Alert archive / North Dakota / Mesoscale Discussions in 2018

Mesoscale Discussion 1421

September 3, 201823 counties in North Dakota

The Storm Prediction Center issued this mesoscale discussion at Sep 3, 2018, 7:14 PM MDT for 23 counties in North Dakota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Sep 3, 2018, 7:14 PM MDT (01:14 UTC)
Expired: Sep 3, 2018, 9:15 PM MDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 23 counties

Adams County, ND, Billings County, ND, Bottineau County, ND, Bowman County, ND, Burke County, ND, Burleigh County, ND, Dunn County, ND, Grant County, ND, Hettinger County, ND, McHenry County, ND, McLean County, ND, Mercer County, ND, Morton County, ND, Mountrail County, ND, Oliver County, ND, Pierce County, ND, Renville County, ND, Rolette County, ND, Sheridan County, ND, Sioux County, ND, Slope County, ND, Stark County, ND, Ward County, ND

The radar

The Bismarck radar (KBIS), 89 km from the middle of the area, began a volume at 01:15 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, 1.2 hours before the alert went out and 92 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: 1312 J/kg
Mixed-layer CIN: -55 J/kg
Mixed-layer LCL: 1501 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 82 m²/s²
0-3 km storm-relative helicity: 140 m²/s²
Significant tornado parameter: 0.3
Supercell composite: 3.9

Open this sounding in Storm Lab

The text

As transmitted.

606 
ACUS11 KWNS 040115
SWOMCD
SPC MCD 040114 
NDZ000-040315-

Mesoscale Discussion 1421
NWS Storm Prediction Center Norman OK
0814 PM CDT Mon Sep 03 2018

Areas affected...Western and central ND

Concerning...Severe Thunderstorm Watch 366...

Valid 040114Z - 040315Z

The severe weather threat for Severe Thunderstorm Watch 366
continues.

SUMMARY...Severe weather threat for large hail and strong/damaging
wind gusts persists, as storms continue to develop across western
North Dakota during the next couple of hours.

DISCUSSION...At 01Z, mosaic radar imagery showed a broken band of
storms extending from extreme southwest ND to extreme southeast
Saskatchewan and adjacent Manitoba.  The stronger storms and
potentially severe caliber so far have been developing across the
southern half of WW 366, potentially given closer proximity to the
greater instability (MLCAPE up to 2500-3000 J/kg).  However, recent
trends indicated continued destabilization with northward extent
(moisture advection) and a stronger storm was forming in northeast
McKenzie County per radar imagery.  Given effective bulk shear
vectors of 35-50 kt oriented near orthogonal to the surface trough
in western ND, semi-discrete supercells will remain a primary storm
mode in the short term (next 2 hours or so).

..Peters.. 09/04/2018

...Please see www.spc.noaa.gov for graphic product...

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

LAT...LON   45950394 47710333 48980252 49009944 47799979 46610010
            45940057 45950394

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Sep 3, 9:40 PM MDT	Mesoscale Discussion	SPC	Adams, Bottineau, Dunn, Grant, Hettinger, McHenry and 7 more	95 min

Nearby

Mesoscale Discussions in North Dakota, 2018 Every mesoscale discussion in 2018

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.