Alert archive / Colorado / Mesoscale Discussions in 2012

Mesoscale Discussion 1086

June 6, 201215 counties in Colorado; 8 counties in Nebraska; Goshen County, Laramie County, Platte County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Jun 6, 2012, 12:54 PM MDT for 15 counties in Colorado; 8 counties in Nebraska; Goshen County, Laramie County, Platte County, Wyoming. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jun 6, 2012, 12:54 PM MDT (18:54 UTC)
Expired: Jun 6, 2012, 3:00 PM MDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 80%

All 26 counties

Adams County, CO, Arapahoe County, CO, Boulder County, CO, Broomfield County, CO, Clear Creek County, CO, Denver County, CO, Douglas County, CO, Elbert County, CO, Gilpin County, CO, Jefferson County, CO, Larimer County, CO, Logan County, CO, Morgan County, CO, Washington County, CO, Weld County, CO, Banner County, NE, Box Butte County, NE, Cheyenne County, NE, Dawes County, NE, Kimball County, NE, Morrill County, NE, Scotts Bluff County, NE, Sioux County, NE, Goshen County, WY, Laramie County, WY, Platte County, WY

The radar

The Cheyenne radar (KCYS), 50 km from the middle of the area, began a volume at 18:54 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.

Tornado Watch 361Jun 6, 3:00 PM MDT

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 6.9 hours before the alert went out and 145 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-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

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: 72 J/kg
Mixed-layer CIN: -389 J/kg
Mixed-layer LCL: 2428 m above ground
0-6 km bulk shear: 21 kt
0-1 km storm-relative helicity: 87 m²/s²
0-3 km storm-relative helicity: 82 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

302 
ACUS11 KWNS 061855
SWOMCD
SPC MCD 061854
NEZ000-COZ000-SDZ000-WYZ000-062100-

MESOSCALE DISCUSSION 1086
NWS STORM PREDICTION CENTER NORMAN OK
0154 PM CDT WED JUN 06 2012

AREAS AFFECTED...NE CO...SE WY...NEB PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY

VALID 061854Z - 062100Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...THUNDERSTORMS ARE EXPECTED TO DEVELOP OVER THE CO FRONT
RANGE NWD INTO SE WY/NEB PANHANDLE BETWEEN 20Z-22Z AND MOVE EAST
INTO AN INCREASINGLY UNSTABLE AIR MASS. SEVERE THUNDERSTORMS ARE
LIKELY POSING A LARGE HAIL/DAMAGING WIND THREAT WITH ISOLATED
TORNADOES ALSO POSSIBLE. WW ISSUANCE IS LIKELY BY 21Z.

DISCUSSION...VISIBLE SATELLITE IMAGERY SHOWS CU FIELD DEVELOPING
OVER THE HIGHER TERRAIN OF NORTH-CENTRAL CO AND ALSO ALONG AND IN
ADVANCE OF A WEAK COLD FRONT FROM THE NEB PANHANDLE INTO NE CO/SE
WY. AS THE AFTERNOON PROGRESSES...THUNDERSTORM DEVELOPMENT IS
EXPECTED ALONG THE CO FRONT RANGE NWD INTO SE WY AND NEB PANHANDLE
WITH STORMS MOVING INTO A MODERATELY UNSTABLE AIR MASS CHARACTERIZED
BY MLCAPE VALUES OF 1500-2000 J/KG. DEEP-LAYER SHEAR VALUES ARE ALSO
EXPECTED TO INCREASE WITH TIME TO AROUND 35-40 KTS BY LATE AFTN. IN
THIS ENVIRONMENT...ORGANIZED MULTICELL/SUPERCELL STORMS ARE LIKELY.
RELATIVELY STEEP MID-LEVEL LAPSE RATES AND THE POTENTIAL FOR UPDRAFT
ROTATION SUGGESTS LARGE HAIL IS LIKELY. STEEP LOW-LEVEL LAPSE RATES
INDICATE A THREAT OF DAMAGING WIND GUSTS AS WELL WITH THE STRONGER
STORMS. ISOLATED TORNADOES ARE ALSO POSSIBLE WHERE STORMS INTERACT
WITH LOW-LEVEL BOUNDARIES.

A WW WILL LIKELY BE REQUIRED BY 21Z.

..BUNTING/WEISS.. 06/06/2012

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...LBF...UNR...PUB...BOU...CYS...

LAT...LON   41200550 42250506 43070392 42880274 41940242 40860270
            39760320 39400358 39060481 39400573 39770582 40380561
            41200550

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 6, 2:58 PM MDT	Mesoscale Discussion	SPC	Huerfano, Las Animas	2 hr
Jun 6, 3:01 PM MDT	Tornado Watch	SPC	Adams, Arapahoe, Broomfield, Denver, Douglas, Elbert and 4 more	8 hr

Nearby

Mesoscale Discussions in Colorado, 2012 Mesoscale Discussions in Nebraska, 2012 Mesoscale Discussions in Wyoming, 2012 Every mesoscale discussion in 2012

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.