Alert archive / Colorado / Mesoscale Discussions in 2021
Mesoscale Discussion 437
The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2021, 2:32 PM MDT for 12 counties in Colorado. It was in force for 118 min.
The area
The outline as issued.
The facts
- Issued
- Apr 27, 2021, 2:32 PM MDT (20:32 UTC)
- Expired
- Apr 27, 2021, 4:30 PM MDT
- In force
- 118 min
- Issued by
- the Storm Prediction Center
- Concerning
- Severe thunderstorm watch 112
Counties Adams County, CO, Arapahoe County, CO, Elbert 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
The radar
The Denver radar (KFTG), 112 km from the middle of the area, began a volume at 20:31 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 nearest sounding before it
Denver, CO (KDNR), launched 12:00Z, 8.5 hours before the alert went out and 2 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
- 3214 m above ground
- 0-6 km bulk shear
- 67 kt
- 0-1 km storm-relative helicity
- 51 m²/s²
- 0-3 km storm-relative helicity
- 72 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted.
742
ACUS11 KWNS 272032
SWOMCD
SPC MCD 272032
NEZ000-KSZ000-COZ000-272230-
Mesoscale Discussion 0437
NWS Storm Prediction Center Norman OK
0332 PM CDT Tue Apr 27 2021
Areas affected...Portions of northeast Colorado
Concerning...Severe Thunderstorm Watch 112...
Valid 272032Z - 272230Z
The severe weather threat for Severe Thunderstorm Watch 112
continues.
SUMMARY...The threat for severe hail and perhaps a damaging gust or
two continues across Severe Thunderstorm Watch #0112, and is
expected to persist through the remainder of the afternoon.
DISCUSSION...Multiple multicellular-clusters are in progress across
the western half of Severe Thunderstorm Watch #0112. While MRMS
mosaic radar data has shown storms potentially producing 1+ inch
diameter hail over the past couple of hours, individual
cells/clusters have demonstrated pulse-like behavior, with
relatively short life spans. Nonetheless, storms are developing in
an ambient environment characterized by 8+ C/km mid-level lapse
rates and over 50 kts of effective bulk shear (per latest
Mesoanalyis). The severe hail threat is expected to persist with the
more intense longer-lived storms, and a damaging gust or two cannot
be ruled out. Convective coverage may also increase somewhat as
convective outflows locally enhance low-level convergence in spots.
..Squitieri/Hart.. 04/27/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...LBF...GLD...PUB...BOU...CYS...
LAT...LON 38990402 39350448 39930457 40580444 40870426 41000366
41020269 40930232 40510206 40010203 39630209 39350218
39080245 38930306 38960349 38990402SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Apr 27, 11:15 AM MDT | Mesoscale Discussion | SPC | Adams, Arapahoe, Elbert, Kit Carson, Lincoln, Logan and 5 more | 3 hr |
| Apr 27, 11:45 AM MDT | Severe Thunderstorm Watch | SPC | Adams, Arapahoe, Cheyenne, Douglas, Elbert, Kit Carson and 8 more | 7 hr |
| Apr 27, 4:24 PM MDT | Mesoscale Discussion | SPC | Cheyenne, Kit Carson, Lincoln, Phillips, Washington, Yuma | 2 hr |
Nearby
Mesoscale Discussions in Colorado, 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.