Wildfire in California, September 1 to 18, 2016

Area Forecast Discussion
National Weather Service Medford OR
929 PM PDT WED AUG 31 2016

.DISCUSSION...Evening update. Low clouds are butting up against the
Cascades with the marine push at this time. This is exactly in line
with the current forecast and will not update at this time. Sven

.PREVIOUS DISCUSSION...An upper level low pressure system off the
coast of British Columbia will gradually move southeast toward
northern Washington by Friday morning. This system will provide
cooler weather the rest of this week through Labor Day weekend with
high temperatures averaging about 5-10 degrees below normal. After a
couple of fronts move onshore...one tonight, then another Thursday
night into Friday...we may be looking at temperatures down close to
freezing over the east side each morning Saturday through Monday
with the potential for frost/freeze headlines.

The first frontal system is pushing onshore this afternoon and
will gradually move to the Cascades this evening before
dissipating overnight. Isolated to scattered showers are occurring
along the coast with just a few hundredths reported in coastal
Douglas, Coos and Curry Counties. Showers will edge eastward this
evening, but we'll see these diminish as they reach the Cascades
and Siskiyous. We're not expecting much, if anything here in the
Rogue Valley, but some of the surrounding foothills may have a
few raindrops.

Expect a break late tonight into Thursday, then another
disturbance will move onshore Thursday night into Friday morning.
Once again, the main forcing for precipitation stays to the north
of the area. Even so, cooling aloft should generate isolated to
scattered showers again along the coast into the Umpqua Basin and
the Cascades from Crater Lake north. Slight chance POPs also exist
down to about the Siskiyous, but we're not expecting any
precipitation south and east of the mountains.

The upper low will push into southern Alberta Friday night into
Saturday morning with the trough axis pushing east of the
Cascades. A chilly air mass for this time of year will move in and
with clearing skies, expect temperatures to fall down to near
freezing over portions of the east side, including Klamath Falls,
Lakeview and Alturas.

Short wave energy on the back side of the trough will dig
southeastward through Washington and into Oregon Saturday night
into Sunday morning. The air mass is pretty dry, so we're not
expecting any precipitation - just a reinforcement of the cool air
mass. This should continue the frost/freeze risk over the east
side through at least Monday morning.

Expect a gradual moderating trend with temperatures getting back
closer to normal by Tue-Wed of next week. Rain chances still
appear minimal at this time. -Spilde

&&

.AVIATION...01/00Z TAF CYCLE...VFR cigs are currently at the
coast as a front moves inland. This will not last long with marine
stratus expected to develop with IFR and local LIFR cigs returning
between 3-5z. Onshore flow is expected to be stronger tonight,
therefore expect stratus to form and move into the Umpqua Basin,
including Roseburg with MVFR cigs possible towards 12z. Elsewhere,
VFR conditions will continue through the TAF period. However, areas
of smoke from the Gap Fire near Seiad Valley in northern California
will be a concern for the Klamath and Shasta Valleys. The smoke is
expected to be thickest and most problematic on the California side
of the Siskiyous eastward into the Shasta Valley through the period.
However, it could still be enough to cause at least a temporary
reduction in visibility in the Rogue Valley, including at KMFR.
-Petrucelli

&&

.MARINE...Updated 200 PM PDT Wednesday, 31 August 2016...A weak front
will move onshore later this afternoon. Weak high pressure will
build in tonight into Thursday morning. Another front will move into
the waters late Thursday afternoon followed by another one Friday.
Winds will remain light through at least Friday. The models are in
good agreement showing a thermal trough developing this weekend with
north winds and seas increasing. Small craft conditions are possible
south of Cape Blanco Saturday afternoon. -Petrucelli

&&

.FIRE WEATHER...Updated 255 PM PDT Wednesday, 31 August 2016...
Gusty southwest winds will be near critical levels in the Modoc and
southern portions of Fremont-Winema National Forest this evening,
and, again, Thursday afternoon and evening. Today criteria will
likely be met for an hour or two at a couple of locations in FWZ285,
short of the required duration. There's likely to be a little more
wind Thursday afternoon and evening, but RHs will be up about 5% as
compared to today.

A weak front will continue to push from the coast to the Cascades
this afternoon through tonight bringing light precipitation to the
coastal counties, areas along and near the Umpqua Divide, and
possibly in the Oregon Cascades and Siskiyous. Amounts will be up to
a few hundredths of an inch. The marine layer will cover much of the
west side Thursday morning, as well as portions of the east side and
northern California as RHs recover to 80-100% at most locations.

Significant smoke will continue in and near the Klamath River
Canyon, worst from Happy Camp east to interstate 5, though it will
also likely affect the Shasta Valley significantly, at times.

Cool conditions persist through the weekend into early next week.
Thursday night and Friday some rain is expected across the northern
portions of the area, and some areas could see amounts around 0.10".
BTL

&&

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

CA...None.

Pacific Coastal Waters...None.

MAS/BTL/MAP