Alert archive / South Dakota / Mesoscale Discussions in 2012

Mesoscale Discussion 470

April 6, 20124 counties in Nebraska; 6 counties in South Dakota; 5 counties in Wyoming

The Storm Prediction Center issued this mesoscale discussion at Apr 6, 2012, 12:11 PM MDT for 4 counties in Nebraska; 6 counties in South Dakota; 5 counties in Wyoming. It was in force for 64 min.

The area

The outline as issued.

The facts

Issued: Apr 6, 2012, 12:11 PM MDT (18:11 UTC)
Expired: Apr 6, 2012, 1:15 PM MDT
In force: 64 min
Issued by: the Storm Prediction Center

Counties Banner County, NE, Dawes County, NE, Scotts Bluff County, NE, Sioux County, NE, Butte County, SD, Custer County, SD, Fall River County, SD, Harding County, SD, Lawrence County, SD, Pennington County, SD, Crook County, WY, Goshen County, WY, Niobrara County, WY, Platte County, WY, Weston County, WY

The radar

The Rapid City radar (KUDX), 114 km from the middle of the area, began a volume at 18:11 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 (KUNR), launched 12:00Z, 6.2 hours before the alert went out and 107 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: 630 m above ground
0-6 km bulk shear: 25 kt
0-1 km storm-relative helicity: 151 m²/s²
0-3 km storm-relative helicity: 113 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.

759 
ACUS11 KWNS 061812
SWOMCD
SPC MCD 061811
SDZ000-NEZ000-MTZ000-WYZ000-061915-

MESOSCALE DISCUSSION 0470
NWS STORM PREDICTION CENTER NORMAN OK
0111 PM CDT FRI APR 06 2012

AREAS AFFECTED...ERN WY...WRN ND/SD AND THE NEB PANHANDLE

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY

VALID 061811Z - 061915Z

AN INCREASING COVERAGE OF MARGINALLY SEVERE STORMS IS LIKELY THIS
AFTERNOON...INITIATING IN WY AND PROGRESSING EWD INTO ADJACENT AREAS
OF WRN ND/SD AND THE NEB PANHANDLE. GUSTY WINDS AND HAIL WILL BE THE
PRIMARY THREATS...THOUGH DUE TO THE MARGINAL NATURE...A WW IS NOT
ANTICIPATED.

18Z VISIBLE IMAGERY SHOWS AN INCREASING CU FIELD WHERE SURFACE
CONVERGENCE IS STRENGTHENING ALONG A COLD FRONT/LEE SURFACE TROUGH.
INCREASINGLY FAVORABLE UPPER DIVERGENCE AHEAD OF A NEWD PROGRESSING
TROUGH WILL FURTHER SUPPORT VERTICAL MOTION...REFLECTED IN THE EARLY
INITIATION OF THE CUMULUS FIELD IN WY. HOWEVER...SCANT MOISTURE IS
LIMITING INSTABILITY...WITH CURRENT MESOANALYSIS ALSO INDICATING
WEAK CONVECTIVE INHIBITION. THIS SHOULD GRADUALLY BE OVERCOME WITH
SURFACE HEATING...AND AS THE FRONTAL/LEE SURFACE TROUGH BOUNDARY
PROGRESSES EWD INTO SLIGHTLY GREATER MOISTURE. DESPITE STRONG DEEP
LAYER WIND FIELDS...WEAK INSTABILITY/MOISTURE WILL HINDER GREATER
SEVERE POTENTIAL...THOUGH GUSTY WINDS/HAIL ARE POSSIBLE WITH THE
STRONGER STORMS.

..HURLBUT.. 04/06/2012

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

ATTN...WFO...UNR...CYS...BYZ...

LAT...LON   45630325 43950273 42580296 41540337 41240420 41370493
            42170536 43410515 45160431 45690391 45630325

Nearby

Mesoscale Discussions in South Dakota, 2012 Mesoscale Discussions in Wyoming, 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.