Alert archive / Nebraska / Severe Thunderstorm Watches in 2021
Severe Thunderstorm Watch 406
The Storm Prediction Center issued this severe thunderstorm watch at Jul 30, 2021, 9:46 PM CDT for 14 counties in Nebraska. It was in force for 4 hr.
The area
The outline as issued.
The facts
- Issued
- Jul 30, 2021, 9:46 PM CDT (02:46 UTC)
- Expired
- Jul 31, 2021, 1:36 AM CDT
- In force
- 4 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1.5 in
- Strongest gust expected
- 55 kt
Counties Antelope County, NE, Blaine County, NE, Boone County, NE, Brown County, NE, Garfield County, NE, Greeley County, NE, Holt County, NE, Loup County, NE, Madison County, NE, Pierce County, NE, Platte County, NE, Rock County, NE, Valley County, NE, Wheeler County, NE
The radar
The North Platte radar (KLNX), 129 km from the middle of the area, began a volume at 02:48 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
- 5%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 50%
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
N. Platte/Lee Bi, NE (KLBF), launched 00:00Z, 2.8 hours before the alert went out and 180 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
- 2904 J/kg
- Mixed-layer CIN
- -55 J/kg
- Mixed-layer LCL
- 1646 m above ground
- 0-6 km bulk shear
- 27 kt
- 0-1 km storm-relative helicity
- 115 m²/s²
- 0-3 km storm-relative helicity
- 200 m²/s²
- Significant tornado parameter
- 0.6
- Supercell composite
- 17.8
The text
As transmitted.
923 WWUS20 KWNS 310243 SEL6 SPC WW 310243 NEZ000-310900- URGENT - IMMEDIATE BROADCAST REQUESTED Severe Thunderstorm Watch Number 406 NWS Storm Prediction Center Norman OK 945 PM CDT Fri Jul 30 2021 The NWS Storm Prediction Center has issued a * Severe Thunderstorm Watch for portions of portions of northern Nebraska * Effective this Friday night and Saturday morning from 945 PM until 400 AM CDT. * Primary threats include... Isolated damaging wind gusts to 65 mph possible Isolated large hail events to 1.5 inches in diameter possible SUMMARY...A band of thunderstorms moving southeastward across northern Nebraska will pose a risk for locally damaging winds, and a few instances of hail in excess of 1" in diameter. The severe thunderstorm watch area is approximately along and 35 statute miles north and south of a line from 25 miles south southwest of Ainsworth NE to 70 miles east southeast of Oneill NE. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU6). 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 405... AVIATION...A few severe thunderstorms with hail surface and aloft to 1.5 inches. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 550. Mean storm motion vector 30030. ...Goss
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jul 30, 8:16 PM CDT | Mesoscale Discussion | SPC | Cass, Douglas, Gage, Johnson, Lancaster, Nemaha and 5 more | 59 min |
| Jul 30, 8:47 PM CDT | Severe Thunderstorm Watch | SPC | Cass, Gage, Johnson, Lancaster, Nemaha, Otoe and 2 more | 5 hr |
| Jul 30, 9:36 PM CDT | Mesoscale Discussion | SPC | Brown, Garfield, Loup, Rock | 24 min |
| Jul 30, 11:05 PM CDT | Mesoscale Discussion | SPC | Nemaha, Richardson | 85 min |
| Jul 30, 11:09 PM CDT | Mesoscale Discussion | SPC | Nemaha, Richardson | 96 min |
Nearby
Severe Thunderstorm Watches in Nebraska, 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.