126
FXUS66 KMFR 061149
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
449 AM PDT Thu Jun 6 2024

.DISCUSSION...The two features of most particular interest remain
a straight-forward forecast of hot temperatures, and a more
challenging analysis of where weak instability and sufficient
mid-level moisture levels will warrant including a slight chance
mention of late-day thunderstorms. Instability this afternoon
through Sunday afternoon is expected to lead to a slight chance to
chance of showers and slight chance of afternoon and evening
thunderstorms over portions of the east side and Siskiyou County.

Patchy morning coastal low clouds are present from Cape Blanco
northward and into the Coquille Valley. This stratus is expected
to dissipate quickly, by mid-morning. Morning stratus coverage,
again mainly north of Cape Blanco, is expected to be at a minimum
on Friday.

The Chetco Effect at Brookings (with warming due to downslope
northeast winds) will peak today, otherwise hot temperatures will
reach their maximum on Friday, with readings expected to be near
or slightly above the hottest of the year so far on the west side,
and the hottest of the year by several degrees (and at or near
record levels) on the east side. The heat is associated with an
unusually strong ridge centered in the Desert Southwest. Meantime,
a reinforcing ridge will push east into the Pacific Northwest on
Friday...kicked eastward by a closed low farther offshore. The
gradual passage of the trough will bring a cooling trend for the
weekend, though with temperatures remaining above normal. The
trough passage will also allow a noticeable trend of more
extensive night and morning coastal stratus coverage during the
weekend.

Beyond Sunday, warmer than normal conditions persist next week
with a stable air mass and typical northerly breezes.

Regarding thunderstorms, instability around peak heating late this
afternoon will lead to a slight chance near Mount Shasta, with a
higher probability over the Warner Mountains of Modoc County, into
southern Lake County and eastward. The region favorable for
development will shift northward for Friday, with the peak of the
heat wave providing more energy. A 10% to 15% probability extends
from central Siskiyou County northeastward into southern Klamath
County, including Klamath Falls. But, the highest probability will
be in northern Klamath County, east of Highway 97, and across
northern Lake County.

Model differences increase regarding the fine details of the
sharpness and position of the trough for the weekend, with an
additional complicating factor of heating on Saturday being
hindered by an influx of high level clouds. As earlier mentioned,
the highest probability will continue to be over northern
California and south central Oregon.

&&

.AVIATION...06/12Z TAFs...Marine stratus is trying to develop
around North Bend this morning, bringing moments of MVFR ceilings.
Given the delayed development, these clouds are unlikely to
endure much sunlight.

VFR levels will be present across northern California and southern
Oregon today, with gusty winds expected along the Oregon coast and
over Roseburg this afternoon. Winds will calm quickly tonight. There
are hints of lower ceilings and visibilities developing over North
Bend at the very end of the TAF period, but confidence in this is
slight so it has not been included in the TAFs yet. -TAD

&&

.MARINE...Updated 200 AM Thursday, June 6, 2024...A thermal trough
will continue to guide marine conditions through today and Friday,
bringing gusty northerly winds over all waters. Very steep and
hazardous seas will be present south of Cape Blanco while steep seas
will continue in waters to the north. Winds will increase through
the day today and peak this evening, with gale winds possible south
of Gold Beach before winds start to decrease overnight and into
Friday morning. Even as winds decrease, very steep seas will
continue south of Cape Blanco into late Friday morning. Steep seas
will remain in all waters into late Friday night.

Please see MWWMFR to see more detailed areas of expected hazards as
well as timing for current Small Craft Advisories and Hazardous Seas
Warnings.

Seas will be calm through Saturday, although westerly swell will
start to increase during the day and a thermal trough will return
late Saturday night. Chaotic seas are expected to return to all
waters Sunday  and continue into early next week as the thermal
trough strengthens. -TAD

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT Friday
     for PZZ350-356-370-376.

Hazardous Seas Warning until 11 AM PDT Friday for PZZ356-376.

&&

$$