Alert archive / Minnesota / Tornado Watches in 2018
Tornado Watch 384
The Storm Prediction Center issued this tornado watch at Sep 20, 2018, 3:33 PM CDT for 28 counties in Minnesota. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 20, 2018, 3:33 PM CDT (20:33 UTC)
- Expired
- Sep 20, 2018, 7:58 PM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 28 counties
Blue Earth County, MN, Brown County, MN, Carver County, MN, Cottonwood County, MN, Dakota County, MN, Faribault County, MN, Freeborn County, MN, Goodhue County, MN, Hennepin County, MN, Jackson County, MN, Le Sueur County, MN, Lincoln County, MN, Lyon County, MN, Martin County, MN, Murray County, MN, Nicollet County, MN, Nobles County, MN, Pipestone County, MN, Ramsey County, MN, Redwood County, MN, Rice County, MN, Rock County, MN, Scott County, MN, Sibley County, MN, Steele County, MN, Waseca County, MN, Washington County, MN, Watonwan County, MN
The radar
The Minneapolis radar (KMPX), 102 km from the middle of the area, began a volume at 20:34 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
- 60%
- One or more EF2 to EF5 tornadoes
- 40%
- Ten or more severe wind reports
- 80%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 40%
- One or more hailstones of 2 inches or more
- 30%
- Six or more combined severe hail and wind reports
- 95%
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 20, 5:02 PM CDT | Severe Thunderstorm Warning | FSD | Jackson | 28 min |
| Sep 20, 5:30 PM CDT | Severe Thunderstorm Warning | MPX | Blue Earth, Faribault, Martin, Watonwan | 45 min |
| Sep 20, 5:59 PM CDT | Severe Thunderstorm Warning | MPX | Blue Earth, Faribault, Waseca | 46 min |
| Sep 20, 6:13 PM CDT | Severe Thunderstorm Warning | MPX | Carver, Dakota, Hennepin, Ramsey, Scott | 47 min |
| Sep 20, 6:15 PM CDT | Severe Thunderstorm Warning | MPX | Carver | 15 min |
| Sep 20, 6:19 PM CDT | Tornado Warning | MPX | Le Sueur, Rice, Waseca | 41 min |
| Sep 20, 6:23 PM CDT | Severe Thunderstorm Warning | MPX | Freeborn, Le Sueur, Rice, Steele, Waseca | 52 min |
| Sep 20, 6:40 PM CDT | Tornado Warning | MPX | Goodhue, Rice, Steele | 35 min |
| Sep 20, 6:41 PM CDT | Severe Thunderstorm Warning | MPX | Anoka, Dakota, Goodhue, Hennepin, Ramsey, Washington | 34 min |
| Sep 20, 6:49 PM CDT | Tornado Warning | MPX | Dakota, Goodhue, Rice | 41 min |
| Sep 20, 7:13 PM CDT | Tornado Warning | MPX | Goodhue | 36 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, 8.6 hours before the alert went out and 101 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
- 18 J/kg
- Mixed-layer CIN
- -80 J/kg
- Mixed-layer LCL
- 461 m above ground
- 0-6 km bulk shear
- 48 kt
- 0-1 km storm-relative helicity
- 195 m²/s²
- 0-3 km storm-relative helicity
- 20 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- -0.1
The text
As transmitted.
029
WWUS20 KWNS 202031
SEL4
SPC WW 202031
MNZ000-210400-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 384
NWS Storm Prediction Center Norman OK
335 PM CDT Thu Sep 20 2018
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Southern Minnesota
* Effective this Thursday afternoon and evening from 335 PM until
1100 PM CDT.
* Primary threats include...
A few tornadoes likely with a couple intense tornadoes possible
Widespread damaging wind gusts to 70 mph likely
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
SUMMARY...Thunderstorms are expected to intensify this afternoon
across southern Minnesota and track quickly northeastward.
Parameters are favorable for a few tornadoes, as well as rather
widespread damaging wind gusts.
The tornado watch area is approximately along and 45 statute miles
north and south of a line from 55 miles east of Mankato MN to 45
miles northwest of Worthington 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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 383...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 25035.
...HartSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 20, 2:15 PM CDT | Mesoscale Discussion | SPC | Blue Earth, Brown, Carver, Cottonwood, Dakota, Dodge and 26 more | 3 hr |
| Sep 20, 5:29 PM CDT | Mesoscale Discussion | SPC | Blue Earth, Brown, Carver, Cottonwood, Dakota, Dodge and 24 more | 2 hr |
| Sep 20, 6:23 PM CDT | Tornado Watch | SPC | Dodge, Fillmore, Houston, Mower, Olmsted, Wabasha and 1 more | 5 hr |
Nearby
Tornado Watches in Minnesota, 2018Every tornado watch in 2018
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.