textproduct: Medford

DISCUSSION

Some shallow fog was observed in the Illinois, Coquille, and Umpqua valleys this morning, along with temperatures right at or just above freezing. In the Rogue Valley and the valleys of Western Siskiyou County, skies remained mostly clear, and temperatures dropped into the upper 20s. With high pressure building in today, a brief warming trend begins, and temperatures will move towards well above normal through the weekend. The area should remain dry through at least the first half of the weekend.

Also, increasing mid to high level clouds are expected tonight, which along with the warming air mass, should preclude any widespread frost west of the Cascades, although some isolated areas, such as in the southern Illinois valley or the higher elevation valleys, could see some spots of frost.

A slow moving upper level low will take position to our west by Sunday, then gradually dig south and east, finally passing to our south sometime midweek. Both southerly flow and moisture aloft will strengthen Saturday night into Sunday with thicker high clouds expected as the low approaches. The main effect of the approaching upper level closed low will be an increase in south to southwest winds for the Shasta Valley and the east side. The strongest winds (gusts up to 45 mph) are expected in the southern Shasta Valley near Weed during Sunday afternoon, secondarily in Lake County near Summer Lake and Silver Lake on Monday and Tuesday (gusts up to 35 mph).

The downslope flow on Sunday (and possibly through Tuesday) will very likely keep the Shasta and Rogue valleys dry, but a few sprinkles can't be completely ruled out from the coast to the Cascades. Even at the coast, a relatively dry lower atmosphere should keep things mainly dry into Sunday evening. The probability of showers will trend higher later Sunday night into Wednesday, with ensemble data showing a wider spread in solutions but also higher average precipitation amounts Tuesday night into Wednesday. The probability of thunderstorms will be highest during Monday and Tuesday in the late afternoons, but it is too soon to tell what portions of our area will be favored for activity. However, given the pattern, the southern portions of the area will have higher chances than the north, but any change in track of the low could easily alter this.

Once the low passes, the scenario flips with a saturated lower portion of the airmass in a noticeably cooler west to northwest flow for a higher probability of more uniformly light showers, especially if a smaller scale trough tracks along the coast as some ensemble members suggest. This new low is likely to track southward with a gradually diminishing probability of showers and gradually warming temperatures late next week.

AVIATION...17/18Z TAFs

Local IFR fog in some west side valleys from earlier this morning has burned off and VFR conditions will prevail for the next 24 hours with generally light winds. A similar scenario of patchy southwest Oregon valley IFR is likely for early Saturday morning. -Spilde

MARINE...Updated 200 PM PDT Friday, April 17, 2026

A weak thermal trough will maintain gusty north winds and steep seas south of Cape Blanco this afternoon into early Saturday morning. Low pressure offshore will bring a return of active weather Sunday into Wednesday, with increasing swell and periods of gusty south winds. Winds are likely to be strongest from Sunday morning through Monday evening, with steep seas possible. -Spilde

MFR WATCHES/WARNINGS/ADVISORIES

OR...None.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 2 AM PDT Saturday for PZZ356-376.