A series of short waves moving through over a cold air mass brought heavy low elevation snow to parts of southwest Oregon.
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The episode as NWS MFR wrote it up.
A series of short waves moving through over a cold air mass brought heavy low elevation snow to parts of southwest 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, 1:47 PM PST, 4 hours 13 minutes earlier.
Area Forecast Discussion
National Weather Service Medford OR
247 PM PDT Fri Mar 23 2018
.SHORT TERM...As expected, the snow level has risen mostly above
1500 feet this afternoon and is wavering between 1500 and 3000
feet. However, in areas of heavier precipitation, there has still
been some wet snow at Camas Mountain, near Sexton Pass and Hayes
Hill Summit. Even so, looking at area web cams, roadways at these
elevations are now mostly wet or at most slushy. This is
partially due to the higher March sun angle, but is also due to a
wave forming along the front, which is inducing warm air
advection.
The low will move onshore and drag a cold front through the area
late this evening and overnight. Snow levels once again will drop
below the major passes (north of Grants Pass) and there could be
additional snow impacts along I-5 and Highway 199. If we're to get
any snow here in the Rogue Valley, it would be late this evening
as snow levels drop, but precipitation at that time will be
pushing to the east. So, right now snow on roads below 1500 feet
here in Medford seems unlikely. There could be some light
accumulation up on the higher hills around the valley, like
Jacksonville, and parts of East Medford up on Roxy Ann. There
could also be a burst of snow with the front east of the Cascades
producing a quick 1-3 inches of snow this evening/overnight. It
should be noted that any wet, untreated roads could turn icy
overnight/Saturday morning, since temperatures will be falling
down to or below freezing. Winter weather advisories and warnings
all remain in effect and details can be viewed at WSWMFR.
We are expecting about a 6 hour break in precipitation overnight,
but the cold pool aloft offshore will move onshore Saturday. This
will renew heavier precipitation for far SW Oregon, including the
Coast Ranges and into portions of western Siskiyou County.
Instead of issuing a new winter storm watch, we have opted to
extend the current headlines out through Saturday morning for the
lower elevations of Josephine/Curry County and through Saturday
evening for the higher elevations there and in western Siskiyou
County. Showers (and perhaps even a thunderstorm) will persist
over the rest of the region with snow levels getting back near or
above 1500 feet. For those traveling through the higher passes on
I-5 on Saturday, the break in precipitation will last through
about midday/lunchtime, then heavier precipitation will move back
in during the afternoon. Since it's late March, there may not be
much accumulation on the highway until late in the day. Even so,
it will likely be snowing in the afternoon, so getting through the
passes earlier is the better bet. Additional advisories may also
be necessary.
The core of the cold upper low will move through the area
Saturday night and we'll be on the back side of the trough on
Sunday, so we'll gradually see coverage of showers diminish and
impacts will lessen with time. -Spilde
.LONG TERM...Sunday night through Friday night...The upper level
trough will exit to the east by Sunday night, but the forecast area
will remain under northwest flow aloft and onshore flow in the lower
levels. High pressure will begin to gradually build in early next
week, but the overall pattern will be slow to transition, and the
ridge axis will remain to our west over the eastern Pacific. For the
most part, this will bring an end to area showers, however, an
impulse or two within the upper level flow could produce a short
period of increased shower chances Sunday night and again Monday
night, but rainfall amounts would be light. Meanwhile, snow levels
by this time will be at or above 3000 feet, so even though some snow
showers are possible at pass level, no major impacts are expected.
From Tuesday onward, the models are continuing to show a sharp
transition to a warm and dry pattern, with upper level ridging
building in overhead and a thermal trough developing to our south.
As can be expected with this type of pattern, the region will begin
to dry out, with east offshore winds increasing and temperatures
jumping up to well above normal. The will keep the days warm and
dry, then overnight, with ridges staying warm and inversions
developing underneath, some fog is possible in area valleys.
Considering the time of year, exactly where and how long fog
persists, or even if it develops at all, is too uncertain to say
with any confidence, but inversions should break and any fog should
dissipate quickly in the mornings. Otherwise, warm and dry
conditions will persist through the end of the forecast term. -BPN
&&
.AVIATION...23/18Z TAF CYCLE...A mix of IFR and MVFR conditions,
along with mountain obscuration, are affecting areas along and west
of the Cascades. This is near a frontal boundary that will remain
there through this afternoon before moving eastward to areas east of
the Cascades this evening and tonight. Gusty south to southwest
winds will impact most areas this afternoon, but conditions will be
windiest in the Shasta Valley and areas east of the Cascades, to
include Kingsley Field at Klamath Falls, where we have an Airport
Weather Warning valid through the afternoon. Freezing levels will
drop again tonight behind the front, lowering to around 1500 feet at
the coast tonight. Snow and low visibility will affect most airports
above 2000 feet elevation late this afternoon into tonight. A mix of
MVFR and VFR conditions with lingering mountain obscuration are
expected tonight and Saturday morning behind the heaviest bands of
precipitation. SK
&&
.MARINE...Updated 200 PM PDT Friday 23 Mar 2018....Unsettled
weather and steep seas with gusty winds will continue through the
weekend. A series of lows will bring periods of gusty south winds
and numerous showers and isolated thunderstorms through Saturday.
Low pressure on Saturday will bring warning level very steeps seas
to much of the waters. Conditions will improve Sunday as swell
subsides and high pressure builds into the area.
There's good agreement that favorable conditions will last through
Monday. A thermal trough develops on Tuesday, and north winds will
be increasing Tuesday afternoon, possibly reaching small craft
advisory levels by Tuesday night. SK
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 2 AM PDT Saturday for ORZ029-030.
Winter Weather Advisory from 7 PM this evening to 5 AM PDT
Saturday for ORZ031.
Wind Advisory until 7 PM PDT this evening for ORZ031.
Winter Weather Advisory from 7 PM this evening to 11 AM PDT
Saturday for ORZ024.
Winter Storm Warning until 8 PM PDT Saturday for ORZ024.
Winter Weather Advisory until 1 AM PDT Saturday for ORZ027-028.
Winter Storm Warning until 1 AM PDT Saturday for ORZ027-028.
Winter Storm Warning until 11 PM PDT this evening for ORZ023.
Winter Storm Warning until 1 AM PDT Saturday above 2500 feet in
the for ORZ025.
Winter Weather Advisory from 7 PM this evening to 1 AM PDT
Saturday for ORZ026.
CA...Winter Weather Advisory until 2 AM PDT Saturday for CAZ084.
Winter Weather Advisory from 7 PM this evening to 5 AM PDT
Saturday for CAZ085.
Wind Advisory until 7 PM PDT this evening for CAZ085.
Winter Weather Advisory until 2 AM PDT Saturday for CAZ082-083.
Winter Storm Warning until 2 AM PDT Saturday for CAZ082-083.
Winter Weather Advisory from 7 PM this evening to 1 AM PDT
Saturday for CAZ080-081.
Winter Storm Warning until 8 PM PDT Saturday for CAZ080.
Wind Advisory until 7 PM PDT this evening for CAZ081.
Pacific Coastal Waters...Small Craft Advisory for hazardous seas
until 11 AM PDT Sunday for PZZ350-356-370-376.
MAS/BPN/NSKPRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MEDFORD OR
201 PM PDT FRI MAR 23 2018
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0200 PM SNOW MOUNT SHASTA 41.32N 122.31W
03/23/2018 E1.0 INCH SISKIYOU CA TRAINED SPOTTER
NO ACCUMULATION ON ROADS. VISIBILITY ROUGHLY
1/2 MILE. THE DURATION OF THE SNOW EVENT WAS
5 HOURS.
&&The national radar mosaic for the moment the first event began.
2 heavy snow. Local standard time, as filed.
ODOT reported 8.0 inches of snow at Camas Mountain Pass (elevation 1450 feet) ending at 24/0100 PDT. The length of the snowfall period has been estimated based on observed snow at nearby locations.
ODOT reported 10.0-12.0 inches of snow at Sexton Summit (elevation 1960 feet) between 23/2000 and 24/0200 PDT.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2018Every state in 2018This day in weather historyWarnings in Oregon, March 2018
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: 737556, 737558.