Wildfire in Oregon, July 17, 2018

Area Forecast Discussion
National Weather Service Medford OR
304 PM PDT Tue Jul 17 2018

.DISCUSSION...Some cumulus buildups are are showing up over the
Siskiyous and Cascades, and are moving slowly eastward.
Thunderstorms are not expected today, as conditions aloft are
simply too dry. Multiple fires all over the west side continue to
put out smoke... a lot of smoke has been able to mix out of areas
farther from fires, but smoke continues to impact those with fire
nearby, including the Applegate and Illinois valley, and near the
Umpqua Divide.

Marine clouds and fog have been slow to clear from the coast, but
the last remnants of coastal fog will probably be gone from
Brookings within the next hour. North of Cape Blanco, expect some
more clearing today, and then a return of the marine layer
tonight. It's 100 degrees here at the Rogue Valley airport, and
conditions will likely warm a few more degrees before day's end.
East of the Cascades, temperatures have reached the low 90s, and
will continue warming over the next few hours... today will
probably be the hottest day east of the Cascades this week.

A steep thermal trough will bring strong offshore (northeasterly)
winds over the southern coast and coastal range over the next
several nights. If winds align just right, expect warm days
hitting 80 or more degrees in Brookings Wednesday and/or Thursday.
North of the Umpqua Divide, zonal flow will decrease daytime highs
a few degrees each day, likely down to the upper 80s this weekend.
Elsewhere, few places will be reaching 100 and heat risk will drop
below hazard criteria, but hot conditions with temperatures
mostly 10 to 15 degrees normal will continue with no dramatic
cooldown in sight.

This weekend, monsoon moisture will support another slight chance
of thunderstorms over Siskiyou and Modoc County.

&&

.AVIATION...For the 17/18Z TAFs...Along the coast...IFR conditions
are present, except near Port Orford. These clouds will gradually
diminish into the afternoon. North to Northwest winds will help to
send marine clouds back into the area from Cape Blanco northward
around 03Z this evening. But, developing low level will keep the
coast clear south of Cape Blanco. Elsewhere, VFR is expected with
clear skies and breezy afternoon north winds. Patchy wildfire smoke
may be dense in Josephine and Jackson Counties. -DW

&&

.MARINE...Updated 830 AM PDT Monday 16 July 2018...High pressure
offshore and a thermal trough at the coast will continue gusty
northerly winds with steep to very steep wind driven seas through
the week. They will be highest south of Cape Blanco beyond 5 nm from
shore...especially starting Wednesday afternoon with gales likely.
Near shore, winds will be lighter but seas will be affected by short
period fresh swell and this will maintain steep hazardous seas even
near shore as well. -BS/DW

&&
.Fire Weather...Updated 300 PM PDT Tuesday, July 17th, 2018...
Northwest winds will be breezy with gusts mostly in the 15 to 25 mph
range this afternoon and evening. There will be a slight cooling
trend of about 7 degrees from today through Saturday, but it will
still generally be hot and dry. This slight cooling trend will occur
gradually from northwest to southeast with time, and some areas over
the east side will probably be a little hotter Wednesday than they
are today.

Light to moderate northeast winds with moderate to locally poor RH
recoveries are expected across the west side mountains, strongest in
the coastal and near coastal mountains, each night and morning from
tonight through Friday morning. Peak gusts at the indicator RAWS are
expected to be 15 to 25 mph during the period of concern. Afternoons
and evenings will become breezy from the north and northwest through
Friday.

As early as Friday, but more likely Saturday and Sunday, there is a
possibility of thunderstorms, mainly over the southeast portions of
the area. While we have retained a mention of a slight chance of
thunderstorms for Friday, all of today's guidance since this morning
keeps the threat to our south and east Friday. Saturday the GFS and
GEFS indicate a slight chance of thunderstorm over SE portions of
the area, mainly south of the Siskiyous. The ECMWF and GEFS are
hinting that the greatest threat of thunderstorms might end up being
on Sunday, again favored over SE sections of the area. The ECMWF
pushes this threat farther north and west than does the GFS mainly
into the Cascades and western Siskiyou County.

Longer range signals for week 2 indicate that the door to potential
thunderstorms will remain open to our south and east. This is in
agreement with the CPC 8-14 day forecast, as well as climatology for
this time of the year. BTL

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Excessive Heat Warning until 11 PM PDT this evening for
     ORZ024-026.
     Heat Advisory until 11 PM PDT this evening for ORZ024-026.

CA...Excessive Heat Warning until 11 PM PDT this evening for
     CAZ080-081.

Pacific Coastal Waters...Gale Watch from Wednesday morning through Thursday evening for
     PZZ356-376.
     Small Craft Advisory until 11 AM PDT Wednesday for PZZ356-376.
     Small Craft Advisory for hazardous seas until 11 AM PDT
     Wednesday for PZZ350-356-370-376.

MSM/BTL/DW