Alert archive / Minnesota / Tornado Watches in 2021
Tornado Watch 504
The Storm Prediction Center issued this tornado watch at Sep 16, 2021, 5:57 PM CDT for 10 counties in Minnesota. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 16, 2021, 5:57 PM CDT (22:57 UTC)
- Expired
- Sep 16, 2021, 10:15 PM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 60 kt
Counties Aitkin County, MN, Carlton County, MN, Crow Wing County, MN, Kanabec County, MN, Lake County, MN, Mille Lacs County, MN, Morrison County, MN, Pine County, MN, Saint Louis County, MN, Todd County, MN
The radar
The Duluth radar (KDLH), 97 km from the middle of the area, began a volume at 22:58 UTC, the scan nearest the moment this went out.
Open the radar archive at this moment
The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 40%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 50%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
11 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 16, 6:03 PM CDT | Severe Thunderstorm Warning | DLH | Aitkin, Crow Wing | 27 min |
| Sep 16, 6:16 PM CDT | Severe Thunderstorm Warning | DLH | Saint Louis | 27 min |
| Sep 16, 6:25 PM CDT | Severe Thunderstorm Warning | MPX | Morrison | 35 min |
| Sep 16, 6:26 PM CDT | Severe Thunderstorm Warning | MPX | Benton, Morrison, Stearns | 49 min |
| Sep 16, 6:27 PM CDT | Severe Thunderstorm Warning | DLH | Aitkin, Saint Louis | 48 min |
| Sep 16, 6:32 PM CDT | Tornado Warning | MPX | Mille Lacs, Morrison | 43 min |
| Sep 16, 7:07 PM CDT | Tornado Warning | MPX | Mille Lacs, Morrison | 23 min |
| Sep 16, 7:09 PM CDT | Severe Thunderstorm Warning | DLH | Saint Louis | 23 min |
| Sep 16, 7:30 PM CDT | Severe Thunderstorm Warning | MPX | Kanabec, Mille Lacs, Morrison | 45 min |
| Sep 16, 7:53 PM CDT | Severe Thunderstorm Warning | MPX | Mille Lacs | 37 min |
| Sep 16, 8:22 PM CDT | Severe Thunderstorm Warning | DLH | Aitkin, Pine | 53 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
International Fa, MN (KINL), launched 12:00Z, 11.0 hours before the alert went out and 199 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.
- Mixed-layer CAPE
- 5 J/kg
- Mixed-layer CIN
- -201 J/kg
- Mixed-layer LCL
- 804 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 279 m²/s²
- 0-3 km storm-relative helicity
- 288 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.0
The text
As transmitted.
772
WWUS20 KWNS 162248
SEL4
SPC WW 162248
MNZ000-170500-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 504
NWS Storm Prediction Center Norman OK
550 PM CDT Thu Sep 16 2021
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Central and northern Minnesota
* Effective this Thursday afternoon from 550 PM until Midnight
CDT.
* Primary threats include...
A couple tornadoes possible
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
SUMMARY...Thunderstorms have developed along/ahead of a cold front
and will continue to intensify for another few hours, offering a
tornado threat, along with damaging gusts and large to very large
hail.
The tornado watch area is approximately along and 60 statute miles
east and west of a line from 40 miles south of Brainerd MN to 25
miles north of Ely MN. For a complete depiction of the watch see the
associated watch outline update (WOUS64 KWNS WOU4).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and severe thunderstorms in and close to the watch
area. Persons in these areas should be on the lookout for
threatening weather conditions and listen for later statements
and possible warnings.
&&
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2.5 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 550. Mean
storm motion vector 23035.
...EdwardsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 16, 3:47 PM CDT | Mesoscale Discussion | SPC | Aitkin, Anoka, Benton, Carlton, Carver, Cass and 25 more | 118 min |
| Sep 16, 6:23 PM CDT | Mesoscale Discussion | SPC | Chippewa, Cottonwood, Jackson, Kandiyohi, Lac qui Parle, Lincoln and 13 more | 97 min |
| Sep 16, 6:39 PM CDT | Severe Thunderstorm Watch | SPC | Benton, Brown, Chippewa, Cottonwood, Isanti, Kandiyohi and 14 more | 4 hr |
Nearby
Tornado Watches in Minnesota, 2021Every tornado watch in 2021
Sources
The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.