377
FXUS66 KMFR 241044
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
344 AM PDT Mon Aug 24 2026

.KEY MESSAGES...

* Daytime highs look to be 5 to 10 degrees above normal,
  especially west of the Cascades.

* A 15-20% chance of thunderstorms remains over southeastern Lake
  and Modoc counties this afternoon and evening.

* A passing shortwave will bring critical fire weather conditions
  (gusty winds and low humidities) to areas west of the Cascades
  on Monday. A red flag warning is in effect for the southern
  Oregon Cascades and westward into Jackson County, the Siskiyou
  Mountains and western/central Siskiyou County.

&&

.DISCUSSION...Today will be the warmest day of the forecast
period for most areas. Temperatures west of the Cascades may reach
up to 10 degrees above normal, while to the east highs look to be
about 5 degrees above normal. A passing shortwave will bring
elevated winds into the Shasta Valley, the Klamath Basin,
Christmas Valley, and parts of the Rogue Valley. For western
Siskiyou County, Jackson County, and western Cascades foothills,
these winds align with ongoing dry conditions to possibly reach
critical fire weather conditions. A Red Flag Warning has been
issued for this afternoon and evening to highlight these
concerns. This shortwave is also support slight (15- 20%)
thunderstorm chances over eastern Modoc and Lake counties, given
its interactions with monsoonal moisture moving over those areas.
While the chances for thunderstorms are not high enough to meet
Red Flag criteria, any thunderstorms that do develop can still be
locally hazardous by bringing lightning strikes or erratic and
gusty winds.

On Tuesday, an approaching trough around a low pressure system over
the Pacific will shift flow to be more southerly. With dry air aloft
precipitation is not expected. Temperatures west of the Cascades
will drop a bit, but highs across the area look to stay about 5
degrees above normal. A weak front swinging around that trough may
bring marine drizzle and some inland cloud cover On Tuesday morning,
but significant impacts are not expected.

For midweek and into the weekend, the upper trough starts to work
against high pressure centered around the Four Corners area. The
first low will weaken and move off to the northeast but another low
follows to keep the trough in place possibly through Saturday. With
this pattern, slow and steady cooling would bring generally
seasonable warmth across the area by Friday or Saturday. Upper
disturbances may bring elevated breezes on Friday, but details that
far out are hard to forecast with high confidence. Overall, the
forecast through the rest of August looks to be unimpactful. -TAD


&&

.AVIATION (06Z TAFs)...

Marine stratus with IFR/LIFR will redevelop along the coast
overnight and persist through late Monday morning.  Otherwise, VFR
conditions are expected for inland TAF sites. Gusty winds will
develop for inland areas late Monday afternoon and evening.
Additionally this is a slight chance (20%) for thunderstorms across
Modoc and southeastern Lake county Monday afternoon and early Monday
evening. Gusty outflow winds may accompany storms on Monday.

&&

.MARINE...Updated 230 AM PDT Monday, August 23, 2026...Gusty
north winds and steep seas will persist across the waters through
this morning. Winds near shore will ease this afternoon and
evening, limiting steep seas to outer waters. A southerly surge of
winds and fog along the inner waters is expected tonight into
Tuesday. Generally light winds and seas will follow mid-week.

&&

.FIRE WEATHER...Updated 230 AM PDT Monday, August 23, 2026...
With ongoing dry conditions, a passing shortwave will bring elevated
winds to areas west of the Cascades this afternoon and evening.
These winds will be southerly in the Shasta and could approach 30
to 35 mph. The Scott Valley could also see southerly winds
approach 20 to 25 mph. In the eastern Rogue Valley, westerly winds
could reach 20 to 25 mph. With RHs forecast to be in the 10-15%
range, this combination represents critical fire weather
conditions as any new fires could quickly spread. A Red Flag
Warning for gusty winds and low RHs has been issued for California
fire weather ones 280 and 281 as well as Oregon fire weather
zones 621, 622, and 623. This Warning will be in place today from
11 AM through 8 PM.

Also later today, there are some signals for thunderstorm chances
across far eastern 285/625, namely the Warner and Hart mountains.
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.


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning from 11 AM this morning to 8 PM PDT this
     evening for ORZ621>623.

CA...Red Flag Warning from 11 AM this morning to 8 PM PDT this
     evening for CAZ280-281.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT this
     morning for PZZ350-356.

     Small Craft Advisory until 8 PM PDT this evening for PZZ370-376.

&&

$$

TAD/TAD/TAD