NWS Medford, OR wrote its last area forecast discussion before the first event at Aug 31, 7:30 PM PST, 4 hours 30 minutes earlier.
Area forecast discussion, Aug 31, 7:30 PM PST, 4 hours 30 minutes before
Area Forecast Discussion
National Weather Service Medford OR
830 PM PDT Wed Aug 31 2022
.DISCUSSION...01/00Z NAM in.
Extensive marine stratus over the coastal waters and along the
coast is now moving into the coastal valleys. Clear skies prevail
over the remainder of the Medford forecast area, although there is
considerable smoke emanating from the Rum Creek Fire in Josephine
County and the 2022 SRF Lightning Complex in Trinity and Humboldt
counties.
Strong high pressure over the Great Basin will persist through
next Wednesday. So, the next week is going to be hot and dry, but
the degree of hotness and dryness will vary from day to day. It
will also be windy on some days.
The primary driver for these variations will be short waves rotating
out of an offshore long wave trough that will also remain in place
over the next week. No such waves will be coming in Thursday, which
looks to be the hottest day of the week.
The next short wave will move onshore Friday night, and this will
bring in a dry cold front Friday with a marine push for cooler
temperatures for the west side and windy conditions on the ridges
and east side. Red Flag conditions will likely develop again
Friday. The cooling trend will continue into Saturday, but winds
will be lighter that day.
Regarding temperatures for the remainder of this week, expect inland
high temperatures across the board to be around 10-15 degrees above
normal with overnight lows hovering between 5 to 10 degrees above
normal. Despite these values, record challenging temperatures are
not expected as the core of the heat looks to be to our south and
east. A look at heat risk indicies suggests some moderate impacts
to those who are sensitive to these hot temperatures, but not
enough risk to the majority of the population to warrant any heat
related headlines at this time. The other wildcard regarding
temperatures is smoke, which if thick enough, can significantly
limit solar heating.
The distribution and thickness of the smoke is a difficult
forecast because it is dependent on factors at least partially
independent of the weather, such as the initiation, spread, and
intensity of fires, as well as smoke generated by firefighting
activities.
That being said, the short wave and the winds associated with
them on Friday may improve conditions in some locations Friday
into Saturday, but those same winds may stoke the fires and
increase activity, thus producing more smoke.
The typical diurnal winds for this time of year favors bringing
smoke from the Rum Creek Fire into the Illinois, Applegate and
Rogue Valleys. An Air Quality Advisory, issued by the Oregon
Department of Environmental Quality, remains in effect and covers
Jackson, Josephine, and Curry counties through at least Thursday.
See PDXAQAMFR for details. The latest smoke forecast, issued by
the U.S. Interagency Wildland Fire Air Quality Response Program,
can be found online at outlooks.airfire.org/outlook. Smoke will
generally be at its worst in the late night into morning hours due
to stable conditions and lighter winds.
Beyond Saturday, there looks to be little in the way of day to day
changes Sunday through Tuesday, although Tuesday looks to be a
bit hotter than Sunday/Monday at this time. Hot and dry conditions
will continue with breezy conditions in the afternoons and
evenings, especially east of the Cascades. Inland high
temperatures will be 5 to 10 degrees above normal, with far
eastern and southeastern areas experiencing high temperatures up
to 15 degrees above normal.
The medium range ensembles indicate that the ridge may break down
next Wednesday. If this happens we will get at least a few days
of cooler weather, but don't write off summer just yet
&&
.AVIATION...01/00Z TAFs...Along the coast, LIFR conditions
will persist into the evening and overnight hours.
Inland areas west of the Cascades will see MVFR to IFR visibilities
with mountain obscurations due to smoke for this evening.
The Rum Creek Fire and Six Rivers Lightning Complex are pretty
active at this time and are putting out a lot of smoke. Fire
activity has decreased in the overnight hours and we would expect
that to hold tonight. So visibilities might improve at some
terminals by 12z or so.
VFR conditions are likely for most locations by tomorrow morning
except for along the coast as marine stratus will still linger.
We're expecting that low stratus to clear up by Thursday afternoon.
-Smith
&&
.MARINE...Updated 830 PM PDT Wednesday 31 August 2022...Fog will
generate some lower visibilities over sections of the coast tonight.
Other than fog, light winds and seas will prevail through Friday.
A thermal trough will develop near the coast on Saturday with gusty
north winds and areas of steep seas developing south of Cape Blanco.
Smith
&&
.FIRE WEATHER...Updated 800 PM PDT Wednesday 31 August 2022...Inland
temperatures will remain hot through the weekend, and Thursday will
be the hottest day over inland areas. The wildcard regarding high
temperatures will be the smoke. If enough smoke fills the valleys,
temperatures may not reach forecast values. Dry conditions will
increase with this warm up, and the day with the lowest humidities
in the region will be Thursday, with RHs < 10% across Northern
California and the east side, and low teens in the valleys of
Jackson and Josephine County.
Haines indices of 5 to 6 are forecast over most of southern Oregon
and northern California through Friday. This could lead to plume
dominated fires.
A dry cold front will move onshore Friday. It will bring in a marine
push behind it, and thus higher humidities and improved recoveries
west of the Cascades. Temperatures will decrease a few degrees,
mostly on the west side. However, it will remain hot and dry east of
the Cascades and over northern California.
The main concern Friday will be strong winds in most of Siskiyou
county, the southern Cascades, and all of the east side in the
afternoon and evening, combined with continuing very low relative
humidities. To top it off, a Haines Index of 6 is forecast for
much of the area Friday. The combination of these factors will
result in Red Flag conditions over most of the east side and
northern California. A Fire Weather Watch is currently in effect.
See PDXRFWMFR for details.
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from Friday morning through Friday evening
for ORZ623>625.
Red Flag Warning until 8 PM PDT this evening for ORZ624.
CA...Fire Weather Watch from Friday morning through Friday evening
for CAZ280>282-284-285.
Red Flag Warning until 8 PM PDT this evening for CAZ284-285.
Pacific Coastal Waters...None.
&&
15/15/11