A strong low in the Gulf of Alaska generated long period swell. This, combined with shorter period waves associated with an oncoming cold front, produced sneaker waves.
Every event with a place to put it; 2 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 strong low in the Gulf of Alaska generated long period swell. This, combined with shorter period waves associated with an oncoming cold front, produced sneaker waves.
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 3, 9:05 AM PST, 5 hours 30 minutes earlier.
Area Forecast Discussion
National Weather Service Medford OR
905 AM PST Sun Dec 3 2023
.DISCUSSION...With the combination of heavy cloud cover and moist
air, Medford saw a change of a whopping 2 degrees since yesterday
afternoon! Shortly after midnight a gust of 65 mph was reported
at Summer Lake, and Rock Creek saw a peak gust since midnight of
51 mph. The Wind Advisory for parts of Lake County including
Highway 31 near Summer Lake continues through this afternoon. A
report of rainfall between Brookings and Gold Beach was just shy
of 5 inches for a 24- hour total as of 8 AM! Our main concern
today will be the heavy rain forecast at the coast. -Hermansen
&&
.PREV DISCUSSION... /Issued 508 AM PST Sun Dec 3 2023/
DISCUSSION...Weather station observations from the last 24 hours
show (on average) 1-2" fallen along the immediate coast, 3-3.5"
in the south OR coastal/Klamath Mountains, 0.5-1" in western
valleys, 2-2.5" over the OR Cascades, and varying totals from 0.1
to 0.5" east of the Cascades. An atmospheric river will continue
to impact the region today, bringing yet more moderate to heavy
rain to the Cascades westwards and lighter rain to areas east of
the Cascades. Areas along the coast, Douglas, western Josephine
and Siksyou, northern Jackson, and the OR Cascades will see
precipitation totals today in similar ranges to the previous 24
hours of observations. Also similar to yesterday, gusty winds will
continue over ridges, along the coast, and in areas east of the
Cascades. In particular, parts of Lake and far eastern Klamath
county will see gusts to 35-55 mph, especially over higher terrain
and in the Summer Lake area (including the stretch of Highway 31
in that area) where our wind advisory continues today.
Snow levels this morning are approaching 7,000 feet, if not
exceeding that along the coast, and will continue to rise today as
southwest flow continues to bring warmer air into the region.
This will limit snow to only the highest mountain peaks in the
area today, and only light snow accumulations are expected to
continue.
Rain will lighten and decrease in area tonight and Monday,
retreating, for the most part, to areas west of the Cascades.
While the coastal Klamath Mountains and parts of the OR Cascades
will continue to see intermittent moderate to even locally heavy
rain with orographic enhancement of showers, amounts elsewhere
will be quite light during this period. Snow levels to work their
way up into the 8 to 9 thousand foot range tonight, and further to
9,000-10,000 feet Monday, restricting any snow to Mt. Shasta's
peak. Heavier, more widespread precipitation shifts to the south
and returns to the area late Tuesday into Wednesday as another
atmospheric river moves into the region. Snow levels will begin
dropping again starting Wednesday as flow aloft turns more
northwesterly and colder air moves in, and areas around Diamond
Lake and Crater Lake could see snow during the day Wednesday.
The extended period of moderate to heavy rainfall is expected to
bring rapid river and stream rises, especially for area rivers
and streams in Coos, Douglas and Curry counties. Additionally,
moderate to heavy rainfall may result in ponding of water on
roadways, localized minor flooding in low lying areas and
localized rockfalls or landslides. A Hydrologic Outlook (ESF) has
been issued for these potential impacts. Please see the ESFMFR for
details.
Cool and unsettled weather continues into the latter end of next
week with yet more systems running down an upper level trough
Thursday into Friday morning. The upper trough shifts east of our
area as ridging moves in Friday afternoon leading to diminishing
precipitation.
-CSP
BEACH HAZARDS...Active weather continues into next week. A
series of fronts will move through the region during this time along
with multiple moderate to high swell trains. An extended period of
sustained wave action is expected. Breaking waves of 15 to 20 ft
will coincide with higher than normal ocean levels, leading to an
increased risk of beach erosion. Additionally, there is a minor risk
of sneaker waves as these swell trains build into the waters.
Confidence is low, however, considering wind wave interference is
likely to limit, but not completely negate the sneaker threat. Late
Tuesday afternoon into Wednesday morning, very large breaking waves
are possible due to large long period west swell. If venturing to
area beaches during this time, use caution when visiting and
remember to never turn your back on the ocean!
-BPN
AVIATION...03/12Z TAFs...Our active weather continues with another
set of tricky TAFs due to uncertainty on exact timing of
precipitation and ceilings/visibilities. That said, we are looking
at unfavorable flying conditions to persist across the region thanks
to MVFR to IFR ceilings and occasional MVFR visibilities. This will
be the case for the next 24 hours, with some relief from
precipitation coming later tonight into Monday morning. This will
result in better ceilings and visibilities, but that remains outside
of this TAF cycle. This will be somewhat short lived with more
precipitation expected across the region next week.
-Guerrero
MARINE...Updated 300 AM Sunday December 3, 2023...A prolonged
period of active weather will continue well into next week. Gusty
south to southwest winds will be common, along with southerly wind
waves and long period west swell.
Gales and very steep seas are likely for much of the area today with
strongest winds again north of Cape Blanco as another front pushes
through. Winds will subside later tonight but only to increase once
again on Monday through Tuesday morning. Seas may become very high
at 15 to 19 ft on Monday and again as they build to a peak of around
16 to 20 ft at 19 seconds on Tuesday night/early Wednesday morning.
Additional disturbances Wednesday and Thursday will not be as
strong, with high and steep seas slowly diminishing into Friday.
-Guerrero
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Beach Hazards Statement through late Monday night for ORZ021-
022.
Wind Advisory until 4 PM PST this afternoon for ORZ030-031.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory until 4 AM PST Monday
for PZZ350-356-370-376.
Gale Warning until 4 PM PST this afternoon for PZZ350-370.
&&Preliminary Local Storm Report
National Weather Service Medford OR
849 AM PST Sun Dec 3 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0849 AM Rain 4 NNE Takilma 42.11N 123.58W
12/03/2023 M1.80 inch Josephine OR Trained Spotter
8AM-8AM.
&&
SBNPreliminary Local Storm Report
National Weather Service Medford OR
1247 PM PST Sun Dec 3 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
1246 PM Rain 2 NW Brookings 42.08N 124.32W
12/03/2023 M2.92 inch Curry OR Trained Spotter
24 HR.
&&
SBNPreliminary Local Storm Report
National Weather Service Medford OR
129 PM PST Sun Dec 3 2023
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0129 PM Rain 1 NE Medford 42.35N 122.84W
12/03/2023 M1.10 inch Jackson OR Trained Spotter
10 AM-10 AM.
&&
SBNThe national radar mosaic for the moment the first event began.
2 sneakerwave. Local standard time, as filed.
A strong low in the Gulf of Alaska generated long period swell. This, combined with shorter period waves associated with an oncoming cold front, produced sneaker waves.
A strong low in the Gulf of Alaska generated long period swell. This, combined with shorter period waves associated with an oncoming cold front, produced sneaker waves.
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, December 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: 1151798, 1151812.