Alert archive / Colorado / Mesoscale Discussions in 2021

Mesoscale Discussion 1734

September 12, 20215 counties in Colorado; Greeley County, Sherman County, Wallace County, Kansas

The Storm Prediction Center issued this mesoscale discussion at Sep 12, 2021, 6:03 PM MDT for 5 counties in Colorado; Greeley County, Sherman County, Wallace County, Kansas. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued
Sep 12, 2021, 6:03 PM MDT (00:03 UTC)
Expired
Sep 12, 2021, 7:30 PM MDT
In force
87 min
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
20%

Counties Bent County, CO, Cheyenne County, CO, Kiowa County, CO, Kit Carson County, CO, Prowers County, CO, Greeley County, KS, Sherman County, KS, Wallace County, KS

The radar

The Pueblo radar (KPUX), 125 km from the middle of the area, began a volume at 00:06 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 00:00Z, 0.1 hours before the alert went out and 147 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.

Skew-T log-pSkew-T log-p diagram, Denver, CO at 00:00Z on 2021-09-13Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 1 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Denver, CO at 00:00Z on 2021-09-13The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -12 square meters per square second.1939Sfc1 km3 km6 km9 kmRMLM
The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.
Mixed-layer CAPE
1 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2604 m above ground
0-6 km bulk shear
34 kt
0-1 km storm-relative helicity
-12 m²/s²
0-3 km storm-relative helicity
74 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

920 
ACUS11 KWNS 130004
SWOMCD
SPC MCD 130003 
KSZ000-COZ000-130130-

Mesoscale Discussion 1734
NWS Storm Prediction Center Norman OK
0703 PM CDT Sun Sep 12 2021

Areas affected...Eastern Colorado and western Kansas

Concerning...Severe potential...Watch unlikely 

Valid 130003Z - 130130Z

Probability of Watch Issuance...20 percent

SUMMARY...An isolated severe wind threat continues across eastern
Colorado and may continue into western Kansas before weakening after
sunset.

DISCUSSION...A line of storms across Lincoln County has shown
increasing intensity over the past hour as it moves into a more
favorable airmass with MLCAPE in excess of 500 J/kg and decreasing
inhibition per SPC mesoanalysis. Further support for the lowering
CINH can be seen by the high based cumulus across eastern Colorado
on visible satellite imagery. Very steep low and mid-level lapse
rates will continue to support a severe wind threat with this
activity, but the threat should start to wane after sunset as the
boundary layer starts to significantly cool and CINH starts to
increase once again.

..Bentley/Grams.. 09/13/2021

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

ATTN...WFO...DDC...GLD...PUB...BOU...

LAT...LON   39370340 39780275 39630152 38700152 37770194 37480273
            37570322 37910353 38410359 39370340

Nearby

Mesoscale Discussions in Colorado, 2021Mesoscale Discussions in Kansas, 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.