textproduct: Medford

DISCUSSION

We are in a lull in the activity as the first storm system is well out of the way. Radar just shows some lighter showers in Siskiyou County and east of the Cascades this afternoon.

A low will strengthen to our west around 140W tonight based on most of the ensemble data and Santa might have a bumpy ride into some chimneys later tonight. The ECMWF ensemble(ENS) performed best with the last low taking it farther east, so we based most of our decisions off that ensemble for this forecast cycle. This low will likely strengthen down to 980 mb or so around 40N and 140W overnight.

Strong southerly winds will cover the forecast area again overnight into Thursday morning with the threat of high winds in the Shasta Valley and along the coast. The ECMWF wind gust forecast hinted at wind gusts up to 60 mph along the coastal headlands in Curry County, so we ended up issuing another high wind warning there. As for the Shasta Valley, there are more than a few good indicators there again. The extreme forecast index(EFI) is showing values near 1 north of Redding for wind gusts. Therefore, the ensembles are showing forecasting stronger wind gusts than average compared to climatology, which is already very windy this time of year. Also the NBM 50th percentile shows wind gusts around peaking at 60 knots tomorrow with 700 mb flow aligned with the valley.

Elsewhere, winds should be a bit weaker. If we do get the mixing tomorrow afternoon, it seems reasonable to see wind gusts around 45mph west of the Cascades. Wind gusts should be stronger farther to the east given the higher terrain out there and still strong flow at 700 mb. However, the EFI wasn't jumping out to us. Perhaps some wind gusts will approach high wind around Klamath Falls, but will allow the next shift to decide on upgrade to high wind instead.

Snow is the other big headline with the major impacts still in Siskiyou County. Snow levels will start to lower through the night as this colder air is ushered in behind the first low. Generally, snow levels start around 4500 feet before lowering to 3500 to 3300 feet later Thursday night around Mt Shasta City. We are anticipating some accumulating snow there as the SPC HREF is forecasting around 12 inches of accumulating snow down to Mt Shasta City with higher totals in the surrounding terrain in Siskiyou County.

Once we move into Friday, the ENS quickly kicks things out Friday with plenty of rain and snow showers. Meanwhile the GFS and some of the GEFS solutions wants to spin up another weaker low off our coast. High pressure begins to build into the weekend with some light showers still possible west of the Cascades and morning valley fog Saturday. The quiet weather continues for the remainder of 2025.

-Smith

AVIATION...24/18Z TAFs

A front is moving across the area today. Strong, gusty winds will continue from the Cascades eastward into early this afternoon, then winds will trend lower. Ceilings are mainly VFR across inland areas with areas of MVFR ceilings along the coast. Expect lower ceilings along the coast to lift to VFR around 21z. Showers will decrease between 21-00z over southwest Oregon, becoming isolated. Expect areas of showers to continue in portions of Northern California.

Another low approaches the coast tonight and early Thursday morning. Expect rain and mountain snow to spread into northern California and rain to spread along the coast, with a mix of MVFR/IFR and widespread mountain obscurations. Snow may develop at Mount Shasta City by late Thursday morning as snow level lower locally in southern Siskiyou County. Inland, over southwest oregon expect areas of rain and mountain snow to develop late tonight and early Thursday with areas of MVFR, including at Klamath Falls.

Strong, gusty south to southeast winds are likely to develop over the mountains and east of the Cascades and in the Shasta Valley as this low nears the area. Areas that do not get the strong winds, are expected to see periods of low level wind shear late tonight and Thursday morning. Breezy southeast winds are expected at Medford tonight into Thursday morning which is expected to limit the development of any lower stratus tonight. At Roseburg there is a 25% chance for IFR tonight before rain showers move into the area. However, with guidance is leaning towards VFR at this times. So have kept Roseburg VFR and will monitor for lower conditions.

-CC

MARINE...Updated 100 PM PST Wednesday, December 24, 2025

Steep seas are expected over the waters into this evening and tonight. South winds will become gusty out of the southeast this evening.

Then, another strong system arrives late tonight and Christmas day, bringing widespread and strong gales (30-40 kt with gusts to 50 kt) along with very steep seas between 13 to 23 ft. Locally storm force gusts are possible late Thursday morning and Thursday afternoon. Guidance indicates a 30-40% chance for storm force gusts for the waters with in 20 nm of shore between Gold Beach and Cape Blanco and a 20% chance for storm force gusts for other areas. With this frontal system, there is also a 20% chance for thunderstorms over the waters on Thursday with the chance for thunderstorms continuing across the waters from Cape Blanco south Thursday night and Friday morning.

As the low pressure moves over the waters from west to east on Thursday night and Friday morning, expect continued areas of gales for the waters from Cape Blanco south. Winds will shift from south to northwest as this low moves through Friday afternoon. Very steep seas will persist across all the waters through at least Friday morning. Gusty north winds (20-30 mph with gusts up to 35 mph) are expected to develop Friday afternoon and evening.

Once the low exits the region Friday night, the overall weather pattern looks to settle down over the weekend, possibly into next week, and conditions will improve overall with light to moderate north winds. Areas of gusty north winds and steep seas are possible south of Cape Blanco.

-CC

MFR WATCHES/WARNINGS/ADVISORIES

OR...Wind Advisory from 1 AM to 1 PM PST Thursday for ORZ023>026- 029>031.

High Wind Warning from 7 AM to 1 PM PST Thursday for ORZ022.

Winter Weather Advisory from 10 PM this evening to 10 PM PST Friday for ORZ027-028.

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

Wind Advisory from 1 AM to 1 PM PST Thursday for CAZ080-083>085.

High Wind Warning from 7 AM to 1 PM PST Thursday for CAZ081.

PACIFIC COASTAL WATERS...Small Craft Advisory until 4 AM PST Thursday for PZZ350-356-370-376.

Gale Warning from 4 AM Thursday to 10 AM PST Friday for PZZ350- 356-370-376.

Hazardous Seas Warning from 10 PM Thursday to 10 AM PST Friday for PZZ350-370.