815
FXUS66 KMFR 090554
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1054 PM PDT Sat Jun 8 2024

...Updated AVIATION discussion...

&&

.DISCUSSION...Instability was sufficient this afternoon and
evening to produce scattered showers and thunderstorms, mainly
east of the Cascades. This activity was in advance of a Pacific
trough. The trough will track inland overnight and across the area
on Sunday into Sunday evening. This will continue a slight chance
to chance of showers and slight chance of thunderstorms into
Sunday afternoon. Though the set up will not be identical, similar
weather to this afternoon is expected during Sunday afternoon with
the focus of activity shifted slightly eastward into far eastern
Siskiyou, eastern Klamath, and Lake, and Modoc counties. By 8 PM
Sunday evening, the trough axis is expected to be at the eastern
edge of our area, with further shower and thunderstorm activity to
occur east of Lake County.

Also, the arrival of the trough will bring an influx of coastal
clouds tonight through Sunday, into Monday morning.

The outlook is still for a seasonable, stable air mass beginning
Monday with inland temperatures similar to those of today during
Monday through Thursday. Weak instability may nudge into Modoc
County by Thursday afternoon, then a trough is likely to bring a
seasonable frontal passage north of our area with a cool down to
near normal temperatures inland for the end of the week.

&&

.AVIATION...09/06Z TAFs...Thunderstorms are largely calming down
over areas east of the Cascades, with only a few isolated cells
traveling to the northeast over Lake County. Instability remains
through the night, so further development is not impossible.
Thunderstorm chances of 15-20% will persist over northern Lake and
Klamath counties overnight before higher 20-40% chances return
across the east side Sunday afternoon. The highest chances will be
across southern Lake County.

Marine stratus will return to the Oregon coast this evening as well,
with ceilings currently fluctuating between VFR and MVFR levels. IFR
ceilings are possible early Sunday morning before sunlight clears
out the marine layer. VFR levels will generally continue through the
day on Sunday, with gusty winds expected across the area in the
afternoon. -TAD

&&

.MARINE...Updated 200 PM Saturday, June 8, 2024...Gusty north winds
will bring steep seas to areas south of Ophir and a few miles away
this evening. Then, a moderate west swell moves in tonight through
Sunday. During this time, the thermal trough will restrengthen,
bringing increasing north winds and steep to very steep seas Sunday
into early next week, especially south of Cape Blanco. Conditions
will at least remain hazardous to small craft south of Cape Blanco
through midweek.

Conditions could worsen again around Thursday as the thermal trough
builds strength.
-Smith

&&

.PREV DISCUSSION... /Issued 247 PM PDT Sat Jun 8 2024/

DISCUSSION...

Short Term...Rest of Today through Monday Night...A trough will
approach the coast this afternoon and evening, move onshore
tonight, and pass over southern Oregon and far northern California
tomorrow. This trough is responsible for the cooler temperatures
today, and it will also be the lifting mechanism the atmosphere
needs to tap into some relatively significant instability in the
low to mid levels, while also providing enough shear to enhance
thunderstorm chances. A few convective cells have already formed
today, and activity is expected to intensify and become more
widespread through the afternoon, mainly along and east of the
Cascades and in northern California. Some of these storms could
be strong; while severe storms are not expected, they are not out
of the question, with around a 5 percent chance for any given
storm to produce strong winds and/or large hail.

Elevated instability is expected to continue through tonight and
into Sunday afternoon as the trough passes onshore. Convective
activity is therefore expected to continue all the way into Sunday
afternoon as well, although over time it will be concentrated more
to the east, ahead of the trough axis.

Ridging returns Sunday night into Monday, along with a
reintensifying thermal trough along the coast. This will dry
things out and bring an end to thunderstorm chances, and it will
also allow temperatures to bump back up, reaching about 10
degrees above normal for this time of year as we head into the
extended period. -BPN

LONG TERM...Tuesday 6/11 through Saturday 6/15...The extended
forecast begins with zonal flow (west to east) at the middle levels
of the atmosphere. While weak disturbances will pass largely to the
north of the area, expect dry weather to continue across southern
Oregon and northern California through the extended period. However,
temperatures will be much slightly above normal with highs in the
upper 80s to low 90s east of the Cascades and lower 80s to upper 70s
east of the Cascades. The coast will be cooler with temperatures in
the 60s.

Then, for the weekend, the general flow pattern will turn to become
more unsettled as a low pressure system approaches the Pacific
Northwest. The general front ahead of the low will be relatively
weak and precipitation is not expected that far south. However, some
precipitation in showers will be possible within the low itself.
Ensembles do show some timing differences, but the general thought
is that temperatures will be even cooler over the weekend, winds
will be breezy, and that a slight showers will be possible largely
north of the Douglas/Lane County Border. However, this could change
as the details of this system become more clear. Have gone with the
National Blend of Models for this forecast package. -Schaaf

&&

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

CA...None.

PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT Monday
     for PZZ356-376.

     Hazardous Seas Warning from 5 AM Sunday to 11 AM PDT Monday for
     PZZ356-376.

&&

$$