409
FXUS66 KMFR 300907
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
207 AM PDT Thu Jul 30 2026

.KEY MESSAGES...

* Very low(<5%) chance of a thunderstorm around Lake and Klamath
  Counties Thursday.

* Temperatures warm up on Friday.

* Dry cold front stalls out over southern Oregon on Saturday with
  winds trending higher and cooler temperatures in some areas.

* Temperatures heat up Monday and Tuesday with moderate heat risk
  in valleys west of the Cascades.

&&

.DISCUSSION...Another strong marine push has brought low clouds to
the coast and the Umpqua Basin this morning. These clouds should
burn off through the late morning, but should help to keep today`s
temperatures just a slight bit cooler. Otherwise, another warm
and dry day is in store for southern Oregon and far northern
California, in an near repeat of yesterday. This includes the
daily push of smoke from the Castle Fire east in the afternoon and
evening before settling and draining down the Cascade foothills
in Douglas County in the evening/overnight, and the smoke from
the central Oregon fires settling into portions of Klamath and
Lake counties through the morning.

Another short wave is anticipated to traverse the west to
southwest flow overhead this afternoon. Most models, including the
CAMS, show very little to no convective development this
afternoon, but a few of the synoptic ensemble members hint at
something. Given the dry atmosphere (PWATs of around half an
inch), and a rather strong mid-level cap, it is highly doubtful
that the shortwave will be able to induce and convection.
Overall, the chances of a weak shower or isolated thunderstorm
remain under 5% in northern Lake and Klamath Counties Thursday
afternoon; not enough to mention in the forecast products.

High temperatures trend warmer by around 5 degrees on Friday as
a warmer air mass under the massive southwest US ridge nudges into
the region on the back side of the departing shortwave. Then, a
dry cold front pushes into the region Saturday as the northeast
Pacific trough moves onshore into BC and Washington state. The
front weakens considerably and begins to stall as it crosses our
forecast area. As a result, temperatures on Saturday will be
around 10 degrees lower than Friday`s highs for areas west of the
Cascades, but there will little to no difference to the east
(although there should be some slight cooling east of the
Cascades on Sunday once the front finally limps through). Also,
some gusty winds will accompany the front Saturday, with peak
afternoon/evening gusts of 20 to 30 mph across the region.

With all this colder air moving in behind the front, the extreme
forecast index(EFI) was picking up on unusually cold temperatures
Saturday night with EFI values around -0.6 to -0.8 for late July.
We are forecasting some lows in the mid 30`s around Chemult and
perhaps sub freezing temperatures south of Chemult in the Klamath
Marsh area. The cooler than normal temperatures will continue
through the weekend as an upper level wave progresses through the
Pacific Northwest. However, this colder air will be short lived.

Some upper level energy from the aforementioned wave will swing
through Washington Sunday night with another dry cold front flying
down the Oregon coast. Pressure gradients help kick off a thermal
trough and temperatures warm up west of the Cascades Monday
afternoon as high pressure builds. That thermal trough will linger
into Tuesday and perhaps Wednesday as Medford is expected to hit
100 degrees on both days. Both the ECMWF and GFS want to push
the thermal trough eastwards towards the end of Wednesday, so
we`ll see if we can get some stronger onshore flow towards the end
of next week.


&&

.AVIATION...30/12Z TAFs...MVFR/IFR in stratus along the coast and in
the Umpqua Basin, including at Roseburg, will persist through much
of the morning, before clearing to VFR by late morning to midday.
Low flight conditions are likely to return late this evening and
tonight.

Elsewhere, VFR levels will prevail with clear skies and normal
diurnal breezes throughout the next 24 hours.

&&

.MARINE...Updated 130 AM PDT Thursday, July 30, 2026...North winds
ease a bit today, with seas diminishing to around 5 ft. These
conditions will persist through Friday, then a low pressure system
passing to the north will produce very strong northerly winds
through the weekend and into early next week, as it tightens the
gradient and enhances the thermal trough to the south. As a result,
gales and very steep seas are highly likely Sunday into Monday south
of Cape Blanco, and periods of storm force gusts possible. Gusty
winds and steep seas are expected north of Cape Blanco. -BPN

&&

.FIRE WEATHER...Updated 200 AM PDT Thursday, July 30, 2026...

Overall, warm and dry conditions continue. Very slight chances
(less than 5%) remain for afternoon/evening dry thunderstorms east
of the Cascades today. Friday looks to be the warmest day of the
week, with temperatures about 5 degrees above normal before
cooling to about 5 degrees below normal over the weekend.

The main fire weather concern will be the passage of a dry cold
front Saturday. As with most dry fronts this time of year, gusty
winds are expected to accompany its passage, with gusts up to 20
mph expected west of the Cascades, and of 25 to 35 mph to the
east. While the front will bring some slightly improved humidities
to the area, conditions will be very close to critical values for
some locations, particularly the high terrain and typically
windier areas of Lake and Modoc counties. This period will be
watched closely, and fire weather headlines may be necessary
should models dry slightly or winds increase slightly from the
current forecast. -BPN



&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

PACIFIC COASTAL WATERS...None.

&&

$$