347
FXUS66 KMFR 110906
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
206 AM PDT Thu Jun 11 2026

.DISCUSSION...Currently, southern Oregon and far northern
California lie under cloud-free skies as high pressure builds in
overhead. These clear skies will allow for good radiative cooling,
with this morning`s lows expected to be just slightly below normal
for this time of year. Additionally, frost is expected east of
the Cascades this morning, and a Frost Advisory is in effect for
many locations there. More details on this can be found at
PDXNPWMFR. This may be the lats time we speak of cool temperatures
for some time, however.

A broad trough over the Rockies and Central Plains will shift
east over the coming days, allowing the upper level ridge over the
eastern Pacific to amplify and build into the western US through
this weekend. Meanwhile, with high pressure in control, a thermal
trough will strengthen along the coast, with temperatures in and
around Brookings expected to rise well into the 80s each day.
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 into
Sunday 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 also 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 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.

The ridge is expected to flatten a bit by Wednesday. This could be
delayed by as much as a day, as these pattern 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 tend to see an increased risk for thunderstorms on
the back side of heat waves. Currently, 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 county. 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.

&&

.AVIATION...11/12Z TAFs...Patchy late night into early morning
IFR/LIFR is possible in the lower portions of the Coquille and
Umpqua valleys, but unlikely. Also, breezy to gusty northwest to
north afternoon and evening winds will develop again on Thursday.
Otherwise, VFR with clear skies will continue across the area
through Thursday night.

&&

.MARINE...Updated 100 AM PDT Thursday, June 11, 2026...A
strengthening thermal trough will produce 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
develop by tonight and persist through the weekend. Winds will ease
on Sunday, but steep fresh swell is likely to persist into Monday,
with north winds strengthening again around Tuesday.

&&

.FIRE WEATHER...Updated 100 AM PDT Thursday, June 11, 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.
Meanwhile, broad east flow will produce moderate to poor ridgeline
recoveries each night, especially over the Klamath, Siskiyous, and
Cascades.

The heat wave will culminate Sunday through Tuesday, with daytime
highs about 20 to 25 degrees warmer than normal for early to mid
June. Our typical diurnal afternoon breezes could become gusty at
times, particularly on Friday. 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.

Also of note, once the heats 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.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Frost Advisory until 7 AM PDT this morning for ORZ029>031.

CA...Frost Advisory until 7 AM PDT this morning for CAZ084-085.

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 from 2 PM this afternoon to 11 PM PDT Saturday for
     PZZ356-376.

&&

$$