textproduct: Medford

KEY MESSAGES

* There is a slight chance of thunderstorms along the Cascades and Cascade foothills this afternoon.

* An unusually strong system for early September will bring wetting rain to the region with gusty winds along the coast Wednesday.

* Rock slides are possible along highways 42, 138 and 38.

* Pockets of frost are possible tonight east of the Cascades.

* Temperatures will be 15 to 25 degrees cooler than normal Wednesday and Thursday.

* Cooler conditions with shower chances persisting into early next week.

DISCUSSION

A closed low just offshore of ORegon will open up and pass overhead today, producing a 20 to 50 percent chance of showers over much of the region. Thunderstorm chances are low as this trough passes overhead, but there should be enough instability and moisture, along with terrain lifting processes, for a few isolated thunderstorms this afternoon along the Cascades and Cascade foothills.

As this occurs, a much stronger closed low over the Gulf of Alaska will dig south, pushing a stronger cold front through southern Oregon and northern California Wednesday, before moving onshore Thursday and remaining overhead through the weekend. This front will produce gusty south winds across much of the area, especially along the coast and east of the Cascades, as well as in the Shasta Valley. This is an unusually strong event so early in the season, more akin to a typical December front in terms of wind and rain, just not as cold.

Speaking of rain, this first front will bring wetting rain to locations along and west of the Cascades, and for a significant portion of the East Side as well. Again, this is an atypical event for so early in the season, so some daily precipitation records will likely fall on the 2nd and 3rd.

As for the impacts, rock slides along highways 38,42 and 138 are possible with this first rain of the season. Also, roads could be slick on Tuesday as a lighter rain brings up some oil to the surface. Those slick roads could continue early into the front passage Wednesday afternoon. It's also not out of the question for a few power outages along the coast as this wind hits some stressed vegetation, especially since trees remain covered in leaves.

Eventually, temperatures will cool behind the front with lows falling into the 40's east of the Cascades and upper 40's and lower 50's west of the Cascades. There is some concern for frost according to the NBM as it's forecasting lows in the mid 30's in Klamath Falls. However, as this is so early in the season, and because it is the first event of its type in several months, the usual bias correction methods of the NBM are very unlikely to represent expected conditions accurately. Therefore, we will lean heavier on deterministic guidance, which has warmer lows with the scattered to widespread cloud cover and windiness. This does not rule out frost occuring in some locations Tuesday night before the big cold front. Temperatures will be 15 to 25 degrees cooler than normal for early September. Mount Shasta City may only hit 57 degrees on Wednesday and 59 degrees on Thursday for highs, which would be record minimum maximums for the respective days. Meanwhile, highs Wednesday and Thursday in Medford will be in the mid 60s, cooler than normal indeed.

It should be mentioned that we are not considering this a "Fire Season ending event" just yet, as it is very early in September, and climatologically speaking, conditions can still be very warm and dry well into October. It is very fair to say, however, that this is will greatly reduce fire weather concerns for at least the near future.

Finally, ensembles keep this upper level low over us for a while. It looks like it could just linger into Monday with cooler than normal temperatures and spotty showers persisting across the forecast area. Kind of hard to believe we could see 5 to 6 days of rain around the region in early September (and such a vast difference from conditions during the Labor Day week just 6 years ago). Ensemble members vary greatly on location and intensity of the QPF from Friday onward, so details remain uncertain, and will be updated as necessary.

AVIATION (00Z TAFs)

Ahead of an incoming front, expect low and mid level clouds to increase with increasing rain chances tomorrow. MVFR conditions are likely along the coast through this cycle with intermittent periods of VFR. The big question ahead of the front is the potential for thunderstorms today which could impact KMFR, but may likely stay over the higher terrain along the Siskiyous and Cascades south and east of Medford. Otherwise, expecting widespread showers and rain to develop tonight/Wed morning along the coast and spread eastward through Wednesday evening. Areas of MVFR will develop with rain late Wednesday morning through Wednesday evening, especially from the Cascades west. Currently, not expecting thunder on Wednesday. Lastly, enhanced breezes are expected ahead of the front Wednesday afternoon and evening.

MARINE...Updated 1200 PM PDT Tuesday, September 1, 2026

South winds will increase today ahead of an approaching early season front. Gusty winds and steep seas will begin in the outer waters this afternoon, then spread to the inner waters this evening into tonight. Winds will increase to gales with very steep and hazardous seas by early Wednesday morning, persisting until the front passes onshore Wednesday afternoon. Winds will diminish behind the front, but remain gusty with steep seas through Thursday night. Periods of heavy rain and low visibility are also expected through this time.

Conditions improve Friday, and remain relatively calm through the weekend and potentially into early next week.

MFR WATCHES/WARNINGS/ADVISORIES

OR...Frost Advisory from 4 AM to 8 AM PDT Wednesday for ORZ029>031.

CA...Frost Advisory from 4 AM to 8 AM PDT Wednesday for CAZ085.

PACIFIC COASTAL WATERS...Small Craft Advisory from 11 PM this evening to 5 AM PDT Wednesday for PZZ350-356.

Gale Warning from 5 AM to 7 PM PDT Wednesday for PZZ350-356-370- 376.

Small Craft Advisory until 5 AM PDT Wednesday for PZZ370-376.