018
FXUS66 KMFR 111034
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
334 AM PDT Tue Mar 11 2025

.DISCUSSION...There will be one more quiet day today before an
extended period of active weather begins this evening. Weak high
pressure will result in temperatures closer to that of early
April today, with mostly clear skies, aside from increasing high
cirrus clouds this morning into this afternoon.

By this evening, clouds will overspread the area and
precipitation chances will begin at the coast as the first of
several systems approaches the area. An upper level trough will
dig in just offshore of the Pacific Northwest, and a surface low
will form offshore then sweep to the northeast, making landfall
in British Columbia. The surface front will pass through southern
Oregon and far northern California Wednesday, bringing with it
gusty winds and plenty of precipitation.

Wind will be a concern in our usual trouble spots: the Shasta
Valley, the East Side, and over high terrain, but will not be
overly strong, as MSLP gradients are on the weaker side, and 700mb
winds are not expected to exceed more than 55 kt. This sets the
area up for mostly advisory level winds. Meanwhile, snow levels of
5000 to 6000 feet this evening will lower to around 4000 feet
with the passage of the front, with the exception of the Mount
Shasta area where upslope precipitation generation will be strong,
and precipitation rates will drag snow levels down to as low as
3500 feet. As a result, several Warnings and Advisories are in
effect for late Tuesday night into Wednesday. A winter Storm
Warning covers much of Siskiyou County, where 12 to 18 inches of
snow is possible above 4000 feet, and several inches are expected
in Mount Shasta City, McCloud, and Dunsmuir. A winter Weather
Advisory is in effect for the Cascades north of Lake of the Woods,
and for portions of the East Side, for a combination of several
inches of snow and gusty winds. Finally, a Wind Advisory is in
effect for the Shasta Valley. Details on the winter headlines can
be found at PDXWSWMFR, and wind advisory details can be found at
PDXNPWMFR.

Showers will then continue for much of the week as the upper
level trough slowly makes its way across the area and onshore flow
persists. It should be noted that much colder air dies return to
the region with the trough, and as showers continue, snow levels
may drop as low as 1500 feet Thursday morning, and 1000 feet by
Friday morning. This means that low elevations snow is possible
for the morning commutes, although amounts should be light.

The upper trough finally passes to the east Thursday night, then
the next trough arrives Friday, followed by another, potentially
stronger system Sunday, which has the potential to produce more
rain, snow, and wind impacts as we head into early next week. -BPN

&&

.AVIATION...11/06Z TAFs...Marine stratus continues to affect flight
levels along the Oregon coast, with MVFR ceilings at North Bend and
LIFR ceilings over Brookings. Satellite is showing clouds developing
in the Umpqua Valley, with a period of MVFR levels expected for
Roseburg into Tuesday morning. Lower levels are possible, but
extended periods of IFR or LIFR conditions in the Umpqua Valley, but
there`s lower confidence in that outcome.

Other areas will remain at VFR through this TAF period under high
ceilings. Cloud cover and winds look to increase towards the end of
the TAF period as active weather approaches the area. -TAD

&&

.MARINE...Updated 230 AM PST Tuesday, March 11, 2025...Calmer
conditions are expected through this afternoon. Then, south winds
will increase later this evening and night as a stronger cold front
approaches the waters. High end Small Craft conditions are likely
and low end gales are possible tonight through Wednesday morning.

The front will move inland later Wednesday morning with south winds
diminishing and shifting from south to southwest. However, a
westerly swell will increase late Wednesday afternoon into Thursday
evening, and seas will remain elevated for Small Craft conditions to
resume and continue through Thursday night once the Gale Warning
headline ends late Wednesday morning.

The pattern will remain active for the reminder of the week with a
series of systems moving through. There`s good agreement the first
could bring strong south winds Friday, followed by another round of
strong winds Saturday, timing of when winds will be strongest will
likely vary this far out into the forecast period, this we`ll keep a
close watch on this. -Petrucelli/Hermansen


&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory from 5 AM Wednesday to 5 AM PDT Thursday
     for ORZ027-028-030-031.

CA...Winter Storm Warning from 5 AM to 11 PM PDT Wednesday for CAZ080-
     082-083.

     Wind Advisory from 2 AM to 2 PM PDT Wednesday for CAZ081.

     Winter Weather Advisory from 5 AM Wednesday to 5 AM PDT Thursday
     for CAZ085.

PACIFIC COASTAL WATERS...Small Craft Advisory from 5 PM this
     afternoon to 11 PM PDT this evening for PZZ350-356-370-376.

     Gale Warning from 11 PM this evening to 11 AM PDT Wednesday for
     PZZ350-356-370-376.

&&

$$