Heavy long period westerly swell brought a brief period of heavy surf to the southern Oregon coast.
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.
Heavy long period westerly swell brought a brief period of heavy surf to 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 20, 4:23 AM PST, 3 hours 37 minutes earlier.
Area Forecast Discussion
National Weather Service Medford OR
423 AM PST Fri Dec 20 2019
.DISCUSSION...The latest satellite image clearly shows the
Atmospheric river (AR) being directed north of our forecast area
and this is where the heaviest precipitation is occurring. There is
good agreement we'll have a relative break in precipitation through
this evening. An upper trough west of where the core of the AR is
located will act as a "kicker" pushing the core of heaviest
precipitation into our area. It will arrive at the coast and coastal
mountains tonight, then moving inland during the day Saturday.
Until then, the main concern today will be moderate to strong winds
at the coast, Shasta Valley and east of the Cascades. Moderate winds
are also expected in the Rogue valley, however observations and
short range guidance suggest winds in the Medford are may not peak
until later this afternoon. Thus, have made some adjustments to the
winds into early this afternoon. Winds will be at their peak this
afternoon through Saturday morning, likely a few hours ahead of to
just ahead of the front. Current high wind warnings and advisories
look good. For more details please see NPWMFR for more details.
As previously mentioned the bulk of the precipitation will arrive
later tonight at the coast, then inland during the day Saturday.
Rainfall amounts will vary depending on location. In general, were
expecting an additional 2 to 6 inches of rain from the coastal
mountains westward, 0.50" to 2 inches for the rest of the area from
the Cascades westward, and mostly 0.50" or less east of the
Cascades. Expect wet roads, ponding, and some mud/rock slide
potential along and near the coast and coastal mountains Saturday
as the core of the heaviest precipitation moves inland.
Snow is not expected to be a concern through Saturday morning.
Snowfall rates are expected to increase Saturday afternoon and
moreso Saturday evening as the core of heaviest precipitation moves
in. Snow levels Saturday are expected to start out around 6000
feet, lowering to around 5000 feet Saturday evening due to a
combination of colder air moving in and heavier precipitation
dragging some of the colder air down. Aside from in the Crater and
Diamond Lake to Highway 97 near Chemult areas (even then amounts
will be light), impacts on the roadways are not expected from snow
until Saturday evening/night.
Saturday night through Sunday will warrant close watching. There's
good agreement among the models showing a wave of low pressure
forming along the front Saturday night through Sunday. This could
result in significant travel impact along Interstate 5 from Siskiyou
Summit south to the Mount Shasta area is the worst case scenario
pans out. Right now, the general consensus is for snow levels to be
around 4500 ft (4000 ft in heavier precipitation) Saturday night,
lowering to 3500 ft (3000 feet in heavier precipitation) by Sunday
morning with light to moderate snowfall on I-5 focused in the Mount
Shasta to Siskiyou Summit areas. The heaviest snow is expected to be
in the mountains (above 4500 feet) in Siskiyou County which would
only affect Sawyers Bar Road and highway 3 south of Callahan. Also
we can't ignore the higher passes along the Cascades, specifically
highway 140 near Lake of the Woods and 230 and 138 near the Diamond
Lake area. Right now were expecting a 30 storm total of 3-6 inches
near Lake of the Woods, 4-8 inches near Diamond Lake. The rest of
the forecast after Sunday night follows below from yesterdays Long
Term Discussion. -Petrucelli
&&
.LONG TERM.../Issued 346 PM PST Thu Dec 19 2019/
Monday through Thursday...A cooler pattern is expected early next
week as an upper trough remains over the area. Some lingering light
showers are possible Monday but most the energy and moisture is
forecast to be south to southeast of the area. So expect any showers
over the area to be light. An offshore shortwave ridge is expected
to move into the area Monday night into Tuesday. So this may result
in mostly dry conditions over the CWA with areas of valley fog. Then
an approaching front and upper trough may spread some light showers
into the area Christmas eve (Tuesday night) into Christmas Day
(Wednesday). A wave develops on the southern end of this front off
the California coast and will affect how quickly the front moves
onshore. Of note, there is a range of model solutions during the
period with some models indicating the front may stall just offshore
and only light isolated or scattered showers may spread inland.
Other model solutions indicate that the front will move onshore on
Christmas Day then weaken as it moves inland. Given the cooler
airmass, snow levels are expected to be relatively low during this
period. So if the front moves onshore and showers spread inland,
this may result in some light snow on lower passes. However, models
continue to show significant variability during this period. In the
GEFS, only about 50% of the model solutions show precipitation over
the area Wednesday. Confidence remains low on the details of the
forecast and will continue to monitor and update as confidence
increases. Then after Christmas, an active pattern is possible with
the latest models and ensembles showing a moist front approaching
the region on Thursday.
-CC
&&
.AVIATION...For the 20/12Z TAFs...MVFR at the coast and VFR
everywhere else. Inland, partial terrain obscuration will continue
through the day. The cold front will push onshore this morning
bringing showers, causing inland VFR to become MVFR where rain is
present. Gusty winds and wind shear will be a concern for KOTH, KMFR,
KRBG (KRBG should not see the gusty winds at the surface), and KLMT
(gusty winds, no wind shear during this TAF period). Did not include
wind shear at KLMT because there was limited directional change.
freezing levels should remain above 6,500 feet for all areas today.
-miles
&&
.MARINE...Updated 415 AM PST Thursday, 20 December 2019...Gales and
very steep and hazardous seas will persist through at least tonight.
Periods of heavy rain will affect northern areas beginning late this
afternoon into Saturday morning, spreading to areas south of Cape
Blanco by Saturday morning. Seas are expected to peak this morning
in the 23-27 foot range and remain very steep, and hazardous through
tonight. Saturday morning conditions will begin to improve as the
winds begin to subside in the outer waters, but near shore winds
will remain gusty, and the overall sea state is likely to remain
chaotic and hazardous through the day.
Mariners should consider altering their plans or remain in port
until this long-lived storm passes. Conditions will begin to improve
Saturday. After a few days of relatively calm conditions early next
week, another system may arrive around midweek. -miles
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...High Wind Warning until 7 AM PST Saturday for ORZ021.
High Surf Warning until 4 AM PST Saturday for ORZ021-022.
High Wind Warning until 4 PM PST Saturday for ORZ030-031.
Wind Advisory until 4 PM PST Saturday for ORZ030-031.
High Wind Warning until 7 AM PST Saturday for ORZ022.
Wind Advisory until 10 AM PST Saturday for ORZ026.
CA...High Wind Warning until 4 PM PST Saturday for CAZ085.
Wind Advisory until 4 PM PST Saturday for CAZ085.
High Wind Warning from 10 PM this evening to 10 AM PST Saturday
for CAZ081.
Wind Advisory until 10 AM PST Saturday for CAZ081.
Pacific Coastal Waters...Hazardous Seas Watch from Saturday morning through Saturday
afternoon for PZZ350-356-370-376.
Gale Warning until 4 AM PST Saturday for PZZ350-356-370-376.
Hazardous Seas Warning from 4 AM to 10 AM PST Saturday for
PZZ350-356-370-376.The national radar mosaic for the moment the first event began.
2 high surf. Local standard time, as filed.
The Umpqua Offshore Buoy (46229) recorded swell sufficiently high to create heavy surf between 20/0800 PST (21 feet at 17 seconds) and 20/0830 PST (22 feet at 15 seconds).
The Umpqua Offshore Buoy (46229) recorded swell sufficiently high to create heavy surf between 20/0800 PST (21 feet at 17 seconds) and 20/0830 PST (22 feet at 15 seconds).
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2019Every state in 2019This day in weather historyWarnings in Oregon, December 2019
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: 861799, 861800.