-- Discussion containing changed information from previous version are highlighted. --
982
FXUS66 KMFR 240544
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1044 PM PDT Sun Jun 23 2024

...Updated AVIATION discussion...

.DISCUSSION...The forecast remains on track for this evening.
Clear skies will continue over most of northern California and
southern Oregon through the night. Another marine push is expected
over Coos and western Douglas counties later this evening, but the
effects will be limited to a stratus layer moving inland. Warm,
dry, and sunny conditions continue during the day Monday.

Please see the previous discussion for more details on the short-
and long-term forecast. -TAD

&&

.AVIATION (24/06Z TAFs)...
-- Changed Discussion --
VFR conditions continue across northern
California and southern Oregon tonight. A marine push is expected to
build a stratus layer along parts of the Oregon coast early Monday
morning. Northerly winds could push these clouds into the southern
Umpqua Valley, but is not expected over Roseburg.

Other areas will remain VFR through the TAF period with elevated
afternoon winds. -TAD
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&&

.MARINE...Updated 800 PM Sunday, June 23, 2024...The thermal
trough is at a peak of strength this evening, but steep seas will
persist for much of the waters south of Cape Blanco into Monday
evening, with very steep and hazardous seas south of Pistol River.
The approach of another front then disrupts the pattern with
improving conditions Monday night into early Thursday. The front is
expected to provide a deep layer of low clouds and a slight chance
of showers Wednesday night.

A return of the thermal trough pattern is expected Thursday into at
least Friday night, with steep seas possible south of Cape Blanco.
-DW

&&

.FIRE WEATHER...Updated 200 PM Sunday, June 23, 2024...Overall, warm
(above normal) and dry conditions are forecast through next week
with only a slight break Thursday. Temperatures are likely to be
about 10+ degrees above normal for many locations through this
period. However, Thursday we get a cooler airmass, and we will be
near normal with great humidity recoveries both Thurs and Fri
morning. Fire weather conditions will unfortunately remain around
elevated to near critical until this cool down occurs.

The overlap of low RH (<20%) and breezy winds (>15mph) will be most
notable today (Red Flag for Modoc County). Conditions do improve
slightly tomorrow (Monday), but we could still see elevated fire
weather conditions across the eastside.

Fuels are of course tricky this time of year in transition to
summer, and this may be the limiting factor regarding fire weather
conditions until fuels transition over to "high". At this time,
elevated to critical fire weather conditions should be anticipated
through at least Wednesday. Even with the passage of the front, we
are only expecting a slight cool down with RH values staying on the
low side.

Another dry front approaches the area Tuesday and moves onshore
Wednesday. Currently, Tuesday looks like the driest day with
afternoon RH values dropping down to around 10% east of the
Cascades. Winds pick up again in the afternoon, but probably not
widespread critical levels. Best chances for elevated to critical
thresholds are going to be across NorCal and Oregon east of the
Cascades. As mentioned yesterday, Wednesday appears to be the day
where we get another period of stronger, gusty WSW winds in
combination with low humidity, especially east of the Cascades. For
most of the area, guidance is showing a drop in temperature and an
increase in humidity to help mitigate this threat, but areas farther
east are more susceptible. We`ll be taking a close look at this in
the next couple of shifts.

The one caveat for Wednesday is the thunderstorm potential. We will
have to watch how this upper low tracks as the moisture fetch will
be key, but right now its not the most favorable setup for thunder
with the lack of instability Wednesday (at this time). Either way,
the track is shaping up to produce breezy/gusty winds, especially
east of the Cascades.

-Guerrero

&&

.PREV DISCUSSION... /Issued 247 PM PDT Sun Jun 23 2024/

DISCUSSION...We are on the backside of a trough and onshore flow
is maintaining some cloud cover around Coos and Douglas County,
and is holding temperatures a few degrees cooler than yesterday;
which if you missed it, produced a record high temperature of 96
degrees at Mt. Shasta City. As the thermal trough builds, the
north winds will strengthen, clearing out the existing clouds and
limiting fog production along the immediate coast tonight. Further
inland across the Coquille and Umpqua river valleys, fog will be
possible tonight.

As high pressure builds in on Monday, temperatures will warm. By
Tuesday temperatures should be back into the 90s, with drier
conditions in the afternoon. This will bring some elevated fire
weather conditions, but the greater impact should be Wednesday
because another front will be moving onshore as a deeper trough
builds over the PNW.

This front will develop gusty WSW winds again east of the
Cascades on Wednesday afternoon/evening (shifting to WNW) with
breezy conditions (NW winds) for the west side. Moisture has
remained limited with the system, but another strong marine push
could induce some light rain/drizzle or mist along the coast and
mountains of Douglas County. The best precip chances are to our
north, but there remains a low probability (<20%) of showers
across northern Douglas County.

There still remains a non-zero chance for thunder because of some
high lapse rates. However, moisture remains limited, which is the
main limiting factor. Another is that the front moves through in
the morning hours of Wednesday, and so the instability is small
due to a lack of solar heating.

The cooler weather will continue on Thursday, but things should
warm up again Friday into Saturday before the next trough arrives,
probably on Sunday.
-Miles

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Monday
     for PZZ356-376.

Hazardous Seas Warning until 11 PM PDT Monday for PZZ356-376.

&&

$$