Winter Storm in Oregon, March 4 to 5, 2024

Area Forecast Discussion
National Weather Service Medford OR
931 AM PST Mon Mar 4 2024

.DISCUSSION...

Not much has changed over the last few days with snow falling on
the valley floors in the morning hours, although struggling to
accumulate with surface temperatures slightly above freezing in
some regions. The pattern will remain fairly showery over the
next few hours before the precipitation mode becomes more
stratiform as a warm front attempts to push through the forecast
area. Impacts from these snow showers for the remainder of the day
will remain minor, although travel impacts will likely be major in
the Cascades later this evening into Tuesday.

For more details on the upcoming winter storm, read the discussion
below.

-Smith

&&

.AVIATION...04/12Z TAFs...Scattered showers continue across
southern Oregon and northern California this morning with snow
levels near a minimum of around 500-800 feet. Expect widespread MVFR
conditions with areas of IFR/LIFR in snow showers.  There is also a
slight chance of thunderstorms from the coastal waters to the Coast
Range.

During the day into this evening, snow levels will rise, to around
2500-3500 feet (locally lower in the Umpqua Basin), while an
approaching warm front brings increasing coverage of precipitation,
mountain obscuration, and continued widespread MVFR with ares of
IFR/LIFR.  The front will remain nearly stationary over the area
tonight into Tuesday, with these conditions continuing. Colder air
north of the front will result in a sharp gradient in snow levels,
with 1000-1500 feet levels to the north of the Umpqua Divide and
2500 to 3500 foot levels to the south. This gradient will impact
where showers turn from rain to snow as well as creating possible
freezing hazards and lower ceilings/visibilities. -DW/CC

&&

.MARINE...Updated 800 AM Monday March 04, 2024...High and steep,
swell-dominated seas continue for all marine waters through late
this morning.

Elevated 15% thunderstorm chances remain over most marine waters
through this morning, with the best chances with 30 nm from the
shore south of Cape Blanco and within 40 nm of shore north of Cape
Blanco. Winds from these cells may gust up to 30 kt.

Low pressure moving into the waters south of Cape Blanco late this
evening and tonight will bring advisory strength southerly winds
south of Port Orford. Northerly winds are then likely to increase
over the outer waters Tuesday night into Wednesday evening, and are
likely to reach advisory strength at least south of Cape Blanco. -CC

&&

.PREV DISCUSSION... /Issued 306 AM PST Mon Mar 4 2024/

DISCUSSION...Once again, light showers continue across the
region early this morning. Accumulations through about midday
today will be light for the most part, although a few localized
areas could pick up several inches in heavier showers. Snow levels
of around 1000 feet early this morning will rise to about 1500
feet by midday, just in time for the next system to arrive.

The upper level trough that has brought so much active winter
weather to the area is beginning to fill and push to the north and
east. Meanwhile, the next upper level trough is approaching the
Pacific Northwest in the wake of the departing system. The
associated surface low arrives at the coast along with a warm
front Monday, then meanders just offshore of southern Oregon as
the upper level trough slowly digs southeast and takes position
offshore of central California. As a result, the warm front stalls
out over our forecast area just as moisture inflow intensifies
from the south.

Snow levels south of the front will rise to about 3000 feet,
while those to the north will hover around 1500 to 2000 feet.
Therefore, exactly where this boundary sets up will make a huge
difference in where and how much snow any given location receives
Monday into Tuesday. Model consensus places the front along a
line from Cape Blanco east to Crater Lake, and right over the
Interstate 5 passes between Grants Pass and Canyonville. This
leaves the Umpqua Basin with much lower snow levels than the rest
of the region, thus the Winter Storm Warnings there encompass much
lower elevations than the rest of the forecast area. Should the
warm front waver to the north or south, conditions could change
drastically, so anyone traveling in the area Monday should keep an
eye out for forecast updates and changes, and be prepared for
unexpected winter weather conditions. Meanwhile, along and east
of the Cascades, widespread snow and gusty winds will be the rule,
and snow levels will see the same variation from north to south.
For more details on snow accumulations and snow levels for
specific zones, please check our WSWMFR Winter Weather Message on
our main page.

The stationary front will remain over the area Tuesday evening
and night, then weaken and shift south on Wednesday. This will
keep precipitation ongoing throughout the region. The colder air
and lower snow levels are expected to remain across central
Douglas and Coos county through this time (north and northwest of
the Rogue-Umpqua Divide), perhaps even dropping as low as sea
level Tuesday night. However, by the time snow levels lower this
significantly, precipitation for these areas will likely be light
or even zero. So this will limit the chances for low elevation
snow. Elsewhere, mountain snow will continue.

As the front weakens and shifts south during the day Wednesday,
light precipitation is favored for northern California zones and
for some areas from the Cascades east. Precipitation then tapers
off Wednesday evening. Northwest portions of the area are likely
to remain dry but colder on Wednesday, including across Coos
County and central/western Douglas County. Morning temperatures
may be down to around freezing or below in the lower Umpqua Basin
and Coquille Valley. Additionally, near to freezing temperatures
are forecast along the Coos and Douglas coast Wednesday morning.

Thursday into Friday, models show good agreement with a shortwave
ridge of high pressure building into the area. Temperatures will
transition from January-like high and lows to more seasonal values
by Friday. Frost may be a concern at the coast again Thursday
morning, but by Friday morning, there will be no such concerns.

Friday night into Saturday, an upper trough and frontal system
approach from the northwest then move into the region. This will
bring rain and snow over the area, Another stronger front, is
forecast to move into the area on Sunday with rain, snow and gusty
winds. Models are showing snow levels ranging from 3000-5000 feet as
precipitation spreads into the area with these fronts. So the
highest chance for snow impacts will be over the higher mountain
passes. -BPN

&&

.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Storm Warning until 4 PM PST Tuesday above 3500 feet for
     ORZ028.

     Winter Storm Warning until 4 PM PST Tuesday for ORZ029>031.

     Winter Storm Warning until 4 PM PST Tuesday below 2000 feet for
     ORZ023-025.

     Winter Storm Warning until 4 PM PST Tuesday above 3000 feet for
     ORZ024-026.

     Winter Storm Warning until 4 PM PST Tuesday for ORZ027.

     Winter Weather Advisory until 4 PM PST Tuesday for ORZ029>031.

CA...Winter Storm Warning until 4 PM PST Tuesday above 3500 feet for
     CAZ080-081.

     Winter Storm Warning until 4 PM PST Tuesday above 3000 feet for
     CAZ082.

     Winter Storm Warning until 4 PM PST Tuesday above 3500 feet for
     CAZ083.

     Winter Storm Warning until 4 PM PST Tuesday for CAZ085.

PACIFIC COASTAL WATERS...Small Craft Advisory until 10 AM PST this
     morning for PZZ350-356-370-376.

     Small Craft Advisory from 10 PM this evening to 7 AM PST Tuesday
     for PZZ356-376.

&&

Preliminary Local Storm Report
National Weather Service Medford OR
904 AM PST Mon Mar 4 2024

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0902 AM     Snow             11 WSW Steamboat        43.30N 122.94W
03/04/2024  M1.3 inch        Douglas            OR   Trained Spotter

            Snow accumulation overnight. Station
            Elevation: 1000 ft.

&&

CZS