Alert archive / North Dakota / Mesoscale Discussions in 2012

Mesoscale Discussion 1645

July 29, 201212 counties in Minnesota; 29 counties in North Dakota; 6 counties in South Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 29, 2012, 3:50 PM CDT for 12 counties in Minnesota; 29 counties in North Dakota; 6 counties in South Dakota. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued: Jul 29, 2012, 3:50 PM CDT (20:50 UTC)
Expired: Jul 29, 2012, 5:45 PM CDT
In force: 115 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

All 47 counties

Becker County, MN, Clay County, MN, Clearwater County, MN, Kittson County, MN, Mahnomen County, MN, Marshall County, MN, Norman County, MN, Pennington County, MN, Polk County, MN, Red Lake County, MN, Roseau County, MN, Wilkin County, MN, Barnes County, ND, Benson County, ND, Cass County, ND, Cavalier County, ND, Dickey County, ND, Eddy County, ND, Emmons County, ND, Foster County, ND, Grand Forks County, ND, Griggs County, ND, Kidder County, ND, LaMoure County, ND, Logan County, ND, McIntosh County, ND, Nelson County, ND, Pembina County, ND, Pierce County, ND, Ramsey County, ND, Ransom County, ND, Richland County, ND, Rolette County, ND, Sargent County, ND, Sioux County, ND, Steele County, ND, Stutsman County, ND, Towner County, ND, Traill County, ND, Walsh County, ND, Wells County, ND, Brown County, SD, Campbell County, SD, Corson County, SD, Marshall County, SD, McPherson County, SD, Walworth County, SD

The radar

The Bismarck radar (KBIS), 88 km from the middle of the area, began a volume at 20:52 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 539Jul 29, 7:50 PM CDT

The nearest sounding before it

Bismarck Municip, ND (KBIS), launched 12:00Z, 8.8 hours before the alert went out and 84 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: 829 J/kg
Mixed-layer CIN: -343 J/kg
Mixed-layer LCL: 1580 m above ground
0-6 km bulk shear: 32 kt
0-1 km storm-relative helicity: 144 m²/s²
0-3 km storm-relative helicity: 220 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.7

Open this sounding in Storm Lab

The text

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

047 
ACUS11 KWNS 292050
SWOMCD
SPC MCD 292050 
MNZ000-SDZ000-NDZ000-292245-

MESOSCALE DISCUSSION 1645
NWS STORM PREDICTION CENTER NORMAN OK
0350 PM CDT SUN JUL 29 2012

AREAS AFFECTED...PORTIONS CENTRAL-ERN ND...EXTREME NRN SD...NWRN MN.

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 292050Z - 292245Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...SVR POTENTIAL SHOULD INCREASE OVER DISCUSSION AREA THROUGH
REMAINDER AFTERNOON AND INTO EARLY EVENING...WITH BOTH DAMAGING TSTM
WIND AND LARGE HAIL PSBL.

DISCUSSION...SFC MESOANALYSIS SHOWS LOW INVOF BIS...WITH EWD-MOVING
CONFLUENCE LINE SWWD ACROSS PORTIONS CORSON/PERKINS/HARDING COUNTIES
SD.  TROUGH EXTENDS FROM LOW NWD TO INTERSECTION WITH COLD FRONT
OVER SRN MB.  FRONT SHOULD MOVE SEWD 10-15 KT...SLOWLY CATCHING UP
WITH SFC TROUGH OVER NRN ND.  SFC DIABATIC HEATING AND SFC DEW
POINTS MID-UPPER 60S F FROM CENTRAL ND TO NERN SD/SERN ND CONTRIBUTE
TO CORRIDOR OF MLCAPE 2000-3000 J/KG THERE AND NEWD ACROSS NWRN MN. 
POCKET OF RELATIVELY WEAK BOUNDARY-LAYER MOISTURE AND MINIMIZED
THETAE IS CONTRIBUTING TO RELATIVE MIN IN BUOYANCY OVER PORTIONS
NERN ND ATTM...BUT STILL WITH SUFFICIENT CAPE TO SUPPORT ANY TSTMS
THAT DEVELOP UPSHEAR NEAR FRONT/TROUGH AND MOVE INTO THAT REGION. 
ALSO...HIGH-BASED/TSTMS DEVELOPING INVOF CONFLUENCE LINE MAY MOVE
EWD INTO MORE FAVORABLE MOISTURE...PERSISTING LONGER AS MLCINH
WEAKENS.  EWD-MOVING SHORTWAVE TROUGH OVER SRN MB SHOULD RESULT IN
STRENGTHENING MID-UPPER FLOW AND ENHANCED DEEP-LAYER SHEAR OVER THIS
REGION...WITH EFFECTIVE SHEAR MAGNITUDES ALREADY 40-50 KT.

..EDWARDS/CORFIDI.. 07/29/2012

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

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

LAT...LON   45500265 46010140 46830050 48410013 49009999 48969520
            46749529 45559778 45330041 45500265

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 29, 2:22 PM CDT	Mesoscale Discussion	SPC	Beltrami, Cass, Cook, Hubbard, Itasca, Koochiching and 3 more	2 hr
Jul 29, 5:49 PM CDT	Mesoscale Discussion	SPC	Brown, Clark, Codington, Day, Edmunds, Faulk and 4 more	86 min

Nearby

Mesoscale Discussions in North Dakota, 2012 Mesoscale Discussions in Minnesota, 2012 Mesoscale Discussions in South Dakota, 2012 Every mesoscale discussion in 2012

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.