High Wind in Oregon, November 4 to 5, 2022

Area Forecast Discussion
National Weather Service Medford OR
414 AM PDT Fri Nov 4 2022

.DISCUSSION...Light intermittent overrunning precipitation in
advance of a warm front is moving through the area. Most of the
precipitation amounts will be along the Cascades and coastal
mountains this morning. Even then were not expecting much.

The main concern late this afternoon into tonight will be moderate
to strong winds, east of the Cascades, specifically in eastern
Klamath, most of Lake County and the Warners in eastern Modoc
County. Also of concern will be above 1500 in Douglas County, where
various guidance suggest some of the higher terrain could experience
moderate to occasionally strong winds. Also a look at the SPC HREF
10m AGL mean wind gust shows higher amounts over the higher terrain
in Douglas County. East of the Cascades, 700mb winds increase late
this afternoon, and peaking out close to 70 kts tonight, then
gradually diminishing Saturday morning. Because of the above
mentioned, the wind advisory east of the Cascades have been expanded
and a high wind warning will also be in effect for the higher
terrain east of the Cascades. In addition a wind advisory has also
been issued from 1500 and higher for Central Douglas County. Please
see NPWMFR for more info.

The main even in terms of precipitation will come late this evening
into Saturday morning. A cold front will push into the area late
tonight with moderate to heavy precipitation pushing in from the
northwest and moving southeast.  The front will move into northern
California late Saturday morning, then south of the forecast area
later Saturday afternoon. Even though were expecting an AR
(Atmospheric River) event, there's good agreement among the
operational models, ensembles and SPC convective allowing models
(CAM) suggesting we'll only have about a 5 to 7 hour period of
moderate to heavy precipitation, with precipitation diminishing and
becoming showery once the front passes through from northwest to
southeast.

Snow levels will remain high (around 8000 feet) ahead of the front
and when precipitation is expected to be heaviest. Snow levels will
lower quickly as the front passes through Saturday, but
precipitation rates will be decreasing, thus limiting the amount of
snow. Even then 2-5 inches are still possible near Crater Lake,
Diamond Lake and Willamette Pass Saturday morning due to moderate to
heavy precipitation dragging snow levels down lower than 8000 feet.

We'll catch a break in the action late Saturday afternoon into
Saturday night, then another front will push into the area Sunday.
The Sunday front could be more problematic in that we'll have a
colder air mass in place and therefore snow levels will be lower
when the heavier perception moves in. It's a good bet, the Cascades
will be dealing with moderate to heavy snow from late Sunday morning
through Sunday evening. Please see the long term discussion below
for more details on the Sunday system.

.LONG TERM...Sunday through Thursday...An active, moist and cold
pattern will continue through mid week. A strong cold front is
expected to move across the area on Sunday followed by a cold and
showery pattern Monday through Wednesday. Then there may be a break
in systems on Thursday.

The GEFS and EC ensemble continue to show a strong upper low and
frontal system moving south out of the Gulf of Alaska Saturday night
and Sunday. This front is expected to move inland on Sunday and
bring moderate precipitation along with relatively low snow levels,
around 3500 to 4500 feet. Moderate to locally heavy snowfall are
expected with this system, especially in the Southern Oregon
Cascades and in the mountains of western Siskiyou County. The SREF
is indicating a 30 to 50 percent chance for 1 inch per hour snowfall
rates in the Southern Oregon Cascades from around Lake of the Woods
north on Sunday and a 30 percent chance in the mountains of Western
Siskiyou. These heavy snowfall rates will bring a potential for
significant impacts to area passes. Additionally, moderate to
locally heavy 24 hour snowfall accumulations are forecast over the
mountains Sunday into Sunday night. If note, the National Blend of
Models continues to indicate a 50-60 percent chance of 6 inches or
more of snowfall accumulations above 4000 feet elevation in the
Southern Oregon Cascades with higher elevations above 5000 feet
potentially seeing 8 inches or more. If models continue to show the
potential for heavy snowfall rates and moderate to locally heavy
accumulations, may need to update the forecast with winter storm
watches. Also, with the lower snow levels on Sunday, light to
locally moderate snowfall accumulations are expected east of the
Cascades as well as in the foothills of the Cascades and Siskiyous.
The Scott and Shasta valleys and the Mount Shasta City area are also
expected to see light snow during this period. Additionally, gusty
winds are likely over the mountains and for areas east of the
Cascades on Sunday. These winds may reach advisory levels,
especially for exposed areas in the higher mountains and in the
Summer Lake area.

Sunday night through Wednesday, models and ensembles continue to
show a cold showery pattern setting up as the upper low gradually
moves southward just off the Oregon and northern California coast
with an upper trough over the region.  Light to moderate snow is
expected during this period with snow levels around 2000 to 3500 ft,
but locally lower at times. With these lower snow levels there is a
potential for periods of light snow down to lower passes, especially
during the nighttime and morning hours. Siskiyou County may see the
highest impacts with snow. The National Blend of Models indicates a
40% chance for moderate to locally heavy snowfall accumulations of 6
inches or more (in 24 hours) in the Mount Shasta area late Monday
into Tuesday. We will continue to monitor this and update as
confidence increases in the details of the forecast for this period.
-CC

&&

.AVIATION...04/12Z TAFs...Widespread MVFR ceilings are present
across the area this morning with higher terrain obscured in areas
of mostly light precipitation. Precipitation is steadiest over
the Cascades and could be in the form of freezing rain there
this morning. Local IFR/LIFR conditions exist in the Rogue
Valley as well. The lower conditions persist until mid-late morning
for most areas before improving some this afternoon.

However, a strong cold front will approach the area tonight. This
will result in some strong, gusty winds over the higher terrain
west of the Cascades. Low-level wind speed shear is likely
preceding the front from coastal areas into the Umpqua and perhaps
even the Rogue Valley this afternoon into tonight. Expect strong
wind gusts to surface east of the Cascades tonight. The front will
be accompanied by a period of moderate to heavy rain overnight
(heaviest near and west of the Cascades) with freezing levels up
above 7000 feet. The front will push south of the area Saturday
and rain will end from north to south with freezing levels
dropping to around 5000 feet by end of day. -Spilde

&&

.MARINE...Updated 230 AM PDT Friday 4 November 2022...
A coastal jet is setting up within about 20NM of shore this morning,
which is resulting in gusty south to southwest winds and steep to
very steep seas, highest near and north of Cape Blanco. Expect these
winds to persist this afternoon into tonight, but also to expand to
most other areas ahead of a cold front. A rather abrupt wind shift
to the north-northwest is expected overnight into Saturday morning
as the front pushes through. The front will be accompanied by a
period of moderate to heavy rainfall and reduced visibility. Winds
will ease behind the front Saturday with post-frontal showers, but
high and steep seas will continue.

Another cold front will bring gusty southwest winds Saturday
night into Sunday and another period of rain. This front will be
followed by another very high and steep northwest swell on Sunday,
which will likely produce waves of 18 to 22 feet. Wave periods
are expected to be around 14 seconds. Following that front, cold air
aloft will bring showers and a chance of thunderstorms Saturday
night into Sunday. -Spilde

&&

.BEACH HAZARDS...Updated 230 AM PDT Friday 4 November 2022...
Another very high swell event is expected by Sunday afternoon. Peak
seas of 18-22 feet at 14 seconds are expected over the coastal
waters, which would result in high surf and breaking waves in the
surf zone of 20-26 feet for all southern Oregon beaches. Therefore,
a high surf advisory has been issued. If you are planning to travel
to the beach this weekend, please observe from a safe distance and
stay clear/off the jetties. Area beaches may become hazardous due
to dangerous surf conditions. Expect the threat to continue
Sunday night, then subside on Monday. -Spilde

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning from 5 PM this afternoon to 11 AM PDT Saturday
     for ORZ030-031.

     Wind Advisory from 5 PM this afternoon to 11 AM PDT Saturday for
     ORZ030-031.

     High Surf Advisory from 10 AM Sunday to 7 AM PST Monday for
     ORZ021-022.

     Wind Advisory from 2 PM this afternoon to 11 AM PDT Saturday for
     ORZ023.

     Winter Weather Advisory until 9 AM PDT this morning for
     ORZ027>030.

CA...High Wind Warning from 5 PM this afternoon to 11 AM PDT Saturday
     for CAZ085.

     Wind Advisory from 5 PM this afternoon to 11 AM PDT Saturday for
     CAZ085.

Pacific Coastal Waters...Hazardous Seas Watch from late Saturday night through late
     Sunday night for PZZ350-356-370-376.

     Hazardous Seas Warning until 4 AM PST Sunday for PZZ350-370.

     Small Craft Advisory until 4 AM PST Sunday for PZZ356-376.

&&