719
FXUS66 KMFR 271752
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
1053 AM PDT Thu Mar 27 2025

Updated Aviation discussion.

.DISCUSSION...A low pressure system is centered off the coast near
45N 132W. This low will track towards the Oregon coast then
northward. This system will bring impacts from strong winds, rain,
and mountain snow today into early Friday. Behind this low expect
a cool and showery pattern over the area Friday, followed by
decreased showers and mainly dry weather on Saturday. Then,
another impactful frontal system may move into the area Sunday and
Monday.

As the low offshore approaches the Pacific Northwest coast and
tracks inside of 130W today, winds will increase with gusty winds
developing across the area and areas strong winds expected along
the coast, in the mountains, east of the Cascades and in the
Shasta and southern Rogue Valleys. Models continue to show a
strong lower level jet moving onshore along the coast today (925mb
winds of 70 kt) and a strong mid level jet moving inland (700 mb
winds of 55 to 65 kt). This combined with surface pressure
gradients of around -8 from North Bend to Arcata and Medford to
Redding, support strong winds with gusts of 60 to 70 mph along the
coast and in the Shasta Valley. Strong winds are also likely for
areas east of the Cascades, such as across mountains and into the
Summer Lake area. High wind warnings (NPWMFR) are in effect for
these areas. Advisory level winds, with winds gusting to around
45 to 50 mph are expected for other areas east of the Cascades and
for the southern Rogue Valley. Winds are expected to peak along
the coast this morning through this afternoon and for inland areas
late this morning into early this evening. Winds will trend lower
tonight, but expect some continued strong winds east of the
Cascades, mainly in the Summer Lake area and over the mountains.

Rain and snow will increase as the upper trough nudges inland
this afternoon into tonight. Today through tonight, heavy
rainfall of 1.5 to 4 inches is expected along the coast and into
the coastal mountains with 1 to 3 inches of rain into far western
Douglas, southwest Josephine and western and south-central
Siskiyou counties. Additional light to moderate rain is expected
on Friday. Snow levels will start out around 4500 to 5500 today,
lowering to around 3500-4500 ft late tonight into Friday morning.
Moderate snowfall accumulations are expected across some higher
passes, including the Diamond Lake and Crater Lake area and
mountains in western Siskiyou County. High resolution models also
indicate a chance (40-60%) for a brief period of 1 inch per hour
snowfall rates this evening over the Diamond Lake and Crater Lake
areas as well as over the summit for the Sawyers Bar road. A
winter weather advisory (WSWMFR) is in effect for these areas
today through Friday morning. Additionally, gusty winds combined
with snow may create lowered visibilities, especially for exposed
mountain locations. Travelers over these passes should be
prepared for winter travel conditions and take caution or delay
travel.

The upper low will remain off the coast of British Columbia on
Friday with an upper trough over the area and moist onshore flow,
bringing a cool and showery pattern over the area on Friday.
Additional light snow is expected across the higher passes in the
Cascades and other mountain passes. Snow levels will be around
3500-400 feet from the Cascades west and 4000-5000 feet east of
the Cascades on Friday.

The upper trough lifts northeast and a weak ridge builds inland
on Saturday. This will bring a break in the activity with only
light showers over western portions of the area, mainly along the
coast into Douglas county and the south-central Oregon Cascades.

Another low approaches from the southwest Saturday night and
sends a front into the area Sunday and Monday. This will bring
additional rain, mountain snow and gusty winds to the area. Winter
impacts are possible over the higher passes again, especially in
the Southern Oregon Cascades and over mountains in
western/southern Siskiyou county. Snow levels are forecast to be
around 4000 feet, rising to 4500-5500 feet during the day Sunday
then lowering again to 3000-4000 feet Monday. We will continue to
monitor this system for the potential for impactful snowfall and
gusty winds.

&&

.AVIATION...27/18Z TAFs...Convective showers are mainly concentrated
along the south coast, and coastal mountains which have resulted in
lower ceilings with the terrain at least partly obscured. This is
expected to be the cast through at least 12z tomorrow  morning.

The main concern to start is low level wind speed shear until the
stronger winds aloft mix down near the surface in the valleys west
of the Cascades in Oregon. This has already happened along the
coast, including North Bend. The stronger winds should surface at
Roseburg between 20-21z, and Medford, although it`s possible it
could be delayed at Medford until after 22z.

Once the stronger winds surface west of the Cascades, it will remain
windy at the terminals because we`ll be in a convective environment,
with gusty winds lasting into at least 6z this evening. Winds will
diminish some tonight, but it will remain breezy.

Strong winds east of the Cascades will continue into tonight. Winds
at Klamath Falls is already gusting to 38 knots as of writing this
discussion and it could gust as high as 45 kts this afternoon.

As previously mentioned, the lower ceilings into this afternoon will
be confined to the coast, and coastal mountains with MVFR and IFR
ceilings/visibility with the terrain obscured. Farther inland, VFR
ceilings are expected to be the predominate condition through for
most of the TAF period. However the higher terrain could be partly
obscured after 22-23z due to convective showers. -Petrucelli

&&

Updated 845 AM Thursday, March 27, 2025...A strong surface low is
just outside of 130 W and will move east inside of 130 W this
afternoon. Winds are increasing over the waters, and they should
peak out for about a 6 hour period late this morning into this
afternoon. An ACAT pass (which is a satellite derived wind speed
observation) from last night shows winds approaching storm force
south and southeast of the low. We should have another pass over our
waters late this morning, so we should have a clearer picture of
what the observations are showing. As of this writing, some of the
buoys are showing observed winds near or at gales and since we
expect winds to increase over time, Storm Force winds are still in
the cards from late this morning into this afternoon.

Winds will shift southwest and gradually diminish this evening and
tonight, but Gale Force winds will follow the Storm Force winds this
evening, followed by Hazardous Seas Warning conditions.

A heavy long period west swell at 14-15 seconds with very high and
dangerous seas of 25 to 30 ft will follow later this evening.

Another strong front is possible Sunday into Monday. This front
could move just south of the region which would limit the strength
of winds and height of the seas. Stay tuned as details become
clearer over the coming days. -Petrucelli

&&

.BEACH HAZARDS...Updated 200 AM Thursday, March 27, 2025...A long
period swell from the southwest (about 220 degrees) will hit the
Oregon coast later this morning, resulting in large breaking waves
along the beaches. Surf heights will be around 28 to 33 feet today
into the evening. Surf will reach peak heights in the afternoon.
Surf heights will decrease later tonight, but remain very high into
Friday morning.

These extremely large breaking waves will create very hazardous
conditions along beaches and area shorelines. Waves will inundate
beaches and surge into normally dry areas. Infrastructure damage and
significant beach erosion can be expected. Beaches and coastlines
will become dangerous due to very large and life-threatening surf
conditions. Stay off of beaches, rocks, jetties, piers, and other
waterside infrastructure. /DW

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 11 AM PDT Friday for ORZ027.

     High Wind Warning until 11 PM PDT this evening for ORZ021-022-
     030-031.

     Wind Advisory until 5 AM PDT Friday for ORZ026-029>031.

     High Surf Warning from 11 AM this morning to 11 AM PDT Friday
     for ORZ021-022.

CA...Winter Weather Advisory until 11 AM PDT Friday for CAZ080.

     High Wind Warning until 11 PM PDT this evening for CAZ081-085.

     Wind Advisory until 5 AM PDT Friday for CAZ084-085.

PACIFIC COASTAL WATERS...Storm Warning until 5 PM PDT this afternoon
     for PZZ350-356-370-376.

     Gale Warning from 5 PM this afternoon to 11 PM PDT this evening
     for PZZ350-356-370-376.

     Hazardous Seas Warning from 11 PM this evening to 11 PM PDT
     Friday for PZZ350-356-370-376.

&&

$$