078
FXUS66 KMFR 031729
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1029 AM PDT Sun Aug 3 2025

...New Aviation Section...


.AVIATION (18Z TAFs)...

Expecting a mainly VFR TAF cycle today and through early parts of
this evening before another marine layer pushes into the coast.
This will result in MVFR to perhaps IFR conditions along/near the
coast which will impact North Bend. However, inland TAFs should
remain VFR throughout the valid TAF cycle with one caveat. There
is a chance for thunderstorms this afternoon and early evening
which could impact Klamath Falls, but these should be high based
thunderstorms if they do impact the terminal. If a thunderstorms
happens to form over the terminal there could be brief visibility
concerns from rainfall. Otherwise, gusty erratic winds could
impact the terminal as well.

-Guerrero

&&

.PREV DISCUSSION... /Issued 641 AM PDT Sun Aug 3 2025/

UPDATE...The forecast has been updated to take into account the
Red Flag Warning that has been issued. please see RFWMFR for more
details. The discussion below from the earlier issuance is still
valid. Also the Aviation Discussion has been updated. -Petrucelli

PREV DISCUSSION... /Issued 300 AM PDT Sun Aug 3 2025/

DISCUSSION...Satellite image shows a stronger upper trough
approaching the area. Ahead of the upper trough it will be rather
unstable and a few lightening strikes have already been observed
in northern Lake and just north of Lake County. The general
consensus among various data sets show rather unstable conditions
later this morning and especially in the afternoon along with
plenty of energy ahead of the upper trough. This will set the
table for thunderstorms to develop late this morning and more so
this afternoon, the focus for storms will be along and east of the
Cascades, but guidance also shows a secondary max from around the
Trinity Horn and points northeast towards southern Klamath
County.

The best chance for scattered thunderstorms will be across
northern Klamath and Lake counties, and Trinity Horn where
effective shear values are in the 25-35kt range. This will support
stronger updrafts/storm maintenance and inverted-v soundings will
promote strong outflow wind gusts with hail in the strongest
cells. The SPC continues to have a marginal risk for severe
storms there with storm motions generally carrying them NNE into
Deschutes County.

A weak thermal trough will maintain gusty north winds south of
Cape Blanco, resulting in low end advisory level winds and seas
that will persist through the wee hours of Sunday morning.
Conditions will be relatively improved through much of the week,
though winds could briefly reach advisory levels between Port
Orford and Gold Beach during the afternoons/evenings. Sub-advisory
seas are expected through much of the week even as a light
northwest swell moves into the waters around mid-week. A stronger
thermal trough could develop next weekend. Over here on the west
side, the environment is generally less favorable for
thunderstorms since moisture will be more limited, and instability
will be marginal at best.

The other concern will be moderate to occasionally strong winds
with afternoon winds between 15-25 mph with gusts to 30-35 mph
this afternoon into early this evening.

Thunderstorms will linger into early this evening, then ending
with not much more than a few showers over northern Lake County
later this evening. Dry weather is likely for the overnight hours
tonight.

After today, it will be dry with afternoon temperatures near or
just below seasonal norms through Thursday with weak upper
troughing over the area. As we get towards the end of the week
into next weekend the operational models, ensembles and clusters
point towards stronger upper ridging resulting in afternoon
temperatures much above normal for the interior. At the same time,
a thermal trough will set up along the coast and could bring much
warmer temperatures near and at Brookings with highs in the lower
80s possible. -Petrucelli

AVIATION...03/12Z TAFs...IFR marine stratus is mainly confined to
the coast from about Bandon north and south of Gold Beach, inland
into portions of Curry and Coos County. The marine stratus in these
areas should burn off later this morning (between 17-18z) with VFR
ceilings the rest of the day.

VFR conditions will continue through the TAF period inland. However,
an increase in thunderstorm activity is expected this afternoon and
evening. Most of the storms will again occur in Siskiyou, Klamath,
and Lake counties. This includes a heightened risk of severe storms
over the Winter Rim in eastern Klamath County northeastward into
northern Lake County. -Petrucelli

MARINE...Updated 200 AM PDT Sunday, August 3, 2025...Moderate north
winds will continue today with the strongest winds south of Cape
Blanco out to 20 nm from shore. However the stronger winds are still
expected to remain below small craft, thus were not expecting any
headlines. Relatively calmer conditions are expected for most of
the week ahead. A thermal trough will set up along the south
Oregon coast towards the end of the week with moderate to strong
north winds likely Thursday afternoon and could persist into next
weekend with steep wind driven seas. -Petrucelli

FIRE WEATHER...Updated 200 AM PDT Sunday, August 2, 2025...The
main concern today will be thunderstorms mainly east of the
Cascades and around the Trinity Horn and points northeast towards
southern Klamath County. In addition moderate to occasionally
strong winds in the in the absence of thunderstorms will also be
a concern as well as gusty and erratic winds near thunderstorms,
this could result in increased fire behavior for existing fires.

A rather strong upper trough will approach the area today and this
in combination with existing instability, and moisture will set
the table for isolated to scattered storms this afternoon into
early this evening. The general consensus for storms to be most
frequent are expected to be around the Trinity Horn, and
northeast towards southern Klamath County and portions of Lake and
Klamath County. SPC continues to highlight a marginal risk for
strong to severe storms, thus there is concern for some storms to
be strong to severe resulting in frequent lightning, strong winds
and hail.

Steering winds will be from the southwest, therefore storms that
develop will general move from southwest to northeast. Also
compared to the last several days, steering winds will be
stronger, therefore storms will not be slow movers. Because of
this and the fact several models soundings east of the Cascades
show an inverted V sounding profile, precipitation could be
limited. Thus a heightened concern for new fire starts.

Storms will diminish and end this evening with mostly dry weather
overnight tonight. A few convective showers are possible in
northern Lake county, but were not expecting any thunderstorms.

A stable pattern is in the works for set up over the area next
week. Weak upper troughing will keep afternoon temperatures
slightly below seasonal norms for the interior, then the
operational models, ensembles and clusters points towards stronger
upper ridging towards the end of the week into next weekend. This
will result in hot afternoon temperatures and lower relative
humidities for the interior. In addition, a thermal trough will
set up along the south Oregon coast and will bring moderate east
to northeast winds and moderate to locally poor overnight
recoveries near and at the ridges in southwest Oregon and Fire
zone 280 starting overnight Thursday. -Petrucelli

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Red Flag Warning from 2 PM this afternoon to 8 PM PDT this
     evening for ORZ624-625.

CA...None.

PACIFIC COASTAL WATERS...None.

&&

$$