925
FXUS66 KMFR 230448
AFDMFR

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

...Update...


.DISCUSSION...

The biggest change this evening was to update Marine hazards (see
Marine and Beach Hazard sections below for further information)
to account for the strong low pressure system making its way
towards the Pacific Northwest. This does include a new High Surf
Advisory for areas along the coast on Monday, as well as the
upgrade to a Storm Warning over the waters on Monday for very
strong wind speeds.

Otherwise, rainfall continues across the area, and for the most
part is falling in line with the current state of the forecast.
The overnight period and into Sunday morning will likely be the
heaviest rainfall from this atmospheric river event. Travel on
Sunday morning could be messy and dangerous at times, especially
areas along and near the coast where the heaviest rainfall is
forecast. However, it should be noted that moderate rainfall is
anticipated to continue Sunday into Monday with messy roads likely
to follow suit. While 24hr rainfall totals wont be as heavy
Sunday into Monday, it should be noted the ground will be very
saturated from previous rainfall, so impacts may be higher on
Sunday into Monday due to saturated soils and increased runoff.
This means the Monday morning commute could be messy and dangerous
again...even with less rainfall forecast. Rainfall is anticipated
to taper off Monday night into Tuesday morning.

-Guerrero

&&

.MARINE...Updated 815 PM PST Saturday, February 22, 2025...An
active weather pattern will cause very hazardous conditions this
weekend into next week. Gales persist into tomorrow afternoon 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 tomorrow morning. There will be brief
break in strong winds later tomorrow 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. With the potential for storm force gusts, the Storm
Watch has been upgraded to a Storm Warning. 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/Hermansen

&&

.BEACH HAZARDS...Updated 815 PM PST Saturday, February 22,
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. A High Surf Advisory will be in effect through
this time. 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/Hermansen

&&

.PREV DISCUSSION... /Issued 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 4 AM PST Sunday through Monday morning for
     ORZ021-022.

     High Surf Advisory from 10 AM Monday to 10 AM PST Tuesday 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 Warning from 4 AM to 7 PM PST Monday for PZZ350-356-370-
     376.

&&

$$