An incoming front brought high winds to at least one location along the southern Oregon coast.
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The episode as NWS MFR wrote it up.
An incoming front brought high winds to at least one location along the southern Oregon coast.
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 Dec 16, 9:17 AM PST, 3 hours 30 minutes earlier.
Area Forecast Discussion
National Weather Service Medford OR
917 AM PST Wed Dec 16 2020
.DISCUSSION...Radar and Satellite show the front just offshore
with precipitation having arrived at the coast and in the Umpqua
Basin. The Rain will spread farther eastward over the next several
hours, and snow will occur in the mountains. The forecast looks on
track, except have cancelled the dense fog advisory in Roseburg
due to the precipitation arriving and clearing out the fog.
Please read the previous discussion below for more details.
-Schaaf
&&
.MARINE...Updated 830 AM PST Tuesday 15 Dec 2020...Steep swell
dominated seas will continue this morning. South winds will increase
ahead of a strong cold front with gales likely from about Brookings
north late this morning into this afternoon. The front will move on
shore late this afternoon with winds shifting to the west to
southwest and diminishing. Steep seas will remain over the waters as
another high swell from the west to northwest comes in later tonight
and last into at least Thursday evening. This doesn't look as high
as the one early this morning, but it will still be significant with
wave heights mostly between 12 to 16 feet.
We should catch a break in the winds Thursday, but guidances suggest
seas will remain elevated enough for at least small craft conditions
to continue. For now we have headlines ending at 10 pm pst Thursday
evening, but this could very well be extended longer.
A front will approach the waters Friday with south winds increasing
and approaching at least small craft conditions in the northern
waters Friday afternoon. After another relative break Friday night
into Saturday morning another front will slowly move towards the
waters Saturday with south winds increasing once again, except this
time, they could be stronger and persist longer with gales possible
in the northern waters. -Petrucelli
&&
.PREV DISCUSSION... /Issued 425 AM PST Wed Dec 16 2020/
DISCUSSION...A developing low pressure system is moving towards
the forecast area this morning. Infrared satellite imagery shows
broad cloud top cooling, indicating a strengthening system, and
1.2+ inch precipitable water amounts supports the idea that this
front will deliver moderate to heavy precipitation across the
forecast area. Another indicator of significant moisture advecting
into the area is Integrated Vapor Transport (IVT) and IVT values
predicted by the models rank in the top 10 percent of what you can
observe this time of year. In addition to precipitation, winds
will be gusty ahead of the front with 700mb winds predicted to be
in the top 10 percent as well for what can be expected this time
of year.
For the significant winds and precipitation, we have some hazard
products valid today into tonight, including Wind Advisories east of
the Cascades and Winter Weather Advisories for the Cascades, Mount
Shasta area, and portions of the East Side. The greatest snow
impacts will be focused at elevations of 5000 feet and higher though
snow levels tonight will dip to 4000 feet behind the front. This
morning we investigated the snow potential east of the Cascades, and
we determined that snow levels will lower sharply as a band of
moderate to heavy precipitation along the front moves through
tonight into early Thursday morning. We think there will be a brief
period of impactful snowfall affecting portions of Highway 140 in
Lake and eastern Klamath Counties, and we have issued a Winter
Weather Advisory for this area. An even shorter period of moderate
snow is expected down to Alturas and Lakeview as snow levels crash
tonight.
Rainfall rates along the front may briefly touch 0.5 inches per hour
in Curry County late this morning into the afternoon, so some travel
difficulties can be expected in this heavy rainfall. Critical
rainfall rates of over a half inch per hour are not expected to
reach inland to the Indian Creek drainage near Happy Camp, but
we'll be monitoring the latest data as it comes in. The heaviest
rainfall is expected over that burn scar is expected between 12pm
and 6pm with rainfall rates peaking around 0.4 inches per hour.
Thursday night into Friday will be mostly dry as a short-duration
ridge of high pressure moves overhead. Plenty of fog/freezing fog
can be expected Thursday night and Friday morning.
A fast-moving shortwave will bring a return to precipitation chances
for the Cascades and west late Friday with a round of low amplitude
ridging and generally drying Saturday before the next Atmospheric
River (AR) impinges on the forecast area Sunday. There exists the
potential for a significant, long-duration (48-hour) precipitation
event over the forecast area from Sunday morning through Monday
night. This is highly dependent on how far south the AR sets up and
whether it stalls over the area or not. One data point that
describes this event is the EC ensemble mean's 72-hour rainfall
total of 4 inches at the Curry County coast, and downscaling that to
include terrain effects would easily double that over some of the
higher terrain of the coast. This has trended higher from the
previous ensemble run. Another data point to consider is the
overall magnitude of the AR per the ECE and GEFS, including
duration and IVT value, is expected to be twice as significant as
the AR that will arrive today. We'll keep an eye on this and
message as necessary as we move forward. Keene
AVIATION...For the 16/12Z TAFs...Ample low level moisture has
resulted in low clouds and areas of fog for most interior valley
locations. Freezing fog is a concern this morning in the Shasta
Valley, Mount Shasta area and Alturas. Klamath Falls is VFR at the
moment, but expect MVFR ceilings to return shortly, therefore kept
MVFR ceilings as the prevailing condition in the TAF.
The main concern today will be low level wind shear for the coast,
including North Bend, Roseburg and Medford later this morning and
afternoon as winds aloft increase ahead of an approaching front.
Inversions remain in place near and at the surface at Roseburg and
Medford this morning, but stronger southeast winds should surface in
Medford this afternoon.
A front moving into the area this afternoon will bring widespread
MVFR/IFR conditions and mountain obscurations with rain and snow
showers. Confidence in low clouds and fog tonight are low due to an
upper trough following the front this evening and tonight which
could keep conditions unstable enough for either one to form
tonight. -Petrucelli
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory from 10 PM this evening to 7 AM PST
Thursday above 5000 feet in the for ORZ030-031.
Wind Advisory until 10 PM PST this evening for ORZ030-031.
High Surf Advisory until 10 AM PST this morning for ORZ021-022.
Winter Weather Advisory until 4 AM PST Thursday above 5000 feet
in the for ORZ027-028.
CA...Winter Weather Advisory until 4 AM PST Thursday above 5000 feet
in the for CAZ082.
Winter Weather Advisory from 4 PM this afternoon to 7 AM PST
Thursday above 5000 feet in the for CAZ083-085.
Pacific Coastal Waters...Small Craft Advisory from 10 PM this evening to 10 PM PST
Thursday for PZZ350-356-370-376.
Gale Warning until 4 PM PST this afternoon for
PZZ350-356-370-376.
Hazardous Seas Warning until 10 PM PST this evening for
PZZ350-356-370-376.The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
The ODOT sensor at Humbug Mountain on US Highway 101 recorded several gusts exceeding 57 mph during this interval. The peak gust was 68 mph recorded at 16/1516 PST.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2020Every state in 2020This day in weather historyWarnings in Oregon, December 2020
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: 925377.