835
FXUS66 KMFR 102206
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
306 PM PDT Thu Jul 10 2025

.DISCUSSION...The main updates today were: to upgrade the Extreme
Heat Watch for Josephine, Jackson, and western Siskiyou counties
on Saturday through Monday to an Extreme Heat Warning, issue a
Heat Advisory for the remainder of our area, excepting the coast,
and southern Oregon Cascades and Siskiyou Mountains, and add a
slight chance mention for thunderstorms into western Siskiyou
County into Sunday afternoon/evening.

There are areas of high pressure far offshore and over southern
California that are both building toward our area. Of the two, the
southern ridge will be the more impactful/more responsible for our
coming heat wave. Meantime, a very weak trough, in-between the
ridges will move east across Siskiyou County on Sunday. This is
not an impressive feature, but warrants the inclusion of the
slight chance of late day thunderstorms for western Siskiyou
County with the 12Z GFS indicating the best chance of a storm to
pop up near Fort Jones.

With more of a westerly flow aloft, and absence of a shortwave
trigger, expect following days to be less favorable for any
thunderstorm development, but patchy lower topped cumulus clouds
will still be possible over the higher terrain.

The extreme heat Saturday through Monday with result in inland
highs from the lower 90s to around 110, with the hottest readings,
as usual, in the valleys of western Siskiyou County.

Model agreement diminishes beyond Monday, with a balance between
slight cooling or slight further heating for Tuesday and
Wednesday. An inside slider trough tracking across eastern
Washington to the Rockies may have a lobe break off and retrograde
offshore. This will either put a small dent in the strength of the
ridge, or the ridge will quickly rebound in strength behind the
trough. Even if we do end up with the `cooler` solution,
temperatures would still be several degrees above normal.


&&

.AVIATION (18Z TAFs)...Patchy IFR/LIFR lingers near Brookings this
morning, with a broader though thinning patch of IFR/MVFR from Cape
Blanco northward into the Coquille and Umpqua valleys. VFR is
expected by the afternoon. Coastal IFR/LIFR is expected to return
north of Cape Blanco early this evening, and expand into the
Coquille Valley overnight. Elsewhere, VFR will persist with breezy
late afternoon and evening northwest winds. -DW

&&

.MARINE...Updated 200 PM PDT Thursday, July 10, 2025...A thermal
trough will intensify today, bringing gusty north winds and steep
wind-driven seas across area waters. By this evening, winds and seas
will expand north of Cape Blanco with gales and very steep seas
developing to the south. The strongest winds and steepest seas will
be south of Port Orford. This pattern will continue through the
weekend and into early next week as the thermal trough maintains
position across the region. -BPN

&&

.FIRE WEATHER...Updated 200 PM PDT Thursday, July 10, 2025...
After warm, slightly above normal temperatures today, heat will
return to the region this weekend into early next week as upper
level ridging builds in aloft and an thermal trough develops at the
surface. Meanwhile, expect fairly typical late-day summertime
breezes, but also dry afternoon humidity. Also, a general
easterly/offshore flow is forecast to develop over the coastal
mountains and Klamath/Siskiyou mountains each night, which may
result in moderate to locally poor RH recoveries, especially over
the ridgetops where overnight gusts could reach up to 25 mph. This
will not be a necessarily strong east wind pattern, but it will be
sustained for several days.

While there are no substantial threats for thunderstorms through hat
least the middle of next week, a passing weak impulse  will help
produce some weak instability over the area Sunday afternoon. As a
result, we will see some cumulus cloud buildups across the area, and
perhaps a stray shower or very isolated thunderstorm over
southwestern Siskiyou county. Most likely, the entire area will be
dry, but some plumes and pyro-cumulus development is possible under
these potential hot, dry, and unstable conditions.
-BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Extreme Heat Warning from 2 PM Saturday to 8 PM PDT Monday for
     ORZ024-026.

     Heat Advisory from 2 PM Saturday to 8 PM PDT Monday for ORZ023-
     025-029>031.

CA...Extreme Heat Warning from 2 PM Saturday to 8 PM PDT Monday for
     CAZ080-081.

     Heat Advisory from 2 PM Saturday to 8 PM PDT Monday for
     CAZ082>085.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 PM PDT this
     afternoon for PZZ350-356-370-376.

     Gale Warning until 8 PM PDT Saturday for PZZ356-376.

&&

$$