Mesoscale Discussion 1000

Issued

Jun 18, 2021, 5:34 PM MDT (23:34 UTC)

Expired

Jun 18, 2021, 7:00 PM MDT

In force

86 min

Issued by

the Storm Prediction Center

Concerning

Severe potential...watch unlikely

Chance of a watch

20%

Counties Adams County, CO, Broomfield County, CO, Denver County, CO, Morgan County, CO, Weld County, CO, Banner County, NE, Kimball County, NE, Scotts Bluff County, NE, Goshen County, WY, Laramie County, WY, Platte County, WY

The Cheyenne radar (KCYS), 34 km from the middle of the area, began a volume at 23:32 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.

840 
ACUS11 KWNS 182335
SWOMCD
SPC MCD 182334 
COZ000-NEZ000-WYZ000-190100-

Mesoscale Discussion 1000
NWS Storm Prediction Center Norman OK
0634 PM CDT Fri Jun 18 2021

Areas affected...Southeastern Wyoming...Northeast Colorado...and the
western Nebraska Panhandle

Concerning...Severe potential...Watch unlikely 

Valid 182334Z - 190100Z

Probability of Watch Issuance...20 percent

SUMMARY...Thunderstorm development across far eastern Wyoming and
northeastern Colorado appears likely over the next 1 to 2 hours. A
few severe storms, including a supercell or two, may evolve and pose
a risk for damaging wind gusts and or severe hail into this evening.
Severe trends will be monitored but currently, a weather watch is
unlikely.

DISCUSSION...Ahead of a weak mid-level shortwave trough, late
afternoon visible imagery showed towering cumulus gradually becoming
more agitated in the weak upslope flow regime across southern
Wyoming and northeastern Colorado. Strong heating, with surface
temps in the mid to upper 80s along with dewpoints in the upper 40s
to low 50s are contributing to moderate buoyancy of 500-1500 J/kg of
MLCAPE. Remaining MLCINH appears negligible and should continue to
be eroded by weak background ascent from the approaching trough and
upslope flow across the front range. Convective initiation appears
likely in the next 1 to 2 hours. Deep-layer shear profiles around 35
to 45 kts will support a few organized updrafts with some potential
for a supercell or two. The degree of buoyancy and steep
low/mid-level lapse rates will support a hail and wind threat with
any strong storms as they move to the east/southeast into the
western Nebraska Panhandle tonight. Storm coverage is forecast to
remain isolated given weak overall forcing. The uncertainty in storm
coverage and resulting severe potential suggests a weather watch is
likely unnecessary, though convective trends will be monitored.

..Lyons/Guyer.. 06/18/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...BOU...CYS...

LAT...LON   41250522 41890520 42340476 42490424 42350378 41980351
            41380351 40660356 40210361 39920391 39730443 39670485
            39920514 40880527 41250522

Mesoscale Discussions in Colorado, 2021Mesoscale Discussions in Nebraska, 2021Mesoscale Discussions in Wyoming, 2021Every mesoscale discussion in 2021

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.