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fxus66 kmfr 241719 

Area forecast discussion
National Weather Service Medford or
919 am PST Fri Nov 24 2017

an update has been made and sent to refine sky coverage and fog
coverage/wording for this morning through tonight. Btl


the tail end of a cold front is sliding west to east through Modoc
County this morning with some light rain and snow showers. Snow
levels there are around 7kft. We do expect the rest of today
to be dry for all areas except for these morning showers over
parts of Modoc County.

To the north and west, behind the front, temperatures cooled
enough overnight to freeze what snow remains on the ground above
about 5kft. Meanwhile, mostly clear skies and mostly below
freezing low temperatures exist east of the Cascades in Oregon,
while a mix of low clouds, fog, and clear skies exist west of the

For the remainder of today we'll see some high cloudiness stream
in from the southwest, and some upslope cumulus under southwest
flow in The Mount Shasta, Medicine Lake, Klamath and Sprague
River basin areas this afternoon. West of the Cascades, in
addition to the higher clouds streaming in, expect fog and low
clouds will take until mid-afternoon to mix out of the lower
Klamath River valley, Illinois Valley, and Umpqua basin of Douglas

We'll be working on refining the forecast for the incoming strong
frontal system due in Saturday through Sunday. We expect winds to
be the primary concern, with some higher elevation snowfall as a
secondary Point of note that may be Worth headlining. Btl


Aviation...24/12z taf cycle...from the Cascades
west...mixing with lingering showers are prevent widespread fog and
low stratus from developing this morning, but as we reach sunrise
this activity may subside enough to allow some minor development. By
late morning VFR conditions will prevail through the night. -Sven


Marine...updated 330 am PST Friday 24 Nov 2017...weak high
pressure building into the area will bring calmer conditions to the
coastal waters today into tonight. A strong front will bring
strengthening south winds Saturday, with gales and very steep seas
possible late Saturday afternoon through Saturday night. There is
increasing confidence that gales will impact most the waters beyond
5 nm from shore as well as within 5 nm near Cape Blanco. Very steep
seas are possible across all areas during this period. Seas will
remain high and steep to very steep on Sunday. High and steep seas
will continue into early next week. On Wednesday, a high long period
west swell is expected to build into the waters. Seas on Wednesday
may build into the 15-20 foot range. /Cc


Previous discussion... /issued 450 am PST Fri Nov 24 2017/

Discussion...showers are slowly dissipating this morning with the
heaviest action in northern California, mostly from Mt Shasta
eastward. However, showers, although light continue over the west
side. With this mixing, fog and low stratus are not nearly as
abundant as expected this morning, but should increase a bit near
sunrise as the showers continue to taper off and low level mixing
decreasing. The zonal flow pattern will transition to a weak ridge
which will bring a break in the wet pattern today into tonight.
With the cooler air mass over the region the high temperature
today will not be as warm as the past several days.

The weak upper level ridge shifts east Sunday ahead of the next
system that moves in on an approaching deepening upper level
trough. After a warm front moves through Saturday morning winds
increase aloft and the pressure gradient from Redding to Medford
increases. Models continue to show 700 mb winds increasing to over
70 kt east of the Cascades, but the timing of each model run
slips the timing of this farther back with these stronger winds
now not being shown until Saturday evening, or 06z. With this
shifting in the models will leave the watch up for the day shift.
This front will bring heavy, but brief, rain to the south coastal
range and then eastward through the day Sunday as it sweeps
eastward. Snow levels drop behind the front to Cascade Pass
levels, but the bulk of the front will have moved through and snow
amounts should not be high at the passes.

Models are in good agreement with the upper low now sweeping into
the California coast midway between the Bay area and Cape
Mendocino Monday morning, shifting the bulk of the precip south
of the forecast area as it moves to the southeast during the day
Monday. -Sven


Mfr watches/warnings/advisories...
or...high wind watch from Saturday afternoon through Sunday afternoon
for orz030-031.

California...high wind watch from Saturday afternoon through Sunday afternoon
for caz085.
High wind watch from Saturday afternoon through Sunday afternoon
for caz081.

Pacific coastal waters...
- gale watch from Saturday afternoon through late Saturday night for
- Hazardous seas watch from Saturday afternoon through Sunday

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