Gale Warning 4, NWS Medford, OR

Area Forecast Discussion
National Weather Service Medford OR
1015 AM PST Tue Feb 11 2025

.UPDATE...Updated Aviation Discussion.

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.AVIATION...11/18Z TAFs...Areas of LIFR/MVFR low clouds and fog
persist late this morning in some of the valleys west of the
Cascades, as well as some basins of the East Side. It has cleared
out to VFR here in the Rogue Valley at Medford and also Klamath
Falls with VFR expected to remain through at least this evening. In
Roseburg, an MVFR ceiling right now should break to VFR this
afternoon. Some of the more sheltered valleys that have the low
conditions right now like the Shasta Valley may take a while into
this afternoon before VFR returns for a few hours.

Tonight, high pressure will allow for some low clouds/fog to reform
in the valleys. We have LIFR at Klamath Falls and this looks good
based model soundings and the trends from the last couple of nights.
And, enough low-level moisture in the Umpqua Basin brings higher
confidence to introduce some there as well toward morning. Model
soundings in Medford/North Bend show less moisture, so confidence is
higher to keep VFR there through Wednesday morning.

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.MARINE...Updated 830 AM PST Tuesday, February 11, 2025...North
winds and steep wind-driven seas will persist through this afternoon
from Cape Blanco southward and beyond 10 NM from shore. Conditions
improve with a break in hazards tonight into Wednesday with seas in
the 4-5 foot range. A frontal system with gusty south winds and very
steep seas is expected to arrive Wednesday night and push through on
Thursday. New model guidance this morning is showing the front
moving in a bit faster late Wednesday evening with a period of
stronger winds overnight into Thursday. This may result in gales for
portions of the area. We'll evaluate these data and make adjustments
to current headlines this afternoon. Thereafter, large long period
swell Thursday night into Friday will follow on the backside of the
low pressure system which could build seas around 14-17 feet at 15-
17 seconds. This will at least maintain hazardous conditions to
small craft over the marine waters, but will also bring hazards to
area surf/beaches.

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.PREV DISCUSSION... /Issued 342 AM PST Tue Feb 11 2025/

DISCUSSION...Frigid temperatures and dry conditions will be the
theme through Wednesday morning. Satellite imagery this morning
shows cloud cover entrenched the East Side and Shasta Valley with
stratus banked up along the Umpqua Divide and Siskiyous. A weak
front is moving through the region this morning. The north to
south trajectory of this front will keep things mostly dry, though
some isolated showers are possible along the Cascades north of
Crater Lake and maybe into northern portions of Klamath/Lake
Counties. Any precipitation amounts will be light, so no big
impacts are expected with this front. Behind the front, however,
the air mass will cool further and overnight temperatures are
expected to trend lower, especially tonight/Wednesday morning.
With the exception of the coast south of Port Orford, a Cold
Weather Advisory remains in place through Wednesday morning.
Additionally, a Freeze Warning remains in effect for communities
along the immediate coast through Wednesday morning. Details on
these cold weather products can be found at NPWMFR.

Wednesday will serve as a transition day. Dry conditions are
expected through the day, though expect increasing cloud cover as
the first impactful system approaches the region. This increasing
cloud cover will to moderate overnight temperatures, so we'll trade
the frigid temperatures for the return of gusty winds and
precipitation Wednesday night into Thursday. There's pretty good
agreement on a front arriving very early Thursday morning and
pushing inland through the day Thursday. The associated low pressure
looks to move onshore along the southern Oregon Coast, and this will
send the bulk of the precipitation into northern California. This
looks like a typical southerly flow system with the more impactful
weather expected across Siskiyou County, with lesser but still
impactful weather expected north of the OR/CA border. Snow levels
are expected to rise with this system, but there is some uncertainty
regarding how fast this happens. Initially, snow levels will be down
to around 1000-1500 ft when precipitation arrives, gradually rising
to around 3500-4000 ft by Thursday afternoon. Given the early
morning arrival time, it's not out of the question that some West
Side Valleys see some light snowfall (0.5-1 inch) early Thursday
morning before transitioning to rain later in the morning,
especially for the Illinois Valley and potentially into the Umpqua
Basin depending on how far north this system ends up. There are some
factors going against snow potential here in the Rogue
Valley...model 850 temperatures look to be too warm, hovering around
-1 degrees C to +1 degrees C and we typically need values at or
below -3 degrees C. Also, we're expecting some breezy southeast
winds in the valley, which not only tends to limit precipitation,
but also keeps temperatures warmer due to downsloping effects. The
question will be how far north in the valley do these winds reach?
It could be gusty in Ashland (warmer/drier?) while winds are calm at
the Medford Airport (colder/wetter?), leading to conditions more
favorable for snow in Medford vs Ashland despite the higher
elevation. Would like to see this resolved by High Resolution
Ensemble Forecast (HREF) as it tends to handle these events the
best, and this time frame will come into that models forecast range
later this morning. Regardless of if precipitation starts out as
snow or not, snow levels will gradually rise through the day
Thursday, and should all be rain for West Side Valleys by late
morning/afternoon hours.

Given the southerly flow nature of this system, we do expect winter
impacts in the Mt Shasta City region where we currently have around
4-8 inches of snow in the forecast from 4 am Thursday - 4 am Friday,
with 12 to 15 inches for areas above 4500 ft. A Winter Storm Watch
remains in place for these potential impacts. For the same time
frame, we have generally 1 to 3 inches in the forecast for areas
east of the Cascades with the exception of the Highway 97 corridor
from Chiloquin northward where the current forecast has 3 to 5
inches. Meanwhile, the Cascades will see a healthy dose of snow
accumulations as well, but more in the Advisory range of 6 to 10
inches. If you have travel plans for the latter half of the week, be
prepared for wintry conditions.

In addition to the return of rain/snow, we'll see gusty winds return
to the area, especially along the coast, east of the Cascades and in
the Shasta Valley. Mid level winds are expected to peak around 45-50
kts, so while we aren't expecting any warning level wind speeds at
this time, there could be a need for some wind advisories for this
system. Gusts of 25-35 mph will be common in the windy locations,
including the southern end of the Rogue Valley, and gusts up to 45-
50 mph are possible for the higher terrain, maybe even the Shasta
Valley. Stay tuned as the time draws nearer and details become more
clear.

Late Thursday into Friday, the trough axis swings through the
region, bringing widespread showers and snow levels around 3500 to
4000 feet. Continued moderate to heavy snowfall is likely across
higher elevations in Siskiyou county during this time along with
light to moderate snow in the Siskiyous, Cascades and across the
East Side. We should catch a break in the weather for much of the
day Saturday before the next system approaches Saturday night into
Sunday. This system will track farther north than the mid-week
front, with low pressure moving inland into Washington. This will
bring higher snow levels late in the weekend/early next week, around
5000-6000 ft or so, as well as another round of gusty winds. The
best chances for impacts from light to moderate snow will be over
the higher passes and in the mountains. There's some uncertainty
regarding how far south precipitation makes it with this system with
some solutions tracking the low farther north than others. Stay
tuned. /BR-y

AVIATION...(11/12Z TAFs)...

Expecting conditions to be mostly VFR through this cycle, but this
morning we are expecting some isolated IFR conditions. Then clouds
will thin out this afternoon with clearing, but high clouds are
expected to infiltrate in from the south/southwest later today.
Uncertainty exist tonight with low cloud/fog development, but
current thinking is low/mid level dry air will win out and we should
be mostly VFR. Klamath Falls currently had enough confidence to
introduce low clouds tonight, but elsewhere confidence was higher
for a VFR forecast with mainly high clouds.

-Guerrero

BEACH HAZARDS...Updated 230 AM PST Tuesday, February 11, 2025...In
the wake of an upcoming low pressure system, a long period west to
southwest swell train will move in likely resulting in hazardous
breaking waves in the surf zone Thursday night into Friday. Guidance
is consistently showing marine waves in the 14-17 foot range which
would bring large breaking waves around 20-24 feet to area surf and
beaches. These waves could wash over rocks/jetties and into normally
dry areas. Beach erosion is also possible. Use extra caution if you
plan to visit area beaches late this week.

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.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Cold Weather Advisory until 9 AM PST Wednesday for ORZ021-
     023>031.

     Freeze Warning until 9 AM PST this morning for ORZ021-022.

CA...Cold Weather Advisory until 9 AM PST Wednesday for CAZ080>085.

     Winter Storm Watch from Wednesday evening through late Thursday
     night for CAZ080-082-083.

PACIFIC COASTAL WATERS...Hazardous Seas Watch from late Wednesday
     night through Thursday afternoon for PZZ370-376.

     Small Craft Advisory until 4 PM PST this afternoon for PZZ376.

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