918
FXUS66 KMFR 230401
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
901 PM PDT Sat Jun 22 2024

.DISCUSSION...The forecast does not require any changes this
evening. A weak dry front will push marine moisture inland
tonight, bringing slight (10-20%) chances of drizzly precipitation
over Coos and Douglas counties. Temperatures on Sunday will cool
by 5 to 10 degrees west of the Cascades and by 5 degrees or less
to the east.

Please see the previous discussion for more details about the
short- and long-term forecast. -TAD


&&

.AVIATION (23/00Z TAFs)...Overnight, LIFR/IFR conditions along the
coast, will surge into the Coquille and Umpqua valleys, generally
lifting to IFR 06Z with the arrival of a weak front. This may also
produce drizzle/light showers near shore into early Sunday morning.

Conditions in the Umpqua Basin are expected to be MVFR, including
beginning around 08Z at Roseburg (KRBG). The marine layer will not
be deep enough to broadly spill over the Rogue-Umpqua Divide, but
there could be some scattered clouds that develop over the Illinois
and Applegate Valleys around sunrise Sunday morning.

The coastal and Umpqua stratus will gradually dissipate after
sunrise, with VFR likely to develop across the area by 19Z.

Elsewhere, conditions will remain VFR with gusty afternoon westerly
winds expected to resemble those from Saturday.

/DW


&&

.MARINE...Updated 800 PM Saturday, June 22, 2024...A weak front will
bring a surge of stratus tonight into Sunday with light showers
possible across the northern waters. The thermal trough will
restrengthen Sunday, bringing increasing north winds and steepening
seas. Steep seas are expected for much of the waters south of Cape
Blanco, with very steep and hazardous seas developing south of
Pistol River by Sunday evening. These conditions will persist
through Monday evening before the approach of another front disrupts
the pattern into mid-week. The outlook is for a return of the
thermal trough pattern late in the week.

/BR-y/DW

&&

.FIRE WEATHER...Updated 200 PM Saturday, June 22, 2024...East of the
Cascades, brief durations of both critical wind & humidity are
possibly today through Monday. Modoc County in particular will reach
critical RH/wind tomorrow for more than 50% of the county, and after
talking with fuels experts, we felt it was necessary to issue a
warning for areas where fuels are more receptive, albeit perhaps
still on the moderate side.

Critical fire weather conditions are not expected for areas on the
westside. This will be thanks to good overnight recoveries (80% and
higher) in valleys and moderate to good humidity recoveries over
upper slopes and ridges (50-70%) overnight. Afternoon humidities in
these areas will bottom out in in the 20 percent range with typical
afternoon breezy conditions.

No lightning is expected over the forecast area through at least
Tuesday.

Looking ahead, Wednesday in particular could bring elevated to
critical fire weather conditions as a strong low pressure system
moves into the area. The threat of strong winds associated with this
system has our attention. Stay tuned as this is Day 5 so changes
could occur. Specifically, if the system trends farther south, we
may have stronger wind speeds and a chance for thunderstorms.

-Guerrero


&&

.PREV DISCUSSION... /Issued 251 PM PDT Sat Jun 22 2024/

DISCUSSION...A decline in temperatures is expected Sunday and
Monday as front moves across the region, most notably west of the
Cascades. This won`t be before we have one last hot day, today. Mt.
Shasta City is already within three degrees of the previous record
max temperature today of 96 degrees (1992), is on track to at least
tie it, and there is a 40% chance the temperature rises above this
record. Some cumulus is beginning to pop along and east of the
Cascades as well, but we are not expecting any of these to become
rain producers.

The rain production, or more likely drizzle, production will be
possible tonight into Sunday morning as moisture gets pooled along
the front, and wrung out through topographic lifting into the Coast
range and Cascade Foothills in Douglas County. The more noticeable
impact from this front will be a strong marine push and the stratus
that will accompany it. There is a high chance that this stratus
fills the coastal valleys, but there remains uncertainty if the
clouds will push into the central Umpqua Basin because of the
existing dry air. Winds will also be amplified today about 4-8 mph
faster than normal, but still from the typical afternoon direction.
Sunday, winds will peak behind this front east of the Cascades and
this will drive gusts of 25 to 35 mph. This could have implications
for fire weather, and is covered in the fire weather discussion
below.

Transient high pressure will build over the region Monday and
Tuesday. That said, the heat risk will remain low, with overnight
low temperatures remaining below 60 degrees.

The next trough is expected on Wednesday and will need some close
monitoring because the mid-level and upper-level jet appear stacked
in many model solutions, and could bring some elevated wind speeds
to the area Wednesday and Thursday. This trough also has some strong
instability and lift associated with it and I would not totally rule
out this having some low end thunderstorm potential. While most of
these impacts will fall into the realm of fire weather, it could
create less than favorable conditions for anyone working or
recreating out in the mountains.

After this trough, the cycle of 2-3 days of high pressure and heat,
followed by another trough looks to repeat.

-Miles

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...CA...Red Flag Warning from noon to 8 PM PDT Sunday for CAZ285.

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

Hazardous Seas Warning from 5 PM Sunday to 11 PM PDT Monday for
     PZZ356-376.

&&

$$