Wildfire in Oregon, October 1 to 20, 2023

Area Forecast Discussion
National Weather Service Medford OR
833 PM PDT Sat Sep 30 2023

.DISCUSSION...It was a quieter evening with the rain
concentrating in areas near and east of the Cascades. A few
showers are heading south down the Cascades this evening. Tonight,
the closed low will move eastward and bring clearing skies to
most inland locations.

The clearing will allow for cooler temperatures tomorrow morning,
and lows are forecast to return to near normal or up to 10
degrees below normal in northern Siskiyou County. After the
morning there will be a warmup for most areas with highs in the
50s east side and upper 60s west side. These warming temperatures
will be most notable east of the Cascades and in Siskiyou County.
Although tomorrow is favoring warmer temperatures, have kept the
15-25% PoP chance for far eastern Lake County tomorrow afternoon
as the low may be west enough to still bring a low chance for
rain. Please see the previous forecast for more details on the
forecast for early next week. -Hermansen

&&

.AVIATION...30/18Z TAFs...VFR conditions continue this evening.
There's some evidence pointing towards marine stratus developing
late tonight, but it's not a slam dunk. The TAF at North Bend
shows MVFR ceilings developing later tonight, but it could remain
VFR due to some of the high resolution guidance showing a light
offshore flow and drying.

The cloud cover will gradually dissipate tonight with VFR
conditions expected early this afternoon at Roseburg. However, the
higher terrain is likely to remain partly obscured until at least
0z. Tonight, VFR conditions will prevail. However, if it remains
clear, low clouds could form in Roseburg and possibly Medford
towards 15z Sunday due to ample moisture from recent rains from
Friday and Friday night.
-Petrucelli

&&

.MARINE...Updated 830 PM September 30, 2023...A thermal trough will
be in place this weekend. The thermal trough will peak in strength
today and result in moderate to strong north winds and steep to very
steep and hazardous wind driven seas through at least Sunday
morning. Small craft conditions are expected area wide with Warning
level seas expected south of Bandon. Strong north winds may approach
gales in the afternoon and evening south of Brookings this afternoon
and again on Sunday.

Conditions improve some Sunday afternoon, but conditions are likely
to remain hazardous to small craft for much of the waters into
Monday morning. A brief period of improved conditions is expected
across the waters late Monday into Tuesday as winds diminish, but
the thermal trough returns late Tuesday into Wednesday and hazardous
conditions are likely to return at that time as north winds increase
again. -Petrucelli/Sven

&&

.PREV DISCUSSION... /Issued 121 PM PDT Sat Sep 30 2023/

DISCUSSION...A deep trough over the western US has developed into
a closed low over the north-central CA/NV border. This is helping
to support some lingering showers moving southwest in northern
CA/southern Lake and Klamath counties and continuing the overcast
skies in the region. The low has also contributed enough
instability that showers are redeveloping over the south Oregon
Cascades and south OR/northern CA Siskiyou Mountains. High-
resolution models agree that showers will continue to pop up over
the mountains over this afternoon and drifting south, before
shower activity dies out as the sun sets tonight. There's a 5-10%
chance for isolated thunderstorms to develop with showers today,
increasing to around 15% at the far south borders of Siskiyou and
Modoc counties.

The upper low then moves eastwards, with skies clearing over
tonight. This will allow better radiational cooling, with chilly
overnight and morning temperatures. There also may be areas of
valley fog and low stratus where recent rains have moistened the
lower atmosphere. As the low spins, it may send a few isolated
showers through far east Lake County, but otherwise tomorrow will
see the first day in a stretch of dry weather. Meanwhile, the
axis of a ridge over the Pacific tilts eastwards into the region,
with upper level high pressure building into the area.

Clouds increase Sunday night into Monday as a weak system slides
down the east side of the ridge, bringing a 25-35% chance for
measurable rain over the north side of the forecast area (Coos, N.
Curry, Douglas, and far north Klamath and Lake counties), and a
5-15% chance for a quarter inch or more to northern Douglas and
Coos counties. Models have been trending wetter with respect to
this system for the last few days, but precipitation will most
likely be light. Following that, models agree that temperatures
will warm over the week, peaking Friday into the weekend, with dry
weather and clear skies. There are rather large model variations
following the weekend, but a general agreement that temperatures
lower into the following week. -CSP

Beach Hazards...Updated 200 PM Saturday September 30,
2023...Long period northwest swell of 5 to 10 feet at 18 seconds
will arrive Monday afternoon and evening leading to high risk of
sneaker waves. Weather conditions will be mostly clear, leading
to increased visitation on the beaches. Sneaker waves are waves
that can run up the beach much higher when compared to other
observed waves. Sneaker waves can sweep up without warning and
knock unsuspecting people over, and pull them out to sea where
shock and hypothermia can occur in the cold Pacific waters. In
addition logs and other debris can be lifted and carried by the
waters. They can crush and entrap unsuspecting victims underneath.
Never turn your back to the ocean!

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Beach Hazards Statement from Monday morning through Monday
     evening for ORZ021-022.

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT Sunday
     for PZZ350-356-370-376.

     Hazardous Seas Warning until 11 AM PDT Sunday for PZZ356-370-
     376.

&&