Alert archive / South Dakota / Mesoscale Discussions in 2012

Mesoscale Discussion 692

May 4, 201211 counties in Nebraska; 17 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at May 4, 2012, 6:49 AM CDT for 11 counties in Nebraska; 17 counties in South Dakota. It was in force for 116 min.

The area

The outline as issued.

The facts

Issued: May 4, 2012, 6:49 AM CDT (11:49 UTC)
Expired: May 4, 2012, 8:45 AM CDT
In force: 116 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 28 counties

Antelope County, NE, Boyd County, NE, Cedar County, NE, Dixon County, NE, Holt County, NE, Keya Paha County, NE, Knox County, NE, Madison County, NE, Pierce County, NE, Stanton County, NE, Wayne County, NE, Aurora County, SD, Bon Homme County, SD, Brule County, SD, Charles Mix County, SD, Clay County, SD, Davison County, SD, Douglas County, SD, Gregory County, SD, Hanson County, SD, Hutchinson County, SD, Jones County, SD, Lyman County, SD, Mellette County, SD, Todd County, SD, Tripp County, SD, Turner County, SD, Yankton County, SD

The radar

The North Platte radar (KLNX), 181 km from the middle of the area, began a volume at 11:49 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

Aberdeen, SD (KABR), launched 00:00Z, 11.8 hours before the alert went out and 218 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: 1775 m above ground
0-6 km bulk shear: 63 kt
0-1 km storm-relative helicity: -42 m²/s²
0-3 km storm-relative helicity: 153 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.

638 
ACUS11 KWNS 041149
SWOMCD
SPC MCD 041149 
NEZ000-SDZ000-041345-

MESOSCALE DISCUSSION 0692
NWS STORM PREDICTION CENTER NORMAN OK
0649 AM CDT FRI MAY 04 2012

AREAS AFFECTED...S CNTRL AND SERN SD...NERN NEB

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 041149Z - 041345Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...A FEW ELEVATED HAIL STORMS MAY PERSIST FOR A FEW HOURS.
ADDITIONAL REDEVELOPMENT LIKELY LATER TODAY WITH HEATING.

DISCUSSION...ISOLATED STORMS ARE CURRENTLY GENERATING OVER S CNTRL
SD...ON THE NOSE OF AN ELEVATED THETA-E AXIS WHERE CONVERGENCE IS
MAXIMIZED NEAR THE 850 MB LOW...AND AIDED BY A WEAK DISTURBANCE
ALOFT. STEEP UPPER LEVEL LAPSE RATES AND MARGINAL SHEAR WILL REMAIN
SUFFICIENT FOR A FEW MARGINALLY SEVERE STORMS THIS MORNING. LATER IN
THE DAY...ONCE HEATING COMMENCES...AN INTENSIFICATION OR
REJUVENATION OF WHAT IS LEFT OF THE CURRENT ACTIVITY MAY
OCCUR...WITH AN INCREASING HAIL AND WIND THREAT.

..JEWELL/CORFIDI.. 05/04/2012

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

ATTN...WFO...FSD...OAX...ABR...LBF...UNR...

LAT...LON   43090065 43460124 43900121 44080087 43709783 43229677
            42759668 42099663 41949690 41789769 42469890 43090065

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 4, 1:50 PM CDT	Mesoscale Discussion	SPC	Antelope, Boyd, Cedar, Dakota, Dixon, Garfield and 9 more	25 min
May 4, 2:00 PM CDT	Severe Thunderstorm Watch	SPC	Antelope, Blaine, Boone, Boyd, Brown, Burt and 20 more	9 hr
May 4, 3:52 PM CDT	Mesoscale Discussion	SPC	Antelope, Boyd, Cedar, Dakota, Dixon, Garfield and 9 more	53 min
May 4, 5:31 PM CDT	Mesoscale Discussion	SPC	Adams, Antelope, Blaine, Boone, Boyd, Brown and 54 more	29 min
May 4, 5:52 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Boone, Buffalo, Burt, Butler, Cass and 27 more	5 hr

Nearby

Mesoscale Discussions in South Dakota, 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.