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Area forecast discussion 
National Weather Service Medford or
246 PM PDT Sat Oct 22 2016


Short term...tonight through Tuesday night...a denser overcast of
mid to high level clouds has kept much of the area out of the sun
today, and this has resulted in a cooler day than forecast, but
not by a significant amount. However, these same clouds could also
keep the region slightly warmer tonight, should they stick around
long enough. Models do show the high clouds thinning and moving to
the northeast through this evening, but satellite imagery shows
only a hint of this upstream, so suspect that most clouds will
remain, and temperatures should not be as cool tonight as last

Tonight, the very edge of a weak and dissipating front will skirt
the coastline, with some light showers possible along the
immediate coast and into the coastal ranges, but not very far
inland. The boundary is then expected to slowly move back offshore
Sunday morning into the afternoon. This is a significant change
from the past few runs, which stalled the front over the west side
for a day or so. Now, with the model solutions trending west, the
bulk of the area should remain dry through Sunday, aside from the
aforementioned coast.

The upper level trough, up until this time Happy to meander just
offshore of British Columbia, will finally dig south Sunday
evening and overnight, reinforcing the front and pushing it
onshore Monday morning. Precipitation will spread from the coast
Monday morning, through to the Cascades by the afternoon, then
across the east side during the evening and overnight. Rainfall
amounts with this front will be typical of our usual wet season
fronts, while gusty winds will be likely at the usual trouble
spots, including along Interstate 5 near Weed in the Shasta
Valley, along Highway 31 near Paisley on the east side, and
perhaps even into the valley near Ashland. Wind advisories may be
needed for some or all of these areas.

While generally, snow levels will remain well above our higher
pass levels, there is some concern for The Mount Shasta area,
where upslope dynamics will likely force snow levels down much
further than the rest of the forecast area. The usual signals for
a heavy wet snow event in this area are marginal at best, and do
not suggest snow levels down into Mount Shasta city, they do show
a healthy mix at Black Butte Summit on Interstate 5 and a full
transition to snow at snowman's Summit along Highway 89. If snow
does make it to these levels, it should only be for a few hours at
most on Monday morning, but this could occur during the morning
commute. While confidence is not high, and snow should melt
quickly due to warm Road surfaces, travelers in The Mount Shasta
area should be ready to deal with some wintry weather along the
passes, just in case.

Showers will then linger Monday night into Tuesday, before the
next front arrives midweek. Temperatures through the week should
hover near to slightly below normal for this time of year. -Bpn

Long term...Wednesday through Saturday...a long-wave upper
trough remains between roughly 130w and 150w throughout the
extended period. A significant spoke of energy rotates around the
base of the trough and up along our coast on Wednesday. The
associated surface cyclone is expected to track south to north
along or just west of 130w. While much depends on the track of
this low, models are in really good agreement that we'll have at
least gales over our outer waters, so winds in our forecast were
raised. It is a little too far out to have enough confidence to
issue any wind headlines for it, so we'll just keep an eye on it.

From Thursday on, there has been a shift in the European model (ecmwf) which
complicates the forecast. Energy feeding into the long wave trough
is expected to form a closed low off California, but the 12z European model (ecmwf)
is now much more progressive with it. The GFS holds the low off
California with rain likely confined to our coast Thursday. The
European model (ecmwf) now moves it northeast much more quickly and would have
widespread rain for US Thursday. The Canadian has a weaker wave as
opposed to a closed low, but its rainfall pattern is much more
like the GFS. Given these complications, we've chosen not make an
major changes from Thursday on. Any solution is likely wet for the
coast, but solutions vary from wet to dry inland. We've kept pops
at or above climo with the highest at the coast. -Wright


Aviation...22/18z taf cycle...VFR conditions will continue through
this evening for most areas. Areas of fog and stratus with IFR
cigs/vis in the Umpqua basin this morning will gradually lift to
VFR by this afternoon. Stratus is possible at the coast and Umpqua
again tonight, but an incoming front may prevent it, so confidence
was not high enough to include in the koth/rbg tafs. -Wright

Note: the ceilometer at FAA site koth is out of service, so there
will be no ceiling observations available generally between the
hours of 04z and 14z.


Marine...updated 230 PM PDT Saturday, October 22, 2016...small
craft conditions continue overnight until the morning as a cold
front moving through the waters increases southerly winds. Another
front moves into the region increasing south winds again Sunday,
possibly to gales. With the pressure gradient aligned from southeast
to northwest the strongest winds will be mostly in the outer waters
until the tail end of the front moves in early Sunday morning.
Southerly winds near gale strength may continue through Tuesday. The
high southerly wind wave combine with an increasing short period
westerly swell to bring high and very chaotic seas in the waters
Tuesday. -Sven


there has been good consistency in the long range guidance in
indicating normal to above normal temperatures across the forecast
area through the end of this month, when averaged over week long
intervals. Additionally, this guidance has also been consistent, of
late, in indicating near to above normal precipitation over the
forecast area for the upcoming month of November. Temperatures look
as if they will be on the cooler side of climatology this week, and
then generally near to slightly above climatological averages for the
remainder of October into November when averaged over week long
intervals. Weak La Nina conditions in the equatorial Pacific and a
very negative Indian Ocean dipole are likely contributing to these
expected conditions. The net result is expected to be a continued
good start to the water year and the higher Elevation Mountain
snowpack (above about 6kft), and removal of the last vestiges of
drought designation in our forecast area. Btl


Mfr watches/warnings/advisories...


Pacific coastal waters...gale watch from Sunday evening through Monday morning for
Small Craft Advisory until 5 am PDT Sunday for
Small Craft Advisory for hazardous seas until 5 am PDT Sunday
for pzz350-356-370-376.



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