Alert archive / North Dakota / Mesoscale Discussions in 2012

Mesoscale Discussion 1379

July 3, 20127 counties in Montana; 22 counties in North Dakota

The Storm Prediction Center issued this mesoscale discussion at Jul 3, 2012, 5:15 PM MDT for 7 counties in Montana; 22 counties in North Dakota. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued: Jul 3, 2012, 5:15 PM MDT (23:15 UTC)
Expired: Jul 3, 2012, 7:15 PM MDT
In force: 2 hr
Issued by: the Storm Prediction Center

All 29 counties

Daniels County, MT, Dawson County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Sheridan County, MT, Wibaux County, MT, Adams County, ND, Billings County, ND, Bottineau County, ND, Burke County, ND, Divide County, ND, Dunn County, ND, Golden Valley County, ND, Grant County, ND, Hettinger County, ND, McHenry County, ND, McKenzie County, ND, McLean County, ND, Mercer County, ND, Morton County, ND, Mountrail County, ND, Oliver County, ND, Renville County, ND, Sioux County, ND, Slope County, ND, Stark County, ND, Ward County, ND, Williams County, ND

The radar

The Bismarck radar (KBIS), 178 km from the middle of the area, began a volume at 23:16 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 458Jul 3, 5:55 PM MDT

The nearest sounding before it

Bismarck Municip, ND (KBIS), launched 12:00Z, 11.3 hours before the alert went out and 182 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: 572 J/kg
Mixed-layer CIN: -242 J/kg
Mixed-layer LCL: 1125 m above ground
0-6 km bulk shear: 18 kt
0-1 km storm-relative helicity: -15 m²/s²
0-3 km storm-relative helicity: 17 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.4

Open this sounding in Storm Lab

The text

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

812 
ACUS11 KWNS 032315
SWOMCD
SPC MCD 032315 
NDZ000-MTZ000-040115-

MESOSCALE DISCUSSION 1379
NWS STORM PREDICTION CENTER NORMAN OK
0615 PM CDT TUE JUL 03 2012

AREAS AFFECTED...PORTIONS ERN MT..WRN ND.

CONCERNING...SEVERE THUNDERSTORM WATCH 457...

VALID 032315Z - 040115Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 457
CONTINUES.

SUMMARY...CONTINUE WW ALONG AND E OF STG-SVR BAND OF CONVECTION THAT
IS BECOMING MORE DENSELY CONCENTRATED OVER NERN MT.  THIS ACTIVITY
SHOULD CONTINUE TO POSE RISK OF DAMAGING GUSTS AND OCNL HAIL EWD
OVER REMAINDER WW AND INTO PORTIONS WRN ND.  AS SUCH...PROBABILITY
IS GETTING HIGH -- 80% ATTM -- THAT ADDITIONAL WW WILL BE NEEDED
FARTHER E...BEFORE SCHEDULED 02Z EXPIRATION OF WW 457.

DISCUSSION...SFC MESOANALYSIS SHOWS LOW COLLOCATED WITH CONVECTIVE
BAND NEAR OLF...COLD FRONT SWD ACROSS YELLOWSTONE/MUSSELSHELL
COUNTIES...WARM FRONT SEWD OVER RICHLAND COUNTY TO EXTREME SWRN
ND...DRYLINE SWD TO MLS AREA THEN SEWD OVER WRN SD.  DRYLINE SHOULD
MOVE LITTLE WHILE COLD FRONT CATCHES UP...AND WARM FRONT DRIFTS NWD.
 MOIST AXIS WAS DRAWN FROM ERN SD NWD ACROSS SWRN ND TO NEAR SDY AND
NWD...JUST N OF WARM FRONT OVER FCST AREA.  THOUGH DEW POINT FIELD
IS PATCHY OVER WRN ND BECAUSE OF DIFFERENTIAL BOUNDARY-LAYER
MIXING...MOISTURE GENERALLY INCREASES WITH EWD EXTENT.  THIS WILL
SUPPORT CONTINUATION OF THREAT INTO THAT REGION DESPITE SOMEWHAT
STRENGTHENED EML-RELATED CAPPING AT LOWER ELEVATIONS AND NE OF WARM
FRONT.  MODIFIED RAOBS AND MODEL SOUNDINGS INDICATE 2500-3000 J/KG
MLCAPE NEAR MOIST AXIS AND 2000 J/KG FARTHER N...WITH WEAKEST MLCINH
INVOF MOIST AXIS.  AS SUCH...CONVECTION MAY BACKBUILD OR TURN MORE
SEWD WITH TIME...ESPECIALLY AS COLD FRONT CATCHES DRYLINE AND
IMPINGES UPON GREATER BOUNDARY-LAYER MOISTURE.  DEEP-LAYER SHEAR
WILL CONTINUE TO BE MORE FAVORABLE WITH NWD EXTENT -- BENEATH
STRONGER MID-UPPER LEVEL WINDS -- AND INVOF WARM FRONT WHERE
RELATIVELY BACKED SFC FLOW CONTRIBUTES.  EFFECTIVE SHEAR MAGNITUDES
45-50 KT ARE EVIDENT OVER ERN MT...AND SHOULD INCREASE WITH TIME
OVER WRN ND AS UPPER RIDGE MOVES PAST.

..EDWARDS.. 07/03/2012

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

ATTN...WFO...BIS...BYZ...GGW...

LAT...LON   46320422 46720564 48990588 48950160 48970056 47370054
            46000105 46070302 46320422

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jul 3, 12:58 PM MDT	Mesoscale Discussion	SPC	Custer, Daniels, Dawson, Garfield, McCone, Petroleum and 7 more	92 min
Jul 3, 1:41 PM MDT	Severe Thunderstorm Watch	SPC	Daniels, Dawson, Garfield, McCone, Petroleum, Phillips and 6 more	8 hr
Jul 3, 5:52 PM MDT	Severe Thunderstorm Watch	SPC	Adams, Billings, Bottineau, Bowman, Burke, Burleigh and 24 more	8 hr

Nearby

Mesoscale Discussions in North Dakota, 2012 Mesoscale Discussions in Montana, 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.