444
FXUS66 KMFR 150557
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
957 PM PST Thu Nov 14 2024

.Updated AVIATION Discussion...

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.AVIATION...15/06Z TAFS...Overall, a mix of VFR/MVFR prevail across
the region with isolated showers that should gradually diminish
after midnight. Though showers will diminish, cloud cover will
linger well into Friday afternoon so expect the continuation of
terrain obscurations through then. If there`s enough breaks in the
cloud cover later tonight, it could result in areas of IFR ceilings
and visibilities for the interior westside valleys late tonight into
Friday morning, but confidence is low in extent and location of this
occuring. Conditions will improve to VFR late Friday morning, with
some showers/terrain obscurations continuing near the Cascades, the
Cascade Foothills, the Siskiyous and over by the Warner Mtns. /BR-y

&&

.PREV DISCUSSION... /Issued 826 PM PST Thu Nov 14 2024/

DISCUSSION...Here are a few 24-hour totals since 7:45 PM:
Medford: 0.54", Roseburg: 0.76", Coos County: Near 0.75"-1",
Western Siskiyou: 0.75"-1.25", and Lake County Airport: 0.32".

Radar currently shows a few more showers at the coast and in Jackson
County moving south. Lingering showers continue through tomorrow
afternoon, and less than an inch of new snow is expected in most
locations with around a tenth of an inch for new rainfall west of
the Cascades. Northerly winds will turn slightly breezy tomorrow
afternoon with gusts near 15-20 kt possible. The forecast is on
track, and the next area of concern is the Sunday system which is
discussed in the previous discussion. -Hermansen

MARINE...Updated 800 PM PST Thursday, November 14, 2024...

Showers and an isolated thunderstorm or two will continue through
tonight. Winds continue to shift, becoming northerly tonight into
Friday and swell dominated seas will remain elevated and hazardous
to small craft through Friday evening. Eventually, seas lower below
10 feet by Saturday morning. This improvement will be short lived,
however, with another front expected late Saturday through Sunday
with gusty south winds and steep to very steep seas. This will be
followed by another large swell late Sunday into Monday.

Lastly, while uncertainty is high due to a widespread variety of
model solutions, we are monitoring the potential for a strong storm
to develop over the eastern Pacific Ocean around mid-week. If far
enough east, this system has the potential (about a 15-30% chance at
this time) to bring high end gales to all the waters with storm
force gusts. Stay tuned as the time gets closer and details become
more clear. /BR-y

PREV DISCUSSION... /Issued 521 PM PST Thu Nov 14 2024/

SHORT TERM...Thursday evening through Sunday morning...A
lingering upper trough will keep scattered showers in the forecast
through Friday evening across northern California and southern
Oregon. Southwest flow aloft will support shower chances west of
and along the Cascades today, while northerly flow on Friday could
bring more activity east of the Cascades. Slight chances for
thunder (10-20%) remain in the forecast for areas west of the
Cascades through this evening given upper level instability, but
lightning flashes have not been sensed so far today so
thunderstorms seem unlikely. Snow levels of are currently between
4000-5000 feet and will lower to 2500-3500 feet on Friday. Snow
showers will be possible over the Cascades, but with only 1 to 2
more inches expected in this area through Friday afternoon. The
upper flow on Friday could bring 2 to 6 inches of snow over the
highest peaks in southern Lake County while other areas will get
an inch of snow or less. Overall, both rain and snow showers look
to be unimpactful through Friday night.

An upper ridge will start developing over the area early Saturday
morning, bringing a few dry hours on early Saturday morning. Later
in the morning to early Saturday afternoon, a warm front will bring
precipitation chances back to the area through early Sunday morning.
Warm air behind the front will lift snow levels to 6500 feet or
higher, so snowfall is not a concern for this part of the weekend.
Showers will start at the coast and move eastward through the day,
with the highest precipitation amounts over the Oregon coast and
eastern Douglas County up into the Cascades. These areas are
forecast to get between 0.75 and 1.0 inches of rain. The Umpqua and
Illinois valleys are expected to get about 0.4 to 0.5 inches, and
the Rogue Valley could get 0.2 inches or less. For areas east of the
Cascades, northern Klamath County could get between 0.25 and 0.33
inches, while other areas will get 0.1 inches or less.

This front will not be impactful as far as hazardous conditions.
Moderate to heavy showers will be possible, especially along the
coast and higher terrain. Strong winds and thunderstorms are not
expected. Taking a look at river forecasts shows a reasonable rise
given expected additional precipitation, but area rivers are not
near flood levels. A cold front follows the warm front on Sunday
afternoon, which will be discussed in the long-term forecast. -TAD

EXTENDED DISCUSSION...(Sunday through Thursday)...The cold front
will push into the area Sunday at which point we`ll have moderate to
occasional precipitation along and just ahead of the front, with
snow levels possibly lowering to the higher passes as colder air
aloft gets dragged down in areas of moderate to heavy precipitation.
The front will move from northwest to south late Sunday afternoon
and night, and we`ll see snow levels dropping down between 3000 and
3500 feet early Monday morning. However precipitation will become
more showery which should put a cap on the amount of snow for the
passes. Even so, snow covered roads for Diamond Lake, Lake of the
Woods, and Siskiyou Summit are likely.

Monday will be a transition day with the upper trough exiting out
with showers diminishing during the morning followed by increasing
dry time in the afternoon.

An upper ridge axis will build into the area Monday night and
continue into Tuesday. It will be dry, but with a subsidence
inversion, could lead to fog and low clouds for the interior
westside valleys.

There`s good agreement among the operational models and ensembles
the upper ridge axis will shift just east of the forecast area
Tuesday night as upper troughing over the eastern Pacific digs.
However the upper trough won`t make much progress east between
Tuesday night and Thursday. At the same time a front will slowly
nudge towards our forecast area during this time, but it will be
nearly parallel to the upper flow. Usually when this happens, front
will have a difficult time making much if any progress. looking f
further into the individual ensembles (ECMWF and GFS) and clusters
show the mean upper trough far enough offshore with a ridge presence
over our area. Given the above, the odds are in our favor of dry
conditions to continue during this time. -Petrucelli

&&

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

PACIFIC COASTAL WATERS...Small Craft Advisory until 10 PM PST Friday
     for PZZ350-356-370-376.

&&

$$