A strong low in the Gulf of Alaska generated long period west swell. This, combined with shorter period, building west swell produced sneaker waves.
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The episode as NWS MFR wrote it up.
A strong low in the Gulf of Alaska generated long period west swell. This, combined with shorter period, building west swell 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 Jan 22, 9:14 PM PST, 2 hours 46 minutes earlier.
Area Forecast Discussion
National Weather Service Medford OR
914 PM PST Mon Jan 22 2024
.DISCUSSION...An upper level ridge will build tomorrow, allowing
for the showers to start drying out. Tomorrow will also be another
morning with valley low clouds and fog will develop in valleys.
Temperatures will be in the upper 20s and low 30s for east side
spots in the morning with low to mid-40s west. Later Tuesday rain
chances start at the coast and continue moving inland through the
night. Please see the previous discussion for more information.
-Hermansen
&&
.AVIATION...23/00Z TAFs...An upper trough is bringing numerous
showers to areas near and west of the Cascades this evening. The
showers will bring a mix of VFR/MVFR, with the lowest ceilings
(perhaps even brief IFR) during heavier showers. Also areas of
higher terrain could be occasionally obscured. Showers remain
isolated over the east side and NE Cal through this evening, but
become more numerous later tonight as the trough moves inland.
The showers this evening west of the Cascades will gradually
diminish overnight. Overall, ceilings will remain a mix of MVFR/VFR,
though IFR will return to west side valleys late tonight into
Tuesday morning with some lower stratus and/or fog. Expect improving
conditions to VFR again Tuesday afternoon. -Spilde
&&
.MARINE...Updated 830 PM Monday January 22, 2024...Generally
improving conditions are expected tonight into Tuesday morning.
An incoming front and west swell will bring increasingly hazardous
conditions Tuesday afternoon into Wednesday with a period of gusty
south winds and steep to very steep seas. High and steep westerly
swell will arrive Wednesday night into Thursday. Another front could
bring strong, gusty south winds and steep to very steep seas
Thursday night through Friday night. While winds and seas could
remain elevated, especially over the outer waters, the outlook is
for improving conditions this weekend. -Spilde
&&
.PREV DISCUSSION... /Issued 348 PM PST Mon Jan 22 2024/
SHORT TERM...An upper trough is moving over the region today. As
the trough axis shifts inland, showers are expected to increase
this afternoon and evening. Shower activity will be focused from
the Cascades west with isolated to scattered showers east of the
Cascades. Activity lingers into tonight. Then showers will
decrease in coverage late tonight into Tuesday morning, with
lingering showers focused mainly along the coast and over the
Cascades. Snow levels will remain high around 6000 feet, lowering
to 5000 ft late tonight as showers decrease in coverage and
intensity. Shower activity will taper off by Tuesday afternoon. as
the trough shifts eastward. The break in activity will be short-
lived and models and ensembles show another frontal system
approach Tuesday evening and night, then moving inland Wednesday.
Early this afternoon, radar imagery shows areas of showers
concentrated along the coast and over the coastal mountains. These
showers will continue to spread inland to the Cascades and into
areas east of the Cascades this afternoon and this evening.
Additionally, weak instability will allow a slight chance for
isolated thunderstorms late this afternoon and this evening,
mainly along the coast where there is a 15-25% chance for
thunderstorms but also inland over Douglas, southwest/western
Josephine and far western Siskiyou counties where there is a 15%
chance for isolated thunderstorms. Other areas west of the
Cascades will see a low chance (10%) for isolated thunderstorms
today.
Late tonight and Tuesday morning, models and ensembles support
decreasing shower activity as a weak upper level ridge builds into
the region. This will bring stable conditions and light winds and
combined with lingering moisture, will allow areas of valley low
clouds and fog to develop Tuesday morning. Temperatures will
remain slightly above normal on Tuesday and highs in the mid 50s
are forecast for inland valleys west of the Cascades and highs in
the mid 40s for valleys east of the Cascades.
The next front will approach from the west Tuesday evening then
gradually move inland Tuesday night and Wednesday.
LONG TERM...Wednesday Morning 01/24 to Mon 01/29...The progressive
pattern with yet more rain on the way continues into the extended
forecast. The forecast for this week will be rinse and repeat in
terms of conditions, with a warming trend expected over the weekend
into early next week.
The next front comes ashore early Wednesday. Breezy south winds will
strengthen early Wednesday over ridges and east of the Cascades,
peaking in the late morning/early afternoon. Model 700 mb wind
speeds are, on average, only 30-35 kts, which indicates that surface
wind gusts over high exposed terrain will generally max out at
around 35 mph and generally won't be impactful.
Meanwhile, light to moderate precipitation will spread east over the
region through the morning, persisting through early Thursday when
precipitation will turn more showery/intermittent before tapering
off. This system is more out of the west than previous systems, and
orientation that is good for upslope flow along the coast, coastal
mountains, and Cascades, areas which will see half an inch to an
inch of liquid precipitation, with generally less than a half inch
expected elsewhere. One thing of note, Wednesday morning will be
somewhat cooler than previous mornings, enough so that many areas
east of the Cascades will see low temperatures at or below freezing.
Associated with this, snow levels will be lower than we've seen
recently east of the Cascades Wednesday morning as the front starts
to move in (around 4100-4600 feet), so light snow is expected across
much of Lake, northern Klamath, and east-central Modoc counties. In
most areas below 5,500 feet, less than a half inch of snow is
expected before snow levels rise again Wednesday afternoon to 5000-
5500 feet. Areas between Crescent and Chiloquin could see 1 to 2
inches, but the heavier snow will be restricted to mountains.
Besides precipitation, daily temperatures will be similar to those
we've seen this weekend. Warmer than average temperatures (5-10
degrees above seasonal normals) continue through the region. Highs
in the 50s west of the Cascades, 40s eastwards, and 30s in the
mountains will be the norm for the work week. Lows will also be
above average, in the 40s west of the Cascades and 30s eastwards.
(Average lows this time of year are 30s west of the Cascades and low
20s eastwards.)
As we get into the weekend, conditions will get even (relatively)
warmer than they are now. Another system moves in early Friday
morning, bringing a warm sub-tropical air mass that will send snow
levels rocketing above 8,000 feet, bringing an end to snow outside
of the highest peaks. Along with this, daytime temperature will see
an uptick each day over the weekend, with highs in the low 60s
possible in valleys and coastal areas west of the Cascades Sunday
and Monday as showers end, though some model differences about the
position of the ridge could tip these temperatures higher or lower.
Most of the precipitation will be restricted to areas west of the
Cascades, especially over the coast (the Klamath Mountains in Curry
particularly). -CSP
BEACH HAZARDS...Updated 200 PM Monday January 22, 2024...There is
a moderate risk of sneaker waves at the beaches of southern Oregon
late tonight through Tuesday morning. Sneaker waves can run up
significantly farther on beaches than normal, including over rocks
and jetties. These waves can suddenly knock people off of their feet
and quickly pull them into the cold ocean waters, resulting in
serious injury or death. Waves may also lift driftwood logs,
trapping anyone caught underneath.
Long period west swell of 3 ft at 19 seconds will build to 6 ft at
17 seconds tonight into Tuesday while shorter period WSW swell
decays from 9 ft at 11 seconds to 6 ft at 10 seconds Tuesday. While
the As a result, the longer period waves will have a higher risk of
running farther up the beach. The incoming (rising) tide that
coincides with the greatest sneaker wave risk is from 4 to 10 am
Tuesday morning. -DW/Spilde
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Beach Hazards Statement from midnight PST tonight through
Tuesday morning for ORZ021-022.
CA...None.
PACIFIC COASTAL WATERS...Beach Hazards Statement from midnight PST
tonight through Tuesday morning for PZZ350-356.
Small Craft Advisory from 1 PM Tuesday to 4 AM PST Wednesday for
PZZ370-376.
Hazardous Seas Watch from late Tuesday night through Wednesday
afternoon for PZZ370-376.
&&The 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 west swell. This, combined with shorter period, building west swell produced sneaker waves.
A strong low in the Gulf of Alaska generated long period west swell. This, combined with shorter period, building west swell produced sneaker waves.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2024Every state in 2024This day in weather historyWarnings in Oregon, January 2024
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: 1154243, 1154244.