Mesoscale Discussion 1214
NWS Storm Prediction Center Norman OK
0542 PM CDT Sat Jun 20 2026
Areas affected...portions of far eastern Colorado...extreme
southwestern Nebraska...and western Kansas
Concerning...Tornado and Severe Thunderstorm Watches 357...358...
Valid 202242Z - 210045Z
The severe weather threat for Tornado and Severe Thunderstorm
Watches 357, 358 continues.
SUMMARY...All severe hazards are possible over the next couple of
hours. However, ongoing storms should merge into an MCS and support
a potential severe wind swath between 00-04Z. A few gusts may reach
85-100 mph.
DISCUSSION...Multiple HP supercells, with a history of hail 1-3
inches in diameter, and measured gusts up to 90 mph (89 mph measured
by NSSL mobile unit), are in the process of gradually merging along
the KS/NE border, with a convective outflow boundary noted across
Cheyenne into Rawlins Counties. Over the next couple of hours, the
more intense and discrete updrafts will persist with a severe hail
threat, with a few stones exceeding 2 inches in diameter. While
storms may become outflow dominant, an additional tornado or two may
still occur given the amount of low-level shear concentrated along
the warm front.
Over the next few hours, the supercells are expected to merge into a
cold-pool-driven MCS, which will surge southward this evening. Given
preceding 8-8.5 C/km mid-level lapse rates, and a corridor of 50-60
kt bulk shear vectors oriented roughly normal to the expected MCS
leading-line orientation, the MCS could become highly organized and
produce a severe wind swath. This swath will most likely occur
somewhere in the 00-04Z period, containing abundant gusts in the
60-70 mph range, with the strongest gusts possibly reaching 85-100
mph, as suggested by some of the latest HRRR and WoFS runs.
..Squitieri.. 06/20/2026
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...ICT...GID...DDC...GLD...PUB...BOU...
LAT...LON 37100100 37220202 37360271 37460296 37660304 38750300
39130299 39800287 40200216 40310147 40280061 40059973
39779902 39229880 38349877 37749879 37329960 37150024
37100100
MOST PROBABLE PEAK TORNADO INTENSITY...100-125 MPH
MOST PROBABLE PEAK WIND GUST...85-100 MPH
MOST PROBABLE PEAK HAIL SIZE...2.00-3.50 IN
Source link