textproduct: Medford

UPDATE

Aviation Discussion Updated.

AVIATION...31/18Z TAFs

Stable conditions are in place today with areas of valley fog and low clouds. A front will move up from the south tonight and early Thursday bringing lower ceilings to and areas of lowered visibilities to the area.

Low clouds and fog with IFR/LIFR conditions are expected to persist in the Umpqua Basin and lower Rogue Valley near Grants Pass through at least late in the afternoon, then may see partial clearing. Guidance supports clearing to VFR in the late afternoon. Confidence is only moderate on this occurring at Roseburg. So will monitor and update the forecast as needed. For other area, fog and low clouds are clearing late this morning and early this afternoon, including at Medford. Rain will move into the area from the south tonight and bring widespread MVFR and local IFR, along with widespread mountain obscurations, tonight and early Thursday morning.

PREV DISCUSSION

/Issued 342 AM PST Wed Dec 31 2025/

DISCUSSION...Take the conditions of the last few days, then rinse and repeat for what's expected on the last day of 2025. Fog/freezing fog and low clouds persist in the same areas as yesterday morning, though a little more so here in the Rogue Valley compared to yesterday. Gusty east to southeast winds continue across the terrain, though a bit weaker than 24 hours ago with Buckhorn Springs and Slater Butte (both of which typically "feel" the offshore flow) are only gusting to around 25 mph this morning.

One notable difference, however, is the increasing amount of high level cloud cover from the south. This not only marks the first signs of a pattern change, but is also keeping low temperatures a few degrees warmer than this time yesterday for locations under this cloud cover. Additionally, this cloud cover is likely to keep afternoon temperatures a few degrees cooler than yesterday, except where fog/low clouds persist through the afternoon (Grants Pass area/Umpqua Basin) where temperatures remain on the chilly side (upper 30s/low 40s). Later this evening and overnight, we'll see light precipitation spreading from south to north with snow levels increasing to around 8000 ft tonight. For details on the change to more active weather, please see the previous discussion below.

MARINE...Updated 200 AM PST Wednesday, December 31, 2025...Overall, sub-advisory conditions are expected through early Thursday as seas remain swell dominated and light south winds persist. Active weather resumes on Thursday and conditions hazardous to small craft return by Thursday evening as south winds increase to advisory levels and seas steepen. Conditions worsen by Friday morning and persist into the weekend with south winds increasing and possibly reaching gales Friday and again Saturday. Have gone ahead with a Gale Watch for the first round of strong winds that are expected to be focused over the outer waters. Winds look to weaken briefly early Saturday, but another round of gales, possibly more widespread, is possible by Saturday afternoon/evening. Steep to very steep and hazardous seas are expected through the weekend, highest and steepest during the periods of gales.

PREV DISCUSSION... /Issued 311 PM PST Tue Dec 30 2025/

DISCUSSION...New Year's Day looks to also make a delineation from our current dry pattern with stagnant air to a very active, wet pattern with persistent southerly flow. Conditions on Wednesday will again resemble those of the previous day, with an Air Stagnation Advisory remaining in effect for valleys east of the Coast Range.

This new pattern at the end of this week into the middle of next week will resemble our most recent active pattern from late last week. As such, Siskiyou County and the coast will receive the bulk of precipitation. Though the duration of wet weather will be unusual, amounts do not look to produce significant rises on rivers, with nothing more than the potential in Siskiyou County and the coast for nuisance street flooding or flooding of small creeks and streams.

The main update for this afternoon forecast issuance was to collaborate with the Eureka and Sacramento offices on issuing a Winter Storm Watch /PDXWSWMFR/ for the higher elevations late Friday afternoon through Sunday afternoon. In our case, this includes portions of western, central, and southern Siskiyou County above 5000 feet. Snow levels will be very high, around 7000 to 8000 feet, as light precipitation begins Wednesday night through Thursday. Thursday night through Friday, moist, upslope southerly flow into southern Siskiyou County will continue light precipitation with a modest lowering of snow levels to around 6500 feet. The high snow levels are representative of this system tracking northeastward from well offshore of southern California.

But, the first sign of at least modestly more impactful weather to follow will be increasing southerly winds in the Shasta Valley. A High Wind Watch /PDXNPWMFR/ has been issued, in effect from late Friday morning into early Saturday morning, for the Shasta Valley of central Siskiyou County. South winds of 25 to 40 mph gusting up to 60 mph are likely, with a stronger minority of ensemble members showing about a 10-20% probability of gusts as high as 85 mph. As usual, the strongest winds are expected near Weed. Peak strength is most likely to occur during Friday afternoon and evening. We will await attaining higher confidence as this event approaches, but gusty southwest winds of 35 to 50 mph east of the Cascades may necessitate issuing a Wind Advisory with similar, slightly later, start and stop timing as the stronger Shasta Valley winds..

Meantime, precipitation rates in Siskiyou County, especially farther south in the Mount Shasta area are likely to intensify Friday night into early Saturday morning, and be accompanied by lowering snow levels to around 5000 feet. Lighter precipitation is likely elsewhere in our area. It is still relatively early, with the potential for future suites of data to warrant adjusting the forecast strength and/or timing.

From Saturday through Sunday, a broader trough will track eastward from the eastern Pacific. There is also a broader range of solutions regarding the strength of this next frontal system. But, the majority of ensemble members do suggest a weaker strength compared to its predecessor, with perhaps Advisory level strength south to southwest winds...again for the Shasta Valley and portions of the east side. This system will produce lowering snow levels, most likely to around 4000 to 5000 feet.

Uncertainty rises another notch or two beyond the weekend for Monday and Tuesday with some potential for either a showery air mass, another weaker front, or even an early week break between systems. The highest probability is for a continued moist, onshore flow with mainly light or very light precipitation but also a continued lowering of snow levels to around 3000 to 4000 feet.

It warrants a quick mention that the majority of ensemble solutions do not favor the interesting, operational GFS depiction of a system of Alaskan origination on Day 9/10 late next week that would bring the lowest snow levels of the season so far.

MFR WATCHES/WARNINGS/ADVISORIES

OR...Air Stagnation Advisory until 4 PM PST this afternoon for ORZ023>026-029>031.

CA...Winter Storm Watch from Friday afternoon through Sunday afternoon for CAZ080-082-083.

High Wind Watch from Friday morning through late Friday night for CAZ081.

PACIFIC COASTAL WATERS...Small Craft Advisory from 4 PM Thursday to 10 AM PST Friday for PZZ350-356-370-376.

Hazardous Seas Watch from Friday morning through late Friday night for PZZ350-356.

Gale Watch from Friday morning through late Friday night for PZZ370-376.