textproduct: Medford

KEY MESSAGES

* While marine stratus persists over coastal areas and clouds stream to the north inland, activity is unlikely this afternoon and evening.

* A Red Flag Warning is in place for the Shasta Valley as well as Klamath and eastern Lake counties this afternoon and evening for gusty winds and low relative humidities (RHs). For Saturday afternoon and evening, a Red Flag Warning is in place across Klamath and Lake counties.

* Winds ease on Sunday, with a generally unimpactful pattern expected for next week.

DISCUSSION

A cutoff low passing to the west will guide area weather today and through much of the weekend. While marine stratus lingers along the Oregon coast and clouds are streaming from south to north over more inland areas, activity is not expected today (although virga may bring some hopes up). Radar returns show a line of higher returns over the Cascades and moving eastward, so a few stray showers are possible into parts of Klamath County. But with cloud cover limiting daytime heating, convective instability will be limited. Thunderstorms aren't entirely out of the question, but chances have trended downward for this afternoon and evening (5- 10%). With gusty winds and dry surface air being observed, a Red Flag Warning is in place for the Shasta Valley as well as across Klamath and eastern Lake counties.

The low stats to swing inland over Washington state on Saturday. With drier air aloft, precipitation is not expected. Gusty southerly winds will move eastward, which will take the Shasta Valley out and put the rest of Lake County in a Red Flag Warning for Saturday afternoon and evening. Areas under marine stratus will see cooler temperatures while inland areas will be at seasonable temperatures.

The cutoff low is expected to be to the northeast by Sunday, bringing a southwest flow pattern that will generally persist through the week ahead. A shortwave ridge is currently expected to bring temperatures 5-10 degrees above normal for Monday and Tuesday. An upper trough passing to the north will bring temperatures back down on Wednesday and Thursday, with elevated westerly winds over Lake and Modoc county terrain possible depending on its position. Deterministic models start to diverge into Friday and beyond, but meteograms show agreement that the rest of August looks to stay dry. -TAD

AVIATION...21/18Z TAFs

Marine stratus will persist through much of the TAF period along the coast and over the marine waters with IFR/MVFR persisting through the afternoon, then lowering again to LIFR/IFR this evening and tonight. Drizzle is possible along and west of the coastal ranges.

Inland, VFR conditions will prevail with high clouds overhead. Gusty winds will develop this afternoon and evening, strongest east of the Cascades and in the Shasta Valley. Winds will ease after sunset and high level clouds will gradually move northeast. /BR-y

MARINE...Updated 0230 PM PDT Friday, August 21, 2026

Light winds and low seas will persist through the weekend. Some southerly winds will increase today, then shift to westerly Saturday as a weak front moves through the waters and passes onshore. A thermal trough will develop by Sunday evening with stronger northerly winds developing offshore. These winds will likely be hazardous to smaller crafts for areas south of Cape Blanco Sunday night into Monday morning.

FIRE WEATHER...Updated 130 PM PDT Friday, August 21, 2026

An upper level trough will pass through the region today into Saturday, bringing a period of increased winds and critical fire weather conditions. Afternoon winds increase today as the trough and associated dry cold front approach the region (gusts 25-35 mph), but daytime humidities will also trend somewhat higher compared to yesterday. Despite the uptick in humidities, it's close enough with the higher confidence on more widespread higher winds on Friday to warrant maintaining a Red Flag Warning for FWZs 281, 284, 285 and 624. Sustained winds won't quite reach criteria for FWZ 625 today, but by Saturday, however, 700 mb winds will peak in strength east of the Cascades and more widespread sustained winds of 15 to 20 mph are expected as the dry front passes. Additionally, daytime RHs will trend lower again, so another day of critical fire weather conditions is expected on Saturday. The Fire Weather Watch has been upgraded to a Red Flag Warning for FWZs 284/285/624/625 for gusty winds and low RH for Saturday afternoon/evening.

In addition to wind/RH concerns for today and Saturday, there is the potential for isolated showers and very isolated thunderstorms today. Ample cloud cover so far is expected to limit daytime heating and instability, which should keep the lightning potential minimal today. There are some returns on radar this afternoon, but very little, if any, precipitation is making it to the ground. By Saturday, the mid-levels dry out and thunderstorm threat will shift well north of the forecast area into northern Oregon/Washington.

More typical summer conditions return Sunday and persist into early next week. There are some signals for thunderstorm chances across eastern 285/625 on Monday, but much will depend on how far west the Four Corners High retrogrades behind this trough passage. Otherwise, another trough drops southward from the Gulf of Alaska and lingers off the BC coast through early next week. There will likely be additional shortwaves/troughs to swing through the region early next week, bringing periods of enhanced winds. Stay tuned for updates. /BR-y

MFR WATCHES/WARNINGS/ADVISORIES

OR...Red Flag Warning until 9 PM PDT this evening for ORZ624-625.

CA...Red Flag Warning until 9 PM PDT this evening for CAZ281-284-285.

PACIFIC COASTAL WATERS...None.