Forks of Salmon, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

089
FXUS66 KMFR 272340
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
440 PM PDT Fri Jun 27 2025

.DISCUSSION...Updated AVIATION Section.

&&

.AVIATION...28/00Z TAFs...Satellite imagery reveals widespread
VFR late this afternoon/evening with some cirrus bisecting
the CWA and a few fair-weather cumulus near the mountains. Marine
layer stratus is currently well offshore, but expect this to return
to coastal areas this evening as MVFR, then remain overnight into
Saturday morning. Areas of IFR/LIFR are possible as well at North
Bend. MVFR ceilings could also redevelop in the Umpqua Basin
around Roseburg toward sunrise, but should only last a few hours.
Gusty NW breezes over the interior this evening die off after
sunset. Expect northerly winds to increase along the coast on
Saturday with gusts to 30 kt possible at North Bend. It won`t be
as breezy over inland areas, but could still gust to 20 kt at
Roseburg in the afternoon.
-Spilde

&&

.PREV DISCUSSION... /Issued 209 PM PDT Fri Jun 27 2025/

DISCUSSION...The broad weak overhead trough has once again
provided support for a strong marine push along the coast this
morning, where stratus and fog pushed into all the coastal valleys
and into the Umpqua Basin all the way to Roseburg. With the trough
weakening and ridging beginning to nudge into the area, the marine
layer will be suppressed, and is expected to only push into the
coastal valleys, and maybe only just spilling into western
portions of the Umpqua Basin just before sunrise.

The ridge will also bring an end to the near normal temperatures
of the last several days. Along with the redevelopment of the
thermal trough over California and the southern Oregon coast, the
ridge will support a rise in temperatures of about 5 to 10
degrees Saturday, and another 5 to 10 degrees on Sunday. Sunday
will be the warmest day of this warm spell for areas west of the
Cascades, then Monday could be the warmest for the East Side
(although cloudiness from thunderstorms and monsoonal moisture
inflow could limit high temperatures Monday, more on that below).
The West Side valleys on Sunday will see highs in the upper 90s to
low 100s, while the highs on Monday for the East Side will peak
out around 90 to 95. Temperatures will then cool slightly heading
further into next week, but will remain above normal. The heat on
Sunday/Monday will not reach HeatRisk thresholds, but could still
pose a risk to susceptible populations and those working or
playing outdoors. Take the proper precautions to prevent heat
illness, and if seeking relief by swimming in area waterways, be
advised that river water temperatures are till cold, as the more
persistent snowpack continues to provide fresh, cold, meltwater.

As is typical with periods of heat in the region, it will come to
an end with the threat of thunderstorms. With the ridge passing
just to our east and strengthening as it moves over the Rockies, a
trough develops off the coast of California, which then attempts
to move onshore around Monday or Tuesday, taking on a negative
tilt as it does so. This is a classic pattern for convection here,
with the trough tapping into monsoonal moisture from the south,
and taking advantage of the warm surface temperatures and cooler
temperatures aloft to produce instability across the inland
portions of the forecast area.

Not much has changed in regards to the thunderstorm forecast.
Convection may begin as early as Sunday afternoon over far
southern portions of Siskiyou and Modoc counties, depending on how
far north the moisture will get by the peak heating hours of the
afternoon. Confidence on thunder Sunday afternoon is very low, and
wording has been left out of the forecast, but a non-zero chance
is there. Most likely, Sunday will be the "priming-of-the- pump"
day, with little to no convection but definite signs of increasing
moisture. As moisture continues to push north into our area, and
with some support from weak energy aloft, more widespread
convection could then begin as soon as early Monday morning (low
probability), although the most likely scenario has convective
initiation beginning Monday afternoon. I suspect that the area
will be greeted by altocumulus clouds and a feeling of "high"
humidity Monday morning, showing the arrival of the moisture and
potential instability of that afternoon.

Given the pattern, thunderstorms could form up anywhere east of
the coastal ranges Monday (although some models show showers and
stray thunder right along the southern coast Monday), with the
marine layer limiting development along the coast and perhaps into
the Umpqua Basin as well. Most convection should be concentrated
along the Klamath, Siskiyou, and Cascade mountains, as well as the
East Side, with cells then drifting off the terrain and into the
valleys. Steering flow appears weak, so storms may be slow moving,
leading to more hit- or-miss "popcorn" style convection.

Some models then continue shower and perhaps thunderstorm
activity overnight, although confidence on that is low. There is
much more confidence on thunderstorms reforming Tuesday afternoon,
although with the eastward progression of the trough, the best
dynamics and support would then be over northern California and
along and east of the Cascades. Other than location, storm
behavior and character should be very similar to Monday. Storms
could then continue on the East Side into Tuesday night, with
some models even keeping some form of convective showers over Lake
County into Wednesday afternoon.

In short, it is nearly a certain thing that there will be
lighting across the majority of the forecast area both Monday and
Tuesday afternoons. Based on current guidance, we do not expect
very strong or severe thunderstorms, but small hail and gusty
winds are possible. Also, given the high moisture content in the
atmosphere that the models are depicting, these storms will be
wet, and could produce periods of moderate to heavy rainfall. As
always with thunderstorms, lightning will be a threat, not only in
regards to new wildfire starts, but also to anyone attempting to
enjoy outdoor recreation in the area.

One caveat to this scenario will be cloud cover. With this much
moisture entering the area, and with the widespread convection
expected Monday, there may be extensive cloud cover over the area
Tuesday limiting incoming solar energy, keeping temperatures
lower, and limiting instability. This has occured with events
like this in the past, and has significantly reduced thunderstorm
development and blown the forecast on the second or third day,
and this may be another example. Keep up to date with the latest
forecasts as the details regarding this thunderstorm threat become
more clear over the next few days.

Broad cyclonic flow and lower heights then continue over the
area for the remainder of the forecast term (midweek next week).
This should keep temperatures at or just above normal, with
mostly dry conditions, although a few models are showing the
arrival of another trough late in the week, keeping showers and
thunderstorms in mind as we head into next weekend. -BPN

AVIATION...27/18Z TAFs...VFR will prevail across the area
through this afternoon, aside from a few small pockets of MVFR along
the immediate coast. MVFR/IFR conditions are likely to return with
the marine layer to the coast and the coastal valleys this evening
and tonight, but coverage should be less than this morning.
Elsewhere, VFR will continue for inland areas, with afternoon
breezes of up to 20 kt possible this afternoon, strongest east of
the Cascades. -BPN

MARINE...Updated 200 PM PDT Friday, June 27, 2025...The thermal
trough is starting to develop along the south Oregon coast and this
has resulted in increasing north winds. Winds will continue to
increase the rest of the afternoon with Small Craft conditions
likely for most of the southern waters late this afternoon into
Saturday afternoon. Winds will be strongest south of Gold Beach.

Moderate to strong winds are likely Saturday, strongest south of
Port Orford where Gales and very steep wind driven seas are likely
by late Saturday afternoon. Meanwhile, Small Craft conditions will
expand over the rest of the waters. These conditions are likely to
last into the start of next week, possibly longer. -Petrucelli

FIRE WEATHER...Updated 300 PM PDT Friday, June 27,
2025...Mostly low impact fire weather conditions are expected the
rest of this week with fairly typical diurnal (afternoon/evening)
breezes, seasonable humidity and near to above normal warmth.

A strengthening upper ridge will bring hotter weather to all but the
immediate coast this weekend with continued drying. The exception
will be the south coast where afternoon temperatures could get into
the low 80s due to an offshore flow and Chetco effect due to
offshore flow with the thermal trough positioned just off the south
Oregon coast. The thermal trough will also bring enhanced E-NE winds
at the mid slope/ridge level tonight and again Saturday night.
However, overnight recoveries tonight morning not don`t look all
that bad. Saturday overnight recoveries will be moderate, but
probably not enough to be concerned about any watches/warnings.
Temperatures increase across the interior Saturday with widespread
highs in the 90s on Sunday.

Sunday will be the hottest day, with afternoon temperatures near or
at triple digit values for the interior westside valleys.

At the same time, an upper low will form off the California coast
Sunday. At the same time, the upper ridge shifts to the Four Corners
region. This will usher in a south to southeast flow aloft from
California into southern Oregon, and will begin to tap into some
monsoonal moisture that will slide up into northern California
Sunday afternoon and evening. The most likely scenario Sunday
afternoon into Sunday night will be building cumulus over the
mountains in northern California, because there is little or no
trigger, mid level moisture is lacking and instability is marginal
at best. Worst case scenario will be a couple of isolated storms
near the Trinity Horn and points northeastward towards the Shasta
Valley late in the afternoon and early evening hours Sunday. In
summary, Sunday will be the day in which the pump is primed for
whats expected for Monday.

Monsoonal moisture will increase late Sunday night through Monday
and at the same time mid level moisture and trigger will increase.
This will set the table for resulting in thunderstorms over most of
the area inland away from the coast, with storms developing as early
as Monday morning. However, the most likely scenario is convective
showers for Monday morning. Monday afternoon and evening will be the
time period of concern with the shear number and areas affected by
thunderstorms. Steering winds Monday are expected to be light,
therefore storms that develop will be slow movers and could produce
locally heavy rain, but this is still a few days out, so the details
could change.

It`s worth noting the risk for nocturnal storms are next to, but not
zero Sunday night, with an elevated risk for lightning Monday and
Tuesday night. The main storm threat shifts to the Cascades and
points south and east Tuesday into Wednesday. As fuels continue to
dry out and the calendar shifts from June to July, fire danger will
increase. So, be on the lookout for potential Fire Weather
Watches/Red Flag Warnings as we head into next week. -Petrucelli

&&

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

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

Gale Warning from 5 PM Saturday to 5 PM PDT Monday for PZZ356-
     376.

&&

$$

MAS/BPN/MAP