Alert archive / South Dakota / Mesoscale Discussions in 2015

Mesoscale Discussion 1012

June 13, 20158 counties in South Dakota; Campbell County, Crook County, Weston County, Wyoming

The Storm Prediction Center issued this mesoscale discussion at Jun 13, 2015, 11:49 PM MDT for 8 counties in South Dakota; Campbell County, Crook County, Weston County, Wyoming. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jun 13, 2015, 11:49 PM MDT (05:49 UTC)
Expired: Jun 14, 2015, 2:15 AM MDT
In force: 2 hr
Issued by: the Storm Prediction Center
Chance of a watch: 20%

Counties Butte County, SD, Custer County, SD, Haakon County, SD, Lawrence County, SD, Meade County, SD, Pennington County, SD, Perkins County, SD, Ziebach County, SD, Campbell County, WY, Crook County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 105 km from the middle of the area, began a volume at 05:49 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

Rapid City, SD (KRAP), launched 00:00Z, 5.8 hours before the alert went out and 105 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: 448 J/kg
Mixed-layer CIN: -119 J/kg
Mixed-layer LCL: 1606 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 18 m²/s²
0-3 km storm-relative helicity: 188 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.5

Open this sounding in Storm Lab

The text

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

867 
ACUS11 KWNS 140550
SWOMCD
SPC MCD 140549 
SDZ000-MTZ000-WYZ000-140815-

MESOSCALE DISCUSSION 1012
NWS STORM PREDICTION CENTER NORMAN OK
1249 AM CDT SUN JUN 14 2015

AREAS AFFECTED...PORTIONS OF NERN WY...FAR SERN MT...CNTRL/WRN SD

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 140549Z - 140815Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THE AREA IS BEING MONITORED FOR A SVR-TSTM RISK THROUGH
THE OVERNIGHT HOURS...THOUGH WW ISSUANCE IS PRESENTLY UNLIKELY.

DISCUSSION...WATER VAPOR LOOPS SUGGEST THAT ASCENT IN THE EXIT
REGION OF MIDLEVEL SPEED MAX IS OVERSPREADING MODEST LOW-LEVEL
MOISTURE N OF A SFC BOUNDARY ARCING FROM CNTRL SD INTO NWRN NEB TO
CNTRL WY. SFC DEWPOINTS ARE HOLDING IN THE MIDDLE 50S TO AROUND 60F
N OF THIS FRONT AS AN ELY/UPSLOPE LOW-LEVEL FLOW COMPONENT CONTINUES
IN THE POST-FRONTAL ENVIRONMENT. THE 00Z RIW RAOB SAMPLED H7-H5
LAPSE RATES AROUND 8 C/KM...CONTRIBUTING TO MODERATE BUOYANCY FOR
PARCELS ELEVATED ATOP A NOCTURNALLY STABILIZING BOUNDARY LAYER.
GIVEN THE OVERLAP OF THE AFOREMENTIONED ASCENT AND BUOYANCY...CAPPI
DATA AT 9 KM SUGGEST AN UPTICK IN CONVECTIVE COVERAGE AND INTENSITY
FROM NERN WY INTO SERN MT...WITH A SUPERCELL TSTM EVIDENT OVER
CAMPBELL COUNTY WY.

THIS ACTIVITY WILL CONTINUE TO SPREAD EWD INTO SD THROUGH THE
OVERNIGHT HOURS...WITH ORGANIZED/SUSTAINED CONVECTION AIDED BY 40-50
KT OF EFFECTIVE BULK SHEAR. GENERALLY ISOLATED INSTANCES OF SVR HAIL
SHOULD BE THE PRIMARY CONCERN...AS NOCTURNAL COOLING CONTRIBUTES TO
INCREASING CINH FOR A SFC-BASED PARCEL...AND THIS WILL LIKELY
MITIGATE THE NEED FOR A WW. HOWEVER...IF AREAS OF UPSCALE CONVECTIVE
GROWTH WERE TO OCCUR WITH COLD-POOL AMALGAMATION ENHANCING THE
POTENTIAL FOR DOWNDRAFTS TO PENETRATE THE NOCTURNAL STABLE
LAYER...THE SVR-WIND RISK WOULD INCREASE. CONFIDENCE IN THIS
SCENARIO IS LOW WITHOUT EVEN STRONGER LARGE-SCALE ASCENT AND THE
INCREASING NOCTURNAL CINH. HOWEVER...CONVECTIVE TRENDS WILL CONTINUE
TO BE MONITORED.

..COHEN/DIAL.. 06/14/2015

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

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

LAT...LON   44700643 45550382 45680198 45240096 44190108 43460422
            43630656 44700643

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 14, 4:01 AM MDT	Mesoscale Discussion	SPC	Brown, Campbell, Dewey, Edmunds, Faulk, Haakon and 10 more	2 hr
Jun 14, 6:34 AM MDT	Mesoscale Discussion	SPC	Aurora, Beadle, Brown, Brule, Buffalo, Clark and 17 more	2 hr
Jun 14, 11:51 AM MDT	Mesoscale Discussion	SPC	Bon Homme, Clay, Hutchinson, Lincoln, McCook, Minnehaha and 3 more	114 min

Nearby

Mesoscale Discussions in South Dakota, 2015 Mesoscale Discussions in Wyoming, 2015 Every mesoscale discussion in 2015

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.