241
FXUS66 KMFR 050042
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
542 PM PDT Wed Jun 4 2025

.UPDATE...Updated Aviation Discussion.


&&

.AVIATION 05/00Z TAFs...The marine layer will return to coastal
areas north of Cape Blanco this evening around 03-06z and persist
through Thursday morning. Models continue to show stratus
spreading into the Umpqua Basin and may even "spill over" into
portions of the Rogue/Illinois Valleys early Thursday morning.
Overall MVFR is expected at Roseburg (KRBG) with Medford likely
to stay VFR.


&&

.PREV DISCUSSION... /Issued 234 PM PDT Wed Jun 4 2025/

DISCUSSION...Satellite image shows fair weather cumulus north of
the Umpqua Divide and the higher terrain east of the Cascades.
Clouds will diminish tonight, except for marine stratus in similar
locations as last night and this morning.

Weak troughing remains over the area Thursday, but at the same time
upper ridging from the west will nudge into the area resulting in
continued dry weather with warmer afternoon temperatures for the
interior.

There`s good agreement for strong upper ridge to 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 Saturday, 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 Saturday. 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 trough is expected to move into the area Monday with
the best instability in portions of northern Cal and along and east
of the Cascades. Therefore could not rule out isolated thunderstorms
again Monday afternoon and early evening east of the Cascades and
portions of northern Cal.

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.

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 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

MARINE...Updated 130 PM Wednesday, June 4, 2025...With high
pressure offshore and a thermal trough near shore through Thursday
night, strong north winds will persist and maintain very steep and
hazardous wind driven seas from Cape Blanco southward. Meanwhile, steep
seas will persist north of Cape Blanco. North winds will be strongest
in the afternoons and evenings, reaching gale force south of Gold Beach
between 5 and 40 nm offshore.

The thermal trough pattern will be disrupted this weekend, leading to
weaker north winds and lower seas Saturday into Sunday. This
improvement may continue into Monday, but the thermal trough pattern
returns early next week with moderate to strong north winds and steep
to very steep wind-driven seas returning next week. /BR-y

FIRE WEATHER...The main concern ahead will be a warming trend with
hot temperatures in the afternoon for the interior for a 3 day
period with max temperatures peaking out Saturday, Sunday and next
Monday along with low afternoon humidity.

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 trough is expected to move east Monday with the best
instability in portions of northern Cal and along and east of the
Cascades. Thus, isolated storms will be a concern Monday afternoon
into Monday evening.

Tuesday could be a repeat of Monday with marginal instability and a
slight chance for storms in portions of northern Cal and east of the
Cascades.

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. -Petrucelli

&&

.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.

&&

$$