High Wind in California, March 12, 2022

Area Forecast Discussion
National Weather Service Medford OR
833 AM PST Sat Mar 12 2022

Added BEACH HAZARDS Section

.DISCUSSION...Some adjustments were made to the forecast for
today. The main changes were to fine tune the timing and location
of precipitation based in part on the high res guidance and HPC
HREF radar reflectivity suite of products. The latest visible
image shows clear skies over most of the area, with cloud cover at
the moment confined to the coast, offshore, Coquille Basin and
southern Curry County. This won't last long as we'll see cloud
cover increase pretty quickly from west to east later this morning
through this afternoon, especially west of the Cascades.

The low center is taking shape further offshore and will rapidly
deepen during the day and bottom out early this evening, before
the surface low begins to gradually weaken as it moves towards the
Washington/Oregon coast by tomorrow morning. Winds are already
increasing in the Shasta Valley with Weed reporting wind gust to
39 mph, and Onion Mountain had wind gusts to 47 mph.

For details on the rest of the forecast starting tonight, please
see previous discussion below. -Petrucelli

&&

.AVIATION...12/12Z TAFs...Over the coastal waters and along the
coast...Widespread IFR cigs/vsbys with higher terrain obscured will
improve to MVFR cigs with areas of IFR cigs later Saturday morning
as rain develops ahead of a front. Higher terrain will remain
obscured. Strong south winds will develop as well. The lower
conditions will persist through Saturday night, but the rain will
turn to showers this evening with isolated thunderstorms. Low level
wind shear will be a concern at KOTH until the front moves inland
late Saturday afternoon. Winds will become southwest behind the
front and will slowly diminish Saturday night.

Over the remainder of the west side west of the Cascades...VFR
conditions will prevail initially, but areas of MVFR cigs in low
clouds and rain will develop Saturday afternoon with higher terrain
becoming obscured. The lower conditions will persist through
Saturday night, but the rain will change to showers. Low level wind
shear will be a concern at KRBG through tonight. There will be
relatively low shear at KMFR as well.

From the Cascades east...VFR conditions will prevail initially.
Areas of IFR cigs/vsbys with higher terrain obscured in low
clouds and rain/snow will develop late Saturday afternoon into
Saturday evening. Strong south winds will develop Saturday
afternoon. The lower conditions will persist through Saturday
night, but the rain/snow will change to snow showers. Winds will
diminish Saturday night.

&&

.MARINE...Updated 815 AM PST Saturday 12 March 2022...Gales
and very steep, hazardous seas are expect passes through the region
Saturday. Expect steep to very steep and hazardous seas with gales
by late Saturday morning across all areas. Winds will ease some,
especially south of Cape Arago, but gales will continue north of
Cape Arago Saturday night into Sunday morning. During this time, a
heavy long period swell will build into the waters with seas peaking
around 20 to 25 ft at 13 to 16 seconds early Sunday morning. Seas
will gradually ease Sunday evening, but conditions will likely
remain hazardous to small craft well into next week as seas remain
elevated around 10 to 13 ft.

Another front is expected Monday afternoon into Monday night, and
this will bring another round of moderate to strong southerly winds.
In addition, guidance indicates another long period heavy northwest
swell (12-14 ft at 15-18 seconds) arriving Monday evening. The
pattern will remain active through much of next week.

&&

.BEACH HAZARDS...With the incoming swell of 20-25 feet at 13-16
seconds, we expect dangerous surf conditions along all of the
southern Oregon coast beginning tonight and continuing through
Sunday. Breaker heights in the surf zone will be 22-27 feet and this
could result in beach inundation. Beachgoers should avoid climbing
on rocks and jetties and remain out of the water to avoid dangerous
conditions. Peak swell will coincide with high tide Sunday morning,
which is roughly between 8 and 10 am PDT. -Spilde

&&

.PREV DISCUSSION... /Issued 338 AM PST Sat Mar 12 2022/

DISCUSSION...Satellite imagery is showing clear skies across most
of southern Oregon and northern California. Some coastal and
offshore stratus are being observed with fog reducing visibilities
to a half mile in some locations in coastal Curry County.
Offshore, a cloud shield associated with the next system is
steadily approaching the Pacific Northwest. This system will begin
a change toward a more active pattern.

The first thing to note with this system is that the time line
has sped up by a few hours. This means that impacts may be felt a
bit earlier than what was discussed by previous shifts. Starting
with the winds, our High Wind Warning begins at the Coast at 10 AM
with a wind advisory beginning in the Shasta Valley at the same
time. On the East Side, our wind products begin at 1 PM. These are
likely when winds will begin increasing in those specific areas,
peaking a few hours later. In addition, some blowing dust will be
possible in the Summer Lake area before the precipitation begins.
The area affected by this includes Highway 31 and areas to the
northeast. This could reduce visibilities in these areas, so
please use extra caution if you are traveling in areas with gusty
winds. Please see the NPWMFR for more details. Last detail to note
is that the Rogue Valley may see periods of breezy to gusty winds
as well--albeit below advisory criteria. The caveat with this is
that these winds would be coming from the southwest, which is
rather unusual for this area. Normally our winds come from the
southeast down the Siskiyous or even occasionally from the east
down the Cascades.

The second thing to mention is the onset of precipitation and in
particular, snow levels. Snow levels will largely hover between
4500 and 5500 feet today. High resolution ensemble guidance like
the HREF show an intriguing pattern in precipitation today--
especially the HRRR. The 00Z run of the HRRR shows 3 distinct
bands of precipitation forming over the area as the front passes
through, focusing precipitation along the Cascades and areas west.
Other HREF members show a couple of bands of precipitation, but
are more diffuse with a more traditional stratiform signature. Our
evening shift was super busy and diligent and interpreted these
sorts of signatures to create periods of moderate to locally heavy
snow over the Cascades above 5000 feet. Thus, a winter weather
advisory was issued for the southern Oregon Cascades north of
Highway 140, including Crater Lake, Diamond Lake, and Willamette
Pass. The big thing to note here is that should these bands
materialize as such, a couple of periods during the advisory
timeframe could produce snowfall rates of an inch an hour. Overall
snow totals from 6 to 10 inches remain possible with some Cascade
locations seeing up to 12 inches of snow. Please see the WSWMFR
for more details.

The other big change to the forecast was to introduce
thunderstorms to the forecast for the coastal waters, coast, and
portions of the coast range. The Calibrated SREF shows a 5 to 10
percent chance over these areas with the NBM showing 15 to 20
percent. Therefore, a slight chance for thunderstorms is
reasonable, especially with the aforementioned bands being hinted
at in the HREF. Overall, expect isolated lighting periods of
moderate to heavy rainfall, and maybe some small hail on top of
the already gusty winds in these areas. Overall precipitation
amounts are modest with this system, and the precipitation will
overall be beneficial in nature. Storm total precipitation
amounts of 1 to 2 inches are possible in the coastal mountains
with an in at the coast. The aforementioned strong southwest winds
could evaporate some of the moisture as it passes into the Rogue
Valley, so expect valley amounts to be considerably less.

Then, expect precipitation to become more showery and focused in
the Cascades and Coast range as the precipitation comes to an end
and a brief break occurs Sunday afternoon. -Schaaf

Previous Long Term Discussion (Written: 3/11/2022 for Monday 3/14
through Friday 3/18)...The axis of a short wave upper ridge will
be just east of the Cascades early on Monday morning. Meanwhile, a
deep upper trough in the Gulf of Alaska will send a more robust
Pacific front (at least in terms of moisture) toward the West
Coast. Models are in excellent agreement that this front will
bring beneficial rainfall to the area. Mountain snowfall though
will be somewhat limited (2-5" above 5000 feet) due to an expected
surge in snow level to around 8000 feet Monday night. Most areas
sneak out a dry day Monday, especially east of the Cascades, but
rainfall will arrive at the coast Monday, spread inland to the
Cascades Monday evening, and then east of the Cascades late Monday
night. Preliminary rain amounts of 1-3 inches appear likely along
the coast, with the best orographics producing the highest
amounts in the Curry coast ranges. We're expecting 0.75-1.25
inches of liquid precipitation for western Siskiyou County
northeastward up into the Cascades. As usual, west side valleys
will get some rain-shadowing, but with expected totals in the
0.25-0.75 of an inch range, this should be one of the better rain-
producing fronts we've seen since the calendar changed to 2022.
East side areas will generally have 0.10-0.25 of an inch, though a
little less in eastern Lake County, and a little more closer to
the Cascades (north of Klamath Falls). In terms of wind, this
system just doesn't look that dynamic at this time. Models do show
peak 700 mb winds in the 45-55 kt range, so we could envision
some advisory-type headlines for that, but the probability of
warning-level headlines are currently less than 5%. Snow levels
will eventually fall back to near or just below 5000 feet in post-
frontal showers on Tuesday.

The vast majority of the area will have another break in
precipitation beneath another short wave ridge Tuesday night through
Wednesday night. There is still a small chance (<20%) of showers in
N&W sections of the area during this period.

A weak system could skirt the area on Thursday with a chance of
showers (20-50%), but this system appears to be in a weak split flow
and, in many of these cases, one piece ends up to our north and the
other to our south (we end up with nothing). The high PoP forecast
for this time period is currently 50% along the coast, so it's
equally as likely not to rain there as it is.

Beyond that, however, model guidance is showing increasing
odds for another robust frontal system to reach our coast late
Friday or Friday night, then move onshore Saturday. At this range,
we won't speculate too much and opt for a blend of the models in the
official forecast, but this one looks quite similar to Monday
night's front. -Spilde

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning until 7 PM PST this evening for ORZ021-022.
     High Surf Advisory from 1 AM PST to 5 PM PDT Sunday for
     ORZ021-022.
     High Wind Warning from 1 PM PST this afternoon to 2 PM PDT
     Sunday for ORZ030-031.
     Wind Advisory from 1 PM PST this afternoon to 2 PM PDT Sunday
     for ORZ030-031.
     Winter Weather Advisory from 4 PM PST this afternoon to 11 AM
     PDT Sunday above 5000 feet in the for ORZ027-028.

CA...High Wind Warning from 1 PM PST this afternoon to 2 PM PDT
     Sunday for CAZ085.
     Wind Advisory from 1 PM PST this afternoon to 2 PM PDT Sunday
     for CAZ085.
     Wind Advisory until 10 PM PST this evening for CAZ081.

Pacific Coastal Waters...
     Small Craft Advisory until 10 AM PST this morning for
     PZZ350-356-370-376.
     Gale Warning until 10 PM PST this evening for PZZ356-376.
     Hazardous Seas Warning from 10 PM PST this evening to 5 PM PDT
     Sunday for PZZ350-356-370-376.
     Gale Warning until 8 AM PDT Sunday for PZZ350-370.