textproduct: Medford

DISCUSSION

Updated aviation discussion.

AVIATION...31/12Z TAFs

Varying amounts of cloud cover can be expected today with scattered showers. Ceilings will be a mix of VFR and MVFR with areas of higher terrain obscured. Area TAF sites are expected to see mostly VFR early this morning, though periods of MVFR and even local IFR (Umpqua Basin) are possible. Conditions are forecast to be VFR late this morning/afternoon though could be temporarily reduced to MVFR in showers. An isolated thunderstorm cannot be ruled out over the East Side this afternoon or early this evening.

A strong front will approach the coast later tonight with more widespread MVFR ceilings and periods of rain which will move inland during Wednesday. Expect breezy to windy conditions ahead of the front, especially over the East Side. -Spilde

PREV DISCUSSION

/Issued 320 AM PDT Tue Mar 31 2026/

DISCUSSION...An upper trough offshore will get a push eastward and move inland today. At this early hour, satellite imagery is showing the greatest cloud cover over our forecast area with radar indicating some light rain showers over the Cascades/Foothills near and north of Crater Lake, across northern Klamath/Lake counties and also across portions of NW Cal into coastal SW Oregon near Brookings. This will be what it's like most of this morning, showers here and there, but it won't be raining everywhere. As the trough moves inland and things destabilize a bit this afternoon, we expect showers to expand in coverage, especially from just west of the Cascades over to the East Side. Instability this afternoon is greatest over portions of Lake County, but also Modoc and southeast Klamath counties, where there can be an isolated thunderstorm or two. Rain amounts since yesterday were highest from the foothills west of the Cascades eastward across Klamath/Lake counties. Generally, those areas received a tenth to a third of an inch of precipitation. Most of the rest of the area had less than that. Today looks very similar with the best chance of wetting rainfall (more than 0.10) in those same general locations, focused in the mountains. At this point, any precipitation is welcome, especially given the dry, warm start to spring so far.

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. This should result in 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. 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.

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. Winter Storm Watches remain up for the Cascades. A Winter Weather Advisory has been added for the Highway 97 corridor from Chiloquin northward for Wednesday night into Thursday morning and additional advisories may be necessary for portions of the East Side, and/or for the higher terrain of Siskiyou County. 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

AVIATION...31/06Z TAFs...A weak front will linger over the area into Tuesday. This will result in variable amounts of cloud cover and showers. Ceilings will be a mix of VFR with areas of MVFR and mountain obscurations overnight and Tuesday morning. Area TAF sites are expected to see periods of MVFR (or local IFR) overnight and early Tuesday morning. Then conditions are forecast to return to VFR late Tuesday morning into Tuesday afternoon. Lingering showers during the Tuesday afternoon and evening will allow for partial mountain obscurations.

MARINE...Updated 230 AM PDT Tuesday, March 31, 2026...Conditions generally improve briefly today with seas subsiding to around 4 ft. Seas are forecast to become steep again late tonight with south gales and very steep seas possible Wednesday. A Gale Watch remains in effect. Steep seas are expected to become swell dominated on Wednesday night and build to a peak on Thursday. Advisory strength north winds are likely to return late in the week while seas remain steep. -Spilde

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 Watch from late tonight through Thursday afternoon for ORZ025-027-028.

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

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

PACIFIC COASTAL WATERS...Gale Watch from late tonight through Wednesday afternoon for PZZ350-356-370-376.