140
FXUS66 KMFR 240530
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1030 PM PDT Mon Jun 23 2025

...Updated AVIATION discussion for 06Z TAFs...

.DISCUSSION...Weak ridging overhead has brought mostly clear
skies and warmer temperatures to the area today. A weak trough,
illustrated by extensive clouds offshore, will dig into the area
this evening and tonight, with little effect other than providing
support for a decent marine layer push overnight and into the
morning. We do expect stratus and fog to push into the coast and
the coastal valleys by sunrise tomorrow morning, and some clouds
could make it all the way to Roseburg. Much like today, any marine
layer cloudiness will quickly burn back offshore through the
morning.

Temperatures on Tuesday will warm by about 5 degrees over those
of today, then we will begin to cool off a bit through the rest
of the work week as weak, but broad troughing sets up over the
region. While the forecast will remain dry, for the most part, and
temperatures are expected to stay around normal for this time of
year, daily marine layer pushes will continue at the coast and
coastal valleys, and at times may push into the Umpqua Basin, or
even portions of the Rogue and Illinois valleys. The strongest
push will likely be Wednesday and/or Thursday morning, due to the
overhead trough allowing for a thicker marine layer that would
more easily pass over some of the area mountains.

The trough axis will pass overhead Wednesday afternoon, and some
models, namely the NAM, are suggesting the possibility of
convection in the Mount Shasta/Medicine Lake area. It does not
appear that atmospheric moisture will be sufficient enough for any
significant convective development, and the NAM is known to
overdue it in situations like this. We will keep an eye on it
nonetheless, just in case, but most likely, we will only see
cumulus fields develop across the area in the afternoon.

Near normal temperatures and dry conditions then continue for the
remainder of the workweek as broad troughing remains in the area,
and we should see daily marine pushes along the coast. Heading
into the weekend, ridging finally begins to nudge into the region,
and the thermal trough is expected to redevelop along our southern
coast. As a result, temperatures will see a quick warm up through
Saturday and Sunday and into early next week, with highs rising
about 10 to 15 degrees above normal for late June.

Ensemble suites are starting to show a potentially interesting
pattern developing early next week. With the ridge passing just
to our east and strengthening as it moves over the Rockies, a
trough develops off the coast of California, which then attempts
to move onshore around Monday, and according to some models, takes
on a negative tilt as it does so. This would allow the area to tap
into monsoonal moisture from the south, and is a prime pattern
for thunderstorms in our forecast area. Have left mention of rain
or thunderstorms out of the forecast for now, mainly due to being
a week out and with low confidence, but will reassess the
situation over the next few forecast cycles.

Lastly, it is worth noting that while outside of the typical
forecast period of concern, the majority of ensemble members
across all suites are showing another deep trough somewhere over
the West Coast middle/late next week (including Independence Day),
in a pattern similar to the cool and showery pattern we
experienced here over the last few days. -BPN

&&

.AVIATION...24/06Z TAFs...Satellite imagery shows marine stratus
building over the Pacific. Onshore flow should bring IFR or LIFR
levels to North Bend tonight or early Tuesday morning. This layer
looks to stay in place for most of the TAF period, with brief
periods of clearing possible Tuesday afternoon or evening as coastal
winds increase.

For inland areas, VFR levels are expected through the TAF period
with only diurnal wind changes to consider. -TAD

&&

.MARINE...Updated 430 PM Monday, June 23, 2025...A thermal trough is
bringing gusty north winds, building steep seas south of Cape Blanco
through Tuesday morning. Winds and seas are expected to improve
Tuesday afternoon and remain below advisory through the middle of
the week. A thermal trough could develop near the end of the week
and persist into the weekend, bringing steep wind-driven seas to all
areas over the weekend.  -Hermansen/TAD

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT Tuesday
     for PZZ356-376.

&&

$$