A low pressure system moving southeast from the Gulf of Alaska brought a lengthy period of low elevation snow to western Oregon.
Every event with a place to put it; 4 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS MFR wrote it up.
A low pressure system moving southeast from the Gulf of Alaska brought a lengthy period of low elevation snow to western Oregon.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Medford, OR wrote its last area forecast discussion before the first event at Mar 23, 7:28 AM PST, 2 hours 32 minutes earlier.
Area Forecast Discussion
National Weather Service Medford OR
828 AM PDT Thu Mar 23 2023
.UPDATE...The current forecast looks to be on track. An upper level
trough is looking to arrive on the Oregon coast this morning then
move over the area over the day. Upper level terrain, especially the
Coastal Range and the Cascades, are looking to get impactful
snowfall. Snow is also expected across the east side, and
persistant rainfall may lower snow levels enough for snow to reach
valley floors. But the chances of this are low (0-30%), and
accumulation would be even less likely. The hazard headlines
created yesterday describe these conditions in more detail. -TAD
&&
.PREV DISCUSSION... /Issued 445 AM PDT Thu Mar 23 2023/
SHORT TERM...Today through Friday. A Winter Storm Warning and
Winter Weather Advisory remains in effect later today into Friday
for most of the west side above 1500 feet, and the higher terrain
of northern and eastern Klamath County and western Lake County.
Precipitation is currently limited to light scattered snow
showers over the southern Oregon Cascades. That will change in a
few hours as a cold front brings rain to the coast. The front will
track across the area with rain and snow today. Precipitation is
expected to reach the Cascades by noon then develop across the
east side into this evening. The most intense rates of precipitation
will occur with the frontal passage. Snow levels will begin
around 3000 to 3500 feet, then fall to around 1000 feet tonight
behind the front with precipitation transitioning to showers.
Westerly low level flow tonight through Friday will bring the
highest amounts to upslope portions of the higher terrain of
southwest Oregon. This includes eastern Curry, western Josephine,
eastern Douglas, and eastern Jackson County. Totals of 12 to 24
inches are expected in the southern Oregon Cascades, 6 to 12
inches in the Kalmiopsis Wilderness, Siskiyou Mountains, and
northern California Cascades, and 3 to 6 inches for the higher
terrain of the east side (including Highway 97 north of
Chiloquin).
LONG TERM...Friday night through Wednesday. A pretty impressive
winter weather pattern persists across the region. We're
expecting cold northwest flow to persist behind the cold front
from Friday night into Saturday. 850 mb temperatures will likely
be around -5 to -6 C. Air this cold is usually supportive of snow
in the valleys west of the Cascades during the winter. We do have
snow in the forecast for the valley floors Friday night into
Saturday morning. This will mostly be dependent if a showers can
hold together as the move off the mountains into the valleys. None
the less, don't be surprised to see snow on the grass Saturday
morning.
By Saturday, the axis of the low enters southern Oregon. This will
promote an unstable atmosphere and pockets of convective available
potential energy(CAPE). With a more showery pattern, temperatures in
some of the valleys will warm up into the mid 40's. Lapse rates are
up to 8C/km up to 650 mb, which is rather unstable. All these things
considered, one should expect plenty of shower activity with the low
chance of a rumble of thunder across the region. With regards to
snow accumulating from Thursday up until Saturday afternoon, we're
looking at up to 2 feet of snow over the Cascades. This seems
reasonable given the persistent westerly flow that favors the west
to east sloping Cascades from Thursday even into Saturday. The
coastal range will also be under focus here as these convective
showery patterns produce a lot of snow in the Kalmiopsis wilderness.
By Saturday night into Sunday, high pressure begins to build over
the forecast area as the upper level low departs. Models still have
a 30 to 50 percent chance of rain along the coast and the higher
Cascades with drier conditions farther to the east. There are some
models disagreements with how Sunday pans out. The NBM currently
shows those PoP chances spreading eastwards into the day Sunday ,
which goes against what some of the deterministic models show right
now. This is probably due to how the models are handling the next
system. Right now, it's looking like Monday into Tuesday is the
best time for weather impacts with this low. The snow percentiles
show 18 inches in the 75th percentile for Mt. Shasta City.
Consequently, there is also 3 inches in the 25th percentile for that
same area. That rather large spread suggests that the track of this
low is still fairly uncertain at this time. The one thing that does
seem reasonable is that this system will be cold and out of the
northwest yet again. So one should prepare for more unseasonably
low snow levels Monday into Tuesday.
-Smith
AVIATION...22/12Z TAFs...For areas along the coast through tonight,
expect a mix of IFR/MVFR conditions with light showers. Inland,
areas of MVFR cigs are expected in showers tonight into early
morning and widespread mountain obscurations are expected from the
Cascades west. Additionally, valleys will see a potential for IFR
ceilings and visibilities to develop in low clouds late tonight and
early morning. Then, a front will move onshore this morning and
gradually push inland over the area through the day. As
precipitation spreads inland, this will result in areas of MVFR and
local IFR ceilings and visibilities along with terrain obscurations.
Freezing levels will be near 2500 to 3500 feet but will lower down
to 1500 to 2000 feet Thursday evening. Gusty westerly winds will
also occur this afternoon and evening, with strongest winds from the
Cascades east. -Sven
MARINE...Updated 230 AM PDT Thursday, March 23, 2023...Another
front will move across the area on Thursday. This will bring another
round of gusty south to southwest winds along with an increase in
wind driven seas. In addition, a heavy, long period northwest swell
will follow late Thursday into Friday, resulting in very steep and
hazardous combined seas. Seas peak early Friday, then gradually
diminish but remain steep through Saturday.
A period of improved conditions is expected Sunday into early next
week. Guidance indicates the potential for strong low pressure to
move into the region Monday. However, there is considerable
uncertainty regarding the location and timing of this. Regardless,
expect active weather with the return of steep and hazardous
conditions early next week, just the details are unclear at this
time. -Sven
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory from 5 PM this afternoon to 11 AM PDT
Friday above 1500 feet for ORZ023.
Winter Storm Warning until 11 AM PDT Friday above 2500 feet for
ORZ024.
Winter Weather Advisory from 5 PM this afternoon to 11 AM PDT
Friday above 1500 feet for ORZ024.
Winter Storm Warning until 11 AM PDT Saturday for ORZ025.
Winter Weather Advisory from 5 PM this afternoon to 11 AM PDT
Friday for ORZ026.
Winter Storm Warning until 11 AM PDT Saturday for ORZ027-028.
Winter Weather Advisory from 2 PM this afternoon to 5 PM PDT
Friday for ORZ030.
CA...Winter Weather Advisory from 2 PM this afternoon to 11 AM PDT
Friday for CAZ080.
PACIFIC COASTAL WATERS...Small Craft Advisory until 5 PM PDT Friday
for PZZ350-356-376.
Hazardous Seas Warning until 5 PM PDT Friday for PZZ370-376.
&&The national radar mosaic for the moment the first event began.
3 winter storm, 1 heavy snow. Local standard time, as filed.
National gridded snowfall analysis indicated 4 to 17 inches of snow at elevations above 2500 feet.
National gridded snowfall analysis indicated 11 to 27 inches of snow at elevations above 2000 feet.
National gridded snowfall analysis indicated 6 to 13 inches of snow at elevations above 2000 feet.
National gridded snowfall analysis indicated 12 to 28 inches of snow.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2023Every state in 2023This day in weather historyWarnings in Oregon, March 2023
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 1089816, 1089818, 1089819, 1089821.