High Wind in Oregon, January 12 to 13, 2020

Area Forecast Discussion
National Weather Service Medford OR
837 AM PST Sun Jan 12 2020

.UPDATE...A cold front lies just offshore this morning, and will
make its way through the area today, producing plenty more rain
and snow before exiting the region this evening. Snow levels
should spend much of the day between 3000 and 3500 feet, but will
lower this evening to below 2000 feet as showers continue
overnight. By day break, snow levels should drop to around 1000
feet, bringing snow down to many of the West Side valley floors.
However, showers will be tapering off at the same time, so snow
amounts should be very light. Main forecast efforts today will
focus on the chance for low elevation snow Monday morning, and
for the more significant chances of low elevation snow Tuesday.

Numerous Winter Weather headlines remain in effect across the
forecast area, and can be found at PDXWSWMFR. For more
details and information on the rest of the forecast, see the
previous discussion below. -BPN

&&

.AVIATION...For the 12/12Z TAF Cycle....Scattered showers will
continue to produce MVFR conditions along the coast. Inland, at KRBG
the scattered showers are likely to produce on again/off again MVFR
conditions. Elsewhere, VFR is likely to be the prevailing flight
category through the morning, with intermittent MVFR returning
around noon. Expect, areas of terrain obscuration and mixed MVFR/IFR
vsbys/cigs through Sunday morning, especially along the Cascades.
Low level southwest winds will be strong and gusty from late Sunday
morning into Sunday evening, strongest from the Cascades eastward.
This will create wind shear concerns at KLMT and KMFR for speed and
direction. Freezing levels will be near 3,500-4,000 ft msl into
Sunday afternoon. Freezing levels will then fall to around 2000
ft msl by early Monday morning. -miles

&&

.MARINE...Updated 830 AM PST Sunday 12 Jan 2020...A series of
strong fronts will continue to bring high to very high and steep to
very steep seas through the week.

Very high seas will continue into Monday morning. Winds will
diminish below advisory level Tuesday, but seas will remain steep
and hazardous to small craft during this time.

The strongest of the fronts looks to be Wednesday into Wednesday
night with storm force winds and very heavy seas possible.

More fronts will follow through the remainder of the week with
periods of gale force winds possible. -Stockton

&&

.PREV DISCUSSION... /Issued 342 AM PST Sun Jan 12 2020/

DISCUSSION... Another round of precipitation will start this
morning and continue into the day with snow levels around 3000
feet. Over the next 24 hours, we're looking at around 12 to 18
inches over the high Cascades near Crater Lake and Diamond Lake.
Elevations down to 3000 feet along the western slopes of the
Cascades will see around 8 to 12 inches of snow. The snow
accumulating today will result in significant impacts for people
traveling through the Cascades. It's also key to point out that
western facing slopes will see more rain and snow accumulation
than north, south, or east facing slopes. So areas like Mt
Ashland and Siskiyou Summit will see roughly 3 to 5 inches of snow
over the next 24 hours instead of the larger amounts listed
above.

Looking at Sunday night into Monday morning, we'll have another
one of these breaks in the action as we'll be between weather systems.
The exception to that statement above might be the Cascades as
models keep the precipitation ongoing. The flow will remain
westerly Sunday night, so it makes sense that some rain and snow
keeps on falling along the Cascades. However, the majority of the
air should be sinking, so the accumulation shouldn't be major. The
other topic worth mentioning is that snow levels will be down to
the valley floors. The forecast currently calls for trace amounts
of snow to a few tenths over the low elevations and low I-5
passes.

The next system will arrive late Monday morning around noon.
Warmer air will push in and circulate around this low. As a
result, snow levels will rise to 3500 feet during the afternoon
hours of Monday. Again, the Cascades will take the main brunt of
this Monday system with 12 to 18 inches of snow accumulating from
10 am Monday until 10 am Tuesday. Snow levels will then crash down
to around 1000 feet Monday night. Just like Monday night we're
calling for between a trace to up to 1 inch in the valleys and
around 2 inches over the low I-5 passes. It's also looking like
more showers, so snow accumulation will be hit and miss.

The last thing we wanted to mention is that model guidance shows a
significant low forming off the coast around Wednesday through
Thursday. Snow levels are expected to be around 2500 to 3000 feet
in northern California. With strong south winds up the Sacramento
Valley, Mt Shasta City and the surrounding area will probably see
6 to 12 inches of snow over 12 hours. Because of this, we had
enough confidence to issue a winter storm watch Wednesday night
into Thursday for areas around Mt Shasta City.

-Smith

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 10 AM PST Tuesday for ORZ029-030.
     Winter Storm Warning until 10 AM PST Tuesday for ORZ027-028-030.
     Winter Weather Advisory until 10 AM PST Tuesday for ORZ031.
     Winter Weather Advisory from 4 AM Monday to 10 AM PST Tuesday
     above 2000 feet in the for ORZ023>026.
     Winter Storm Warning from 4 AM Monday to 10 AM PST Tuesday above
     2500 feet in the for ORZ024.
     Winter Storm Warning until 10 AM PST Tuesday above 3000 feet in
     the for ORZ025-026.
     Winter Weather Advisory from 4 AM Monday to 10 AM PST Tuesday
     for ORZ028.

CA...Winter Weather Advisory until 10 AM PST Tuesday for CAZ085.
     Winter Weather Advisory until 10 AM PST Tuesday above 3500 feet
     in the for CAZ080.
     Winter Weather Advisory from 4 AM Monday to 10 AM PST Tuesday
     for CAZ082-083.
     Winter Storm Watch from Wednesday afternoon through Thursday
     morning above 3000 feet in the for CAZ082-083.

Pacific Coastal Waters...Hazardous Seas Warning until 10 AM PST Tuesday for
     PZZ350-356-370-376.