379
FXUS66 KMFR 101554
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
854 AM PDT Sat Aug 10 2024

.DISCUSSION...The forecast is on track for today. Smoke from fires
in Douglas and Lane counties continues to affect inland areas. The
heaviest smoke this morning will be in central and eastern Douglas
county as northeast winds guide the plume near the Umpqua Valley.
Winds across the area will turn westerly will increase into the
afternoon, hopefully helping to clear out areas of accumulated
smoke.

Please see the previous discussion for more details on the short-
and long-term forecast. -TAD

&&

.AVIATION (12Z TAFs)...

A marine layer will cause MVFR conditions along the coast (KOTH),
but inland TAF sites are expected to remain mostly in VFR; however,
smoke from wildfires across the region could cause some minor
visibility restrictions this afternoon. Otherwise, typical diurnal
breezes expected with mainly clear skies inland.

Guerrero

&&

.MARINE...Updated 230 AM Saturday, August 10, 2024...Northerly
winds, especially south of Cape Blanco, will create advisory
strength conditions later today as seas become steep. These steep
seas and northerly winds are expected to last through Sunday evening
resulting in conditions hazardous to smaller crafts. Wind speeds
will peak Sunday afternoon. The probability for wind gusts of 34
knots or greater south of Cape Blanco is roughly 40-60% where we
have the current Small Craft Advisory. Thereafter, winds and seas
will both ease through the middle of next week.

-Guerrero

&&

.FIRE WEATHER...Issued 200 AM Saturday August 10, 2024...The
forecast period will trend cooler today through next week with
increasing onshore flow. The increased onshore flow will result in
good overnight recoveries for the coast, coastal valleys, Coquille
and Umpqua Basin, including the complex of fires in central and
eastern Douglas County.

Weak upper troughing is expected today with cooler afternoon
temperatures. There`s good agreement instability is marginal at
best, with little or no trigger and mid level moisture is lacking,
therefore the threat for thunderstorms are next to zero. The most
likely scenario will be cumulus build ups in the afternoon over the
Cascades and higher terrain east of the Cascades and northern Cal.

The potential for isolated thunderstorms will be higher Sunday as
the upper trough deepens, with increased mid level moisture and
stronger trigger ahead of the approaching upper low. Even then they
will be isolated. There`s good agreement the best chance for
isolated storms will be centered over northern Fire Zones 624, 625
and portions of Fire zones 284 Sunday afternoon into Sunday evening.

General upper troughing to remain over the area through next week.
Instability is marginal Monday afternoon east of the Cascades and
portions of northern Cal and some some evidence supporting a slight
chance of storms Monday, Wednesday and Thursday afternoon and
evening, but trigger is lacking and this confidence is low we`ll get
any storms. For now we`ll keep a low end chance (10%) of storms for
those days.

Also higher afternoon relative humidities are expected with fairly
good overnight recoveries, even for the eastside and northern
California. We`ll still have to deal with gusty breezes in the
afternoon and early evening hours, but with higher humidities in the
afternoons, were not expecting critical conditions. -Petrucelli

&&


PREV DISCUSSION... /Issued 315 AM PDT Sat Aug 10 2024/

DISCUSSION...The latest satellite image shows marine stratus along
the coast and inland into the coastal river valleys and Coquille
Basin. The inland push of the marine stratus has been slow but
steady and could move into portions of the Umpqua Basin towards
daybreak. Elsewhere skies are clear.

Dry weather will continue today with the marine stratus away from
the coast gradually burning off during the morning. Meanwhile the
marine stratus is expected to persist at the coast and just offshore
through the day. Also the exception to the dry weather will be
patchy drizzle along the south coast, including Brookings this
morning.

Weak upper troughing remains over the area through the weekend. The
marine stratus will remain deep and the models show an extensive
area of QPF over the waters and along the coast. Typically when the
models show an extensive area of QPF in these areas, it usually
results in patchy to areas of drizzle. Thus, the forecast for
Saturday morning will reflect this. Therefore patchy drizzle at the
coast is expected this morning and again later tonight into Sunday
morning.

Weak instability exist over the northern Cascades this afternoon,
but mid level moisture and trigger is lacking, therefore were not
expecting thunderstorms. However, we`ll see cumulus build ups in the
afternoon.

The upper trough axis will move into southwest Oregon Sunday
afternoon. This will provide a slightly stronger trigger along with
increasing mid level moisture and instability in portions of
northern Cal and east of the Cascades. The combination of the above
may be sufficient for at least isolated thunderstorms in northern
Klamath, Lake, and portions of Siskiyou County late in the afternoon
and early evening.

After Sunday, not much change in the pattern is expected through
next week. The general consensus among the operational models,
ensemble members and clusters all point to weak troughing over the
area. This will result in cooler afternoon temperatures that will be
near normal for this time of the year for the interior. It`s also
expected to remain dry.

Next weekend, the clusters suggest the upper trough will deepen some
with the center of the upper trough over the PAC NW. The operational
models are in good agreement showing a rather strong upper low for
this time of the year centered over the eastern pacific with a
southwest flow. This would also suggest cooler temperatures (near or
slightly below normal) with continued dry weather. -Petrucelli

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory from 2 PM this
     afternoon to 2 AM PDT Monday for PZZ356-376.

&&

$$