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000
FXUS66 KMFR 060545
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
945 PM PST Tue Dec 5 2023

...New Aviation Discussion...


.AVIATION (06/06Z TAFs)...

The Medford terminal (KMFR) is under a layer of fog/low clouds.
Visibilities at KMFR are a quarter mile as of writing this, and
this is forecast to remain in place through most of the morning
hours until expected rainfall breaks this up. KMFR will likely be
in IFR or MVFR (close to IFR) conditions through the remainder of
this cycle. Otherwise, VFR conditions are in place elsewhere at
the three other terminals. Rainfall is expected to persist at the
North Bend terminal through the morning hours and early afternoon
before this rain shifts eastward towards Roseburg, Medford, and
Klamath Falls.

&&

.PREV DISCUSSION... /Issued 818 PM PST Tue Dec 5 2023/

UPDATE...

No notable updates are required this evening, and we are still on
track for breezy/gusty conditions to arise starting
tonight along slopes and ridges and continuing through tomorrow.
A Wind Advisory remains in effect for tomorrow for areas on the
eastside from starting at 7 AM and going all day. Please see the
latest Wind Advisory product for more details. We are also looking
at rainfall transitioning to snow tomorrow, and hence the Winter
Weather Advisory in effect starting at 4 PM tomorrow afternoon.
Please see the latest Winter Weather Advisory for further details.
The main concerns here are the possibility for blowing snow which
will could lead to poor visibilities, in addition to unfavorable
driving conditions from slick/messy roads.

PREV DISCUSSION... /Issued 319 PM PST Tue Dec 5 2023/

.UPDATED AVIATION SECTION...

SHORT TERM...After a brief lull in the wet and active pattern
today, the wet and active pattern will return shortly with the
next front moving into the northern coast at this time. This pause
has allowed the Coquille at Coquille to subside below warning
stage, and the flood warning has been cancelled. However, periods
of heavy rain are expected once again near the coast tonight into
Wednesday and the areal flood watch continues in this area into
tomorrow afternoon. With very saturated soils the possibility of
additional mud and debris slides is more than slight. As the front
moves inland winds ahead of it will increase, and wind advisories
are in place in the Shasta valley and portions east of the
Cascades Wednesday. Advisory strength winds are also possible on
the ridges across the region, but should not surface into
populated areas. as the front moves inland snow level start at
around 7000 feet or higher, dropping below 4000 feet late
Wednesday evening into Wednesday night, and finally leveling off
to around 3500 feet by Thursday morning. A winter weather
advisory has been issued for the Cascades, and for western
Siskiyou county and the Mt Shasta area above 3500 feet. some
portions east of the Cascades will also see advisory snow amounts.

LONG TERM...Thursday morning through Monday...An upper level
shortwave will impact the region Thursday morning...with colder
air moving into the region lowering snow levels as precipitation
remains in the area. Snow levels will hover around 3,500 feet with
all of the short term models in good agreement regarding
precipitation through much of the region. As far as snow
amounts...there is between a 50% and 75% for much of the southern
Cascades and the Siskiyou mountains of at least 4 inches of snow
in a 6 hour period ending late Thursday morning. In fact...right
around Crater Lake...there is about a 50% chance of 6 inches of
snow in a 6 hour period from early to mid Thursday morning. We
will continue to monitor the snow situation closely...as winter
products may be needed.

Upper level northwest flow takes over late Thursday night into
Friday morning...with snow levels dropping again...to between 2000
and 2500 feet. By this time...the bulk of the precipitation will
have moved east...but a few showers will continue to linger. A
dusting to a few inches of snow will be possible in and around 2,500
feet.

Upper level high pressure will nudge east Friday afternoon into the
weekend as seen in both the meteograms and in the clusters. In
fact...by Saturday afternoon all of the clusters indicate ridging
over the west coast...adding to the confidence in a break in the
weather. Uncertainty sneaks into the forecast during the second half
of the weekend into early next week as there is quite a bit of
disagreements in the upper level pattern.

AVIATION...06/00Z TAFs...A front will approach the region this
evening, then pass over the area through the day Wednesday. Expect
VFR to MVFR conditions, but IFR ceilings and visibilities will occur
as precipitation rates increase to moderate to heavy amounts,
especially along the coast and in the coastal mountains. Terrain
obscuration will be a concern as well tonight, spreading from west
to east with the precipitation. The Freezing level will be start
around 7000 feet MSL this evening and begin dropping to about 4500
ft MSL by the end of the TAF period. -Schaaf

MARINE...Updated 100 PM Tuesday December 5, 2023...An active period
of weather will continue this week over the waters. Gusty south to
southwest winds will be common, along with southerly wind waves and
long period west swell.

A very large and steep seas of around 15 to 19 ft will continue to
build to a peak around 16 to 22 ft this evening into early Wednesday
morning. During this same time period, wind speeds are forecast to
weaken slightly. However, since seas are still expected to remain
very large, this will result in a Hazardous Seas Warning across all
the waters Tuesday into Wednesday morning. Additional disturbances
Wednesday and Thursday will not be as strong, with southerly winds
likely at advisory strength while high and steep seas slowly
diminish. Winds and seas will reach a minimum late Friday, then
another strong front is likely Saturday with gales possible.
-Schaaf/DW

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Wind Advisory from 7 AM to 10 PM PST Wednesday for ORZ029>031.

     Winter Weather Advisory from 4 PM Wednesday to 4 PM PST Thursday
     for ORZ030-031.

     Flood Watch through Wednesday afternoon for ORZ021>024.

     High Surf Advisory until 10 AM PST Wednesday for ORZ021-022.

     Winter Weather Advisory from 4 PM Wednesday to 4 AM PST Friday
     above 3500 feet for ORZ024-027-028.

CA...Winter Weather Advisory from 4 PM Wednesday to 4 PM PST Thursday
     above 3500 feet for CAZ080-082-083.

     Wind Advisory from 7 AM to 4 PM PST Wednesday for CAZ081.

     Wind Advisory from 7 AM to 10 PM PST Wednesday for CAZ084-085.

     Winter Weather Advisory from 4 PM Wednesday to 4 PM PST Thursday
     for CAZ085.

PACIFIC COASTAL WATERS...Hazardous Seas Warning until 8 AM PST
     Wednesday for PZZ350-356-370-376.

     Small Craft Advisory from 8 AM Wednesday to 4 AM PST Friday for
     PZZ350-356-370-376.

&&

$$