Wildfire in Oregon, September 1 to 9, 2020

Area Forecast Discussion
National Weather Service Medford OR
845 PM PDT Mon Aug 31 2020

.UPDATE...Changes to cloud cover and Wx grids along the coast.

&&

.DISCUSSION...Changed the cloud cover and weather grids to account
for a slight timing change of a southerly stratus surge along the
coast. The surge is now expected in Brookings early Tuesday night,
expanding up the coast at least to Cape Blanco before morning.
This surge will create foggy conditions along the coast and marine
waters during the overnight and early morning hours. It is likely
marine stratus envelops most of the inner marine waters by late
Wednesday morning, where it will struggle to break up. This marine
stratus is then expected again overnight for the next few days.

Otherwise, the forecast remains on track and with at least a week
of triple digits high temperatures for west side valleys, with
poor overnight cooling. This has prompted a heat advisory, that is
likely to be continued into the weekend. It will be the duration
of this heat wave that poses the most significant harm.
-Miles

&&

.AVIATION...For the 01/00Z TAFs...Over the coastal waters and along
the coast...VFR conditions will prevail initially, then areas of IFR
cigs/vsbys will develop, mostly along the coast north of Cape Blanco
and the adjacent coastal waters.  The lower areas will clear to VFR
over the land areas by late Tuesday morning.  Nearshore winds will
become southerly south of Brookings Tuesday morning, spreading north
through the day. These south winds will allow IFR cigs/vsbys to
migrate northward along the coast through the day, covering the
nearshore waters and immediate coast as far north as Cape Arago
Tuesday night.

Inland areas from the Cascades west and Siskiyous north...VFR
conditions will prevail through Tuesday night. It will be breezy
through this evening.

East of the Cascades and south of the Siskiyous...VFR conditions
will prevail through Tuesday night, except for local MVFR vsbys
in wildfire smoke.

&&

.MARINE...Updated 845 PM PDT Monday 31 August 2020....A thermal
trough will remain in place along the coast through tonight,
producing gusty north winds and steep to very steep seas across the
region. The very steep seas and gale conditions are expected
generally from Nesika Beach southward and beyond 4NM from shore;
small craft conditions are expected elsewhere. The thermal trough
will shift and move inland late tonight into Tuesday. Conditions
will be slow to improve as gusty northerly winds gradually lower and
northwest swell arriving Wednesday maintains steep seas until at
least Thursday morning. -Schaaf/Keene/Rogers

&&

.FIRE WEATHER...Updated 800 PM PDT Monday 31 August 2020...Low
humidities and gusty winds will continue along the coastal range in
fire weather zones 618 and 619 tonight. Compared to Sunday night,
humidity recoveries will be higher, so no Red Flag Warning is
necessary.

Conditions will change quickly Tuesday as high pressure builds over
the region. Humidities will trend lower and temperatures will trend
higher Tuesday through the rest of the week. This extended period of
hot weather will likely continue into next week. As the hot air and
high pressure settle in, recoveries will gradually worsen,
eventually becoming moderate in the valleys and poor over the ridges.

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory from 2 PM Tuesday to 11 PM PDT Thursday for
     ORZ023>026.

CA...Heat Advisory from 2 PM Wednesday to 11 PM PDT Thursday for
     CAZ080-081.

Pacific Coastal Waters...Small Craft Advisory until 5 AM PDT Thursday for
     PZZ350-356-370-376.
     Gale Warning until 11 AM PDT Tuesday for PZZ356-376.