542
FXUS66 KMFR 102100
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
200 PM PDT Sun Aug 10 2025

.DISCUSSION...Winds at the coast will still be a concern this
afternoon as the thermal trough moves inland. Gusts near 20-30 mph
are possible this afternoon for portions of the Coos County
coast. Inland, winds will not be as strong as yesterday.

The incoming thermal trough will bring the heat today for inland
areas. A Heat Advisory for the Umpqua Basin and an Extreme Heat
Warning for the Rogue, Illinois, Shasta and Klamath River valleys is
now in effect and will continue through Tuesday. Please see NPWMFR
for more information.

Clearer skies under the high pressure will help temperatures warm
back into the tripe digits for more west side locations today,
including the Rogue, Illinois and Klamath River valleys. There is a
near 100% certainty to see 100 degrees in the Rogue, Illinois and
Klamath River valleys today. While the thermal trough begins to move
inland, the Coos County coast will see the warmest temperatures of
this string today with low/mid-70s expected.

Monday will be the warmest of the stretch. In fact, it will be so
warm that the record warm low temperature at Medford will be in
jeopardy. The current record is 66 from 2021, and the forecast is 69
degrees. More west side valley locations have forecast highs between
103-107 degrees. The probability for reaching 105 degrees in Grants
Pass, Medford and portions of the Klamath River Valley is around
90%. The Umpqua Basin and portions of the Illinois Valley,
including Selma, have an 80-90% chance to warm to 100 degrees
Monday afternoon. Areas east of the Cascades will also be under
the risk of these warmer temperatures, and portions of eastern
Siskiyou, Modoc and Klamath counties will be under a Heat Advisory
Monday morning into Tuesday. Please see NPWMFR for more
information. Precautions need to be made to protect yourself from
the heat. Drink plenty of water, avoid peak heating between 10 AM
and 4 PM, and stay in an air- conditioned room as much as
possible.

Tuesday morning will be the last record to watch out for as
Medford`s record warm low temperature is 69 degrees from 2021, with
a forecast low of 69 degrees. The heat products continue for all
areas through Tuesday evening.

After Tuesday, the ridge starts to break down and temperatures will
start to fall back to near normal for this time of year. For now,
dry conditions are forecast for the beginning of the long term.
However, the Euro has more ensembles showing the chance for rain
coming Friday and reaching the coast early Friday. One of the
differences in these models is the placement of the low pressure.
The low with the Euro is slightly farther south, but in the recent
model run the GFS is starting to match more with the Euro in
bringing this low farther south to impact southern Oregon more.
There is a 15-25% chance of rain starting Friday morning and
continuing into at least Saturday morning. This week we will be
looking into these chances after the heat is over. -Hermansen

&&

.AVIATION...10/18Z TAFs...North winds will strengthen again near the
coast this afternoon (gusts of 25-30 kt). LIFR is expected to surge
back to the coast early this evening into Monday morning. Inland,
VFR will continue with fairly typical breezes this afternoon/evening
breezes. -Spilde/Hermansen

&&

.MARINE...Updated 130 PM PDT Sunday, August 10, 2025...A thermal
trough will weaken and move inland today. Even with the thermal
trough weakening and moving inland we are still expecting moderate
north winds and steep to very steep hazardous seas to linger,
gradually subsiding early this evening. Thereafter, steep seas will
persist through the early evening hours of Monday. Beyond Monday,
hazardous conditions should be confined to the outer waters.

&&

Updated 130 PM PDT Sunday, August 10, 2025...

Today and Monday, offshore flow at the coast will get cut off as the
thermal trough shifts inland. This will result in afternoon winds
easing for west side valleys compared to yesterday. Expect very hot
highs with triple digits west of the Cascades, though coastal areas
south of Blanco will begin to cool off, and 90s will be evident for
areas over the eastside. Relative humidities will still be low in
the afternoons (10-15%) and moderate to poor RH recoveries (25-40%)
can be expected to continue for the upper slopes/ridges area wide
through at least Tuesday night/Wed morning.

There`s good agreement for upper troughing to develop over the area
Tuesday through Thursday. We are pretty confident this will not
result in any thunderstorms, but the tradeoff will be increasing
winds, and low relative humidities, especially east of the Cascades.
At this time, it`s too early to say with much confidence if critical
conditions will be met, but it will be something we`ll keep a close
watch on as fire weather conditions will be at least elevated
through this stretch.

Lastly, some guidance is showing a chance of showers along and near
the coast as well as the Umpqua Basin Friday into Saturday. At this
time, guidance is showing very little--to no--instability so not
expecting thunderstorms. Light rainfall amounts could become evident
over these areas.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Extreme Heat Warning until 2 AM PDT Wednesday for ORZ024-026.

     Heat Advisory until 2 AM PDT Wednesday for ORZ023-029.

CA...Extreme Heat Warning until 2 AM PDT Wednesday for CAZ080-081.

     Heat Advisory until 2 AM PDT Wednesday for CAZ082>085.

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

     Hazardous Seas Warning until 8 PM PDT this evening for PZZ356-
     376.

&&

$$