textproduct: Medford

DISCUSSION

Southerly flow aloft is guiding atmospheric moisture into northern California and parts of southern Oregon early this morning. Currently, radar shows showers over Siskiyou and Modoc counties as well as southern Lake county. Later this morning, showers will reach into eastern Jackson, southern Klamath, and western Lake counties. By the afternoon, this moisture will bring showers to western Siskiyou, western Jackson, and southern Josephine and Curry counties. For most areas, these amounts will be light. Steady rainfall will bring 1 to 2 inches of precipitation to Weed, Mount Shasta City, Dunsmuir, and McCloud. Other areas in Siskiyou County look to get between 0.25 and 1 inches. Initial snow levels of 5000-5500 feet may allow for snow showers on Highway 97 and Sawyers Bar Road this morning, but snow levels rising to 6000-7000 feet in the afternoon look to turn precipitation into rain showers while snowfall continues over peaks and valleys.

Uncertainty remains in the forecast for Tuesday evening into Wednesday, although some amount of activity is likely. A compact surface low approaching from the south will be the source of these impacts, but the path of this low seems to vary with almost every model. If this low stays over the Pacific, strong winds are possible across the area. If this low moves inland over northern California, winds impacts may be limited to breezy conditions over terrain and little else. To help illustrate the uncertainty, the interquartile range of HREF sustained winds for Medford on Wednesday morning is between 8 and 27 mph. Or in other words, those outcomes have an equal 25% chance of occurring. At the more extreme end, HREF shows a 10% chance of sustained winds reaching 30-45 mph across the area and gusts of 50 to 75 mph possible through Wednesday morning as the low travels north. The orientation of winds into west side valleys will also play a role for local impacts. Current high-resolution guidance does generally keep the low over the Pacific to some degree which brings some amount of gusty winds, although one high-res model does show the less impactful path over northern California. Given the small scale of this low, additional runs of high-resolution models today will help to solidify a more confident forecast. For the moment, awareness of the impacts as well as the chances can guide preparation. This period will certainly be a focus of today's afternoon update, given the holiday travel period.

The effects of this low are not limited to winds. The Mount Shasta region could see another 2 to 3 inches of rainfall from Tuesday evening into Wednesday morning while coastal areas could see 1 to 1.5 inches. With snow levels remaining at 6000-7500 feet in this period, snowfall will be limited to area peaks and ridgelines. Other areas look to see 0.33 inches or less of precipitation. Of course, these forecast amounts result from a certain path for the first low, and updated information could cause changes.

After a brief period of minor showers on Wednesday afternoon and evening, activity resumes from Wednesday night through as late as Friday afternoon. For this period, an upper low drops into the trough and brings cooler air with it. Continuing southerly flow would keep precipitation focused on the Mount Shasta region as well as terrain along the southern border of western Siskiyou County. With forecast snow levels dropping to 5000 feet on Thursday morning and 4000 feet on Friday morning, upslope flow could bring 1 to 4 feet of snow to terrain in these areas. This looks to be most impactful for Sawyers Bar Road west of Etna, but Snowmans Pass could see snow showers as well. The most recent forecast has only light snow showers for Interstate 5 between Highway 89 and Weed. Cascades passes could also see snow showers, but current amounts look short of Advisory levels. At lower elevations, another round of light to moderate rainfall is forecast. Areas east of the Cascades could see scattered snow showers on Friday, with total amounts staying below an inch away from area terrain.

In the long term, the upper trough weakens late Friday. An upper ridge looks to take its place, with deterministic imagery keeping this ridge in place through next week. Ensemble guidance is showing growing agreement with this outcome, although some ECMWF members show some chances for coastal showers towards midweek. Overall, 2025 looks to end with more stable conditions than Christmas Eve and Day are expecting. -TAD

AVIATION...23/12Z TAFs

A warm front is bringing rain showers to Siskiyou and Modoc counties at the start of the TAF period. Showers look to reach into southern Oregon through this morning and afternoon, with VFR to MVFR levels generally expected through the TAF period. Passing showers may bring locally lower ceilings and visibilities as well.

Gusty winds are expected along and east of the Cascades as well as around Mount Shasta this evening through the end of the TAF period. Periods of gusty winds are also possible west of the Cascades. Low level wind shear will develop over area terrain this evening and tonight, then spread across the area through the end of the TAF period. The warm front will keep snow levels in the 5500-7000 foot range tonight into early Wednesday morning. -TAD

MARINE...Updated 850 PM PST Monday, December 22, 2025

Winds gradually ease tonight into Tuesday, but seas will remain steep.

Two potentially significant storm systems will impact the area this week...the first, quick-moving system, arrives late Tuesday through Wednesday morning and the second, slower-moving system, arrives late Wednesday night and persists into Friday morning.

There is STILL quite a range in solutions (and therefore, low confidence) for the first system as it moves south to north along the coast. This brings a wide range of possible scenarios in terms of wind strength over the marine waters since the position of the low is uncertain. Most of the guidance maintains that gale force winds and very steep seas are the most likely scenario and this is what the forecast reflects. Two other scenarios, which lie closer to the extremes (on both ends) are possible, however. Stronger model solutions (about a 20-30% chance) show a period of southerly storm force winds occurring during the early morning hours Wednesday. Weaker solutions (similar %) move the low into Cape Mendocino and keep the strongest winds to our south. We will maintain the gale watch and allow future shifts to upgrade as new information becomes available.

The second system remains farther offshore on Thursday and lingers over a longer period of time into Friday morning. Confidence is higher regarding some details with this system as guidance is in better agreement, but another round of gales is likely with this storm. Both systems will also bring a round of very steep and hazardous seas and difficult bar crossings. Winds will gradually ease late Friday, but seas are likely to remain steep into early Saturday. Once the Christmas system moves out of the region, the overall weather pattern looks to settle down over the weekend, possibly into next week, and conditions will improve overall. /BR-y/Spilde

MFR WATCHES/WARNINGS/ADVISORIES

OR...High Wind Warning from 4 PM this afternoon to 10 AM PST Wednesday for ORZ029>031.

Wind Advisory from 10 PM this evening to 10 AM PST Wednesday for ORZ023>026.

Winter Weather Advisory from 10 AM this morning to 10 AM PST Wednesday for ORZ027-028.

CA...Winter Storm Warning until 10 AM PST Friday for CAZ080-082>085.

High Wind Warning from 4 PM this afternoon to 10 AM PST Wednesday for CAZ081-084-085.

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

Gale Watch from this evening through Wednesday afternoon for PZZ350-356-370-376.