A ridge building in behind a deep, cold trough created a strong pressure gradient with gusty southwest winds in south central Oregon.
Every event with a place to put it; 1 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 ridge building in behind a deep, cold trough created a strong pressure gradient with gusty southwest winds in south central Oregon.
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 Apr 3, 9:36 PM PST, 3 hours 39 minutes earlier.
Area Forecast Discussion
National Weather Service Medford OR
1036 PM PDT Mon Apr 3 2023
.UPDATE...Updated aviation section for 06z TAFs.
&&
DISCUSSION...Radar imagery is showing some showers across
portions of southern Oregon and northern Oregon. These showers
have generally been relatively light, are still helping to prime
conditions for later tonight when another disturbance moves
through the area. Snow levels will fall back to the West Side
valley floors, so additional snow accumulations are possible for
much of the area. Please see the Winter Weather Advisory in effect
for the Cascades and Cascade foothills for the overnight period.
(WSWMFR)
Overall, the forecast looks good from a big-picture perspective,
and will not be making any changes in this update cycle. -Schaaf
&&
AVIATION...04/06Z TAFs...Continuing showers will bring a mix of
VFR/MVFR to the area for the remainder of tonight, with a re-
invigoration of showers Tuesday morning into the afternoon. Areas
of higher terrain will be obscured and local IFR conditions are
expected under the heavier showers. Brief gusty winds and even a
lightning flash or two could also accompany any of the stronger
showers with small hail or graupel. Lightning could occur just
about anywhere, but is most likely along the coast and over the
marine waters. Freezing levels at 500 to 1000 feet tonight are
expected to rise to 2000 to 2500 feet again Tuesday afternoon.
-Miles
&&
MARINE...Updated 830 PM PDT Monday, April 3, 2023...An active
pattern with northwest swell and high and steep seas will persist
through tonight. Seas diminish Tuesday into Wednesday with northwest
winds turning southerly and strengthening again later Wednesday.
Model guidance is coming into better agreement with a stronger front
expected to arrive over the coastal waters Wednesday night. Most are
now showing, at a minimum, small craft conditions with steep wind
driven seas Wednesday night into Thursday. But, some are indicating
an increased risk for gales and very steep seas Wednesday night into
Thursday. We have held off on a watch for this forecast cycle, but
one may be necessary if the trend in the models for a stronger front
continues. Unsettled conditions are expected to continue through at
least Friday. -Hermansen/Miles
PREV DISCUSSION... /Issued 456 PM PDT Mon Apr 3 2023/
UPDATE...Updated aviation section for the 00z TAFs.
SHORT TERM...Tonight through Wednesday, April 5th...
A Winter Weather Advisory has been issued above 1500 feet for late
this evening through Tuesday morning for far eastern Coos, eastern
and southern Douglas, and northern and eastern Jackson counties.
Accumulations of 1 to 5 inches are expected in that area, with up
to an inch of snow above 1000 feet elsewhere in southwest Oregon.
Scattered to numerous light showers and snow showers are occurring
with an unseasonably low snow level of around 2500 feet. With the
sun angle higher than in the heart of winter, and day-time
heating, accumulations on roadways have been rare and minor. Our
area is now on the back side of a cold upper low. A shortwave
arriving in the northwest flow aloft will bring an increase of
showers and snow showers late tonight through Tuesday morning,
with accumulation favored north of the Umpqua Divide and
secondarily on northwest facing slopes. Snow levels will drop to
1500 feet late this evening then to around 1000 feet early
Tuesday. The other noteworthy aspect of Tuesday morning will be
much colder than normal low temperatures (below normal by 8 to 15
degrees). Low clouds and showers are expected to prevent frost at
the coast, but it will still be a chilly start to the day.
Showers will decrease slightly in coverage and intensity later
Tuesday into Tuesday evening, with snow levels rising to 2500 to
3000 feet. Weak high pressure will provide a very brief break
between systems late Tuesday night into early Wednesday morning.
Despite the dry break, cloud cover will be thickening ahead of a
warm front. The probability of rain will gradually increase from
west to east during Wednesday with rain likely to reach at least the
Coast Range of western Douglas, eastern Curry, and western
Josephine counties in the afternoon. As is inherent in its name,
snow levels of around 4500 feet will accompany the front edge of
the warm front.
LONG TERM...Wednesday night, April 5th through Monday, April 10th...
An active but warmer pattern is expected Wednesday night through
early Saturday. Then models show moderate confidence is a warm and
dry pattern developing late Saturday through Monday.
Wednesday night through Friday, a warm front will gradually move
inland and will bring precipitation and elevated snow levels. Snow
levels are expected to rise to 4000 to 5500 feet Wednesday night
then to 5500 to 6500 ft Thursday. Models and ensembles support
mainly light to moderate precipitation, with heaviest amounts along
the coast and into the coastal mountains. A cold front will approach
the coast early Friday then models show this front and an upper
trough will move inland across the area Friday into Saturday. There
is variability on how quickly this front and trough will move exit
the area. So chances for precipitation remain in the forecast on
Saturday.
Saturday night into Sunday, models and ensembles show good
agreement that a high pressure ridge will amplify over the region
resulting in warmer conditions. However there is variability on the
strength of the ridge and the details of a front moving into the
ridge from the west Sunday and Monday. Overall, with the
ridge in place ensembles continue to support warm daytime
temperatures reaching the mid 60s to lower 70s in valleys west of
the Cascades on Sunday and the upper 50s to 60s in valleys east to
of the Cascades as well as along the coast. However, ensembles also
indicate a front will push into the ridge late Sunday into Monday.
There is variability on the timing and strength of this front, which
will factor into the chance for precipitation on Sunday and
Monday, as well as with how warm temperatures get across the area.
-CC
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Winter Weather Advisory until 11 AM PDT Tuesday above 1500 feet
for ORZ023-025-026.
Winter Weather Advisory until 11 AM PDT Tuesday for ORZ027-028.
CA...None.
PACIFIC COASTAL WATERS...Small Craft Advisory until 11 PM PDT this
evening for PZZ350-356.
Small Craft Advisory until 11 AM PDT Tuesday for PZZ370-376.
&&The national radar mosaic for the moment the first event began.
1 high wind. Local standard time, as filed.
Summer Lake RAWS intermittently reported high southwest winds with a peak of 39 MPH gusting to 63 MPH. Similarly, the FW5687 Summer Lake CWOP site reported peak winds of 43 MPH gusting to 65 MPH.
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, April 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: 1092666.