textproduct: Medford

DISCUSSION

/Issued 221 PM PST Fri Jan 16 2026/An upper level ridge will remain in control over the area for several more days. Temperatures will be unseasonably warm outside of the west side valleys, with strong inversions resulting in colder temperatures within those valleys.

Persistence remains the appropriate description for the duration of the forecast. While areas outside of the inland valleys will be relatively warm, dry, and with clear skies, the interior valleys will continue to experience strong inversions and stagnant air. According to the NBM, there is a 30-40 percent chance for fog in the valleys west of the Cascades tonight, and roughly 25 percent chance of temperatures at or below freezing. Typically, this pattern results in persistent fog and freezing fog within the valleys, with some areas clearing in the afternoon, and others never clearing at all, before fog reforms and spreads out within the valleys once again after sunset. With the earlier clearing in the upper Rogue Valley today, fog may be much later to reform there tonight, if at all. In some situations in the past, fog never forms and instead a very heavy frost develops instead. Despite the higher probability in the NBM, which was drastically underdone yesterday, the pattern today lends itself to much more uncertainty, mainly in fog onset times and locations. Therefore, have held of on any new fog/freezing fog advisories until confidence improves, or fog forms, whichever comes first.

An air stagnation advisory remain in effect out to Tuesday next week, along with a state issued Air Quality Advisory for Lake County, also through Tuesday.

The models continue to show the ridge breaking down and the introduction of precipitation chances and mixing air. These ridges are very well known to take a long time to break down, and this one is no exception. Despite the NBM saying the breakdown occurs Wednesday or Thursday, experience and the bulk of the longer range model suites say it could be as late as late next week, right around the end of the month. -BPN

AVIATION...17/06Z TAFs

LIFR ceilings and visibilities have built back into the Umpqua and parts of the Illinois Valley near Grants Pass this evening. Roseburg and Grants Pass should remain socked in with fog and freezing fog until mid day Saturday when VFR conditions are expected.

Medford was a topic of discussion with the other forecaster tonight. With a decent mix this afternoon and some drier air the boundary layer, fog isn't looking as good tonight. It looks like the GFS MOS bulletins have some fog later tonight around 12-15Z. Using the cross over method, fog is also looking less likely tonight here at KMFR. So we would put the odds of LIFR visibilities at KMFR tonight at a coin flip right now.

-Smith

MARINE...Updated 800 PM PST Friday, January 16, 2026.

Seas remain below Advisory level through the weekend. Northerly winds look to increase on Monday, which may build localized areas of steep seas in outer waters. Winds look to ease into Tuesday and Wednesday. - TAD/Smith

MFR WATCHES/WARNINGS/ADVISORIES

OR...Air Stagnation Advisory until 10 AM PST Tuesday for ORZ023-024- 026-029>031.

CA...None.

PACIFIC COASTAL WATERS...None.