textproduct: Medford

Updated AVIATION Discussion

AVIATION...08/00z TAFs

Plenty of cloud cover is resulting in a variety of conditions across the region this afternoon with widespread terrain obscurations present. Not much change in overall conditions is expected into Monday morning. Areas of precipitation are bringing a mix of LIFR/IFR conditions along the coast, MVFR conditions in the Umpqua Basin and Illinois Valley, and VFR conditions for the remainder of the region. Depending on any level of clearing this evening and overnight, LIFR conditions could develop in West Side Valleys, but cloud cover is expected to be persistent enough to at least limit development and extent of these LIFR conditions.

Moderate to strong winds aloft will result in mountain wave turbulence along and east of the Cascades with stronger winds near and at the ridges. /BR-y

PREV DISCUSSION

/Issued 206 PM PST Sun Dec 7 2025/

DISCUSSION...While a very heavy rain/flooding event is expected to materialize to our north through midweek, our forecast area in SW Oregon and NorCal will largely dodge those threats. We'll explain the reasons for that below. Please continue to follow NWS Portland and Seattle for the details on how much rain and the associated flooding risks up there.

Currently, a weak disturbance is moving through our area today, and is bringing a little light rain/drizzle from the Siskiyous/Cascades north/west to the coast. A few drips may also occur in Siskiyou County. Amounts so far though, as of 1 pm PST, have been generally light -- 0.01-0.10" in most areas, but 0.34" at Charlotte Ridge RAWS and up to 0.59" at Burnt Ridge RAWS. Snow levels are generally around 7000 feet. Expect mostly intermittent light rain/drizzle to continue tonight across NW sections of the CWA. Meanwhile, SE areas like Alturas and even most areas east of the Cascades in Oregon will stay dry.

On Monday, a deep plume of subtropical moisture, or atmospheric river, will gather over the Pacific and become directed into British Columbia, Washington and NW Oregon. This will set the stage for the prolonged period of heavy rainfall for our neighbors to the north. Our forecast area will be largely spared of the impacts though. This is primarily due to the strength of an upper level high centered near 30N and 130W (off the California Coast). This high will remain strong enough to deflect most of that moist plume off to our north. The main source of uncertainty has been the strength of this high and just how far south the moist plume could jog Monday night to Wednesday. Models are trending farther north (at least in terms of QPF) compared to yesterday. 12Z GEFS solutions have come more in line with the ECMWF and now show very little rain even here in Medford with rain shadowing significantly impacting amounts south of Roseburg. Favored areas along the coast and over to the Cascades as well as north of Roseburg along the Douglas/Lane County border still could see amounts of 1-3 inches during that time period, but we're not concerned about flooding. We issued a Hydrological Outlook yesterday to raise awareness of the risks, but we'll allow that to expire this evening.

One thing that continues to be shown is a fairly strong gradient and mid-level jet (55-65kt) across the Cascades that could lead to stronger winds east of the Cascades in Oregon and north of Highway 140 beginning Monday night and continuing through Tuesday evening. Not completely sure these strong winds aloft mix down to the surface, but could at the higher terrain and locally channeled valleys like around Summer Lake. As such, have gone with a wind advisory for those locations 7 pm PST Monday through 10 pm PST Tuesday for gusts up to 50 mph.

After Wednesday, the upper ridge off the California coast is expected to amplify and that should push the front well off to our north and bring a period of dry weather to most, if not all, of the area Thursday into the weekend. Slight chance PoPs remain along the coast, but wouldn't be surprised to see these fall out of the forecast. Some guidance breaks down the ridge over the weekend with a front reaching the coast sometime Saturday night, but most hold this front off until later in the weekend or early next week. This will maintain the milder pattern through at least mid-month. -Spilde

MARINE...Updated 200 PM PST Sunday, December 7, 2025...South winds will strengthen later tonight over the waters and conditions become hazardous to smaller crafts during this time. The south winds sill strengthen even further by Monday night into Tuesday with a surface low hitting British Columbia and high pressure to our south. Wind gusts will approach, yet stay under gale force, but conditions will surely be hazardous to smaller crafts Monday night and Tuesday. The pattern will remain unsettled through the rest of the week before high pressure builds off the Oregon coast around the weekend.

-Smith

MFR WATCHES/WARNINGS/ADVISORIES

OR...Wind Advisory from 7 PM Monday to 10 PM PST Tuesday for ORZ030- 031.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory from 10 AM Monday to 1 PM PST Tuesday for PZZ356-376.

Small Craft Advisory until 1 PM PST Tuesday for PZZ350-370.