High Wind in Oregon, February 26, 2021

Area Forecast Discussion
National Weather Service Medford OR
259 AM PST Fri Feb 26 2021

.DISCUSSION...Satellite imagery show the next system to impact our
area start moving southward . The clouds are generally banking up
against the western sides northern Oregon Cascades (and
evaporating on the eastern sides), and this feature is sliding
southward. Beyond that, some lower clouds are banking up against
terrain in southern Oregon and in Modoc County. Meanwhile, Radar
does not show any real precipitation of note reaching the ground
in our forecast area. That is expected to change later this
morning, however. Snow levels will start around 2500 feet and will
rise to around 3000 feet today.

The main snow impacts will be above 3000 feet, with the period of
heaviest snow occurring between 7 AM and noon with moderate snow
occurring after that. A winter weather advisory continues for
portions of the Cascades from Highway 140 at Lake of the Woods
northward through Crater Lake, Diamond Lake, and Willamette Pass
(including the resort). This is largely since the precipitation is
coming in from the west that the Cascades will be hit the hardest.
For terrain that is already east-west (Siskiyous, Marble
Mountains, Umpqua Divide), there will be some snow, but the
accumulations will be less since the orographic (terrain-induced)
lift will be on the far western slope. Please see the WSWMFR for
more details.

In addition, winds from the west will be increasing throughout the
day, largely focusing in areas of exposed terrain in north-south
mountain chains like the Cascades tunneling through east- west
oriented valleys, or in areas without a lot of terrain influence,
like a large majority of the East Side. As a result, a wind
advisory and high wind warning remain in effect for most of the
East Side (the Cascades will put the wind in the winter weather
advisory as necessary). Please see the NPWMFR for more details.

This pattern will continue throughout the day Friday before
dissipating Saturday morning. The area will remain between the
influences of the low pressure system to the east and a high
pressure system to the west with flow from the north possibly
bringing an additional weak system into the area Sunday night into
Monday. Ensemble guidance suggests that this system will stall
somewhere in Oregon, with operational runs keeping the system to
the north with the National Blend of Models being more
progressive. Am inclined to believe more of the ensemble guidance
at this point, which is reflected in the forecast. That being
said, the guidance suggests that this system will not be strong
as typical winter storms, and snow levels will be around 3500
feet falling to around 1500 feet as the system breaks up and
things become more showery in nature Monday night into Tuesday
morning.

Mid-week should remain dry, under the influence of high pressure,
with the possibility of fog and stratus returning, but the
influence of the sun angle being early March means that we are
transitioning out of fog/stratus season...meaning that anything
that developed would be short-lived in the mornings.

The next system could arrive in our area as early as Thursday but
it could be prolonged into late next weekend. It appears as if the
system will be a frontal boundary, with a quick shot of moisture.
Models, however, are varied on the details of this system. This
includes the timing, strength, and flow pattern. Therefore, will
go with the National Blend of Models which appears to be hedging
its bets by spreading the precipitation chances over several days
for now. Expect this to be cleaned up in subsequent runs when the
ensemble guidance starts getting a better handle of the
probabilities of situations occurring. -Schaaf

&&

.AVIATION...For the 26/12Z TAF Cycle...From the Cascades west...VFR
conditions will prevail initially, but an incoming front will bring
areas of MVFR cigs in low clouds and rain later this morning with
higher terrain becoming obscured. There will be some improvement
later this morning and this afternoon behind the front with showers,
but areas of MVFR cigs will return this evening in low clouds and
showers, persisting into Saturday morning.

East of the Cascades...VFR conditions will prevail through Saturday
morning, but there will be some obscuration of higher terrain. There
will also be strong winds through Friday evening.

Low level wind shear will be a concern at all TAF locations ahead of
and with the front through early this afternoon.

&&

.MARINE...Updated 200 AM PST Friday 26 Feb 2021...Steep swell
dominated seas will become very high and very steep Friday as a
front moves through the waters. The heaviest swell will move into
the waters Friday morning and remain near a peak into late
afternoon. Seas will peak at 16 to 19 feet at 16 to 17 seconds.
This will result in hazardous seas and dangerous bar crossings.
High surf between 20 and 25 feet will be a concern on Friday as
well. A High Surf Advisory remains in effect. See CFWMFR for
details.

Seas will gradually diminish but remain high and steep Friday night
into Saturday night, due to a combination of a moderate northwest
swell and choppy seas due to northwest winds. On Saturday, winds
will shift from northwest to north with speeds diminishing over much
of the waters, though remaining gusty and at advisory strength into
the evening south of Gold Beach. This will be due to high pressure
building offshore and a thermal trough developing along the south
Oregon coast. See MWWMFR for details.

North winds will gradually lower Saturday night with diminishing
seas expected into Monday morning as the offshore high weakens and a
low approaches the offshore waters. This low will likely bring
increasing winds Monday night into Tuesday, but its intensity and
trajectory are uncertain at this time.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Surf Advisory until 4 PM PST this afternoon for ORZ021-022.
     High Wind Warning from 7 AM this morning to 7 PM PST this
     evening for ORZ030-031.
     Wind Advisory until 4 AM PST Saturday for ORZ030-031.
     Winter Weather Advisory until 4 AM PST Saturday for ORZ027-028.

CA...High Wind Warning from 7 AM this morning to 7 PM PST this
     evening for CAZ085.
     Wind Advisory until 4 AM PST Saturday for CAZ085.

Pacific Coastal Waters...Small Craft Advisory until 2 AM PST Sunday for
     PZZ350-356-370-376.
     Hazardous Seas Warning until 4 PM PST this afternoon for
     PZZ350-356-370-376.