Mostly clear skies and a cold air mass allowed temperatures to drop below freezing in some of the valleys of southwest Oregon.
Every event with a place to put it; 3 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.
Mostly clear skies and a cold air mass allowed temperatures to drop below freezing in some of the valleys of southwest 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 8, 7:17 PM PST, 5 hours 43 minutes earlier.
Area Forecast Discussion
National Weather Service Medford OR
817 PM PDT Thu Apr 8 2021
.UPDATE...A cool, dry night is in store for the area, with another
warm and dry day expected tomorrow. breezy winds will also return
tomorrow ahead of the next mostly dry front expected to move
through the area tomorrow night into Saturday morning. No
forecast updates are needed tonight, with everything running right
on track. -BPN
&&
.AVIATION...For the 08/00Z TAF Cycle...There is a small chance
for low ceilings to develop tonight in the Umpqua Basin and coast
north of Cape Blanco. Elsewhere...VFR conditions will continue
through the TAF period, with breezy winds expected in the
afternoon. Keene
&&
.MARINE...Updated 800 PM PDT Thursday, 8 Apr 2021...
North winds and seas are expected to remain at advisory levels
for portions of the waters from Port Orford south through late
Friday morning, then from Cape Sebastian south Friday afternoon.
Friday evening through Saturday morning another relatively light
period of winds and seas is expected as another weak front moves
through. This is then likely to be follow by a longer and stronger
north wind event with steep to very steep seas late Saturday into
early next week. Winds may rise to gales for portions of the waters
south of Cape Blanco on Sunday and continue into Monday. Gusty,
north winds and elevated seas may continue into Tuesday. -CC/Miles
&&
.PREV DISCUSSION... /Issued 326 PM PDT Thu Apr 8 2021/
SHORT TERM...Tonight through Saturday night...A weak disturbance
brought a measurement of as much as 0.23 inches at Seven Mile in
the Coos County mountains late last night into this morning with
measureable amounts for most higher elevation sites in Coos,
Curry, and Douglas counties. Low clouds north of the Umpqua Divide
will continue to dissipate into this evening, with residual
moisture bringing a modest increase of late night/early morning
stratus in the Umpqua Valley.
Otherwise, weak high pressure tonight will lead to clear skies
with low temperatures generally 5 to 10 degrees below normal. As
a result, a frost advisory is in effect for the coast and a freeze
warning for valley portions of Douglas, Josephine, and Jackson
counties.
Coastal high temperatures will be at a minimum on Friday with
high temperatures 5 to 10 degrees below normal while highs inland will
be 5 to 10 degrees above normal.
Another trough that is now in the Gulf of Alaska will move
southeast into the Pacific Northwest Friday night into Saturday
morning. This will be similar to this morning's system, though
with the highest probability of Douglas County showers during the
morning rather than late night hours. Isolated to scattered
showers are expected for the coast and across Douglas
County...though mainly for the Coos coast and Coast Range. Also,
increased coverage of clouds will result in west side low
temperatures trending slightly higher.
Behind the trough, Saturday will resemble today with diminishing
clouds, especially south of the Umpqua Divide. Away from the
coast, highs will be at a minimum on Saturday with readings in the
50s to lower 60s expected. A cold Saturday night will follow with
a light northeast flow aloft.
LONG TERM...Sunday through Thursday...The impacts in the long-term
involve agricultural (cold low temperatures due to cool, dry air
mass) and fire weather (drier than normal conditions including
weather and fuels).
Sunday starts off behind a cold front in a cooler, drier air mass,
and Sunday morning low temperatures will be 5 to 10 degrees below
normal. Lows in the teens are expected east of the Cascades, and
frost/freeze conditions are expected in many valleys west of the
Cascades. Warm air above the surface is unlikely Sunday morning, so
in terms of mitigating impacts to agriculture, mixing warm air from
above the surface to the surface will likely not be effective.
Agricultural and growing interests should plan now for these cold
temperatures and potential impacts.
By Sunday afternoon, a warming trend will be starting and will
continue through most of the week. By the end of next week, high
temperatures will likely be 10 to 15 degrees above normal.
Another potential impact is in the realm of fire weather and the
potential wind event Tuesday. Ensemble data suggests about a 40
percent chance that a strong shortwave trough just to the east of
the forecast area will dig south from north and help generate gusty
northeast winds across much of the forecast area. Gusts to 40 mph
will be possible east of the Cascades and in high terrain, and gusts
to 35 mph will certainly be possible in the Coast Range. We've
increased winds Tuesday afternoon to account for this possibility.
~Keene
&&
.MFR WATCHES/WARNINGS/ADVISORIES...
OR...Frost Advisory from 2 AM to 9 AM PDT Friday for ORZ021-022.
Freeze Watch from late Saturday night through Sunday morning for
ORZ023-024-026.
Freeze Warning from 2 AM to 9 AM PDT Friday for ORZ023.
Freeze Warning from 2 AM to 9 AM PDT Friday for ORZ024-026.
CA...None.
Pacific Coastal Waters...Small Craft Advisory until 5 PM PDT Friday for PZZ356-376.The national radar mosaic for the moment the first event began.
3 frost/freeze. Local standard time, as filed.
Reported low temperatures ranged from 30 to 32 degrees.
Reported low temperatures ranged from 27 to 34 degrees.
Reported low temperatures ranged from 27 to 32 degrees.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Oregon in 2021Every state in 2021This day in weather historyWarnings in Oregon, April 2021
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: 942090, 942091, 942092.