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fxus66 kmfr 202159 

Area forecast discussion
National Weather Service Medford or
259 PM PDT sun Aug 20 2017

Discussion...current visible satellite, air quality, and in
person observations are showing that the smoke from nearby
wildfire has settled across the west side valleys. There is some
smoke across a few of the east side valleys, mainly Klamath Falls
as well as for portions of Siskiyou County. Unfortunately, it does
not appear that there will be much reprieve from the smoke as the
afternoon progresses. The smoke at kmfr is so dense that it has
reduced visibility to one and a half to one and three quarter
miles, which is comparable to when we had the Stouts creek fire
in 2015. Short term smoke models suggest that overnight smoke may
mix out somewhat, but overall thoughts is that air quality will
still have some effects from the smoke.

For the eclipse tomorrow morning, we are expecting mostly clear
skies everywhere except for the coast from Cape Blanco northward
and a few miles inland into the Umpqua basin. This is similar as
to what occurred this morning, but winds will be less over that
area, and this could prolong the cloud dissipation for the
eclipse. Elsewhere, despite cloud-free skies, viewers will be
watching the eclipse through smoke. The exception to this is going
to be in Lake County, say areas like Summer Lake, Lakeview,
paisely and eastward. These areas will have the best chance for an
unobstructed view for the partial eclipse.

The other effect that the smoke will have is that it will prevent
heating throughout the day as sunlight is absorbed and reflected
by the smoke. Have lowered the temperature forecast for tomorrow
to accommodate this effect. Although temperatures should be
somewhat warmer tomorrow than they are today.

Instability will increase on Tuesday while increased moisture
rotates northwestward into northern California and south central
Oregon. A lower but still significant probability of thunderstorms
will extend to the southern Oregon Cascades and Siskiyou
Mountains. Confidence on this will continue to be low,
particularly for areas where there is significant smoke as the
reduced heating for the day could prevent thunderstorms from

A significant probability of thunderstorms will also exist on
Wednesday. But, the pattern will change from Tuesday as a broad
low approaches British Columbia. This will shift the steering flow
to southwesterly but the main risk will once again be from the
Siskiyous and Cascades southward and eastward.

A cold frontal passage associated with the trough will bring a
slight chance of light drizzle or showers to the Douglas and Coos
County coast late Wednesday night into Thursday morning. The front
will bring gusty afternoon winds to the east side, but also the
coolest high temperature readings of the week.

There is increased model agreement toward ridging developing over
the West Coast late in the week into the weekend with a warming
and drying trend. Have continued with a blend of the GFS and
European model (ecmwf). -Schaaf/weygand


Aviation...20/18z taf cycle...gusty north to northeast winds
will continue in the coastal mountains through this evening with a
persistent thermal trough. Skies are expected to remain clear for
the remainder of the afternoon and early evening. The biggest
concern now is the smoke reducing visibilities off shore and in
the valleys. Look for smoke and haze to really obstruct visibility
near the Brookings area from the Chetco Bar fire. As for the
Rogue Valley and taf site mfr, we'll see visibilities improve from
MVFR/IFR to VFR during the late afternoon and evening as northwest
valley wind picks up. -Bunnag/Smith


Marine...updated 230 PM PDT Sunday 20 August 2017...high
pressure offshore and a thermal trough along the coast will
generate moderate to strong north winds and very steep seas
through this evening. Conditions will at least be hazardous to
small craft over all of the forecast area, and warning level
winds/seas will occur beyond 5 nm from shore from Gold Beach
south. Winds and seas will be highest this afternoon and evening,
easing during the overnight and early morning hours. The thermal
trough will weaken beginning Monday, and winds will diminish but
seas are expected to remain steep through the middle of the week
due to short period swells. Have extended the warnings and
advisories to account for this. -Bunnag/schaaf


Mfr watches/warnings/advisories... flag warning until 11 PM PDT this evening for orz618-619.


Pacific coastal waters...Small Craft Advisory until 5 PM PDT Monday for
Gale Warning until 11 PM PDT this evening for pzz356.
Hazardous seas warning from 11 PM this evening to 5 PM PDT
Monday for pzz356-376.
Gale Warning until 2 am PDT Monday for pzz376.

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