Alert archive / Colorado / Mesoscale Discussions in 2021
Mesoscale Discussion 1012
The Storm Prediction Center issued this mesoscale discussion at Jun 19, 2021, 12:46 PM MDT for 14 counties in Colorado; 8 counties in Nebraska. It was in force for 89 min.
The area
The outline as issued.
The facts
- Issued
- Jun 19, 2021, 12:46 PM MDT (18:46 UTC)
- Expired
- Jun 19, 2021, 2:15 PM MDT
- In force
- 89 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...severe thunderstorm watch likely
- Chance of a watch
- 80%
All 22 counties
Adams County, CO, Arapahoe County, CO, Cheyenne County, CO, Elbert County, CO, Kiowa County, CO, Kit Carson County, CO, Lincoln County, CO, Logan County, CO, Morgan County, CO, Phillips County, CO, Sedgwick County, CO, Washington County, CO, Weld County, CO, Yuma County, CO, Banner County, NE, Box Butte County, NE, Cheyenne County, NE, Deuel County, NE, Garden County, NE, Kimball County, NE, Morrill County, NE, Scotts Bluff County, NE
The radar
The Denver radar (KFTG), 127 km from the middle of the area, began a volume at 18:50 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.
The watches that followed
Watches SPC issued over any of the same counties within four hours of this discussion.
The nearest sounding before it
Denver, CO (KDNR), launched 12:00Z, 6.8 hours before the alert went out and 66 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 2627 m above ground
- 0-6 km bulk shear
- 16 kt
- 0-1 km storm-relative helicity
- -23 m²/s²
- 0-3 km storm-relative helicity
- 44 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
302
ACUS11 KWNS 191847
SWOMCD
SPC MCD 191846
NEZ000-COZ000-WYZ000-192015-
Mesoscale Discussion 1012
NWS Storm Prediction Center Norman OK
0146 PM CDT Sat Jun 19 2021
Areas affected...east-central and northeast CO...NE Panhandle...far
southeast WY
Concerning...Severe potential...Severe Thunderstorm Watch likely
Valid 191846Z - 192015Z
Probability of Watch Issuance...80 percent
SUMMARY...A severe thunderstorm watch will likely be needed for
northeastern CO and parts of western NE. Large hail and severe
gusts will be the initial threats before a transition to a more
widespread risk for severe gusts towards early evening as storms
move towards the KS border.
DISCUSSION...Midday water-vapor imagery shows a subtle disturbance
moving east across southern WY and towards the central High Plains.
At the surface, strong heating is resulting in temperatures warming
through the 80s across east-central CO northward into the NE
Panhandle. Storms are beginning to develop over the Front Range
where upwards of 2000 J/kg SBCAPE in the greater Denver area by RAP
forecast soundings.
Expecting storms to gradually develop over the next 1-3 hours in the
vicinity of the I-25 corridor from Pikes Peak northward to the
Cheyenne Ridge. Very steep low to mid-level lapse rates will favor
the risk for isolated hail/severe gusts to become more common as
storms intensify as they move east into richer low-level moisture
(longitude of Akron and areas east).
Forecast shear profiles will be strongest over northeast CO into the
NE Panhandle where southeasterly surface winds veering to 30 kt
westerly in the mid levels supports 30-40 kt effective shear. Of
particular note, suite of convection-allowing model guidance from
this morning showed a unanimous depiction of storms growing upscale
into a squall line over northeast CO and moving into northwest KS
and southwest NE by early evening.
..Smith/Hart.. 06/19/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LBF...GLD...PUB...BOU...CYS...
LAT...LON 42240391 42350297 41980207 38450205 38210243 38280373
38820443 41530446 42240391SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jun 19, 1:44 PM MDT | Severe Thunderstorm Watch | SPC | Adams, Arapahoe, Baca, Bent, Cheyenne, Crowley and 17 more | 7 hr |
| Jun 19, 3:24 PM MDT | Mesoscale Discussion | SPC | Logan, Morgan, Phillips, Sedgwick, Washington, Yuma | 2 hr |
| Jun 19, 4:00 PM MDT | Mesoscale Discussion | SPC | Kit Carson, Logan, Phillips, Sedgwick, Washington, Yuma | 90 min |
| Jun 18, 8:27 PM MDT | Mesoscale Discussion | SPC | Cass, Gage, Johnson, Lancaster, Nemaha, Otoe and 2 more | 2 hr |
| Jun 18, 9:08 PM MDT | Severe Thunderstorm Watch | SPC | Johnson, Nemaha, Pawnee, Richardson | 8 hr |
| Jun 19, 3:58 PM MDT | Mesoscale Discussion | SPC | Dawes | 92 min |
| Jun 19, 4:48 PM MDT | Severe Thunderstorm Watch | SPC | Chase, Dawson, Dundy, Frontier, Furnas, Gosper and 8 more | 6 hr |
Nearby
Mesoscale Discussions in Colorado, 2021Mesoscale Discussions in Nebraska, 2021Every mesoscale discussion 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.