Alert archive / South Dakota / Mesoscale Discussions in 2012

Mesoscale Discussion 1245

June 22, 201216 counties in South Dakota; Campbell County, Crook County, Weston County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Jun 22, 2012, 5:02 PM MDT for 16 counties in South Dakota; Campbell County, Crook County, Weston County, Wyoming. It was in force for 118 min.

The area

The outline as issued.

The facts

Issued: Jun 22, 2012, 5:02 PM MDT (23:02 UTC)
Expired: Jun 22, 2012, 7:00 PM MDT
In force: 118 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

Counties Bennett County, SD, Butte County, SD, Custer County, SD, Fall River County, SD, Haakon County, SD, Jackson County, SD, Jones County, SD, Lawrence County, SD, Lyman County, SD, Meade County, SD, Mellette County, SD, Oglala Lakota County, SD, Pennington County, SD, Stanley County, SD, Todd County, SD, Tripp County, SD, Campbell County, WY, Crook County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 29 km from the middle of the area, began a volume at 23:03 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.

Severe Thunderstorm Watch 420Jun 22, 5:50 PM MDT

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 11.0 hours before the alert went out and 26 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1613 m above ground
0-6 km bulk shear: 39 kt
0-1 km storm-relative helicity: 133 m²/s²
0-3 km storm-relative helicity: 90 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

The text

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

758 
ACUS11 KWNS 222303
SWOMCD
SPC MCD 222302
SDZ000-MTZ000-WYZ000-230100-

MESOSCALE DISCUSSION 1245
NWS STORM PREDICTION CENTER NORMAN OK
0602 PM CDT FRI JUN 22 2012

AREAS AFFECTED...NORTHEAST WY AND WESTERN/CENTRAL SD

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 222302Z - 230100Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...TSTMS CAPABLE OF SEVERE HAIL/WINDS ARE EXPECTED TO
DEVELOP/GRADUALLY INCREASE...AT LEAST ON AN ISOLATED BASIS...THROUGH
EARLY/MID EVENING ACROSS NORTHEAST WY INTO WESTERN SD. A GREATER
TSTM COVERAGE IS EXPECTED LATER THIS EVENING/OVERNIGHT ACROSS
SD...WITH SEVERE HAIL POSSIBLE.

DISCUSSION...WHILE SHORTWAVE RIDGING/CAPPING CURRENTLY EXISTS ACROSS
THE WESTERN DAKOTAS/HIGH PLAINS...WATER VAPOR IMAGERY IS INDICATIVE
OF THE LEADING EDGE OF HEIGHT FALLS/AN EMBEDDED IMPULSE SPREADING
ACROSS WY LATE THIS AFTERNOON. AS THIS OCCURS...AN INCREASE IN
DEEPENING CU HAS BEEN NOTED WITHIN A HOT/DEEPLY MIXED BOUNDARY LAYER
ACROSS MUCH OF EAST/NORTHEAST WY IN GENERAL VICINITY OF AN INTERIOR
WY SURFACE LOW/ASSOCIATED TROUGH. AS THE AFOREMENTIONED SHORTWAVE
TROUGH/SPEED MAX CONTINUES TO TRANSITION EAST-NORTHEASTWARD ACROSS
THE REGION...ISOLATED TO PERHAPS SCATTERED TSTMS SHOULD
DEVELOP/INCREASE THROUGH EARLY/MID EVENING WITHIN THE INSTABILITY
AXIS ACROSS NORTHEAST WY INTO WESTERN SD. WHERE SUSTAINED STORMS
OCCUR...WEAK TO MODERATE INSTABILITY AND STRENGTHENING VERTICAL
SHEAR WILL SUPPORT ORGANIZED STORM MODES INCLUDING A FEW SUPERCELLS
CAPABLE OF SEVERE HAIL/DAMAGING WINDS.

A GREATER/MORE CERTAIN COVERAGE OF TSTMS SHOULD OCCUR BY LATE
EVENING/OVERNIGHT ACROSS WEST-CENTRAL/MUCH OF SOUTHERN SD AS A LOW
LEVEL JET/ASSOCIATED ISENTROPIC ASCENT INCREASES. AT LEAST BOUTS OF
SEVERE HAIL WILL BE POSSIBLE WITHIN A STEEP MID-LEVEL LAPSE
ENVIRONMENT.

..GUYER/MEAD.. 06/22/2012

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

ATTN...WFO...FSD...ABR...UNR...CYS...BYZ...RIW...

LAT...LON   43119953 43030236 43140404 43590484 44000651 44760662
            45190335 44840099 44029917 43119953

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 22, 5:48 PM MDT	Severe Thunderstorm Watch	SPC	Bennett, Butte, Custer, Fall River, Jackson, Lawrence and 4 more	7 hr
Jun 22, 2:59 PM MDT	Mesoscale Discussion	SPC	Goshen, Laramie	91 min
Jun 22, 3:52 PM MDT	Severe Thunderstorm Watch	SPC	Goshen, Niobrara, Platte	9 hr

Nearby

Mesoscale Discussions in South Dakota, 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.