074
FXUS66 KMFR 120819
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
119 AM PDT Fri Jun 12 2026

.DISCUSSION...We`re having another clear night in southern Oregon
and far northern California. Cool overnight temperatures are being
experienced across the region, but we will warm up quickly again
today. The warm trend continues late this week into the weekend,
culminating in a broad heat wave expected during the Sunday to
Tuesday (maybe Wednesday - esp east side) time frame.

A broad trough over the Rockies and Central Plains will shift
east over the coming days, allowing an upper level ridge over the
eastern Pacific to amplify and build into the western US through
this weekend. With high pressure in control, a thermal trough
has strengthened along the coast, with temperatures in and around
Brookings expected to rise well into the 80s again today and
Saturday. Models show the peak of offshore flow tonight into
Saturday morning, so it could be quite warm at the mouth of the
Chetco tonight (not much cooling) as the NE winds funnel down the
river valley. With onshore flow lacking into Saturday, it could
conceivably reach into the 90s, even though current models don`t
explicitly show that potential. Inland, temperatures will rise by
2 to 5 degrees over the previous day each afternoon into this
weekend.

The upper level ridge will weaken slightly Saturday night as a
trough interrupts the flow briefly, then the ridge rebuilds
quickly and remains overhead through the first part of next week.
This interruption will push the thermal trough inland, and this
will result in very warm temperatures Sunday through
Tuesday/Wednesday. Daytime highs across the area will be 20 to 25
degrees above normal for early to mid June, with widespread triple
digit, or upper 90s, highs west of the Cascades, and upper 80s to
low 90s to the east. Model forecast 850 temperatures (a very
reliable signal for daily highs) are forecast to reach 26 to 28
degrees C, which when mixed to the surface (especially now during
our longest daylight hours of the year), suggest highs could reach
as high as 105 degrees F in Medford and Grants Pass, and as high
as 110 in the lower Klamath and Salmon valleys in western Siskiyou
County. These will be the highest temperatures we have seen so
far this year, and chances are very good that we will see record
daily highs for many locations across the region. NWS HeatRisk is
showing widespread moderate impacts with areas of major impacts.
At this time, it appears as if nighttime temperatures will be
somewhat of a mitigating factor to the heat, since most areas
should be able to cool off adequately. As such, this looks like an
advisory level event. We`ll be evaluating the need for heat
headlines over the next couple of shifts.

The ridge is expected to flatten a bit by Wednesday. This could
be delayed by as much as a day, as these patterns typically are,
which will let temperatures cool slightly through the rest of the
week. However, temperatures are still expected to remain above
normal. Of note, we also tend to see an increased risk for
thunderstorms on the back side of heat waves. As has been the case
over the last few shifts, model suites keep the area dry at the
end of this one, but there are some hints of instability starting
to appear in some runs on Wednesday or Thursday afternoon, mainly
over Modoc and Siskiyou counties. The limiting factor will be
atmospheric moisture, which appears lacking as of now, and a clear
trigger to set off convection. So while chances are very low now,
we can not rule out some lightning around the middle of next
week. Confidence should improve as we get closer to the time
period in question, and model better resolve the situation.
-Spilde/BPN


&&

.AVIATION...12/12Z TAFs...VFR levels persist across northern
California and southern Oregon under stable atmospheric conditions.
Chances for cloud development over North Bend and along other
coastal river valleys near sunrise remain, but chances for a dense
enough layer to affect flight levels remain slight. If stratus
does develop, clearing is expected within a few hours after
sunrise. Gusty winds are expected along the coast and possibly at
the Roseburg terminal late Friday morning and through the
afternoon. -TAD

&&

.MARINE...Updated 100 AM PDT Friday, June 12, 2026...A thermal
trough pattern will maintain gusty north winds and steep to very
steep wind-driven seas across the southern Oregon coastal waters
through this weekend. The worst conditions are expected south of
Cape Blanco, where gales and very steep seas will persist through
the weekend. Winds ease some on Sunday, but steep fresh swell is
likely to persist into Monday. Gusty north winds likely strengthen
again around Tuesday. /BR-y

&&

.FIRE WEATHER...Updated 100 AM PDT Friday, June 12, 2026...A
steady warming and drying trend is expected through the rest of
this week, culminating in an early season heat wave this weekend
into early next week. Generally, temperatures will warm by 3 to 5
degrees and humidities will trend about 3 to 5 percent drier each
afternoon (minimum RHs 10-20%). Meanwhile, broad north through east
flow will produce moderate to poor RH recoveries over upper
slopes/ridges each night, especially over the Klamath mtns,
Siskiyous, and Cascades. There could be a period of gusty offshore
E-NE winds over the Siskiyou Mtns and coast ranges Friday
night/Saturday morning with peak gusts in the 25-35 mph (40 mph?)
range.

Our typical diurnal afternoon breezes could become gusty at
times, particularly Friday/Saturday. While critical conditions
are not expected within the current forecast, localized conditions
could get close, especially considering the low teens and single
digit minimum humidities that are likely during the peak of the
heat wave. The heat wave will reach a peak Sunday through Tuesday,
with daytime highs about 20 to 25 degrees warmer than normal for
early to mid June.

Also of note, once the heat begins to ease midweek, we will need to
keep an eye out for possible thunderstorms. Model guidance is not
currently showing any significant convection chances, but there are
some hints in the various model suites, and thunderstorms do
typically accompany the breakdown of a heat wave in this area, so
there is at least a very slight potential, probably focused on far
northern California and the East Side. Confidence is low right now,
but we will update the forecast as necessary over the coming days.
-Spilde/BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory from noon today to 8 PM PDT Saturday for ORZ022.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT
     Saturday for PZZ356-376.

     Small Craft Advisory until 11 PM PDT Saturday for PZZ350-370.

     Gale Warning until 11 PM PDT Saturday for PZZ356-376.

&&

$$