Strong low pressure over Alaska and a thermal trough along the Oregon coast produced long period west-northwest swell and elevated north-northwest wind waves. These combined to produce sneaker waves along the southern Oregon coast.
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The episode as NWS MFR wrote it up.
Strong low pressure over Alaska and a thermal trough along the Oregon coast produced long period west-northwest swell and elevated north-northwest wind waves. These combined to produce sneaker waves 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 May 27, 11:00 AM PST, 5 hours earlier.
Area Forecast Discussion
National Weather Service Medford OR
1200 PM PDT Wed May 27 2026
.DISCUSSION...An upper level closed low will stay spinning over
the Sierra Nevada will be the main weather-maker today and
Thursday. This system will produce an active pattern of showers
and thunderstorms, some of which will become strong (and perhaps
even severe) this afternoon/evening and again Thursday
afternoon/evening.
Multiple shortwave disturbances will rotate around the low and
since the low is located to our southeast, the showers/storms will
move in a general east-west fashion across NorCal and SW Oregon.
Currently, radar is showing an area of showers moving east-northeast
to west-southwest over Siskiyou County, which put out a few
lightning strikes as it crossed over Lake county earlier this
morning. These showers will move out of the forecast area over
the next hour or so.
Meanwhile, another strong mid-level disturbance will develop over
NW Nevada and move over the area this afternoon/evening. As the
first shortwave moves away, this should allow for good
destabilization late this morning and this afternoon with MUCAPE
of 250-500J/KG. Good forcing, shear and steep lapse rates should
support the convection this afternoon. In fact, a few showers
have already formed up around Winnemucca and McDermitt, NV, with
a handful of lightning strikes, as of noon. The shortwave will be
within a belt of strong mid- level easterly flow of 35-45 kt, so
storm motions will be very fast. Hi- res guidance shows cells
developing early this afternoon around Modoc/southern Lake County
and then potentially developing into a line of storms that will
move east- west across NorCal & southern Oregon reaching Klamath
Falls/Mount Shasta regions ~2-5 pm. By then, storms should have
the ability to bring strong, gusty outflow winds of 40-50 mph,
small hail and a good amount of cloud to ground lightning. This
would also normally cause increasing concern for fire starts, but
wetting rainfall across a good portion of the area yesterday
significantly muted this potential. Showers/storms will continue
to move quickly off to the west to the Cascades/Siskiyou Mountains
3-6 pm. The main uncertainty with storms this afternoon is if
they will hold together once they move onto the west side during
the evening. Models are showing much more stable air over here,
but there is still some elevated instability/forcing that could
maintain the storms at least until mid evening (8 pm or so). HRRR
(a bit of an outlier) is showing the convection moving all the way
to the coast by around 10pm- midnight. We think by then, it will
mostly just be leftover showers. Tonight, while there is still a
chance of showers, the thunder risk should end for a while.
It won't last long though as another shortwave moves into the
area Thursday. Convection could get going Thursday morning in
portions of Klamath/Lake counties, where instability is greatest.
Models are showing 500-1000J/KG CAPE, steep lapse rates and good
forcing, resulting in the potential for another round of gusty
wind/hail producing storms. Mid-level flow isn't as strong as it
will be today, so storm motions will be slower and this could add
a heavy rainfall risk, especially for storms that tend to form
consistently over the same locations. While just about anywhere
could see strong storms (except the coast), the most likely area
for possible severe storms is up the Cascades (near/north of
Crater Lake) and also over northern Klamath/Lake counties. This is
where the Storm Prediction Center has a marginal risk. An inverted
trough will maintain an area of forcing for showers to continue
Thursday night focuses near the Cascades, but also over portions
of the east side.
On Friday, coverage of showers is greatest through the morning
hours, but should diminish some as upper ridging noses in from
the Pacific. Even so, there is still enough instability for a
slight chance of thunder of the far east side. The next upper
trough swings through the area on Saturday, but most areas likely
remain dry (outside of S&E sections, where there's still a chance
of showers/t-storms). Sunday, PoPs are low (generally 10% or
less), so most areas should be dry. Temperatures remain around
normal this weekend.
Models are consistently showing a warmup early next week -- the
degree of which is uncertain. The majority of the guidance shows
highs here in Medford in the upper 80s to near 90F Mon-Wed
(peak of warmth on Tuesday) and about 5-10F lower at Klamath
Falls. The range of solutions for Medford for Tuesday is 82-97F
with a 50% chance of 90F or higher. A reasonable worst-case (90th
percentile) would be 96F. -Spilde/BPN
&&
.AVIATION...27/18Z TAFS...A mix of VFR/MVFR conditions with higher
terrain obscurations prevails across the region this morning.
Conditions improve to VFR by early afternoon, but expect another
round of showers, thunderstorms and gusty winds this
afternoon/evening, especially east of the Cascades. Guidance
continues to show storms forming into a line that moves east-west
across the region later this afternoon/evening. Initially impacting
Klamath Falls between 23z-01z, then moving west of the Cascades
around 02z, possibly reaching the Rogue Valley around 02-03z. Storms
probably weaken as they move westward, with showers possibly
reaching as far west as Roseburg/Grants Pass this evening before
dissipating late this evening. -Spilde/BR-y
&&
.MARINE...Updated 1200 PM PDT Wednesday, May 27, 2026...Gusty north
winds will persist today, maintaining very steep wind-driven seas
through tonight into early Thursday. There could be a brief period
of gale force north winds this afternoon, south of Gold Beach and
beyond 1-2 nm from shore. Otherwise, the strongest winds and highest
seas will be from Gold Beach south. North winds will ease Thursday,
but a long period west-northwest swell will build into the waters
tonight into Thursday. This will maintain steep seas through
Thursday, but seas will transition to swell dominated with the
easing of winds.
Conditions briefly improve early Friday, but this improvement will
short lived as north winds increase again Friday afternoon, then
persist through the weekend. Initially, advisory level winds and
steep seas (possibly very steep seas) are expected south of Cape
Blanco by Friday afternoon, but are likely to spread north of the
Cape over the weekend. /BR-y
&&
.BEACH HAZARDS...Updated 1200 PM PDT Wednesday, May 27, 2026...Long
period northwest swell, originating from recent storms near the
Kamchatka and western Aleutian Islands, will build into the southern
oregon coastal waters today. Initially arriving as 2 to 3 feet at
around 20 seconds, swell will peak at 6 to 8 feet at around 17
seconds during the day Thursday. The threat will be highest during
periods of incoming tides, which will be during the morning, and
during the late afternoon and evening on Thursday.
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 sweep them into the ocean. The
waves can also move logs or other objects which could crush or trap
anyone caught underneath. Avoid climbing on rocks and jetties. Stay
away from the ocean and remain out of the water to avoid hazardous
conditions. Never turn your back on the ocean!
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Beach Hazards Statement from this evening through late Thursday
night for ORZ021-022.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory until 11 AM PDT this
morning for PZZ350-356-370-376.
Hazardous Seas Warning until 5 PM PDT Thursday for PZZ350-356-
370-376.
&&Special Weather Statement
National Weather Service Medford OR
148 PM PDT Wed May 27 2026
ORZ031-272130-
Central and Eastern Lake County OR-
148 PM PDT Wed May 27 2026
...A strong thunderstorm will impact portions of southeastern Lake
County through 230 PM PDT...
At 147 PM PDT, Doppler radar was tracking a strong thunderstorm 7
miles southeast of Warner Valley Scenic Overlook, or 43 miles
northeast of Lakeview, moving west at 35 mph.
HAZARD...Winds in excess of 40 mph and pea size hail.
SOURCE...Radar indicated.
IMPACT...Gusty winds could knock down tree limbs and blow around
unsecured objects. Minor damage to outdoor objects is
possible.
Locations impacted include...
Warner Valley Scenic Overlook and Warner Wetlands.
PRECAUTIONARY/PREPAREDNESS ACTIONS...
If outdoors, consider seeking shelter inside a building.
Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.
&&
LAT...LON 4261 11954 4244 11946 4226 12000 4252 12011
TIME...MOT...LOC 2047Z 072DEG 31KT 4250 11961
MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH
BPNPreliminary Local Storm Report
National Weather Service Medford OR
409 PM PDT Wed May 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0345 PM Hail 13 ESE Bly 42.32N 120.80W
05/27/2026 U1.00 Inch Lake OR Dept of Highways
ODOT webcams show hail covering Highway 140
estimated approx 1 inch deep.
&&
BPNPreliminary Local Storm Report
National Weather Service Medford OR
426 PM PDT Wed May 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0422 PM Hail Bly 42.40N 121.04W
05/27/2026 U1.00 Inch Klamath OR Dept of Highways
ODOT cams show hail covering highway 140 at
Bly, OR, estimated depth of >1 inch.
&&
BPNPreliminary Local Storm Report
National Weather Service Medford OR
434 PM PDT Wed May 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0414 PM Tstm Wnd Gst 1 N Bly 42.41N 121.04W
05/27/2026 M60 MPH Klamath OR Dept of Highways
Gust reported by ODOT weather station.
&&
BPNPreliminary Local Storm Report
National Weather Service Medford OR
449 PM PDT Wed May 27 2026
..TIME... ...EVENT... ...CITY LOCATION... ...LAT.LON...
..DATE... ....MAG.... ..COUNTY LOCATION..ST.. ...SOURCE....
..REMARKS..
0445 PM Hail 9 SSE Sprague River 42.34N 121.40W
05/27/2026 U1.00 Inch Klamath OR Dept of Highways
ODOT road camera shows hail covering highway
140 at Bly Mountain at a depth estimated as
>1 inch.
&&
BPNThe national radar mosaic for the moment the first event began.
2 sneakerwave. Local standard time, as filed.
Strong low pressure over Alaska and a thermal trough along the Oregon coast produced long period west-northwest swell and elevated north-northwest wind waves. These combined to produce sneaker waves along the southern Oregon coast.
Strong low pressure over Alaska and a thermal trough along the Oregon coast produced long period west-northwest swell and elevated north-northwest wind waves. These combined to produce sneaker waves along the southern Oregon coast.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2026Every state in 2026This day in weather historyWarnings in Oregon, May 2026
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: 1341065, 1341066.