076
FXUS66 KMFR 222245
AFDMFR

Area Forecast Discussion
National Weather Service Medford OR
245 PM PST Sat Feb 22 2025

.DISCUSSION...

The leading edge of a a strong atmospheric river has started to
make landfall this afternoon and evening. So far, precipitation
has been light with little to no accumulation, although we`re
expecting 2 to 6 inches of rain along the Oregon coastline with
the lower amounts east of the Cascades through Monday. The thing
of concern remains how warm this airmass is and how much moisture
is arriving. Precipitable water, which is a good measure for how
much moisture is in a column of air, is in the 99th to 99.5th
percentile for this time of year. Record values for Medford is
about 1.2 inches, although we`ll fall short of those values by
only hitting 1 inch. In any case, that is a testament to how much
moisture will be in the air through tonight into Monday.

With snow levels shooting up to 9000 feet, essentially all areas
will see rain through the weekend with rain falling on the heavy
snow east of the Cascades. There is concern the flooding risk
could be higher in that section of our area near Chemult and
Crescent with 1 inch of rain falling on all the snow. However, the
snow can absorb some of that rain. Also, the rivers are not rising
rapidly and hitting action stage, so some of that liquid can
become trapped in that snow if we`re cool enough. In any case, it
will be something to watch as we move through tonight and Sunday.

By Monday, winds will be the biggest concern with a strong low
deepening 100 miles west of Astoria. The latest set of ensembles
are starting to converge with a stronger low around 988mb forming
around that location with some of the deterministic guidance
dropping down to 979mb. In any case, the high wind watches look
pretty good at this point and the wind threat will likely spread
to other areas in form of advisories. This storm isn`t historic
wind wise and is pretty typical for a strong winter storm.
However, a few power outages along with unsecured objects blowing
in the wind could result of the strong wind gusts arriving Monday
afternoon.

High pressure will begin to build Tuesday afternoon and persist
into Wednesday over southern Oregon and northern California with
precipitation on the downtrend. Temperatures will begin to feel
more spring like with highs in the mid 60`s west of the Cascades
and upper 50`s east of the Cascades. These highs are about 10
degrees warmer than normal for this time of year.

Ensembles are then predicting a low chance of precipitation towards
Thursday as an upper level wave or cutoff low pushes into
southern Oregon. Precipitation will likely be light with the QPF
under 0.01 inches Thursday.

-Smith

&&

.AVIATION...22/18Z TAFs...Widespread VFR prevails early this morning
with a mid-level cloud deck moving in from the Cascades west. Patchy
MVFR fog (visibility) has been in and out at Klamath Falls this
morning, but should clear out by 19z. This afternoon and tonight,
light rain and MVFR ceilings/vis will overspread the area from west
to east as a frontal system offshore moves in. Gusty south winds
will develop at the coast at North Bend, perhaps up to ~30kt. While
t his could preclude low-level wind shear (LLWS), have decided to
include in the TAF for the instances when the wind dies down at the
surface at times. However, there is a higher probability of LLWS at
RBG, MFR and LMT since surface winds in those locations are probably
a bit lower. Have also bumped up the start time for LLWS for areas
along the coast and west of the Cascades, beginning between 21z-00z
this afternoon. -Spilde/BR-y


&&

.MARINE...Updated 130 PM PST Saturday, February 22, 2025...An active
weather pattern will cause very hazardous conditions this weekend
into next week. Winds will soon increase to gales this afternoon and
persist into Sunday with very steep, hazardous seas, highest near
and north of Cape Blanco. A coastal jet looks likely to develop near
and north of Cape Blanco this evening, which will likely expand
south of Cape Blanco at times through Sunday morning. There will be
brief break in strong winds late Sunday into early Monday, but seas
will remain very steep and hazardous across all areas well into
Monday.

The strongest system in the series is expected on Monday as a
deepening surface low moves northward along 130 W, then eventually
onshore near the WA/Canadian border. This is a classic pattern for
very strong winds over the marine waters, and we expect widespread
strong gales Monday morning and afternoon. Guidance is in fairly
good agreement indicating storm force gusts during this time as
well. There remains some uncertainty in the exact track of the
storm, and this could change where the strongest winds are. We have
left the Storm Watch in place for all waters, but at this time, it
looks like the best chances for storm force gusts will be north of
Cape Blanco, but possibly as far south as Brookings. In addition to
these strong winds, this front will build dangerous seas of 20-28 ft
from Gold Beach northward, with seas peaking at 16-20 ft south of
there.

Winds will ease Monday night, but very steep seas will persist into
Tuesday. Things should calm down from Wednesday onward, but guidance
has trended higher with a moderate long period west swell (11-13 ft
@ 15-17 seconds) building into the waters for the latter half of the
week. /BR-y

&&

.BEACH HAZARDS...Updated 130 PM PST Saturday, February 2,
2025...Strong, potentially storm force, winds will affect the marine
waters on Monday. This will quickly build seas, and when combined
with an increasing west swell, is likely to result in breaking waves
heights of 25 to 30 ft Monday afternoon into Tuesday morning.
Hazardous beach conditions will be possible during this time, and
these large breaking waves could inundate beaches and low lying
structures. Beach erosion will be possible, and exposed
infrastructure may be damaged. Avoid area beaches during this storm
Monday. /BR-y

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Watch from Monday morning through Monday evening for
     ORZ021-022-030-031.

     Flood Watch from late tonight through Monday morning for ORZ021-
     022.

CA...High Wind Watch from Monday morning through Monday evening for
     CAZ081-085.

PACIFIC COASTAL WATERS...Gale Warning until 4 PM PST Sunday for
     PZZ350-356-370-376.

     Hazardous Seas Warning from 4 PM Sunday to 4 AM PST Monday for
     PZZ350-356-370-376.

     Storm Watch from late Sunday night through Monday evening for
     PZZ350-356-370-376.

&&

$$