Alert archive / North Dakota / Mesoscale Discussions in 2007

Mesoscale Discussion 855

May 21, 200713 counties in North Dakota; 11 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at May 21, 2007, 9:59 PM CDT for 13 counties in North Dakota; 11 counties in South Dakota. It was in force for 61 min.

The area

The outline as issued.

The facts

Issued: May 21, 2007, 9:59 PM CDT (02:59 UTC)
Expired: May 21, 2007, 11:00 PM CDT
In force: 61 min
Issued by: the Storm Prediction Center

All 24 counties

Benson County, ND, Cavalier County, ND, Eddy County, ND, Emmons County, ND, Foster County, ND, Kidder County, ND, Logan County, ND, McIntosh County, ND, Nelson County, ND, Ramsey County, ND, Stutsman County, ND, Towner County, ND, Wells County, ND, Campbell County, SD, Edmunds County, SD, Hughes County, SD, Hyde County, SD, Jones County, SD, Lyman County, SD, McPherson County, SD, Potter County, SD, Sully County, SD, Todd County, SD, Walworth County, SD

The radar

The Bismarck radar (KBIS), 102 km from the middle of the area, began a volume at 03:04 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, 3.0 hours before the alert went out and 98 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: 1843 J/kg
Mixed-layer CIN: -57 J/kg
Mixed-layer LCL: 1774 m above ground
0-6 km bulk shear: 31 kt
0-1 km storm-relative helicity: 37 m²/s²
0-3 km storm-relative helicity: 70 m²/s²
Significant tornado parameter: 0.1
Supercell composite: 2.2

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000
ACUS11 KWNS 220259
SWOMCD
SPC MCD 220259 
NDZ000-SDZ000-220400-

MESOSCALE DISCUSSION 0855
NWS STORM PREDICTION CENTER NORMAN OK
0959 PM CDT MON MAY 21 2007

AREAS AFFECTED...CNTRL AND ERN DAKOTAS

CONCERNING...SEVERE THUNDERSTORM WATCH 282...283...

VALID 220259Z - 220400Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH
282...283...CONTINUES.

THREAT FOR ISOLATED DAMAGING WIND AND HAIL PERSISTS WITH STRONGER
STORMS FROM CNTRL ND SWD THROUGH CNTRL SD. STRONGEST STORMS EXIST
ACROSS ND PORTION OF LINE. SEVERE THREAT IS EXPECTED TO BECOME
INCREASINGLY MARGINAL WITH TIME. ANOTHER WW EAST OF 282 AND 283 WILL
PROBABLY NOT BE NECESSARY UNLESS TRENDS BEGIN TO SUGGEST OTHERWISE.

SCATTERED STORMS FROM CNTRL ND SWD THROUGH CNTRL SD ARE MOVING EAST
AT 20 TO 25 KT. DOMINANT MODE HAS EVOLVED INTO A LINE WITH A COLD
POOL INDICATED ALONG SD PORTION. STORMS DEVELOPING ACROSS ND HAVE
ALSO BECOME OUTFLOW DOMINANT. RADAR DATA SUGGEST PRESENCE OF AN MCV
EMBEDDED WITHIN THE LINE NEAR THE SD/ND BORDER LIFTING NEWD. WARM
SECTOR EAST OF THE STORMS REMAINS MODERATELY UNSTABLE WITH MLCAPE
1500 TO 2000 J/KG. THE SLY 40 TO 50 KT LOW LEVEL JET WILL HELP
MAINTAIN A FORWARD PROPAGATING SYSTEM NEXT FEW HOURS WITH A THREAT
OF ISOLATED DAMAGING WIND AND HAIL. OTHER STORMS MAY DEVELOP OVER E
CNTRL ND WITHIN ZONE OF ENHANCED LIFT NE OF MCV. HOWEVER...THE
STABILIZING BOUNDARY LAYER...MODEST DEEP LAYER SHEAR IN WARM SECTOR
AND TENDENCY FOR THE LOW LEVEL JET TO VEER WITH TIME SHOULD SERVE AS
LIMITING FACTORS FOR A MORE ROBUST AND ORGANIZED SEVERE THREAT
OVERNIGHT.

..DIAL.. 05/22/2007

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

ATTN...WFO...FGF...ABR...BIS...UNR...

48529786 46049898 43509954 43140081 45170053 46320049
46860045 48539964 49279833

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 22, 2:08 PM CDT	Mesoscale Discussion	SPC	Aurora, Beadle, Bennett, Brule, Buffalo, Charles Mix and 19 more	2 hr
May 22, 2:25 PM CDT	Severe Thunderstorm Watch	SPC	Aurora, Beadle, Brown, Brule, Buffalo, Campbell and 22 more	8 hr

Nearby

Mesoscale Discussions in North Dakota, 2007 Mesoscale Discussions in South Dakota, 2007 Every 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.