Small Craft Advisory 13, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
1011 AM PST Fri Jan 31 2025

Updated AVIATION section

.DISCUSSION...Rain and snow began overnight, and some areas from
a line of Grants Pass to Roseburg west have seen near 0.5"-1.0"
already! Current radar shows the heaviest precipitation in Jackson
and southeastern Douglas counties with showers across most areas
west of the Cascades. On average snow levels will remain at 5,000
feet and above today. Later this morning and into the afternoon
there is a 70+% probability for more areas in the southern Oregon
Cascades to have an inch of snowfall per hour, and the Winter
Storm Warning will continue through tomorrow morning for this
snowfall. New rainfall amounts through this evening will bring
another 0.10"- 0.25" for west side valleys.

The next area of concern will be Saturday night into early next week
with the next wave of precipitation moving back north into the area.
The forecast still brings lower snow levels in the coming days, but
we will be analyzing this to see how quickly they lower to west side
valley floors. -Hermansen

&&

.AVIATION...31/18Z TAFs...A front continues to move across the area
at this time with widespread MVFR, local IFR and widespread higher
terrain obscuration due to rain and snow. These conditions will
persist tonight into Saturday morning. Gusty winds will also
accompany the front with the highest gusts over the East Side. These
winds should ease though tonight as mid-level winds lower behind the
front moving into northern California. -Spilde

&&

.MARINE...Updated 815 AM Friday, January 31, 2025...Rain showers
are expected to continue over the waters today and tonight with a
small chance (<20%) for an isolated thunderstorms or two. Conditions
are shifting back to small craft advisory conditions through the
rest of today. Though light to moderate west to northwest winds will
diminish through the weekend, steep seas are expected through early
Sunday morning. This is due to a fresh northwest swell train. Low
pressure will persist early next week with swell dominated seas
expected to diminish slightly.

-Guerrero/Hermansen

&&

.PREV DISCUSSION... /Issued 329 AM PST Fri Jan 31 2025/

DISCUSSION...The upper ridge that had been so dominant over past
weeks has moved to the east, with a upper trough approaching to
take its place. Showers are being observed at North Bend as well
as coastal and western Siskiyou County RAWs sites, and radar is
showing ample returns as clouds move over northern California and
southern Oregon.

Westerly flow aloft from the trough will help to bring
precipitation through the end of the week and possibly into next
week. An initial cold front will support an initial wave of
activity today through Saturday morning. While snow levels will
remain somewhat high at 5000 feet or above, the significant amount
of moisture moving over the area will allow for substantial
snowfall totals. 12 to 24 inches of snowfall are expected along
the Cascades for most areas, with up to 36 inches possible over
the highest peaks and ridges. Snowfall rates of 1 inch per hour or
more will be possible over the Cascades through Saturday morning.
Higher terrain on the Lake/Klamath County border, the Warner
Mountains, terrain east of Mount Shasta, and higher terrain in
western Siskiyou County could also see 8 to 24 inches of snowfall.
A Winter Storm Warning along the Cascades and Winter Weather
Advisories for these other areas are in place through Saturday at
10 AM to communicate expected hazardous conditions in these areas.

The highest rainfall amounts are expected over coastal areas
south of Cape Blanco and westernmost Siskiyou County. These areas
could get 2 to 3 inches of rain, with guidance suggesting area
peaks could get up to 4 inches. Areas north of Cape Blanco as well
as west side valleys are forecast to get between 0.5 and 1.0
inches of rainfall. Areas east of the Cascades below expected snow
levels are expected to get 0.5 inches or less of rainfall.

Gusty southerly winds will also develop in certain areas today as
the cold front moves over the area. Gusts along the coast could
reach 20 mph in low-lying areas to around 40 mph over higher
terrain. Observations indicated that southerly winds funneling into
southern Shasta Valley have reached 58 mph, with higher speeds
possible through the day. A previous Wind Advisory for the southern
Shasta Valley has been escalated to a High Wind Warning, and will
remain in place until 7 PM tonight. Other areas that might see gusty
winds (Cascades, other elevated terrain) are already under winter
hazard products.

Activity is expected to decrease Saturday afternoon into Sunday,
although continuing westerly flow aloft could allow for additional
scattered showers west of and over the Cascades. Uncertainty remains
for Sunday and beyond, as slight variations in the actual pattern
could substantially change the outcome. To summarize the general
expected pattern, the low pressure system forming the upper trough
bringing today's activity looks to move southward, then stall
somewhere near the Pacific northwest. A separate low pressure system
looks to settle over the central Pacific and move moisture far
enough north to be drawn into the low over the PNW. This could bring
both abundant moisture and arctic air, as well as southerly flow that
tends to bring snowfall to the Mount Shasta area. In some outcomes,
impactful snowfall could reach valley floors. Using Medford as an
example, some members for both the ECMWF and GFS expect multiple
inches of snowfall while others expect nothing at all. Of course,
all of this depends not only on the actual placement of the system
moving over the PNW but on the low over the Pacific and how these
two systems interact. Activity does look to continue, as indicated
by the 60-80% precipitation chances that are in the forecast for
Sunday morning and beyond. But what that activity is and how much of
it there will be remains to be seen. Please stay tuned to future
forecasts as additional information brings additional clarity to
what could be a very unique situation. -TAD

AVIATION (12Z TAFs)...

A front is bringing widespread showers across the region which has
resulted in deteriorating conditions. Expecting conditions to only
worsen through the TAF cycle, with IFR/MVFR conditions very likely
for all terminals. At times, wind speeds will be breezy as the front
passes, but by tonight we should see those wind speeds ease.
However, this will allow for ceilings and visibilities to lower
overnight as well.

-Guerrero

&&

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

     High Wind Warning until 7 PM PST this evening for CAZ081.

PACIFIC COASTAL WATERS...Gale Warning until 10 AM PST this morning
     for PZZ350-356-370-376.

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

&&