247
FXUS66 KMFR 140236
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
736 PM PDT Tue Aug 13 2024

.Updated Aviation Discuassion.

.DISCUSSION...An upper level trough continues to dominate the
weather in the short term...with temperatures below normal. Today
is the more benign of the weather days through the end of the work
week...with no chance of precipitation. Things change tomorrow as
an upper low off the OR coast moves almost due east early
Wednesday morning...with the low moving onshore Wednesday
afternoon into the evening hours. Our main concern with this low
coming onshore will be the chance for thunderstorms...especially
the potential for a nocturnal event. There are some disagreements
with the short term models as far as location/intensity of showers
and the possibility of thunderstorms...but as of now...it looks
like showers will develop between 00z and 03z Thursday in central
Siskiyou county...moving northeast into Lake and Klamath counties
into Thursday morning. A few of the short term models are showing
showers in central Jackson county Wednesday night...generally
between 03z and 06z...however we have left thunder out of that
area for now. The better chance for thunderstorms arrives to the
area on Thursday afternoon and evening and the low moves directly
over OR. Showers and thunderstorms are expected to develop in
Klamath county around 21z...moving northeast into Lake
county...and especially the northern half of Lake county by the
late afternoon/early evening hours. The thunderstorm threat moves
out of the area during the overnight hours on Thursday.

There is quite a bit of uncertainty in the forecast Friday into
the weekend and early next week as an upper low sits off the Pac
NW. Some clusters indicate that the upper low will move closer
onshore...bringing showers and cooler temps...while others show
the low retrograding...bringing us dry and slightly warmer
weather. Please continue to monitor the forecast for the latest
information.

-Riley

&&

.FIRE WEATHER...Issued 200 PM Tuesday August 13, 2024...Temperatures
will trend cooler through next week with increasing onshore flow,
improving humidities, and breezy afternoon winds as upper level
troughing settles in and remains over the Pacific Northwest.

Another relatively strong marine push is expected tonight into
tomorrow, with extensive stratus and fog decks west of the Cascades
that may push into the Umpqua Basin by daybreak Tuesday. Afternoon
breezes could be gusty in the afternoon, especially west of the
Cascades. Despite these winds, rising humidities should keep us well
outside of any critical thresholds.

With the trough remaining overhead through the week, we can not
completely rule out additional afternoon convection, particularly
tomorrow and especially Thursday afternoons and evenings as
additional shortwaves pass through the region. Isolated storms are
possible over much of northern California and along and east of the
Cascades late Wednesday and Wednesday night. Then, on Thursday, the
thunderstorm coverage begins to push eastward, with scattered
thunderstorm chances possible Thursday afternoon for portions of
northern 624 and 625 largely north of 140 and east of highway 95,
but it does include portions northern Klamath County to include
Chemult. A Fire Weather Watch is in effect Wednesday through
Thursday for the thunderstorm chances in northern zones 624 and 625
to include the Warner Peak Fire.

Models are showing the potential for a much stronger, broader trough
arriving and setting up over or very near the area late this week
into this weekend. This will maintain our cooler temperatures and
higher humidities, and may also produce more widespread chances for
showers and thunderstorms Friday into Saturday. While wetting rains
are very unlikely, we will keep a close eye on how the system
develops, as cooler temperatures, higher humidities, and even a
small amount of rain will be very welcome to fire concerns. -
BPN/Hermansen

&&

.AVIATION...14/00Z TAFS...Along the coast and just offshore, VFR
conditions will continue into this evening, Marine stratus will
develop later tonight and last unto at least the mid morning hours.
Guidance shows ceilings lowering to IFR. However, weak instability
may be enough to keep ceilings at MVFR.

Inland areas will remain VFR through the TAF period. The exception
will be MVFR visibility from the smoke from the fires in eastern
Douglas county, and northern Klamath county as smoke from those
fires gets transported there.. Some of this smoke may reach Klamath
Falls early Wednesday morning, but visibility is not expected to
lower as a result. -Petrucelli


&&

.MARINE...Updated 200 PM Tuesday, August 13, 2024...Relatively calm
conditions will continue for the next several days. Winds and seas
will remain low through Thursday morning. North winds will increase
some Thursday afternoon and lasting into Friday. However they are
likely to remain below small craft. -Petrucelli

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Fire Weather Watch from Thursday morning through Thursday
     evening for ORZ623>625.

CA...None.

PACIFIC COASTAL WATERS...None.

&&

$$