083
FXUS66 KMFR 290518
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1017 PM PDT Fri Jun 28 2024

Updated Aviation Discussion.

.DISCUSSION...Satellite imagery this evening reveals a few fair-
weather cumulus out near Winter Rim and the Chewaucan Valley.
Other than some cirrus near and offshore, skies are clear nearly
everywhere else. Some smoke can be seen emanating from the Upper
Applegate fire, then drifting off to the south just east of
Applegate Lake. We`ll have some marine clouds move back onshore
overnight into Saturday morning north of Cape Blanco and into the
Coquille Valley. Patchy low clouds may also develop in the Umpqua
Basin.

We will see an uptick in mid-high clouds by Saturday morning in
those areas as an upper trough offshore approaches. This trough
will bring an increase in breezy afternoon/evening winds this
weekend. Models are showing weak instability near the Cascades
north of Crater Lake and across northern Klamath/Lake counties
later Saturday afternoon/evening. This is fairly low probability
(~15% chance), but could see how a cell pops up here or there, so
have introduced a slight chance of a shower/thunderstorm in those
areas, especially near Winter Rim area. Other than that, the
going forecast remains unchanged for the remainder of the weekend
and into next week. It does look like will get quite hot by the
end of next week with a solid 60-70% chance of our first 100+
readings of the year here in Medford July 4th/5th. -Spilde

&&

.AVIATION 29/06Z TAFS...Tonight, areas of IFR and LIFR ceilings will
build into the coast and eventually spread into the Umpqua Basin and
into Roseburg (KRBG) later tonight and early Saturday for a few
hours. These conditions will clear to VFR in the mid to late morning
Saturday. Areas of MVFR ceilings are expected to return to the coast
Saturday evening. Elsewhere, expect VFR through the TAF period.
Smoke from a few wildfires could produce some locally low visibility
near those fires, otherwise the smoke will not be an issue near
terminals.

-CC

&&

.MARINE...Updated 830 PM Friday, June 28, 2024...Gusty north
winds will continue into tonight, with steep seas affecting areas
south of Gold Beach. Look for steep wind driven seas with wave
heights peaking around 8 feet or so.

Winds and seas lower Saturday afternoon into Sunday for most of the
area. However, areas from Pistol River south within about 15 NM of
shore could observe brief and isolated advisory level seas as winds
peak in the afternoon, generating a steep wind wave. These
conditions will likely be too short lived and localized to warrant
needing a warning, but you`ll want to watch Buoy 27 to monitor
conditions in this area to be safe before heading out.

Then, a very strong thermal trough is expected to develop next week
beginning on Monday and lingering towards the end of the week. The
peak should be either Tuesday or Wednesday evening, but there is
some spread in the forecast and uncertainty here. As for the wind
speeds expected during the peak of the thermal trough, the chance
for gale force wind gusts south of Cape Blanco is 70% or greater
(90% plus south of Pistol River) and this will drive very steep
waves. There is also a moderate (20-40%) chance that gale force
winds develop over the waters north of Cape Blanco.

-Smith/CC

&&

.PREV DISCUSSION... /Issued 446 PM PDT Fri Jun 28 2024/

DISCUSSION...Clear skies continue over northern California and
southern Oregon this afternoon, with the slightest hints of terrain-
influenced cumulus flickering on satellite imagery.

A weak trough will pass over the area through the weekend, helping
to keep daytime temperatures near seasonal levels on Saturday and
Sunday. This pattern will continue to push marine moisture over the
Oregon coast in the mornings. This layer could move into the
Umpqua Valley on Sunday morning. However, no precipitation is
expected under these clouds.

The weekend trough trough will also bring evening chances for active
weather east of the Cascades. Model soundings showing CAPE values
between 100 and 200 J/Kg on Saturday evening as well as upper level
vorticity and above average moisture. These conditions will make
evening thunderstorms a possibility around the northern Klamath/Lake
County border on Saturday evening. These chances are slight,
currently topping out at 10% in a small area, but the chances have
been increasing by a percentage or two daily. Thunderstorm chances
are looking higher for Sunday evening, reaching 10-15% in eastern
Lake and Modoc counties. Less moisture will be present but CAPE
values could be in the 300-400 J/Kg range which is more than enough
to trigger thunderstorms in this area.

A pattern change to upper level ridging will build next week and
could remain. This period is particularly important, as this upper
level stability will drive conditions on the 4th of July. Ridging
looks to build through the week, with the highest temperatures and
the driest air present on July 4th, 5th, and 6th. Temperatures in
the Rogue and Shasta valleys as well as in western Siskiyou valleys
have a 50% of exceeding 100 degrees in this period. Other west side
valleys and areas east of the Cascades look to be in the low to mid
90s under the ridging pattern. Exceptionally low relative humidity
values are expected in all inland areas. With gusty afternoon winds
continuing, fire hazards for next week will be substantial.
Activities that could create sparks or flames should be avoided, as
fuels will be dry and winds will easily carry sparks or embers to
new areas.

Some details will require additional guidance. Forecast temperatures
for Brookings may increase as next week`s pattern comes into better
focus, as periods of  Chetco Effect winds are possible. Additionally,
Heat Risk values increase through the week. Areas of Advisory-level
conditions possible in the Rogue, Shasta, Scott, and western
Siskiyou valleys possible by the end of the week. Finally, the NBM
temperature guidance does show a 8-12 degree interquartile range for
daytime highs, suggesting some uncertainty in the timing of how
ridging will build. So hot and dry is expected, but please check
back as the finer points come into focus.

-TAD

Today, we bid farewell to Ryan Sandler, our Warning Coordination
Meteorologist, as he begins his much anticipated and well-deserved
retirement. Ryan began his career at Neena, WI in December of 1989,
before moving on to Milwaukee, WI, then Wilmington OH, and finally
here to Medford in 1998. Ryan has been a knowledgeable and respected
colleague, a dedicated public servant, and an all-around great
friend to those of us here at the Medford forecast office these past
many years. We wish you fair winds, fifty-five degree temperatures,
and following seas as you embark on this next journey. Go Sox!

AVIATION 29/00Z TAFS...Some cumulus clouds are building over the
higher Cascades this afternoon with little to no cloud cover
elsewhere. This trend will persist into evening hours as VFR
conditions prevail over the majority of the forecast area. Smoke
from a few wildfires could produce some locally low visibility near
those fires, otherwise the smoke will not be an issue near terminals.

Later tonight, some more LIFR ceilings will build into the coast and
should eventually spread into the Umpqua Basin and into
Roseburg(KRBG) later tonight for a few hours. VFR conditions are
anticipated for most of Saturday.

-Smith

MARINE...Updated 230 PM Friday, June 28, 2024...Gusty winds will
pick up later this afternoon into the early evening, especially
south of Gold Beach.  Look for steep wind driven seas with wave
heights peaking around 8 feet or so. These conditions will remain
hazardous to smaller crafts through Friday night.

Winds and seas lower Saturday afternoon into Sunday for most of the
area. However, areas from Pistol River south within about 15 NM of
shore could observe brief and isolated advisory level seas as winds
peak in the afternoon, generating a steep wind wave. These
conditions will likely be too short lived and localized to warrant
needing a warning, but you`ll want to watch Buoy 27 to monitor
conditions in this area to be safe before heading out.

Then, a very strong thermal trough is expected to develop next week
beginning on Monday and lingering towards the end of the week. The
peak should be either Tuesday or Wednesday evening, but there is
some spread in the forecast and uncertainty here. As for the wind
speeds expected during the peak of the thermal trough, the chance
for gale force wind gusts south of Cape Blanco is 70% or greater
(90% plus south of Pistol River) and this will drive very steep
waves. There is also a moderate (20-40%) chance that gale force
winds develop over the waters north of Cape Blanco.

-Miles/Smith

&&

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

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Saturday
     for PZZ356-376.

&&

$$

MAS/CC/TAD/CZS