Alert archive / Colorado / Mesoscale Discussions in 2021
Mesoscale Discussion 1745
The Storm Prediction Center issued this mesoscale discussion at Sep 14, 2021, 1:08 PM MDT for 11 counties in Colorado. It was in force for 2 hr.
The area
The outline as issued.
The facts
- Issued
- Sep 14, 2021, 1:08 PM MDT (19:08 UTC)
- Expired
- Sep 14, 2021, 3:15 PM MDT
- In force
- 2 hr
- Issued by
- the Storm Prediction Center
- Concerning
- Severe potential...watch possible
- Chance of a watch
- 40%
Counties Bent County, CO, Cheyenne County, CO, Crowley County, CO, El Paso County, CO, Elbert County, CO, Kiowa County, CO, Kit Carson County, CO, Lincoln County, CO, Otero County, CO, Prowers County, CO, Pueblo County, CO
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, 7.1 hours before the alert went out and 142 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
- 17 J/kg
- Mixed-layer CIN
- -309 J/kg
- Mixed-layer LCL
- 1437 m above ground
- 0-6 km bulk shear
- 39 kt
- 0-1 km storm-relative helicity
- 21 m²/s²
- 0-3 km storm-relative helicity
- 265 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.1
The text
As transmitted.
347
ACUS11 KWNS 141908
SWOMCD
SPC MCD 141908
COZ000-142115-
Mesoscale Discussion 1745
NWS Storm Prediction Center Norman OK
0208 PM CDT Tue Sep 14 2021
Areas affected...eastern CO
Concerning...Severe potential...Watch possible
Valid 141908Z - 142115Z
Probability of Watch Issuance...40 percent
SUMMARY...Isolated thunderstorms capable of large hail are possible
this afternoon. Convective trends are being monitored for possible
watch issuance in the next few hours.
DISCUSSION...Convection is increasing over higher terrain west of
I-25 this afternoon as instability increases amid strong heating.
Boundary-layer moisture remains poor, with surface dewpoints
generally in the mid 40s to mid 50s F. As a result, convection may
struggle to persist as storms move eastward off of higher terrain,
with additional storms possibly developing in weak low level
confluence/upslope flow near the Palmer Divide over the next few
hours. Despite poor low-level moisture, steep midlevel lapse rates
around 7.5-8 C/km will support 500-1000 J/kg MLCAPE. Low and
midlevel flow also is rather weak, but easterly winds below 700 mb
veering to northwesterly is contributing to around 30-40 kt
effective shear magnitudes. This should support at least isolated,
briefly organized cells this afternoon/evening. Long, straight
forecast hodographs indicate splitting cells capable of large hail
will be the main hazard this afternoon/early evening.
..Leitman/Thompson.. 09/14/2021
...Please see www.spc.noaa.gov for graphic product...
ATTN...WFO...GLD...PUB...BOU...
LAT...LON 37510322 37530398 37760453 38640501 39140494 39480456
39700389 39650324 39470273 39080231 38920220 38380206
37710236 37510322SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Sep 14, 1:55 PM MDT | Severe Thunderstorm Watch | SPC | Baca, Bent, Cheyenne, Crowley, Elbert, El Paso and 10 more | 7 hr |
| Sep 14, 5:30 PM MDT | Mesoscale Discussion | SPC | Bent | 90 min |
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.