textproduct: Medford

DISCUSSION

A closed low off the NorCal coast will head eastward and move onshore near or just south of Cape Mendocino tonight, then inland across NorCal and into the Great Basin on Monday. Southerly mid-level flow ahead of this system is bringing a solid corridor of moisture northward into SW Oregon this afternoon and this is resulting in showers and also a few thunderstorms. Instability is modest with about 200-400 J/KG MUCAPE out there. This is leading to some healthy showers with cores in the 45-55 dBZ range. Best cells as of early this afternoon have been down around or just south of Mt. Shasta, where some cloud to ground (CG) lightning has been observed. We had one roll through the east side of Medford around 1 pm (with a few CGs NE of Talent around or just north of Grizzly Peak) and headed toward Butte Falls. So, that's pretty much how this afternoon/evening will go with some decent showers that will produce brief downpours and occasional lightning in the strongest cores. There is little or no risk of severe weather due to limited CAPE/winds aloft. Focus for rainfall through tonight will be from the Mt. Shasta region northward up the Cascades, but also over the East Side in Oregon. Rain amounts of 0.25-0.75" will be common across the CWA with a little less in areas along the SW coast and a little more possible over the higher terrain, where showers tend to be favored/concentrated. Of course, there could be areas in between showers, where not much happens at all. Lightning risk wanes tonight as instability lessens.

The closed low opens into a trough as it heads across northern Nevada on Monday. This will allow the air mass to dry out a bit, though showers linger in some areas, especially east of the Cascades in the morning (also near the Cascades and along the coast). These should diminish in coverage as the day progresses with only a few hundredths (QPF) here and there after 18z.

A brief dry period is expected Monday night and Tuesday beneath short wave upper ridging. This will likely result in nighttime/morning low clouds/areas of fog in west side valleys, but no precip over inland areas. Models do show higher PoPs along the coast Tuesday (60-80%), but don't really think this amounts to much. It's more/less onshore flow that could bring some light rain there -- maybe a few hundredths at best and PoPs may be over done here. Temperatures remain mild for early March with highs in the upper 50s/low 60s west of the Cascades and 55-60F over the East Side.

The next upper trough and cold front will arrive in WNW flow aloft Tuesday night into Wednesday. Expect a period of widespread light to moderate precipitation to accompany the cold front with the focus along the coast and into the Cascades (amounts of 0.50-1.00 inch common, though up 1.50 inches in areas of favored WNW-facing terrain). Snow levels will drop during this event, from around 6000 feet Tuesday evening, down to 4000-5000 feet by Wednesday evening. This will keep most winter impacts confined to the higher terrain and Cascade passes. Snow amounts are still shown to be 3-7 inches above 5000 feet in the Cascades (north of Howard Prairie) with higher amounts to 10 inches above 5500 feet (Crater Lake). Snowfall rates on Wednesday morning remain a concern at those higher elevations, as parts of highways 62, 230, and 138 near Crater Lake and Diamond Lake may see snowfall rates of 0.5 to 1 inch per hour Wednesday morning into the afternoon. Some travel impacts are also possible over the pass on Highway 140 near Lake of the Woods, but amounts from there southward (including the Siskiyous/Mt Ashland) will be 1-4 inches above 5000 feet. Impacts to I-5 (Siskiyou Summit at ~4300 ft) aren't likely with NBM probability of 1" or greater of snow only ~10%. Right now, it's borderline at best for a Winter Weather Advisory for areas north of Highway 140, but we could see how potential for snowfall rates around 1 inch per hour Wed am push us toward issuing something. We'll continue to evaluate and decide over the next couple of shifts. Expect breezy conditions to develop Wednesday afternoon, especially over the East Side. Wind gusts of 30-40 mph are possible, but probably not high enough for wind headlines. With the trough axis shifting eastward, post-frontal showers diminish by Wednesday evening for the Rogue Valley (and southeast of the Cascades), but onshore flow keeps them going along the coast, to around the Rogue-Umpqua Divide and over to the Cascades right through Wednesday night. Back side energy could still bring low chances (15-30%) of showers on Thursday across NW sections, with dry weather taking hold elsewhere.

Late this week into the weekend, there's broad agreement in an upper ridge developing over the Pacific with the core of a strong upper jet directed to our north. But, there's some variation in the details. A majority of ensemble members show the ridge development out along 140W, but near or south of 40 N. This could allow some systems to slide over the top of the ridge and bring the possibility of light coastal rainfall at times. However, many outcomes also keep the precipitation to our north. NBM PoP guidance shows slight chance to chance PoPs over NW sections of the CWA, with dry and milder conditions to the south and east. Either way, this doesn't look like a period of stormy weather coming up, but rather glancing blows from systems coming over the top. CPC forecasts favor near to above normal temps and drier than normal for Week 2 (through mid-March). -Spilde

AVIATION...01/18Z TAFS

Active weather will likely bring fluctuating flight levels through most of the TAF period. Generally, VFR/MVFR conditions will prevail in showers through tonight, with areas of IFR possible in heavier showers and where clearing allows for fog/low stratus overnight. Also, some afternoon instability could result in isolated to scattered thunderstorm activity into this evening.

Showers diminish through tonight, with drying expected Monday, although lower flight conditions will persist through much of the morning.

MARINE...Updated 200 PM PST Sunday, March 1, 2026

Showers, light south winds, and relatively calm seas are expected through Monday night. Winds increase and seas steepen Tuesday into Wednesday as a front moves through the area. Steep west seas follows through the end of the week, with winds becoming north Friday into next weekend.

MFR WATCHES/WARNINGS/ADVISORIES

OR...None.

CA...None.

PACIFIC COASTAL WATERS...None.