Alert archive / Wyoming / Mesoscale Discussions in 2012

Mesoscale Discussion 1092

June 7, 2012Larimer County, Weld County, Colorado; Sioux County, Nebraska; 7 counties in Wyoming

The Storm Prediction Center issued this mesoscale discussion at Jun 7, 2012, 10:59 AM MDT for Larimer County, Weld County, Colorado; Sioux County, Nebraska; 7 counties in Wyoming. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Jun 7, 2012, 10:59 AM MDT (16:59 UTC)
Expired: Jun 7, 2012, 12:30 PM MDT
In force: 91 min
Issued by: the Storm Prediction Center
Chance of a watch: 80%

Counties Larimer County, CO, Weld County, CO, Sioux County, NE, Albany County, WY, Converse County, WY, Goshen County, WY, Laramie County, WY, Niobrara County, WY, Platte County, WY, Weston County, WY

The radar

The Cheyenne radar (KCYS), 82 km from the middle of the area, began a volume at 17:01 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 362Jun 7, 11:45 AM MDT

The nearest sounding before it

Denver, CO (KDNR), launched 12:00Z, 5.0 hours before the alert went out and 266 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: 1398 J/kg
Mixed-layer CIN: -35 J/kg
Mixed-layer LCL: 671 m above ground
0-6 km bulk shear: 34 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: 105 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 1.8

Open this sounding in Storm Lab

The text

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

613 
ACUS11 KWNS 071659
SWOMCD
SPC MCD 071659 
SDZ000-NEZ000-COZ000-WYZ000-071830-

MESOSCALE DISCUSSION 1092
NWS STORM PREDICTION CENTER NORMAN OK
1159 AM CDT THU JUN 07 2012

AREAS AFFECTED...ERN WY AND ADJACENT PORTIONS OF THE NEBRASKA
PNHDL/SWRN SOUTH DAKOTA...N CNTRL/NERN CO

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 071659Z - 071830Z

PROBABILITY OF WATCH ISSUANCE...80 PERCENT

SUMMARY...TIMING IS STILL SOMEWHAT UNCERTAIN...BUT A WW WILL LIKELY
BE NEEDED BY 20-21Z...IF NOT BEFORE.

DISCUSSION...ISOLATED TO WIDELY SCATTERED STORMS HAVE ALREADY
INITIATED OFF THE MEDICINE BOW MOUNTAINS IN RESPONSE TO BOUNDARY
LAYER DESTABILIZATION AND OROGRAPHIC FORCING.  THIS PROBABLY HAS
BEEN AIDED BY FORCING FOR UPWARD VERTICAL MOTION ASSOCIATED WITH
LARGER SCALE MID/UPPER TROUGHING LIFTING OUT OF THE EASTERN GREAT
BASIN...WHICH IS EXPECTED TO CONTRIBUTE TO ADDITIONAL INCREASING
STORM DEVELOPMENT NEAR/NORTH AND EAST OF THE LARAMIE MOUNTAINS BY
THE 18-20Z. 

MODERATELY SHEARED DEEP LAYER MEAN FLOW IS STILL SOUTHERLY...BUT
EXPECTED TO VEER WITH TIME WHICH WILL CONTRIBUTE TO EASTWARD
PROPAGATION OF STORMS THROUGH THE HIGH PLAINS...WHERE CONVECTIVE
INHIBITION WILL CONTINUE TO WEAKEN...AS MIXED LAYER CAPE INCREASES
IN EXCESS OF 1500 J/KG.  LARGE HAIL APPEARS THE PRIMARY SEVERE
THREAT...PARTICULARLY WITH INITIAL ACTIVITY NEAR THE HIGHER TERRAIN.
 HOWEVER...AS ACTIVITY STRENGTHENS AND DEVELOPS EASTWARD...A FEW
SUPERCELLS ARE EXPECTED...ALONG WITH THE RISK FOR LOCALLY DAMAGING
WIND GUSTS...PERHAPS AN ISOLATED TORNADO OR TWO.

..KERR/WEISS.. 06/07/2012

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

ATTN...WFO...UNR...BOU...CYS...RIW...

LAT...LON   40260544 41110594 41670623 42630622 43530564 43990524
            44100457 43630394 42810364 41400378 40750386 40040438
            40100507 40260544

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 6, 6:47 PM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Broomfield, Denver, Douglas, Elbert and 4 more	58 min
Jun 6, 8:37 PM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Broomfield, Denver, Douglas, Elbert and 2 more	23 min
Jun 7, 11:46 AM MDT	Tornado Watch	SPC	Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas and 8 more	10 hr
Jun 7, 1:59 PM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Broomfield, Denver, Morgan, Weld	91 min
Jun 7, 5:52 PM MDT	Mesoscale Discussion	SPC	Adams, Arapahoe, Boulder, Broomfield, Crowley, Denver and 11 more	53 min

Nearby

Mesoscale Discussions in Wyoming, 2012 Mesoscale Discussions in Colorado, 2012 Mesoscale Discussions in Nebraska, 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.