121
FXUS66 KMFR 221147
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
447 AM PDT Sun Sep 22 2024

.DISCUSSION...Updated Aviation Section...

&&

.AVIATION...22/12Z TAFS...VFR conditions will prevail for most of
the area through the TAF period. The exception being some localized
LIFR conditions in fog and low clouds around the Coquille Basin,
which is affecting North Bend (KOTH). Any lower conditions that
develop will quickly improve to VFR later this morning. Afternoon
gusts of 20-25 kt are possible near the coast.
/BR-y/Hermansen

&&

.PREV DISCUSSION... /Issued 253 AM PDT Sun Sep 22 2024/

DISCUSSION...
As high pressure remains in place, warm to very warm and dry
conditions will continue through Tuesday. A thermal trough along
the coast will bring breezy to gusty northeast winds over ridges,
strongest over the Coast Range, through Tuesday morning.
Offshore, northeast winds are expected to also bring a mild
warming, Chetco Effect, to the Brookings area today and Monday,
with high temperatures likely into the 80s.

Then, mid to late week, this pattern will change as a couple weak
fronts and upper level troughs arrive. The first of these, on
Wednesday, will bring a 20-50% chance of light rain to southwest
Oregon with highest probability along the coast and lower chances
(15-25%) into Douglas County Wednesday into Wednesday night. For
areas in and around Medford, chances for light rain are lower,
around 10%. Models are showing fairly good agreement on the timing
of the front with the best chances for rain occurring Wednesday
afternoon into Wednesday evening. Additionally, with this front,
models continue to show the potential for gusty westerly winds
east of the Cascades on Wednesday afternoon/evening.

A weaker front is then forecast to arrive Thursday night into
Friday. Temperatures are expected to trend cooler on Friday and
there will be additional chances (20-40%) for light rain, mainly
along the coast and into Douglas County.

Variability in the model forecasts increase beyond Friday, with
the possibility of another upper trough and front moving into the
area late om the weekend. However, models show variability in the
track, timing and strength of this system. So confidence is low
in the details.

MARINE...Updated 200 AM Sunday, September 22, 2024...A thermal
trough and associated pressure gradient along/near the coast will
remain in place through early this week; as a result, strong
northerly winds and very steep seas are expected through at least
Monday. The steep seas will focus south of Coos Bay this morning and
eventually south of Bandon later this afternoon, with a a main
emphasis on areas south.

The thermal trough is forecast to move inland with weakening winds
and easing seas late Tuesday into Wednesday. This will result in
relatively calm seas and light wind speeds through at least Friday.

-Spilde/Hermansen

FIRE WEATHER...Issued 200 AM Sunday September 21, 2024... A
thermal trough will remain along the coast, resulting in breezy
to gusty, overnight/morning northeast winds over the coastal
ridges through Tuesday morning. A high pressure ridge will remain in
place through Tuesday, resulting in afternoon temperatures
trending warmer.

During the day Tuesday, the thermal trough will expand north,
weaken and move inland. This will result in afternoon
temperatures peaking for the interior westside valleys. Meanwhile
weak onshore flow will set up near and at the coast, resulting in
higher afternoon humidities.

There`s good agreement that an upper trough will push into the area
Wednesday along with a surface front which could bring light
precipitation to the northwest part of Fire Zone 616 and most of 615
Wednesday night. However of bigger concern will be moderate to
occasionally strong winds east of the Cascades Wednesday afternoon
into Wednesday evening. Right now, the combination of winds and
relative humidities won`t result in critical conditions, but it will
be close and there could be brief periods of time where critical
conditions could be met in portions of fire zones 625 and 285. For
now we`ll headline the winds and low RH`s and we`ll continue to
monitor the situation.

Thursday will be dry with gusty afternoon and early evening breezes
for the interior west valleys and east of the Cascades. Another
front will push into the area Friday with the best chance for
precipitation in fire zones 616 and 615. However, rainfall amounts
will likely be less than a 0.10 of an inch.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Frost Advisory until 9 AM PDT this morning for ORZ029>031.

CA...Frost Advisory until 9 AM PDT this morning for CAZ085.

PACIFIC COASTAL WATERS...Small Craft Advisory until 2 PM PDT Monday
     for PZZ350-356-370-376.

&&

$$