Winter Storm in Oregon, February 1, 2025

Area Forecast Discussion
National Weather Service Medford OR
1002 PM PST Fri Jan 31 2025

.DISCUSSION...

Showers are ongoing this evening with snow levels stuck around
4500 feet, although colder air is lurking just to the northwest
behind this front. The QPF will be low within this cooler air and
snow accumulation should be trace amounts right around 2500 feet
tonight. With that being said, the high central Cascades will
still see up to an additional foot of snow accumulate overnight
into Saturday morning.

-Smith

.AVIATION...01/06Z TAFs...LIFR to MVFR ceilings and visibilities
have been observed over the past few hours among all our TAF sites.
In general, LIFR ceilings will settle into the coastal locations
and some of the valleys tonight, although the showers could mix
things up briefly.

Farther inland, some LIFR visibilities have been observed here at
the office, although the cloud cover seems to be enough to keep
mixing the boundary layer and clear us out briefly. That trend
should continue overnight.

In general, conditions will improve in Oregon towards the end of the
TAF period as most of the moisture and precipitation will be farther
to the south. North Bend and Roseburg could see VFR conditions
Saturday afternoon.

-Smith

.MARINE...Updated 815 PM Friday, January 31, 2025...Rain showers
will continue over the waters through Saturday morning. Southwest
winds will shift to northwest and gradually diminish overnight as a
cold front slowly shifts inland. But, seas will remain steep tonight
through early Sunday morning. Low pressure will persist early next
week with swell dominated seas expected to diminish slightly. A
series of stronger disturbances may arrive as early as Tuesday
night, with gales and very high seas possible late in the week.
-DW

.PREV DISCUSSION... /Issued 248 PM PST Fri Jan 31 2025/

A very challenging forecast is upon us. The first front that
moved onshore last night and this morning is moving east and
another secondary front will move through tonight, then gradually
push south of the area on Saturday. This is creating winter
hazards for the mountains (mostly 4000 feet and above). Web cams
and observations this afternoon have shown some snow at Mount
Shasta City and along I-5 near Siskiyou Summit, but most of the
snow impacts are above those elevations. This will continue to be
the case tonight into Saturday morning with snow levels generally
wavering between 4000 and 5000 feet ahead of/with the front. As
the front settles southward, snow levels will drop to 2000-3000
feet west of the Cascades, but precipitation will also be ending
from NW- SE, so we don't expect any lower elevation snow impacts.
Precipitation should taper off for most areas Saturday
afternoon/evening, so those initial winter headlines will probably
be allowed to expire.

The front will then stall across northern California and a surge of
subtropical moisture with high IVT will traverse along the stalled
frontal boundary allowing precipitation to return from the south.
Models continue to show significant spread in the position of this
moisture boundary and that has huge implications with snow levels
and snow amounts, just based on where it sets up. But, it does
look like the largest impacts from this moisture plume will be in
northern California and up into portions of southern Klamath/Lake
counties. Right now, we have decided to issue a Winter Storm Watch
for elevations above 4500 feet for most of Siskiyou and Modoc County
as well as portions of SE Klamath and southern Lake Counties for
Saturday night through Monday morning. Snow amounts in these areas
could range from 10-20 inches with more than that on the highest
peaks (Warner Mtns). Significant rainfall will occur below the snow
level and this could bring ponding of water on roadways, but also
significant rises to area creeks, streams and rivers. These areas
could have 2 to 5 inches of liquid precipitation. While some
flooding is a possibility, since river systems have been running low
due to the long stretch of dry weather we just had and snow levels
are fairly low, the risk still remains on the low side.

Meanwhile, cold low pressure to the north just off the BC coast,
will continue to press slowly southward. Snow levels will continue
to drop Sunday into Monday west of the Cascades, perhaps to 1500-
2500 feet (1000 feet close to the coast?), but QPF amounts appear on
the light side. While there may be some minor winter impacts over
the higher passes north of Medford, it'll take a bit longer for the
colder air to move in. Models show a wave forming along the front to
the south, which should move through NorCal on Monday. Eventually,
the low to the north will increase westerly flow from the Pacific
and this will kick the moist plume eastward (most likely Monday
night into Tuesday). The cold air mass will then take over causing
snow levels to plunge to the valley floors (and perhaps even to
the coast). Next week is setting up to be quite wintry around here,
so please keep checking back here for updates on the forecast as we
get closer and we'll have more information on potential snow
amounts. -Spilde

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 10 AM PST Saturday for ORZ029>031.

     Winter Storm Watch from Saturday evening through Monday morning
     for ORZ030-031.

     Winter Storm Warning until 10 AM PST Saturday for ORZ027-028.

CA...Winter Weather Advisory until 10 AM PST Saturday for CAZ080-082-
     083-085.

     Winter Storm Watch from Saturday evening through Monday morning
     for CAZ080-082-083-085.

PACIFIC COASTAL WATERS...Small Craft Advisory until 4 AM PST Sunday
     for PZZ350-356-370-376.

&&