped up with the benefit of afternoon heating and a shortwave in the northwest flow aloft. This meager level of activity may linger for another few hours while a ridge centered far offshore builds into our region.

There is high confidence that the ridge will continue to build over Oregon and northern California through Tuesday, then persist on Wednesday. This will bring the very typical winter conditions that occur when it is not precipitating. Valley low clouds and fog/freezing fog are expected to develop late this evening, especially but not exclusively in southwest Oregon and western Siskiyou County. Most of this will be in the form of freezing fog. Valleys are expected to have varying degrees of success in improving/breaking out of the freezing fog during the afternoons from Sunday through Wednesday. In collaboration with our neighboring offices, have determined that the forecast stays just beyond criteria for a potential Air Stagnation Advisory with mixing heights expected to exceed 1000 ft AGL. This will continue to be monitored with subsequent shifts.

Beyond Wednesday afternoon, a broad trough in the Gulf of Alaska, and a weaker (but, potentially developing) trough offshore from central California will shift toward the west coast. The NBM looks a highly appropriate solution for the latter part of the week, indicating gradually increasing precipitation chances, with the highest probability Thursday night into Friday night. The ECMWF ensemble, in comparison with the GEFS, has a more sizeable minority of members that more strongly deepen the Californian trough and would create a scenario around New Year's Day with some resemblance to the weather of Christmas Day. This would be relatively high snow levels (above 4500 feet or higher), but with moderate to heavy precipitation for northern California. Of higher probability is that the flow aloft will more broadly split with our region affected by the generally weaker southern portion of the northern branch of the jet stream. This would be colder, placing snow levels around 3000 to 4500 feet, but with lower precipitation amounts than in the aforementioned scenario. More in the realm of potential Advisory level snowfall late in the week with a focus for the Cascades, rather than a Warning event. Please stay tuned for updates.

AVIATION...28/06Z TAFs

VFR conditions continue across northern California and southern Oregon tonight. Expected offshore flow will minimize fog chances for coastal areas. While current guidance takes a step away from fog in the Rogue Valley and a step towards development over Klamath Falls, the TAF forecast will still reflect possible timing for developments in low-lying areas. Anything that develops overnight looks to clear late Sunday morning or early in the afternoon. VFR will prevail once valleys clear out, with fog looking to return to these areas on Sunday night. -TAD

MARINE...Updated 200 PM PST Saturday, December 27, 2025

Steep seas are expected across all waters through this evening. Tonight into Sunday northwest swell will gradually lower but expect gusty north winds and steep seas across the waters south of Cape Blanco beyond 10 nm from shore. Winds and seas are expected to ease early next week.

MFR WATCHES/WARNINGS/ADVISORIES

OR...CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 10 PM PST this evening for PZZ350-356-370-376.