038
FXUS66 KMFR 071143
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
443 AM PDT Fri Jun 7 2024

Updated AVIATION Section

.DISCUSSION...Skies are clear across the region this morning per
satellite imagery, with the exception of patchy stratus just over
Coos Bay and the Coquille Basin. High pressure will remain in
control today as a ridge pushes east into the region and amplifies
along the West Coast. This will maintain hot temperatures today,
with most areas (away from the immediate coast) seeing the hottest
day of the forecast period and of the year so far. High temperatures
this afternoon will peak around 15 to 20 degrees above normal for
this time of year. Mid to upper 90s are expected for many of the
West Side Valleys, except low 90s for the Umpqua Basin. Upper 80s
and even local areas of low 90s are expected for areas east of the
Cascades. Some records will be challenged this afternoon: Klamath
Falls (91/1996), Alturas (93/1996) and Mount Shasta City (92/2015).
Heat Risk values do show these temperatures will affect most
individuals sensitive to heat, especially those without adequate
cooling and hydration, so be sure to take it easy if outside during
the peak heating hours today.

Thunderstorms will again be possible this afternoon and evening.
Aside from the additional energy from daytime heating, the
atmosphere remains fairly similar to Thursday`s conditions. Isolated
thunderstorms are possible (15-20% chance) across portions of the
East Side and southwestward across the Medicine Lakes region, Shasta
Valley and the southwest portion of Siskiyou County. Tonight into
Saturday morning, models show a shortwave coming through the area,
which in a convective pattern, raises the concern for overnight
thunderstorms. Right now, it looks like moisture and stability are
not optimal for elevated convection, and we`ll most likely see an
influx of mid to high level clouds with some isolated showers
possible over the marine waters/coastal locations.

The ridge axis shifts east of the Cascades on Saturday, and this
will result in about a 7 to 10 degree cooldown for West Side
locations. For the East Side, however, temperatures may be cooler by
a few degrees, but for the most part, Saturday looks to be similar
to today`s high temperatures. Regarding thunderstorm potential on
Saturday, this looks like the best day in terms of coverage for
showers and thunderstorms. Chances still remain east of the Cascades
and across western Siskiyou County, but instability and moisture
parameters increase on Saturday and we could see scattered
thunderstorms over portions of Klamath and Lake Counties. The
limiting factor, however, will be the amount of cloud cover around
on Saturday. Models do show quite a bit of mid and high level cloud
cover in advance of an approaching weak trough, so this could hinder
thunderstorm development.

This weak trough passes through the region late Saturday night into
Sunday, and guidance indicates the potential for showers 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 for the
same areas, but again the amount of cloud cover could extensively
limit thunderstorm development.

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 losing the
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...07/12Z TAFs...Widespread VFR conditions prevail
this morning. The exception is in the Coquille River Valley and
along the coast from Cape Arago to near Bandon where stratus is
causing IFR/LIFR ceilings. The sky is clear at North Bend as of 5
am, but the terminal has been in and out of lower ceilings since
about midnight. Confidence is low on how much stratus will fill in
near KOTH this morning, so we`ve gone with a TEMPO for IFR ceilings
from 13-16Z. Otherwise, expect VFR there. Gusty north winds are
expected along the Oregon coast and at Roseburg this afternoon.

While VFR will mostly continue for the remainder of the TAF period,
isolated to scattered showers and thunderstorms are expected to
redevelop this afternoon/evening and could cause brief MVFR. These
will be in much the same areas as on Thursday -- from this Trinity
Alps and Mt. Shasta region of Siskiyou County eastward across Modoc
and Lake Counties. Portions of Klamath and Lake counties will also
have isolated thunderstorms, perhaps even at Klamath Falls. However,
confidence is too low to include in the TAF at this time. -Spilde

&&

.MARINE...Updated 200 AM Friday, June 7, 2024...A thermal trough
will maintain gusty north winds and steep wind-driven seas over the
coastal waters today, with very steep and hazardous seas south of
Gold Beach and beyond 5 NM from shore. Winds and seas will gradually
decrease later today, but will lower even more tonight into
Saturday.

The break will be short-lived, however, as a moderate west swell
moves in late Saturday through Sunday. At the same time, the thermal
trough will restrengthen, bringing increasing north winds and steep
seas to all waters Sunday into early next week. -Spilde

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 5 AM PDT Saturday
     for PZZ350-356-370-376.

Hazardous Seas Warning until 5 PM PDT this afternoon for PZZ356-
     376.

&&

$$

MNF/MAS