Alert archive / South Dakota / Mesoscale Discussions in 2013

Mesoscale Discussion 1921

October 2, 20134 states

The Storm Prediction Center issued this mesoscale discussion at Oct 2, 2013, 2:59 PM CDT for 4 states. It was in force for 61 min.

The area

The outline as issued.

The facts

Issued: Oct 2, 2013, 2:59 PM CDT (19:59 UTC)
Expired: Oct 2, 2013, 4:00 PM CDT
In force: 61 min
Issued by: the Storm Prediction Center
Chance of a watch: 20%

All 62 counties

Lyon County, IA, Sioux County, IA, Big Stone County, MN, Chippewa County, MN, Douglas County, MN, Grant County, MN, Lac qui Parle County, MN, Lincoln County, MN, Lyon County, MN, Murray County, MN, Pipestone County, MN, Pope County, MN, Rock County, MN, Stevens County, MN, Swift County, MN, Traverse County, MN, Yellow Medicine County, MN, Antelope County, NE, Boone County, NE, Buffalo County, NE, Cedar County, NE, Custer County, NE, Dixon County, NE, Garfield County, NE, Greeley County, NE, Holt County, NE, Howard County, NE, Knox County, NE, Loup County, NE, Madison County, NE, Nance County, NE, Pierce County, NE, Platte County, NE, Sherman County, NE, Stanton County, NE, Valley County, NE, Wayne County, NE, Wheeler County, NE, Bon Homme County, SD, Brookings County, SD, Clark County, SD, Clay County, SD, Codington County, SD, Davison County, SD, Day County, SD, Deuel County, SD, Grant County, SD, Hamlin County, SD, Hanson County, SD, Hutchinson County, SD, Kingsbury County, SD, Lake County, SD, Lincoln County, SD, McCook County, SD, Miner County, SD, Minnehaha County, SD, Moody County, SD, Roberts County, SD, Sanborn County, SD, Turner County, SD, Union County, SD, Yankton County, SD

The radar

The Sioux Falls radar (KFSD), 56 km from the middle of the area, began a volume at 20:00 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 12:00Z, 8.0 hours before the alert went out and 149 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: 2571 m above ground
0-6 km bulk shear: 60 kt
0-1 km storm-relative helicity: 200 m²/s²
0-3 km storm-relative helicity: 293 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.

428 
ACUS11 KWNS 021959
SWOMCD
SPC MCD 021959 
MNZ000-IAZ000-NEZ000-SDZ000-NDZ000-022100-

MESOSCALE DISCUSSION 1921
NWS STORM PREDICTION CENTER NORMAN OK
0259 PM CDT WED OCT 02 2013

AREAS AFFECTED...ERN SD/SWRN MN SWD INTO CENTRAL NEB

CONCERNING...SEVERE POTENTIAL...WATCH UNLIKELY 

VALID 021959Z - 022100Z

PROBABILITY OF WATCH ISSUANCE...20 PERCENT

SUMMARY...THUNDERSTORMS WILL LIKELY CONTINUE TO EXPAND IN COVERAGE
AND SPREAD NEWD WITH TIME...WITH A FEW OF THE STRONGEST STORMS
CAPABLE OF PRODUCING MARGINALLY SEVERE HAIL/WIND.  WITH THE THREAT
EXPECTED TO REMAIN LIMITED...A WW WILL LIKELY NOT BE REQUIRED.

DISCUSSION...CONVECTIVE DEVELOPMENT CONTINUES THIS AFTERNOON ACROSS
PORTIONS OF THE NRN PLAINS/MID MO VALLEY REGION...AS A WEAK
SHORT-WAVE TROUGH -- VISIBLE ATTM IN WV IMAGERY OVER THE ERN NEB
VICINITY -- CONTINUES SHIFTING SLOWLY NEWD.  CONVECTION IS
DEVELOPING NEAR A WEAK SURFACE LOW ANALYZED OVER CENTRAL SD...WHERE
A BROAD ZONE OF LOW-LEVEL WARM ADVECTION PERSISTS.

STORMS ACROSS NERN SD AND ADJACENT SERN ND/WRN MN REMAIN SLIGHTLY
ELEVATED...BUT HAVE BECOME MORE NEARLY SURFACE BASED SWD INTO NERN
NEB.  OVERALL HOWEVER...SHEAR/BUOYANCY COMBINATION REMAINS ONLY
MARGINALLY SUPPORTIVE OF ORGANIZED CELLS -- AND WITH TIME THE FLOW
ALOFT IS PROGGED TO WEAKEN ACROSS THE AREA AS THE UPPER SYSTEM
DEPARTS.  THUS...THREAT SHOULD REMAIN LOW-END AND RELATIVELY SHORT
LIVED...DIMINISHING IN INTENSITY BY EARLY EVENING.

..GOSS/THOMPSON.. 10/02/2013

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

ATTN...WFO...MPX...FGF...FSD...OAX...ABR...GID...LBF...

LAT...LON   46249577 45589492 43749576 41769696 40749897 41039990
            41679981 43449825 45239811 45959688 46249577

Nearby

Mesoscale Discussions in South Dakota, 2013 Mesoscale Discussions in Nebraska, 2013 Mesoscale Discussions in Minnesota, 2013 Every mesoscale discussion in 2013

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.