textproduct: Medford

DISCUSSION

A cutoff low is expected to drop through a broader ridge and run parallel to the Pacific coast through today and Saturday. The overall effect of this pattern will be continuing warm temperatures, with chances of afternoon and evening thunderstorms. For today, the highest chances (15-20%) are present from western Siskiyou County across Jackson County to the Cascades. Somewhat modest CAPE values, modeled in the 200-400 J/Kg range, indicate generally isolated to scattered activity. Model soundings for Roseburg and Medford are showing inversions in the atmosphere, a layer of stable air that can "cap" uplift and in turn prevent thunderstorm development. If this cap is in place through the afternoon, development in these areas may be limited. Inversions are less present in model sounding for western Siskiyou County, which would make development easier in that area. Inversions can weaken into the evening, meaning chances for thunderstorm activity increases into the evening for Jackson County and eastern Douglas County. Thunderstorm chances across the CWA dissipate into the late evening and nighttime hours, although some showers may persist.

For Saturday afternoon and evening, thunderstorm chances expand to Josephine and Modoc counties. SPC paintball guidance shows the highest concentration of storms with reflectivity over 40 dBZ (an indicator of more substantial activity) is expected over Modoc, Josephine, and eastern Modoc counties on Saturday. Other models still include western Siskiyou and Jackson counties in chances for thunderstorms, so a broad area of 20-25% thunderstorm chances across these areas is in place to address these possibilities. Model soundings and guidance show weaker or no inversions and higher CAPE values (200-400 J/Kg over Modoc County and 400-700 J/Kg for west side areas), indicating more substantial activity is possible.

For Sunday and Monday, the cutoff low starts to head inland over California. This will bring wraparound flow aloft and chances for rain showers with embedded thunderstorms rather than the cellular thunderstorms that are more likely on Friday and Saturday. Chances for rain and thunderstorms are both dependent on how far south the cutoff goes before heading inland, so forecasts may continue to vary slightly as models come into better agreement on that path. Broadly, most areas will see some amount of unimpactful rainfall through Sunday and Monday with Coos, northwest Douglas, and northeast Lake counties possibly staying dry. Thunderstorm possibilities have also shifted some as the expected path of the cutoff changes. For both Sunday and Monday, 20-25% thunderstorm chances are present over Siskiyou and Modoc counties. On Sunday, 15-20% thunderstorm chances are present over Josephine, Jackson, and eastern Douglas counties. On Monday, those 15-20% chances move to Klamath and southern Lake counties.

Thunderstorms anywhere can include gusty and erratic winds, locally heavy rainfall, small hail, and lightning. Given the isolated to scattered nature of possible activity and how rapidly thunderstorms can develop , please be aware of your local conditions while spending time outside or traveling.

Some light rain showers may linger over Modoc and eastern Lake counties into early Tuesday morning, but in general Tuesday looks to start of a warm and dry period that could last through the rest of next week under an upper ridge. Currently, temperatures would peak on Thursday with highs in the high 70s to mid 80s for lower elevation areas across the CWA. Low pressure systems over the Pacific could start flattening the ridge on Friday, bringing some slightly cooler temperatures to the area. -TAD

AVIATION...01/18Z TAFs

IFR/MVFR ceilings persist along the Oregon coast and Umpqua Valley this morning with VFR elsewhere. The lower ceilings should tend to lift/break up later this morning/this afternoon, but may be more persistent along the coast. Expect marine stratus to return again late tonight, bringing another round of IFR/MVFR ceilings.

Meanwhile, we expect convective activity to begin this afternoon with some cumulus buildups during the mid-late afternoon. Isolated showers and thunderstorms should develop late afternoon/evening near and just west of the Cascades, including around the Rogue Valley. The chance of thunderstorms is about 20-30% around the MFR terminal this afternoon, so gusty outflows are possible with cloud to ground lightning. Confidence is lower for thunderstorm activity north of the Rogue-Umpqua Divide for this afternoon/evening. However, model guidance shows some elevated instability up that way overnight tonight, and there's about a 10-20% chance for some lightning activity near the Roseburg terminal between 10z-15z Saturday.

MARINE...Updated 1230 PM PDT Friday, May 1, 2026.

A thermal trough pattern will bring gusty north winds with steep to very steep and hazardous seas through Saturday evening. The strongest winds and very steep seas are expected south of Gold Beach today, with steep seas elsewhere. Conditions improve some Saturday afternoon as winds begin to weaken, with only steep seas expected for all areas from Coos Bay southward. Winds diminish moreso late Saturday night while a longer period northwest swell builds, then becomes dominant later Sunday into Monday along with a fresh north swell.

BEACH HAZARDS...Updated 115 PM PDT Friday May 1, 2026

A short period northwest swell and a building long period northwest swell may combine their energy to produce unpredictable waves washing up on area beaches this weekend. The risk will be highest around sunrise on Sunday morning.

Sneaker waves can run up significantly farther on beaches than normal, including over rocks and jetties. These waves can suddenly knock people off of their feet and sweep them into the ocean. The waves can also move logs or other objects which could crush or trap anyone caught underneath. Never turn away from the ocean!

MFR WATCHES/WARNINGS/ADVISORIES

OR...Beach Hazards Statement from Saturday evening through Sunday morning for ORZ021-022.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Saturday for PZZ350-356-370-376.

Hazardous Seas Warning until 11 AM PDT Saturday for PZZ376.