Alert archive / Minnesota / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 505
The Storm Prediction Center issued this severe thunderstorm watch at Sep 16, 2021, 6:39 PM CDT for 20 counties in Minnesota. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 16, 2021, 6:39 PM CDT (23:39 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 Benton County, MN, Brown County, MN, Chippewa County, MN, Cottonwood County, MN, Isanti County, MN, Kandiyohi County, MN, Lincoln County, MN, Lyon County, MN, McLeod County, MN, Meeker County, MN, Murray County, MN, Nicollet County, MN, Pipestone County, MN, Redwood County, MN, Renville County, MN, Sherburne County, MN, Sibley County, MN, Stearns County, MN, Wright County, MN, Yellow Medicine County, MN
The radar
The Minneapolis radar (KMPX), 141 km from the middle of the area, began a volume at 23:39 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
- 20%
- One or more EF2 to EF5 tornadoes
- 5%
- 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
- 30%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
7 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 16, 6:40 PM CDT | Severe Thunderstorm Warning | MPX | Chippewa, Lac qui Parle, Renville, Yellow Medicine | 35 min |
| Sep 16, 6:48 PM CDT | Severe Thunderstorm Warning | MPX | Stearns | 42 min |
| Sep 16, 7:08 PM CDT | Severe Thunderstorm Warning | MPX | Chippewa, Kandiyohi | 37 min |
| Sep 16, 7:18 PM CDT | Severe Thunderstorm Warning | MPX | Chippewa, Kandiyohi, Renville | 27 min |
| Sep 16, 7:44 PM CDT | Severe Thunderstorm Warning | MPX | Kandiyohi, Renville | 31 min |
| Sep 16, 8:12 PM CDT | Severe Thunderstorm Warning | MPX | Kandiyohi, McLeod, Meeker, Renville | 33 min |
| Sep 16, 8:45 PM CDT | Severe Thunderstorm Warning | MPX | McLeod, Meeker, Wright | 30 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
Minneapolis, MN (KMPX), launched 12:00Z, 11.7 hours before the alert went out and 139 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1213 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 362 m²/s²
- 0-3 km storm-relative helicity
- 428 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 3.0
The text
As transmitted.
554
WWUS20 KWNS 162336
SEL5
SPC WW 162336
MNZ000-170700-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 505
NWS Storm Prediction Center Norman OK
640 PM CDT Thu Sep 16 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Central and southwestern Minnesota
* Effective this Thursday night and Friday morning from 640 PM
until 200 AM CDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
A tornado or two possible
SUMMARY...Strengthening and backbuilding convection near a cold
front will pose a threat mainly for severe hail and damaging gusts
into tonight.
The severe thunderstorm watch area is approximately along and 50
statute miles east and west of a line from 60 miles southwest of
Redwood Falls MN to 15 miles north northeast of Saint Cloud MN. For
a complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU5).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Severe Thunderstorm Watch means conditions are
favorable for 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. Severe thunderstorms can and occasionally do produce
tornadoes.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 504...
AVIATION...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
23030.
...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, 5:57 PM CDT | Tornado Watch | SPC | Aitkin, Carlton, Crow Wing, Kanabec, Lake, Mille Lacs and 4 more | 4 hr |
| Sep 16, 6:23 PM CDT | Mesoscale Discussion | SPC | Chippewa, Cottonwood, Jackson, Kandiyohi, Lac qui Parle, Lincoln and 13 more | 97 min |
Nearby
Severe Thunderstorm Watches in Minnesota, 2021Every severe thunderstorm 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.