Alert archive / South Dakota / Mesoscale Discussions in 2007

Mesoscale Discussion 521

April 20, 20076 counties in North Dakota; 33 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Apr 20, 2007, 10:56 PM CDT for 6 counties in North Dakota; 33 counties in South Dakota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Apr 20, 2007, 10:56 PM CDT (03:56 UTC)
Expired
Apr 21, 2007, 1:00 AM CDT
In force
2 hr
Issued by
the Storm Prediction Center
All 39 counties

Dickey County, ND, LaMoure County, ND, McIntosh County, ND, Ransom County, ND, Richland County, ND, Sargent County, ND, Aurora County, SD, Beadle County, SD, Bennett County, SD, Brown County, SD, Brule County, SD, Buffalo County, SD, Campbell County, SD, Charles Mix County, SD, Clark County, SD, Day County, SD, Dewey County, SD, Edmunds County, SD, Faulk County, SD, Gregory County, SD, Haakon County, SD, Hand County, SD, Hughes County, SD, Hyde County, SD, Jackson County, SD, Jerauld County, SD, Jones County, SD, Lyman County, SD, Marshall County, SD, McPherson County, SD, Mellette County, SD, Potter County, SD, Roberts County, SD, Spink County, SD, Stanley County, SD, Sully County, SD, Todd County, SD, Tripp County, SD, Walworth County, SD

The radar

The Aberdeen radar (KABR), 109 km from the middle of the area, began a volume at 03:58 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

Bismarck Municip, ND (KBIS), launched 00:00Z, 3.9 hours before the alert went out and 242 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-pSkew-T log-p diagram, Bismarck Municip, ND at 00:00Z on 2007-04-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Bismarck Municip, ND at 00:00Z on 2007-04-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 106 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
2720 m above ground
0-6 km bulk shear
53 kt
0-1 km storm-relative helicity
106 m²/s²
0-3 km storm-relative helicity
243 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 210356
SWOMCD
SPC MCD 210356 
MNZ000-SDZ000-NDZ000-NEZ000-210600-

MESOSCALE DISCUSSION 0521
NWS STORM PREDICTION CENTER NORMAN OK
1056 PM CDT FRI APR 20 2007

AREAS AFFECTED...CENTRAL NEB

CONCERNING...SEVERE THUNDERSTORM WATCH 153...

VALID 210356Z - 210600Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 153
CONTINUES.

CLUSTER OF STORMS INCLUDING A TORNADIC SUPERCELL CONTINUES TO MOVE
NEWD OVER SERN CUSTER COUNTY.  THIS CELL PRODUCED SEVERAL TORNADO
REPORTS FROM MOOREFIELD THRU GOTHENBURG NEB.  LOOKS ACTIVITY
DEVELOPED ON NOSE OF 40-50 KT LOW LEVEL JET JUST OVER SELY SURFACE
WINDS OF 25-30 KT ENHANCING 0-1 KM SHEAR.  AIR MASS CONTINUES TO BE 
VERY UNSTABLE AS WELL AS MLCAPE VALUES ARE AROUND 2500 J/KG ACROSS
THIS AREA.

RUC PFC SOUNDINGS SUPPORT THIS WITH SFC-1 KM SHEAR OF 32 KT WITH
FAVORABLE HODOGRAPH TO SUPPORT STRONG UPDRAFTS AS WELL AS MID LEVEL
LAPSE RATES OF 8C/KM.  RADAR CONTINUES TO SHOW THIS CELL RECYCLING
AGAIN AT THIS TIME AND WILL CONTINUE TO DO SO AS STRONG SFC-LOW
LEVEL FLOW CONTINUES.  THE AIR MASS REMAINS UNSTABLE NEWD INTO NORTH
CENTRAL NEB WHERE LATEST RUC FCST SHOWS ACTIVITY CONTINUING THRU
06Z.

..MCCARTHY.. 04/21/2007

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

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

46629831 46629679 46309660 46019660 45679674 45599682
45469670 45379651 45339648 45329695 45299703 45299723
45139719 45139744 44539750 44539781 44179783 44189835
43489830 43499869 43399869 43179809 42989809 42859815
42859823 42949845 42969855 42970209 43130208 43150211
43420211 43500215 43650215 43660206 43770199 44520200
44530182 44580167 44580157 44620147 44690135 44730114
44990110 44990148 45470147 45450092 45490094 45460035
45570043 45640039 45690028 45720026 45900044 45940044
45939985 46279987 46279902 46629901

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 21, 5:25 PM CDTSevere Thunderstorm WatchSPCCass, Grand Forks, Ransom, Richland, Sargent, Traill7 hr
Apr 21, 1:31 AM CDTMesoscale DiscussionSPCAurora, Beadle, Brule, Buffalo, Charles Mix, Davison and 11 more59 min
Apr 21, 1:35 PM CDTMesoscale DiscussionSPCBeadle, Brown, Brule, Buffalo, Clark, Day and 14 more55 min
Apr 21, 2:30 PM CDTTornado WatchSPCAurora, Beadle, Bon Homme, Brookings, Brown, Brule and 38 more8 hr
Apr 21, 6:20 PM CDTMesoscale DiscussionSPCAurora, Beadle, Brown, Brule, Buffalo, Campbell and 32 more115 min

Nearby

Mesoscale Discussions in South Dakota, 2007Mesoscale Discussions in North Dakota, 2007Every mesoscale discussion in 2007

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.