Alert archive / South Dakota / Mesoscale Discussions in 2009

Mesoscale Discussion 2000

September 8, 2009Cherry County, Garden County, Grant County, Nebraska; 20 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Sep 8, 2009, 1:32 PM MDT for Cherry County, Garden County, Grant County, Nebraska; 20 counties in South Dakota. It was in force for 88 min.

The area

The outline as issued.

The facts

Issued: Sep 8, 2009, 1:32 PM MDT (19:32 UTC)
Expired: Sep 8, 2009, 3:00 PM MDT
In force: 88 min
Issued by: the Storm Prediction Center

All 23 counties

Cherry County, NE, Garden County, NE, Grant County, NE, Beadle County, SD, Bennett County, SD, Brown County, SD, Brule County, SD, Buffalo County, SD, Edmunds County, SD, Faulk County, SD, Hand County, SD, Hughes County, SD, Hyde County, SD, Jerauld County, SD, Jones County, SD, Lyman County, SD, Mellette County, SD, Potter County, SD, Spink County, SD, Stanley County, SD, Sully County, SD, Todd County, SD, Tripp County, SD

The radar

The Rapid City radar (KUDX), 194 km from the middle of the area, began a volume at 19:33 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 737Sep 8, 1:55 PM MDT

The nearest sounding before it

Rapid City, SD (KUNR), launched 12:00Z, 7.5 hours before the alert went out and 197 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: 515 J/kg
Mixed-layer CIN: -372 J/kg
Mixed-layer LCL: 1252 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 235 m²/s²
0-3 km storm-relative helicity: 215 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.

000 
ACUS11 KWNS 081932
SWOMCD
SPC MCD 081932 
SDZ000-NEZ000-082100-

MESOSCALE DISCUSSION 2000
NWS STORM PREDICTION CENTER NORMAN OK
0232 PM CDT TUE SEP 08 2009

AREAS AFFECTED...CNTRL SD...NW NEB

CONCERNING...SEVERE POTENTIAL...WATCH LIKELY 

VALID 081932Z - 082100Z

A SEVERE THREAT IS EXPECTED TO DEVELOP OVER THE NEXT 1 TO 2 HOURS AS
STORMS INITIATE ACROSS CNTRL SD AND NW NEB. ISOLATED LARGE HAIL AND
WIND DAMAGE WILL BE POSSIBLE WITH THE STRONGER CELLS. A WW WILL
LIKELY BE NEEDED ACROSS THE AREA BY 20Z.

19Z SFC ANALYSIS CURRENTLY SHOWS A WELL-DEFINED COLD FRONT EXTENDING
FROM ERN ND SSWWD ACROSS CNTRL SD INTO NW NEB WITH A SFC LOW NEAR
PIERRE SD. RUC ANALYSIS SUGGESTS THE CAP HAS WEAKENED OVER THE LAST
HOUR ALONG THE FRONT IN SCNTRL SD AND THIS SHOULD ALLOW FOR
CONVECTIVE INITIATION WHICH APPEARS TO BE OCCURRING ON VISIBLE
SATELLITE IMAGERY. SHORT-TERM MODEL FORECASTS ARE IN AGREEMENT
RAPIDLY EXPANDING STORM COVERAGE ACROSS THE MCD AREA AFTER 21Z. A
MID-LEVEL JET EVIDENT ON WATER VAPOR IMAGERY AND ANALYZED BY THE RUC
IS LOCATED ACROSS THE NRN HIGH PLAINS. THIS FEATURE IS HELPING TO
CREATE MODERATE TO STRONG VERTICAL SHEAR PROFILES WHICH WILL MAKE
ORGANIZED STORMS LIKELY. ISOLATED SUPERCELLS WILL BE POSSIBLE LATE
THIS AFTERNOON BUT LINEAR DEVELOPMENT ALONG THE COLD FRONT SHOULD
BECOME THE DOMINANT MODE WITH TIME. STEEP MID-LEVEL LAPSE RATES AND
MODERATE INSTABILITY WILL SUPPORT A LARGE HAIL THREAT. LOW-LEVEL
LAPSE RATES WILL CONTINUE TO STEEPEN AND LOW-LEVEL FLOW WILL
INCREASE LATE THIS AFTERNOON INTO EARLY EVENING SUGGESTING A WIND
DAMAGE THREAT SHOULD ALSO DEVELOP.

..BROYLES.. 09/08/2009

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

ATTN...WFO...FSD...ABR...LBF...UNR...CYS...

LAT...LON   43510153 42690215 42130275 41740286 41480263 41780164
            42300087 42900000 43849869 44649802 45189791 45579825
            45779865 45789919 45599966 44850038 44420079 43980117
            43510153

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 8, 1:53 PM MDT	Severe Thunderstorm Watch	SPC	Arthur, Blaine, Boyd, Brown, Chase, Cherry and 20 more	8 hr
Sep 8, 12:44 AM MDT	Mesoscale Discussion	SPC	Corson	91 min

Nearby

Mesoscale Discussions in South Dakota, 2009 Mesoscale Discussions in Nebraska, 2009 Every mesoscale discussion in 2009

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.