High Wind in Oregon, February 7 to 8, 2020

Area Forecast Discussion
National Weather Service Medford OR
218 PM PST Fri Feb 7 2020

.SHORT TERM...Today through Tuesday morning...Onshore flow along the
coast is maintaining some broken stratus there and into the Umpqua
Basin. Low clouds remain entrenched in the Rogue Valley, but are
slowly eroding from all directions so am still expecting to see at
least some peaks of sunshine within the next hour or two. Elsewhere,
skies are cloud free and temperatures have climbed into the lower to
mid 50s.

Cloudy skies will make a swift return this evening and overnight as
a cold front and associated upper level trough move through the
area. Overall, this system won't be too impactful. Precipitation
will generally be focused west of the Cascades and north of the
OR/CA border. There will generally be less than a tenth of an inch
for the valleys west of the Cascades with between a quarter to half
an inch for the higher terrain and coastal areas. Initially, snow
levels will be around 5000 ft but will lower down to around 2500-
3000 ft overnight into Saturday after the bulk of the precipitation
moves through. Snow amounts look to be around 2 to 5 inches for the
Cascades, mainly from Crater Lake northward. The more noticeable
aspect of this front will be the much cooler temperatures expected
Saturday where high temperatures will be around 10 to 15 degrees
cooler than today's highs.

Once this trough moves south of the area, upper level ridging will
nudge back in. The orientation of the ridge and departing trough
aloft combined with a thermal trough at the surface will put the
area under deep north to northeasterly flow. This will lead to some
breezy winds across the area Sunday afternoon, especially for the
Coastal Range of Curry county and the higher terrain in western
Siskiyou county where winds could gust in the 20 to 30 mph range.
Given the breezy north-northeasterly flow, it's not unreasonable for
a Chetco Effect to develop Sunday into Monday and relatively warm
temperatures (mid 60s) are possible for the Curry Coast. This
pattern will linger into the extended with the flow aloft becoming
more northerly. Low level flow will remain northeast to easterly
with a thermal trough in place, and mild temperatures will continue
for the area Monday under clear skies. /BR-y

.LONG TERM...Tue 11 Feb through Fri 14 Feb 2020.

The EC and GFS both depict an omega block in place over the eastern
Pacific at the beginning of the extended period.  The high will be
near 40N 135W and the eastern anchor low will be over southern
California. The Medford CWA will be under north to northeast flow
aloft, which usually translates to easterly low level flow.

The EC and the GFS solutions have converged somewhat since
yesterday. Both models are now breaking down the block during the
course of the extended by moving short waves over the top of it.
These short waves then support a digging long wave trough over the
intermountain states.

During most of the extended, the flow aloft over the Medford CWA
remains north to northwest, with most of the short wave energy
directed to the north and east of the CWA.  This supports a mostly
dry forecast over the CWA, the exception being the north coast,
Umpqua Basin, and the adjacent Cascades on Tuesday, which may see
some light precipitation. Wednesday will be dry everywhere.

This changes Thursday, when the strongest of the short waves pushes
onshore and brings a stronger front with it. This will bring more
widespread precipitation to the area at that time. Amounts will
still be on the light side.

Once that trough pushes through, ridging quickly returns Thursday
night into Friday and the area will start to dry out again.

&&

.AVIATION...For the 07/18Z TAF Cycle...Along the coast, LIFR and IFR
conditions will prevail into the afternoon with slight improvement
to MVFR in the afternoon with showers becoming likely. IFR is
expected to return overnight. For southern Oregon west of the
Cascades, mainly MVFR will persist through the next 24 hours with
periods of clearing in the afternoon, then increasing clouds and
showers developing in the evening. MVFR/IFR with showers and
widespread terrain obscuration is expected tonight. In northern
California and east of the Cascades, VFR is expected through the TAF
period, with the exception of western Siskiyou County, where valley
MVFR and showers are possible tonight. -BPN

&&

.MARINE...Updated 200 PM PST Friday 7 Feb 2020...Conditions will
be relatively calm through today. A cold front will push through the
waters tonight, then gusty north winds will develop behind the front
with building northwest swell, creating steep to very steep seas
through Saturday night. As swell diminishes Sunday, a thermal trough
will form near the coast, resulting in continued north winds and
steep to very steep and hazardous seas through the first half of
next week. Gales are possible south of Cape Blanco during this time,
but models are trending a bit weaker, so winds may stay just e blow
gale force. Winds and seas will diminish toward the end of the week,
but gusty north winds will persist south of Cape Blanco. -BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...None.

CA...None.

Pacific Coastal Waters...Small Craft Advisory from 1 AM Saturday to 4 PM PST Sunday for
     PZZ356-376.
     Hazardous Seas Warning from 4 PM Saturday to 4 PM PST Sunday for
     PZZ356-376.
     Small Craft Advisory from 1 AM to 4 PM PST Saturday for
     PZZ350-370.
     Hazardous Seas Warning from 1 AM Saturday to 4 PM PST Sunday for
     PZZ350-370.

MNF/JRS/BPN