247
FXUS66 KMFR 282147
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
247 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 28/18Z TAFS...The only clouds on satellite are some lower
cu along the coastal range this afternoon.  VFR conditions are
anticipated through the remainder of the day.  More lower ceilings
will likely build into the coast tonight, although the inversion
doesn`t appear as strong as the last few nights.  Periods of LIFR
ceilings remain possible over North Bend and sections of the coast
with clearer conditions farther inland.
-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...CA...None.

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

&&

$$

TAD/BPN/CZS