textproduct: Medford

KEY MESSAGES

* After yesterday's cooler day, temperatures trend warmer through the weekend, becoming several degrees above normal again with highs in the 90s to low 100s across inland valleys.

* Gusty winds and low humidities will bring elevated fire weather conditions today. Critical fire weather conditions are expected in portions of southeast Klamath, southwest Lake, Modoc, and central and eastern Siskiyou counties. Breezy afternoon winds will then trend back to near normal strength by Sunday while the air mass remains drier than normal.

* An unstable air mass is possible with the potential for thunderstorms Monday through Wednesday, mainly from the Cascades eastward and across Northern California. The higher probability is for stronger influence of a ridge which would bring weaker instability but hotter temperatures.

* Smoke from the East Evans Creek Fire will result in continued impacts downwind of of the fire, from Jackson into southern Klamath and northern Siskiyou counties, with some improvement in visibility due to stronger afternoon winds.

DISCUSSION

Please see the fire weather section below for details regarding critical conditions this afternoon and evening for portions of both the east side and Siskiyou County.

Forecast confidence is high through Sunday, then lower than typical thereafter. Although, with a general consensus for slight cooling (temperatures remaining above normal) and stabilization or further stabilization of the air mass during the latter portion of next week.

A warming trend, gusty winds, and a very dry air mass of lower than normal humidity will persist through Sunday.

Regarding the middle (Monday through Wednesday) portion of the forecast, when such a stark difference occurs between the GFS and ECMWF solution sets, later today is often the time that model solutions start to trend in one direction or the other. The operational GFS and a higher percentage of its ensemble solutions (about 1/3rd of them) would both keep a trough farther offshore and a ridge farther to the east. In between, a surge of moisture aloft tracking north along the spine of the Sierra Nevada could bring a heightened risk of thunderstorms in our area, possibly over a large portion of our area, and particularly on Tuesday and Wednesday. Meantime, while not completely stable, there is a higher probability of stronger ridging. This would lessen the risk and areal coverage of thunderstorms, but bring stronger heating that would be reaching the realm of Heat Advisory issuance inland. For now, the NBM solution was utilized which, to reiterate, favors only a 5-10% probability of late day convection with the highest probabilities east of the Cascades.

AVIATION...17/12Z TAFs

Areas of smoke and coastal stratus will remain the two exceptions to VFR conditions this morning into Saturday morning. Also, there will be gusty, stronger than typical winds for much of the area this afternoon and evening due to a slow moving dry front. Winds will be strongest in the Shasta Valley and east of the Cascades.

The smoke from the East Evans Creek wildfire will continue to produce areas of MVFR visibilities from northern Jackson County extending south and southeastward across Jackson, southern Klamath, and northern Siskiyou counties. Smoke will be thickest during the night and morning hours. Both stronger winds and heating in the day- time will result in some improvement and lifting of the smoke.

LIFR marine stratus extends northward to Brookings, while patchy MVFR stratus is present north of Cape Blanco, and into the Coquille and Umpqua valleys. Stratus coverage will be at a maximum around sunrise, with improvement to VFR expected by 18Z. Stratus is expected to develop again along the coast this evening, but make less progress inland. MVFR ceilings are expected into the Coquille valley tonight.

MARINE...Updated 200 AM PDT Friday, July 17, 2026

Increasing north winds will build steep seas south of Cape Blanco this afternoon, with steep seas spreading to all waters on Saturday. North winds peak on Sunday, strongest south of Port Orford. During Saturday afternoon, and particularly during Sunday afternoon there is a chance of seas becoming high and very steep south of Gold Beach. Steep seas may linger into Monday, but conditions will improve with dominant wind waves transitioning to fresh swell. Improved conditions are likely to persist into Wednesday.

FIRE WEATHER...Updated 200 AM PDT Friday, July 17, 2026

The two main aspects of the forecast for particular analysis this morning were the extent of hot, dry, and breezy/windy conditions today through Sunday, and the potential risk and coverage of thunderstorms while inland temperatures remain above normal during Monday through Wednesday.

The forecast was updated this morning to expand the Red Flag Warning this afternoon and evening, remaining in effect for southwest Lake and southeast Klamath counties, while expanding coverage across the remainder of zone 285 in Modoc County and much of central and eastern Siskiyou County. This now includes the Shasta Valley, where the strongest south winds of this event (gusts up to 35 mph) are expected to occur. A slow moving dry front will winds to a peak of strength in the late afternoon.

The forecast through the weekend is consistent and pretty straight- forward. Temperatures will trend upward, humidities will remain drier than normal, and afternoon winds will trend back to typical strength for Sunday.

Hot, dry, and breezy conditions are expected Saturday and Sunday. Temperatures of 5 to 10 degrees above normal are expected through the weekend. Afternoon wind speeds will trend back to typical values by Sunday. Minimum afternoon humidities will remain very low on Saturday then trend slightly upward on Sunday. The slight moistening of the air mass on Sunday will be accompanied by a late day increase of high clouds, and perhaps some east side cumulus buildups. The majority of ensemble solutions favor the hotter, drier ECMWF. But, there is about a 20% probability of a slightly less hot, but noticeably more moist air mass as depicted by the operational GFS run.

In that case, instability could develop as early as late Sunday night into Monday morning, with a few very light showers or virga possible over the higher terrain. A risk of thunderstorms could develop as early as Monday afternoon, with a higher probability of thunderstorms, highest for Lake and Modoc counties, on Tuesday and Wednesday afternoons. Though not as indicated by the GFS, a more expansive analysis shows chances for Monday thunderstorms remain very slight (5-10%) and predominantly over the east side. On Tuesday, 10-15% chances cover most of the east side, with a lesser 5% to 10% probability extending into Jackson, Siskiyou, and eastern Douglas counties. Particularly if the GFS were to verify, for areas where thunderstorms do not develop, the potential instability added to continuing hot and dry conditions could lead to elevated critical condition concerns and enhanced behavior on existing fires.

Model uncertainty still increases further beginning Wednesday with differences in whether an unstable air mass will linger or shift east of our area. Late in the week (Thursday/Friday), some eastward movement in the pattern is likely, which is likely to shift the region of instability east of our area. But, with a plausibly slower solution keeping instability over eastern portions of Lake and Modoc counties.

MFR WATCHES/WARNINGS/ADVISORIES

OR...Red Flag Warning from 2 PM this afternoon to 8 PM PDT this evening for ORZ624.

CA...Red Flag Warning from 2 PM this afternoon to 8 PM PDT this evening for CAZ281-284-285.

PACIFIC COASTAL WATERS...Small Craft Advisory from 11 AM to 11 PM PDT Saturday for PZZ350-356-370-376.