textproduct: Medford

KEY MESSAGES

* 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.

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

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

* Scattered thunderstorms expected on Thursday.

DISCUSSION

Showers are ongoing this morning as a deep trough approaches the Oregon coast. Clouds are widespread with very little clearing. Frost looks unlikely tonight as temperatures hover in the mid 40's and actually increased in a few spots over the last few hours.

Like we've mentioned the last few nights, the extreme forecast index(EFI) continues to hint this is an unusually strong event for early September. EFI values are between 0.9 to 1 for wind gusts, temperatures and the QPF today. The coast and coastal mountains are an area for concern today with respect to wind gusts. The NBM max wind gust over 24 hours is showing 50kts over the coastal terrain. The EFI product also shows shift of tails of 1 and winds are already exceeding forecast there. In any case, pockets of power outages are possible as this front approaches the coast with gusts to 50 mph a reasonable bad case scenario.

With regards to precipitation, rain will become more widespread this morning into the afternoon hours. the ECMWF ensemble is predicting some heavy rain around the Brookings area with some locations seeing up to 2 inches of rain between 11am and 5pm this afternoon. That is a hefty amount of QPF in 6 hours for our wetter winter storms. Otherwise, the precipitation will move eastwards by the evening hours with locations east of the Cascades seeing some rain.

By Thursday, the cold front will be in south eastern Oregon and weakening. In addition, the trough and surface low will push into the Oregon coast by Thursday afternoon. Ensembles are split on how much rain will fall along the weakening cold front in Lake County with some showing over an inch while others are significantly drier. In addition, showers and a few thunderstorms will probably develop over southern Oregon and northern California Thursday afternoon. the HRRR BUFKIT soundings show ~100J/kg of surface based convective available potential energy(SBCAPE) at a few sites Thursday afternoon. The SBCAPE is tall an skinny, so we're not expecting any strong storms. However, some lightning is not out of the question as the CAPE touches the -10C to -15C level. The NBM Tstorm probability is also 15-20% across the majority of the area.

Although the air is unusually cold with this system, our overnight low temperature forecast with the NBM/NDFD is likely too cold, especially in some of the valleys east of the Cascades. Lingering cloud cover from a low being overhead should keep temperatures from dropping too low. For example, the NBM has 28 for a low at KLMT with a 30% probability of precipitation in the region and a 6400 foot snow level Thursday night. Other deterministic guidance has lows in the mid to upper 30's at KLMT.

Lastly, this upper level low will hang around until Monday. All the ECMWF ensemble members show that with the exact location of the low varying 200-400 miles. Shower intensity and location still varies some from Friday into Monday, although we feel confident PoPs will remain in the forecast within our warning area.

-Smith

AVIATION (06Z TAFs)

Ahead of an incoming front, expect low and mid level clouds to increase tonight with increasing rain chances tomorrow. MVFR conditions are likely to become widespread along the coast tonight with MVFR and local IFR conditions Wednesday. Inland, areas of MVFR will develop with rain Wednesday morning, especially from the Cascades west, becoming widespread Wednesday afternoon and Wednesday evening. Gusty winds are expected along the coast beginning Wednesday morning and for many inland areas Wednesday afternoon and evening. Areas of low level wind shear are expected along the coast in the morning and early afternoon.

MARINE...Updated 200 AM PDT Wednesday, September 2, 2026

South winds will soon increase ahead of an approaching cold front. Conditions will be hazardous to smaller crafts for most of this morning before gale force winds are expected this afternoon as the cold front approaches with gusts around 45 knots. Once the front moves through, a westerly swell around 10 feet at 10 seconds will move into the waters Thursday afternoon.

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

MFR WATCHES/WARNINGS/ADVISORIES

OR...Frost Advisory until 8 AM PDT this morning for ORZ029>031.

CA...Frost Advisory until 8 AM PDT this morning for CAZ085.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT early this morning for PZZ350-356-370-376.

Gale Warning until 7 PM PDT this evening for PZZ350-356-370-376.