469
FXUS66 KMFR 080538
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1038 PM PDT Sat Jun 7 2025

.DISCUSSION...Updated Aviation section...

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.AVIATION...07/06Z TAFs...The marine stratus is bringing IFR/LIFR
ceilings to the coast, and visibility is forecast to reach these
levels between 11-13Z. Northerly winds are starting to weaken
tonight at the coast, and these will pick up along with other
locations inland tomorrow afternoon. Inland areas will remain under
VFR levels.

Tomorrow afternoon will bring chances for showers and isolated
thunderstorms to Siskiyou and Modoc County. PWATs are nearing 0.75"-
1.00" tomorrow afternoon, but forecast soundings keep dry air in the
lower levels. That means that although heavy downpours are possible,
they will be isolated if they can combat the dry air.
-TAD/Hermansen

&&

.PREV DISCUSSION... /Issued 908 PM PDT Sat Jun 7 2025/

DISCUSSION...The heat was felt inland this afternoon with highs
reaching the mid-/upper 90s for more west side valley locations.
Roseburg tied the record high of 96 from 2016 this afternoon, and
after help from electronic technicians, our official observation
for Medford was set at 98 degrees. As there is a 75% probability
for Roseburg to reach 98 degrees the next few afternoons, the high
temperature has been increased for tomorrow in the Umpqua Basin.
This puts more areas in the Umpqua Basin under a moderate heat
risk for tomorrow afternoon, and it will continue through Monday
afternoon. With this in mind, the Umpqua Basin has been added to
the Heat Advisory that starts tomorrow at 11 AM for the Rogue and
Illinois Valleys. Find the rest of the details in NPWMFR.
Reviewing high temperatures for the coast, the marine stratus once
again withheld warmer temperatures there. Edits have been made to
cool that area down the next two afternoons.

The chance for thunder was also analyzed, and minor adjustments were
made to increase the coverage in surrounding locations as newer
model data has come in. This is still on track for the thunderstorm
risk to focus on Northern California tomorrow afternoon and expand
to more locations near and east of the Cascades Monday afternoon. -
Hermansen

MARINE...Updated 830 PM Saturday, June 7, 2025...Gusty north winds
will decrease tonight into Sunday morning, with steep seas lingering
for the remainder of the evening.

Far north of our area, a broad area of gusty winds will build north-
northwest fresh swell that will move into the area through the day
Sunday. Swell-aided steep seas are forecast for all waters by Sunday
evening, and will continue through the day Monday. Gusty northerly
winds will build across area waters on Monday as well, with the
highest speeds south of Cape Blanco. Areas of very steep and
hazardous seas are possible on Tuesday especially south of Cape
Blanco as a thermal trough returns. Gusty north winds then continue
through the rest of the week with very steep seas possible south of
Cape Blanco.-TAD/DW

PREV DISCUSSION... /Issued 220 PM PDT Sat Jun 7 2025/

DISCUSSION...Satellite image shows marine stratus along the coast
with the exception for areas just south of Cape Blanco to Port
Orford. Elsewhere it`s clear with the exception for developing
cumulus over the higher terrain at Mount Shasta and areas east to
northeast of Mount Shasta. The expectation is for more cumulus
development to occur over the higher terrain in northern Cal, the
Siskiyous and southern Cascades during the course of the afternoon
into early this evening.

Temperatures for the interior are between 3-5 degrees higher
compared to this time yesterday as of this writing and we are likely
to have hot afternoon temperatures for the next few days (today-
Monday). Triple digit values are likely for the interior westside
valleys the next few days (including today), with warmer overnight
lows. Because of this, a Heat Advisory remains in effect. Please see
NPWMFR for more details.

It will be dry most of the time and for most locations into early
next week. However there`s some evidence suggesting mid level
moisture creeping into northern California as a weak upper low
creeps closer to the area Sunday. Instability parameters are
marginal and there could be enough of a trigger for isolated
thunderstorms to pop up Sunday afternoon and lasting into Sunday
evening for portions of norther Cal, southern Cascades and portions
of the eastside. Although current data suggest instability will be
most favorable in western Siskiyou County.

Any storms should fizzle out later Sunday evening with dry weather
Sunday night into Monday morning.

It will be slightly more unstable Monday along with increasing mid
level moisture that could set the table for isolated thunderstorms
Monday afternoon into Monday evening. The rigger is weak, but given
the amount of instability, it won`t take much of a trigger to get
storms to develop. The best chance for storms are expected to be in
portions of Siskiyou county which could also result in some
precipitation due to higher water content in the column of the
atmosphere.

Of the three days (Sunday, Monday and Tuesday afternoon and early
evening). Tuesday is the one of most concern in terms of
thunderstorms. A stronger upper trough will approach from the west
and there`s good agreement the upper trough axis will still be
just offshore late Tuesday afternoon. This will put the area in a
favorable position for isolated to scattered thunderstorms along
and east of the Cascades and northern Cal, with the instability
parameters greatest in Western Siskiyou County. Given the position
of the upper trough axis and stronger trigger ahead of it could
bring a heighten threat for isolated strong to severe storms. The
one element that could put a cap on the amount of storms Tuesday
will be the amount of cloud cover from Monday night into Tuesday
morning. Keep in mind, this is still a ways out and the details
could change, so stay tuned for the latest updates.

There`s some evidence pointing towards storms lingering into the
overnight hours Tuesday, but they are likely to be isolated and
confined to portions of Lake and Klamath County.

Beyond Tuesday night, the ensemble means  and clusters are all
pointing towards upper troughing to set up over the area for the
latter part of next week into Fathers Day weekend, with temperatures
near normal. Odds are it will be dry during this time, However,
precipitation chances will be be zero as a small number of
individual ensemble members show some precipitation -Petrucelli

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Heat Advisory from 11 AM Sunday to 8 PM PDT Monday for ORZ023-
     024-026.

CA...Heat Advisory from 11 AM Sunday to 8 PM PDT Monday for CAZ080-
     081.

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

     Small Craft Advisory from 5 PM Sunday to 5 PM PDT Monday for
     PZZ350-356-370-376.

&&

$$