Tornado Watch 280

Issued

Jul 18, 2018, 3:43 PM CDT (20:43 UTC)

Expired

Jul 18, 2018, 10:47 PM CDT

In force

7 hr

Issued by

the Storm Prediction Center

Largest hail expected

2 in

Strongest gust expected

60 kt

The Rapid City radar (KUDX), 163 km from the middle of the area, began a volume at 20:46 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.

Two or more tornadoes

30%

One or more EF2 to EF5 tornadoes

10%

Ten or more severe wind reports

50%

One or more gusts of 65 knots or more

20%

Ten or more severe hail reports

70%

One or more hailstones of 2 inches or more

30%

Six or more combined severe hail and wind reports

95%

• Mesoscale Discussion 1074Jul 18, 1:39 PM CDT
• Mesoscale Discussion 1077Jul 18, 4:59 PM CDT
• Mesoscale Discussion 1078Jul 18, 5:16 PM CDT
• Mesoscale Discussion 1079Jul 18, 9:21 PM CDT

481 
WWUS20 KWNS 182040
SEL0  
SPC WW 182040
NEZ000-SDZ000-190400-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 280
NWS Storm Prediction Center Norman OK
340 PM CDT Wed Jul 18 2018

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Northern Nebraska
  South Dakota

* Effective this Wednesday afternoon and evening from 340 PM
  until 1100 PM CDT.

* Primary threats include...
  A couple tornadoes possible
  Scattered large hail likely with isolated very large hail events
    to 2 inches in diameter possible
  Scattered damaging wind gusts to 70 mph possible

SUMMARY...On the southern periphery of an upper-level system moving
slowly eastward over the Dakotas, storms will continue to increase
in coverage and intensity through the remainder of the afternoon
into this evening. A relatively moist environment and strengthening
winds aloft (reference 19Z Rapid City special observed sounding)
will support supercells capable of large hail. A concern for a
couple of tornadoes also exists especially along a warm front that
extends across central/southern South Dakota into northern Nebraska.
Otherwise, storms will eventually cluster and move southeastward
across the region this evening with some increased potential for
damaging winds.

The tornado watch area is approximately along and 70 statute miles
north and south of a line from 70 miles northwest of Philip SD to 45
miles northeast of Oneill NE. For a complete depiction of the watch
see the associated watch outline update (WOUS64 KWNS WOU0).

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 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 500. Mean
storm motion vector 29025.

...Guyer

Tornado Watches in South Dakota, 2018Tornado Watches in Nebraska, 2018Every tornado watch in 2018

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.