textproduct: Medford

AVIATION (18Z TAFs)

Very similar overall conditions will persist through this cycle. This includes a marine layer that will reestablish tonight bringing IFR/LIFR conditions to KOTH overnight with relief starting early afternoon (similar to today). We will also continue to see smoke from the Wrights Spring Fire impact KLMT bringing ceilings and reduced visibilities. There remains a lot of uncertainty with smoke forecasting due to fire activity/suppression efforts. Otherwise, expect VFR conditions for other inland areas and typical diurnal breezes.

-Guerrero

PREV DISCUSSION

/Issued 712 AM PDT Tue Aug 11 2026/

KEY MESSAGES...

* An uneventful upper level pattern will allow a weak cooling trend to continue, though with inland and Brookings highs still generally several degrees above normal through tomorrow/Wednesday. Breezy afternoon winds will also continue, with strength similar to that of yesterday. * Coastal areas will see the marine stratus clear again today. But, a more widespread and thicker onshore push is expected early this evening into Wednesday morning, which is also expected to bring a deck of low clouds into the Umpqua Valley late this evening/overnight. Clearing on Wednesday will be slower than lately, toward afternoon inland with patches persisting through the day north of Cape Blanco.

* Periods of smoke accumulation are expected for Klamath, Lake, central/eastern Siskiyou, and northern/eastern Modoc counties. Areas around Klamath Falls are likely to see morning smoke accumulation, ahead of afternoon improvement.

* Slight chance thunderstorm probabilities Thursday through Sunday are focused upon Friday and Saturday and for northern portions of Klamath and Lake counties. But, not exclusively limited to that area.

DISCUSSION...One of two main changes today is a higher confidence in a stronger marine push for the coast and Douglas County arriving tonight, trending slightly weaker during subsequent nights through the weekend. Also, increasing confidence in the convective forecast. A weak upper level trough will track southward and sharpen slightly over the Pacific today through Thursday. A stable air mass persists through Wednesday with low topped cumulus on Wednesday for northern California the east side, and convective activity on Thursday being limited to taller, more widespread cumulus buildups over south central Oregon and northern California (although with a 10% risk of thunderstorms near Fort Jones in California and also in northern Lake County).

The probability of thunderstorms is highest (around 15%) for Friday afternoon in northern Klamath, northwest Lake, and western Siskiyou counties as a wave rotating through the base of the upper level trough carves out its own trough near the northern California coast. Model solutions show a wider variation beginning Saturday, but weekend agreement is better than it was yesterday. This means a likely north and eastward shift of the convective risk, with the southern extent of a slight chance risk still covering at least northern Klamath County, at least on Saturday, roughly from Crater Lake north and northeastward.

Low clouds from Cape Blanco northward and into the Coquille Valley will clear this morning, but return quickly this evening. Low clouds are then likely to fill the coast, and Coquille and Umpqua valleys tonight and be slow to clear during Wednesday. Clearing for the afternoon in the Umpqua, then by mid-morning on Thursday, failing to fill the Umpqua Valley on Friday morning, and limited to the coast and Coquille Valley on Saturday morning. Meantime, low clouds south of Cape Blanco are expected to be most extensive/widespread during Friday and Saturday mornings, with continued though weaker northeast flow during the next few mornings.

Beyond the weekend, model differences do become large with the GFS cohort allowing for weak but broad coverage of ridging in our region and a closed low far offshore. Meanwhile, the ECMWF is more progressive and indicates the low will track toward the area with more extensive cooling, at least mid and upper level cloud cover, and even rain and thunderstorm chances. We will obviously, be watching this closely.

AVIATION...11/12Z TAFs...Smoke will be concentrated south and east of the Wright's Spring Wildfire, across southern portions of Klamath and Lake counties, central/eastern Siskiyou County, and northern/eastern Modoc County. This likely includes MVFR ceilings and visibility reductions at Klamath Falls this morning. Smoke is not expected to be as concentrated at Lakeview and Alturas. Montague may see a period of MVFR ceilings/visibilities in smoke later this morning. Afternoon winds are expected to bring improvement to Siskiyou County and western/northern Klamath County.

Marine stratus along the coast is bringing LIFR ceilings north of Cape Blanco (including North Bend) and also near Brookings. Gradual clearing is expected after 16z. Gusty afternoon winds are expected again along the coast with gusts to around 30 kt. A thicker and more extensive push of marine stratus is expected this evening into Wednesday morning with LIFR/IFR at the coast, and MVFR stratus into the Umpqua Valley (including Roseburg).

Otherwise, expect VFR conditions with areas of breezy winds this afternoon and evening (gusts of around 20 kt).

MARINE...Updated 200 AM PDT Tuesday, August 11, 2026...Seas briefly diminish for today in the area north of Cape Arago. But, gusty north winds will continue through Wednesday evening, with areas of gales and very steep seas south of Port Orford. Elsewhere, steep seas are expected. Winds will begin to ease Thursday, with north winds at Small Craft Advisory strength south of Port Orford. But, with the combination of wind wave and fresh swell, steep seas are likely to persist across the area into Friday morning. Weak winds and low seas are expected for the weekend, and likely into early next week.

FIRE WEATHER...Updated 200 AM PDT Tuesday, August 11, 2026...The two main changes this morning are a continued model trend of reducing the probability of thunderstorms on Wednesday and Thursday, and a increasing confidence in a slight chance of afternoon thunderstorms on Friday and Saturday (especially Friday) that is sufficient to declare the highest probability (15-20%) will be for northern portions of Klamath and Lake counties, secondarily (15%) for western Siskiyou County, and tertiarily (10-15%) connecting those areas...across Jackson, far eastern Douglas, and far western Klamath counties. Rather than rehashing things, the previous discussion follows below.

Main message remains the same -- we expect dry conditions through Wednesday, then slight chances of thunderstorms/lightning in NorCal Thursday. These chances expand up the Cascades and over the East Side Fri/Sat. Latest 12Z guidance has diminished the overall risk/coverage area compared to yesterday, so confidence still remains low, especially with the specifics of where activity will be focused each day.

We'll stay in a pattern of very warm, very dry, and breezy conditions through Wednesday. This pattern includes overnight breezy east to northeast winds at ridge tops of SW Oregon and NW California (most notably the Coast Range and Kalmiopsis Wilderness) along with poor to moderate RH recovery tonight/Tuesday morning, trending to improved but still moderate recovery in subsequent mornings. A channeling of winds down the Chetco could result in some drier/warmer conditions along the SW Oregon coast as well (though the marine influence has held so far at the beaches).

The trend through midweek will be to lower daytime MaxTs down by a degree or two each day, and this should subsequently allow daytime MinRHs to be slightly higher. Even so, it'll be dry and unstable, so any fires on the landscape will still have the ability to grow significantly, especially during the peak burning periods during the afternoons/evenings. Overnight RH recoveries haven't been good the last couple of nights, generally only in the 20-35% range for some of the upper slopes and ridges. There should be slight nightly improvement in recoveries from NW to SE through the period. Things trend toward normal after Wednesday, but temperatures still probably remain a few degrees above normal for most locations.

Models and ensemble guidance continue to show a weakness or upper trough developing near the California coast Wed/Thu and also show an increase in monsoonal moisture coming up from the south late week. The best chance for isolated thunderstorms is Fri/Sat from NorCal up the Cascades and across portions of the East Side. Given plenty of uncertainty in strength of forcing mechanisms, overall instability and moisture advection, confidence is low in the locations where activity will be focused. Keep checking back for updates since any lightning brings with it the risk of new fire starts. -Spilde

MFR WATCHES/WARNINGS/ADVISORIES

OR...CA...None.

PACIFIC COASTAL WATERS...Gale Warning until 11 PM PDT Wednesday for PZZ356-376.

Small Craft Advisory until 11 PM PDT Wednesday for PZZ350-356- 370-376.