textproduct: Medford

DISCUSSION

Overall, the forecast remains on track and the main changes involved upgrading/updating various wind and winter headlines for the Wednesday system. Shower activity continues across the region this afternoon, focused mainly along and west of the I-5 corridor. Widespread clouds mixed with some spots of sunshine is resulting in near normal temperatures for the area. Overall, not much change is expected through the afternoon and into the evening.

A big change is coming beginning late tonight and continuing Wednesday into Thursday. Models continue to show a strong upper trough moving southward from the Gulf of Alaska. The leading edge of this system will be a cold front that will approach the coast later tonight, and move onshore Wednesday. The upper level cold pool will then move onshore into Washington/Oregon Wednesday night into Thursday. Pressure gradients in advance of this system increase Wednesday afternoon, with mid-level winds peaking around 55 kt. It will be windy everywhere, with gusts of 20-30 mph common, even for West Side areas. We expect widespread peak wind gusts in the 40-50 mph range for areas from the Cascades eastward, perhaps 55 mph in some areas. Wind advisories have been issued for portions of Lake/Modoc counties where winds will be strongest. The Shasta Valley will be breezy at least, due to the fairly strong pressure gradient, but the mid level flow will not be aligned with the terrain, keeping winds there weaker than may otherwise be expected, but still close to advisory level strength. Peak gusts of 40-45 mph are possible, but we'll forego an advisory for now. Strong winds are also expected along the coast, but should remain just below warning levels. The capes and headlands could briefly see gusts up to 60 mph, but overall, gusts in the 40-50 mph range are the more likely scenario.

The main frontal band will be accompanied by a period of moderate rainfall with the heaviest precipitation from the coast to the Cascades from late Wednesday morning through the afternoon. We are NOT concerned about flooding with this event, other than some minor/typical nuisance ponding of water on roadways. Since river levels are very low for this time of year, most of the rain expected from this system will be beneficial/welcome. Amounts of 1-3 inches are likely along the coast, with 0.50-1.00 inch common inland to the Cascades with 0.25-0.50 inch over the East Side. Snow levels of 5000- 5500 feet Wednesday will drop to 2500-3000 feet by Thursday morning.

It looks like a pretty healthy snow storm for the Cascades and Siskiyous with 6-12 inches common above 5000 feet. The Winter Storm Watch has been upgraded to a Warning for the Cascades. A Winter Weather Advisory remains in place for the Highway 97 corridor from Chiloquin northward for Wednesday night into Thursday morning and we've added the Warner Mountains of Modoc County and the mountains of western Siskiyou County to the Advisory as well. The heaviest snow will fall near Crater/Diamond Lakes and near Willamette Pass where it will be a bit colder, with NBM probabilities showing a high probability (>80%) of >12 inches of snow. At Crater Lake (~7000 feet), the 48-hour probability of >18 inches of snow ending Thursday evening is now nearly 100%! All in all, expect winter travel impacts in the mountains and over some of the higher passes, especially at Lake of the Woods by Thursday morning. Main I-5 passes should be OK, but some slippery spots could develop at Siskiyou Summit and/or around Mt Shasta City/Snowman Summit early Thursday morning.

With the core of the cold pool shifting into northeast Oregon and Idaho on Thursday, showers and even an isolated thunderstorm or two will continue for a while into Thursday afternoon, but then diminish rapidly around sunset Thursday evening as high pressure builds in. It should be noted that models are still showing a fairly high probability (50-70% chance) that temperatures drop into the low to mid 30s for the west side valleys by Friday morning. So, that will introduce some frost/freeze risk. Greatest risk of that occurring is in the Illinois Valley (Cave Junction/Obrien/Selma). The probability of temperatures less than 28F, however, are quite low, generally 10% or less.

Models are showing the upper ridge rebuilding across the area Friday into the weekend, so look for temperatures to rebound to above normal levels again (highs in the 70s again west side valleys) along with little to no chance at precipitation. -Spilde/BR-y

AVIATION...01/06Z TAFs

Scattered showers continue to move over northern California and southern Oregon, but instability has eased and additional thunderstorms are not expected. MVFR ceilings are present in some areas, notably at North Bend as well as over some east side areas, ahead of an approaching low pressure system.

This low pressure system will bring active weather through the TAF period. Initial activity is expected over Curry County and the Cascades, with precipitation becoming more widespread into the afternoon afternoon. Moderate to heavy rain showers are possible west of the Cascades. Snow levels start at 6000 feet early Wednesday morning, then look to start dropping in the afternoon and reaching 3000 feet by Wednesday night. This will allow for snow showers over higher terrain in western Siskiyou County as well as over and east of the Cascades. Rain and snow showers could bring locally lower ceilings and visibilities across the area as well as obscure elevated terrain.

Most areas will see some amount of gusty winds, with these winds persisting into the end of the TAF period along the coast and east of the Cascades. Guidance shows areas of low level wind shear developing along the Oregon coast then over elevated terrain from west to east through the day. The inclusion of wind shear in the forecast for North Bend covers the duration of shear over coastal areas. Other terminals are not expected to have shear overhead. -TAD

MARINE...Updated 1230 PM PDT Tuesday, March 31, 2026

Conditions generally improve today with seas subsiding to around 4 ft. However, seas are forecast to become steep late tonight with south gales eventually leading to very steep seas through early Wednesday afternoon. A Gale Watch has been upgraded to a warning for all waters. Steep to very steep seas are expected to become swell dominated Wednesday night and build to a peak Thursday morning. A hazardous seas warning has been issued to account for this threat late Wednesday afternoon through Thursday morning. Advisory strength north winds are likely to return late in the week while seas remain steep.

MFR WATCHES/WARNINGS/ADVISORIES

OR...Winter Weather Advisory from 8 PM Wednesday to 11 AM PDT Thursday for ORZ029-030.

Wind Advisory from 11 AM to 11 PM PDT Wednesday for ORZ031.

Winter Storm Warning from 5 AM Wednesday to 5 PM PDT Thursday for ORZ025-027-028.

CA...Winter Weather Advisory from 8 PM Wednesday to 11 AM PDT Thursday for CAZ080-085.

Wind Advisory from 11 AM to 11 PM PDT Wednesday for CAZ085.

PACIFIC COASTAL WATERS...Gale Warning from 2 AM to 2 PM PDT Wednesday for PZZ350-356-370-376.

Hazardous Seas Warning from 2 PM Wednesday to 11 AM PDT Thursday for PZZ350-356-370-376.