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FXUS66 KMFR 241118
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
318 AM PST Wed Jan 24 2018

.DISCUSSION...The frontal system is approaching the coastline,
but its forward progression has slowed. Latest guidance shows the
front taking its time arriving at the coast, now expected around
mid-morning. Models also indicate a secondary front and wind
surge arriving late morning or early afternoon, and this is really
what forces the whole mess inland. Until then, it will remain
windy over the waters, coast, Shasta Valley, and portions of the
east side. This slowing many delay the onset of precipitation
inland, but not to enough of a degree to be worth meddling with
the forecast. All current headlines seem to be on track and remain
in effect.

A second front will push in on Thursday, really dropping snow
levels and producing another round of precipitation. This should
produce advisory level snow down to around 2500 feet, but light
snowfall is expected down to around 1500 feet. Snow never really
stops falling between the two systems, so in Northern California,
the winter weather headlines were extended out to cover Thursday.
In others, such as for the western slopes of the Cascades and the
Cascades themselves, an Advisory has been issued to cover the
likelihood of several inches of additional snow during the day
Thursday.

Showers are expected to continue into Friday as the upper trough
moves east of the area and moist onshore flow continues. Snow
levels Thursday night into Friday are expected to be around 1500
to 2500 feet and the best area for showers will be along the coast
and inland across Douglas and Josephine counties and into the
Cascades.

The active pattern will continue through early next week.
Considering the run to run changes in the models, and somewhat
inconsistent trends, forecast confidence is not high, but has
improved. A low will drift into the marine waters Friday evening,
pushing a warm front through the Medford CWA, bringing a
substantial round of precipitation during the day Saturday, along
with some gusty south or southwest winds in the usual areas: the
coast, the Shasta Valley, and the East Side. Warm air advection
will cause rising snow levels throughout the day. Expect snow
levels around 2500 to 3000 feet when precipitation begins Friday
night, then snow levels will reach 6000 to 6500 feet Saturday
night. Another stream of moisture with subtropical origins will
impact the Pacific Northwest Sunday into Monday. Right now, it
looks like most impacts will be felt in northern Oregon and
southern Washington, so kept PoPs as mostly chance in southern
Oregon/ northern Cal, but this feature will need to be monitored.
If the track shifts south, there could be river flooding
concerns.

&&

.AVIATION...24/12Z TAF CYCLE...A slow moving cold front will finally
move inland early this morning. MVFR cigs and mountain obscuration
will be widespread. Conditions could lower to IFR at times in heavy
rain and mountain snow...mainly from the coast to the Cascades.
Freezing levels will fall from around 6000 feet msl early this
morning to around 2500 to 3000 feet tonight. Strong winds aloft will
lead to LLWS concerns through around 16Z for terminals west of the
Cascades, including along the coast, at KRBG and KMFR. Strong winds
will briefly diminish at the coast this morning but will continue
east of the Cascades through this afternoon. -DW

&&

.MARINE...Updated 300 AM PST Wednesday 24 Jan 2018...A hazardous
seas warning is in effect through Thursday night. The main change to
the forecast was to upgrade the portion of the hazardous seas
warning that is roughly north of Gold Beach and beyond 8 nm from
shore to a gale warning from late tonight into Thursday morning. The
other change was to shorten the duration of the hazardous seas
warning with a slight improvement to advisory conditions during
Friday.

First, south gales with a cold front early this morning will be
strongest south of Cape Blanco. Winds then very briefly diminish but
will begin to increase again before noon. Gales will accompany the
next front late tonight into Thursday morning. There is also a
slight chance of thunderstorms this afternoon through Thursday
afternoon. Very steep seas will build tonight through Thursday and
become very high. Another couple of very strong fronts are expected
Friday night into Saturday and on Saturday night with gales possible
and seas reaching a new peak. -DW

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning until 10 PM PST this evening for ORZ030-031.
Winter Weather Advisory until 10 PM PST this evening for
ORZ029-030.
Winter Weather Advisory from 7 AM to 10 PM PST Thursday for
ORZ027>030.
Wind Advisory until 10 PM PST this evening for ORZ030-031.
Winter Storm Warning until 10 PM PST this evening for
ORZ029-030.
Winter Storm Warning until 10 PM PST this evening above 5000
feet in the for ORZ027-028.
Winter Weather Advisory from 7 AM to 10 PM PST Thursday
above 2500 feet in the for ORZ023-025-026.

CA...High Wind Warning until 10 PM PST this evening for CAZ085.
Wind Advisory until 10 PM PST this evening for CAZ085.
Winter Weather Advisory until 10 PM PST Thursday below 3500 feet
in the for CAZ082.
Winter Storm Warning until 10 PM PST Thursday above 3500 feet in
the for CAZ082.
Winter Storm Warning until 10 PM PST Thursday for CAZ080.
High Wind Warning until 1 PM PST this afternoon for CAZ081.
Winter Weather Advisory until 10 PM PST Thursday for CAZ083.
Winter Storm Warning until 10 PM PST Thursday for CAZ083.

Pacific Coastal Waters...Gale Warning until 4 AM PST early this morning for
PZZ350-356-370-376.
Gale Warning from 11 PM this evening to 8 AM PST Thursday for
PZZ350-356-370-376.
Hazardous Seas Warning until 4 AM PST Friday for
PZZ350-356-370-376.

$$

BPN/DW/TRW/MSC
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