Alert archive / North Dakota / Mesoscale Discussions in 2011

Mesoscale Discussion 1621

July 14, 201112 counties in North Dakota; 6 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 14, 2011, 11:55 PM CDT for 12 counties in North Dakota; 6 counties in South Dakota. It was in force for 65 min.

The area

The outline as issued.

The facts

Issued: Jul 14, 2011, 11:55 PM CDT (04:55 UTC)
Expired: Jul 15, 2011, 1:00 AM CDT
In force: 65 min
Issued by: the Storm Prediction Center

Counties Barnes County, ND, Cass County, ND, Dickey County, ND, Emmons County, ND, Kidder County, ND, LaMoure County, ND, Logan County, ND, McIntosh County, ND, Ransom County, ND, Richland County, ND, Sargent County, ND, Stutsman County, ND, Brown County, SD, Campbell County, SD, Edmunds County, SD, Marshall County, SD, McPherson County, SD, Walworth County, SD

The radar

The Aberdeen radar (KABR), 99 km from the middle of the area, began a volume at 04:58 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 646Jul 15, 3:00 AM CDT

The nearest sounding before it

Bismarck Municip, ND (KBIS), launched 00:00Z, 4.9 hours before the alert went out and 148 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: 2132 J/kg
Mixed-layer CIN: -66 J/kg
Mixed-layer LCL: 698 m above ground
0-6 km bulk shear: 35 kt
0-1 km storm-relative helicity: 101 m²/s²
0-3 km storm-relative helicity: 76 m²/s²
Significant tornado parameter: 0.5
Supercell composite: 3.2

Open this sounding in Storm Lab

The text

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

734 
ACUS11 KWNS 150456
SWOMCD
SPC MCD 150455
SDZ000-NDZ000-150600-

MESOSCALE DISCUSSION 1621
NWS STORM PREDICTION CENTER NORMAN OK
1155 PM CDT THU JUL 14 2011

AREAS AFFECTED...PARTS OF CENTRAL/ERN ND AND NRN/NERN SD

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE

VALID 150455Z - 150600Z

A NEW WW MAY BE NEEDED IF STORMS INCREASE IN COVERAGE/INTENSITY
ACROSS CENTRAL/ERN ND AND ADJACENT PARTS OF NRN-NERN SD DURING THE
EARLY OVERNIGHT PERIOD.

REGIONAL RADAR IMAGERY SHOWED A RECENT INCREASE IN TSTM DEVELOPMENT
ACROSS SOUTH CENTRAL ND WITHIN WAA REGIME ALONG THE NOSE OF A
STRENGTHENING SLY LLJ.  IN ADDITION TO THIS ASCENT...FORCING FOR
ASCENT ATTENDANT TO A WEAK MIDLEVEL IMPULSE TRACKING EWD ACROSS THE
DAKOTAS MAY PROVE SUFFICIENT IN SUPPORTING ADDITIONAL STORMS THROUGH
THE OVERNIGHT PERIOD.  GIVEN THE DEGREE OF MUCAPE /2000-4000 J PER
KG/ AND EFFECTIVE BULK SHEAR OF 35-50 KT...THE POTENTIAL FOR
ORGANIZED SEVERE STORMS DOES EXIST.  HOWEVER...AT THIS TIME...THERE
IS SOME UNCERTAINTY IN THE OVERALL COVERAGE FOR STRONGER/ROBUST
ELEVATED TSTMS.  IF INTENSITIES SHOW A GREATER INCREASE...THEN A NEW
WW MIGHT BE NEEDED.

..PETERS.. 07/15/2011

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

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

LAT...LON   46230106 47310005 47469786 47249702 46019671 45549700
            45269863 45250069 46230106

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 14, 9:46 PM CDT	Mesoscale Discussion	SPC	Adams, Emmons, Grant, Kidder, Logan, McIntosh and 1 more	59 min
Jul 14, 11:01 PM CDT	Severe Thunderstorm Watch	SPC	Adams, Billings, Bowman, Burke, Divide, Dunn and 14 more	6 hr
Jul 15, 2:54 AM CDT	Mesoscale Discussion	SPC	Adams, Billings, Bottineau, Bowman, Burke, Divide and 12 more	2 hr
Jul 15, 2:56 AM CDT	Severe Thunderstorm Watch	SPC	Barnes, Cass, Grand Forks, Griggs, Nelson, Ramsey and 6 more	7 hr
Jul 15, 6:30 AM CDT	Mesoscale Discussion	SPC	Barnes, Cass, Ransom, Richland	2 hr
Jul 15, 6:10 PM CDT	Mesoscale Discussion	SPC	Barnes, Cass, Dickey, LaMoure, Ransom, Richland and 2 more	65 min

Nearby

Mesoscale Discussions in North Dakota, 2011 Mesoscale Discussions in South Dakota, 2011 Every mesoscale discussion in 2011

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.