Alert archive / North Dakota / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 478
The Storm Prediction Center issued this severe thunderstorm watch at Aug 30, 2021, 5:56 PM MDT for 12 counties in North Dakota. It was in force for 3 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 30, 2021, 5:56 PM MDT (23:56 UTC)
- Expired
- Aug 30, 2021, 8:47 PM MDT
- In force
- 3 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 65 kt
Counties Adams County, ND, Burleigh County, ND, Dunn County, ND, Emmons County, ND, Grant County, ND, Hettinger County, ND, McLean County, ND, Mercer County, ND, Morton County, ND, Oliver County, ND, Sioux County, ND, Stark County, ND
The radar
The Bismarck radar (KBIS), 68 km from the middle of the area, began a volume at 23:59 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
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 50%
- One or more hailstones of 2 inches or more
- 40%
- Six or more combined severe hail and wind reports
- 70%
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Bismarck Municip, ND (KBIS), launched 12:00Z, 11.9 hours before the alert went out and 72 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
- 8 J/kg
- Mixed-layer CIN
- -262 J/kg
- Mixed-layer LCL
- 1949 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 93 m²/s²
- 0-3 km storm-relative helicity
- 131 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
693
WWUS20 KWNS 302345
SEL8
SPC WW 302345
NDZ000-310500-
URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 478
NWS Storm Prediction Center Norman OK
645 PM CDT Mon Aug 30 2021
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Central and southern North Dakota
* Effective this Monday night from 645 PM until Midnight CDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible
Isolated significant damaging wind gusts to 75 mph possible
A tornado or two possible
SUMMARY...Several severe thunderstorms, including a few supercells,
may persist into the evening for a few hours beyond the scheduled
expiration of watch 476, which this replaces.
The severe thunderstorm watch area is approximately along and 60
statute miles east and west of a line from 70 miles north northeast
of Dickinson ND to 55 miles south southwest of Bismarck ND. For a
complete depiction of the watch see the associated watch outline
update (WOUS64 KWNS WOU8).
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...This severe thunderstorm watch replaces
severe thunderstorm watch number 476. Watch number 476 will not
be in effect after 645 PM CDT. CONTINUE...WW 477...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2.5 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 500. Mean storm motion vector
33020.
...EdwardsSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 30, 12:38 PM MDT | Severe Thunderstorm Watch | SPC | Adams, Burleigh, Dunn, Emmons, Grant, Hettinger and 6 more | 5 hr |
| Aug 30, 1:54 PM MDT | Mesoscale Discussion | SPC | Adams, Dunn, Emmons, Grant, Hettinger, McLean and 5 more | 2 hr |
| Aug 30, 4:58 PM MDT | Mesoscale Discussion | SPC | Adams, Dunn, Emmons, Grant, Hettinger, Mercer and 4 more | 62 min |
Nearby
Severe Thunderstorm Watches in North Dakota, 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.