264
FXUS66 KMFR 081051
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
351 AM PDT Sat Jun 8 2024

.DISCUSSION...The upper level pattern will begin to transition
today. The ridge axis will shift east of the Cascades and a weak
trough will approach the region. Ahead of this trough, a shortwave
is passing through the area early this morning, bringing a swath
of mid and high level clouds. There are some light returns showing
up on radar, but we don`t expect these returns to amount to
anything. Elevated instability just isn`t there for any
thunderstorm development this morning, and while a few areas may
see some sprinkles out of these showers, it will be very isolated
and limited to areas west of the I- 5 corridor and over the marine
waters. Ahead of this shortwave, areas of stratus have returned
to portions of the coast, with quiet conditions overall expected
for the morning hours.

With the shift in the upper level pattern, high temperatures today
will be around 5 to 10 degrees cooler for locations west of the
Cascades compared to Friday`s readings. A few records were broken
yesterday: Mt Shasta City recorded 95 degrees, breaking the old
record of 92 set in 2015 and Alturas recorded 93 which ties the
record set in 1996. Klamath Falls came close, reaching 90 degrees
which is just shy of 91 set in 1996. While we expect several degrees
of cooling west of the Cascades, temperatures east of the Cascades
will only be cooler by a few degrees, reaching into the mid to upper
80s. We don`t anticipate any record challenging temperatures today
as high temperatures will be several degrees out of reach of current
records.

The forecast is on track for a likely broader area with more
thunderstorm activity this afternoon and evening. The focus for
activity is expected to be in similar areas as the previous two
days: in the vicinity of the border of Klamath and Lake counties,
extending primarily into the northern portions of those counties,
including Chemult and Summer Lake, where coverage of storms
(isolated to scattered) will be greater today. A secondary, isolated
risk for storms will cover much of Siskiyou and Modoc counties, the
remainder of south central Oregon, and the southern Oregon Cascades
and Siskiyou Mountains.

The previously mentioned weak trough passes through the region late
tonight into Sunday, and guidance indicates the potential for
showers and isolated thunderstorms to continue across northern
Klamath/Lake Counties during this time. The cooling trend continues
on Sunday as the weak trough passes through, with the most notable
cooling expected east of the Cascades where high temperatures are
expected to be about 7 to 10 degrees cooler. West Side will cool
further as well, but only by a few degrees. We`ll see yet another
day of thunderstorm potential Sunday afternoon, but the focus will
shift eastward into Lake and Modoc counties as the trough pushes the
moist unstable air farther east as the day progresses.

Late Sunday into Monday, energy from this week trough gets cut off
from main flow and forms a cut off low off the coast of southern
California. The flow will become more zonal over the PacNW through
about mid-week, resulting in a stabilizing atmosphere and the loss
of daily thunderstorm potential. With zonal flow, we don`t
anticipate a big warm up, but temperatures will remain about 10
degrees above normal for the first half of the week. /BR-y

&&

.AVIATION...08/06Z TAFs...Clear skies and light winds are keeping
levels at VFR across northern California and southern Oregon this
evening. There is increased confidence in marine stratus developing
along the Oregon coast early Saturday morning, with good chances (50-
60%) for IFR ceilings over North Bend and Brookings. This layer
looks to clear out by late Saturday morning.

A weak trough will bring upper level instability on Saturday
afternoon and evening. This will increase thunderstorm chances for
areas east of the Cascades, with the best chances (30-40%) over Lake
and Klamath counties. Lesser chances (15-25%) will be present over
Siskiyou and Modoc counties. While chances for precipitation are low
in these areas (15-25%), "dry" thunderstorms can still bring
lightning activity and locally gusty winds. -TAD


&&

.MARINE...Updated 200 AM Saturday, June 8, 2024...North winds
will be just strong enough to produce an area of steep seas
hazardous to small craft south of Ophir today and tonight, generally
beyond 2 NM from shore. 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. -Spilde

&&

.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.

&&

$$

MNF/MAS