504
FXUS66 KMFR 032122
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
222 PM PDT Tue Jun 3 2025

.DISCUSSION...Satellite image shows clear skies over the entire
forecast area. Surface analysis shows a strong thermal trough along
the coast. This has resulted in gusty northeast breezes near and at
the ridges in southwest Oregon and western Siskiyou county. Relative
humidities in these areas are not as low as they were at this time
yesterday.

It will remain clear through this evening. A weak disturbance will
move through tonight which will increase the onshore flow just
enough for marine stratus to develop along the coast, north of Cape
Blanco and banking up along the Umpqua Divide. Marine stratus could
also fill into portions of the Coquille Basin later tonight into
Wednesday morning.

Meanwhile, the thermal trough won`t move much this evening and
tonight, therefore gusty northeast breezes are likely to continue
through tonight near and at the ridges in southwest Oregon and
western Siskiyou County. The offshore flow will also prevent marine
stratus from forming south of Cape Blanco.

Wednesday will be dry with slight cooling for the interior,
especially west of the Cascades. Afternoon temperatures east of the
Cascades could end up similar to today.

There`s strong evidence suggesting the strong upper ridge that is
west of the forecast area will gradually move east towards the end
of the week into early next week. This will likely result in
afternoon temperatures heating up for the interior. Afternoon
temperatures for the interior westside valleys could flirt near the
tripe digit mark Sunday and next Monday.

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
drifts from the west towards the Bay Area. 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. Isolated storms could be a concern first in northern Cal.
Steering is expected to be from the southeast, and some of these
storms could make their way into southern Oregon late Sunday
afternoon into Sunday evening.

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

The weak upper low is expected to move east Monday with the best
instability in portions of northern Cal and along and east of the
Cascades.

Tuesday could be a repeat of Monday with some evidence pointing
towards marginal instability and a slight chance for storms in
portions of northern Cal and east of the Cascades. However the
evidence for a repeat scenario is not as strong.

Given this is a ways out, the details on the locations that could
get affected by isolated storms will vary. Stay tuned for the latest
updates.

It still looks like the mainly dry and hot weather may only be a 2-3
day event with gradual cooling starting next Tuesday. Beyond
Tuesday, the ensemble means suggesting weak upper troughing to
return the latter part of next week into Fathers Day weekend.
-Petrucelli


&&

.AVIATION...03/18z TAF`s...For the most part, expecting a mainly VFR
cycle through the next 24 hours with one exception being along
the coast. There will be a marine layer that returns tonight that
will likely (~80%-90%) bring MVFR conditions, but IFR chances
(50%-70%) are possible as well. Otherwise, mostly clear skies and
breezy winds expected this afternoon. Wind speeds are expected to
diminish near/after sunset.


&&

.MARINE...Updated 1200 PM Tuesday, June 03, 2025...Strong northerly
winds continue across all waters today. This will result in very
steep wind-driven seas and gale gusts south of Cape Blanco, with
steep seas continuing to the north. Very steep wind-driven seas and
gale gusts will continue through at least Thursday evening; as a
result, we have extended the current warnings out further in time to
account for these hazardous conditions. Beyond this, we may need to
consider further extension as it does look like steep wind-driven
seas will continue into at least parts of this weekend with some
signs of easing Saturday night into Sunday.

-Guerrero


&&

.FIRE WEATHER...With generally stable atmospheric conditions
interrupted by weak fronts, daytime relative humidities are forecast
to be between 15-25% east of the Cascades and between 20%-40% for
inland areas west of the Cascades. These weak fronts can still bring
breezy or gusty winds without bringing precipitation, especially
east of the Cascades. Also, with the thermal trough situated along
the coast, gusty northeast winds are also likely near and at the
ridges into Wednesday night along the coastal mountains in southwest
Oregon and western Siskiyou county.

The one change we`ll see from the previous couple of days is an
increased onshore flow that will bring marine stratus along the
coast north of Cape Blanco and into portions of the Umpqua Basin
right up to the Umpqua Divide. This will result in higher relative
humidities.

Wednesday we`ll have slight cooling west of the Cascades, but
afternoon temperatures east of the Cascades will be similar to
today. The typical gusty afternoon and early evening breezes
are likely for most locations.

Afternoon temperatures will trend higher Thursday, with mainly dry
and hot weather Saturday into next Monday (at least these are the
three days in which we expect afternoon temperatures to be highest).

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
drifts from the west towards the Bay Area. 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. Isolated storms could be a concern first in northern Cal.
Steering winds are expected to be from the southeast, and some of
these storms could make their way into southern Oregon late Sunday
afternoon into Sunday evening.

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

The weak upper low is expected to move east Monday with the best
instability in portions of northern Cal and along and east of the
Cascades.

Tuesday could be a repeat of Monday with some evidence pointing
towards marginal instability and a slight chance for storms in
portions of northern Cal and east of the Cascades. However the
evidence for a repeat scenario is not as strong.

One thing of note: While mid level moisture will increase, it does
not appear to be a deep moisture layer, therefore storms that do
develop could be high base producing little or no precipitation.
Especially with hot temperatures and low afternoon humidities
resulting in a dry sub layer below the cloud base.

Given this is a ways out, the details on the locations that could
get affected by isolated storms will vary. Stay tuned for the latest
updates.

While current fuel conditions do not represent significant wildfire
concerns, the combination of dry and windy conditions can create
conditions for small fires to quickly spread. Human activity has
already caused multiple fires in the area. Please use extra care
when participating in activities that may create sparks or embers.
These can ignite fires that can quickly grow out of control,
especially around abundant dry or unmaintained fuels.


&&

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

PACIFIC COASTAL WATERS...Hazardous Seas Warning until 5 AM PDT Friday
     for PZZ356-376.

Small Craft Advisory until 5 AM PDT Friday for PZZ350-370.

     Gale Warning until 5 AM PDT Friday for PZZ356-376.

&&

$$