Alert archive / Montana / Mesoscale Discussions in 2012

Mesoscale Discussion 1101

June 8, 201212 counties in Montana; Divide County, Williams County, North Dakota

The Storm Prediction Center issued this mesoscale discussion at Jun 8, 2012, 5:07 PM MDT for 12 counties in Montana; Divide County, Williams County, North Dakota. It was in force for 53 min.

The area

The outline as issued.

The facts

Issued: Jun 8, 2012, 5:07 PM MDT (23:07 UTC)
Expired: Jun 8, 2012, 6:00 PM MDT
In force: 53 min
Issued by: the Storm Prediction Center
Chance of a watch: 60%

Counties Custer County, MT, Daniels County, MT, Dawson County, MT, Garfield County, MT, McCone County, MT, Petroleum County, MT, Phillips County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Sheridan County, MT, Valley County, MT, Divide County, ND, Williams County, ND

The radar

The Glasgow radar (KGGW), 51 km from the middle of the area, began a volume at 23:07 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 363Jun 8, 5:45 PM MDT

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 11.1 hours before the alert went out and 53 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: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1188 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 42 m²/s²
0-3 km storm-relative helicity: 98 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.0

Open this sounding in Storm Lab

The text

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

816 
ACUS11 KWNS 082307
SWOMCD
SPC MCD 082307 
NDZ000-MTZ000-090000-

MESOSCALE DISCUSSION 1101
NWS STORM PREDICTION CENTER NORMAN OK
0607 PM CDT FRI JUN 08 2012

AREAS AFFECTED...N-CNTRL AND NERN MT / FAR NWRN ND

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 082307Z - 090000Z

PROBABILITY OF WATCH ISSUANCE...60 PERCENT

SUMMARY...STORMS ARE EXPECTED TO CONTINUE TO DEVELOP/INTENSIFY
THROUGH THE LATE AFTERNOON AND EARLY EVENING HOURS.  IT APPEARS
INCREASINGLY PROBABLE THAT A DEVELOPING ISOLD LARGE HAIL/SEVERE WIND
RISK WILL EVENTUALLY NECESSITATE A SEVERE WW.

DISCUSSION...LONG LOOP OF WATER VAPOR IMAGERY SHOWS AN UPPER LOW
CONTINUING TO SLIDE EWD FROM THE ERN PACIFIC INTO THE PACIFIC
NW...AND THIS IS CONTRIBUTING TO MORE APPRECIABLE MID LEVEL HEIGHT
FALLS OVERSPREADING ERN MT/WRN ND.  IN THE LOW LEVELS...A NORTH TO
SOUTH BAROCLINIC ZONE EXTENDS FROM NEAR THE ALBERTA/SASKATCHEWAN/MT
BORDER SWD TO A LOW INVOF THE UT/WY BORDER.  TO THE E OF THE
FRONT...ELY FLOW HAS ADVECTED LOW TO MID 50S DEWPOINTS INTO THE
REGION AND HAS AIDED IN DESTABILIZING THE AIRMASS ACROSS THE
DISCUSSION AREA.  FOCUSED CONVERGENCE/FRONTAL FORCING AND FURTHER
HEATING HAS CONSIDERABLY WEAKENED THE EXISTING CAP ACROSS CNTRL MT
BY 23Z...IMPLIED BY BUILDING CU/REFLECTIVITY FIELD INVOF THE
BOUNDARY.  

SHORT-TERM MODEL GUIDANCE GENERALLY SHOWS STORMS DEVELOPING AND
INCREASING IN AREAL COVERAGE/INTENSITY IN THE 00-03Z PERIOD.  AS
STORMS MATURE...STRONG DEEP LAYER SHEAR WILL ACT TO ORGANIZE
INITIALLY ISOLD ACTIVITY INTO A GROWING CLUSTER OF STORMS AS FRONTAL
FORCING/WAA INCREASE DURING THIS TIMEFRAME.  THE MAIN HAZARDS WITH
THIS ACTIVITY WILL BE ISOLD LARGE HAIL/SEVERE WIND GUSTS AS STORMS
MOVE FROM NERN MT INTO WRN ND TOWARDS THE OVERNIGHT.  GIVEN A
SUPERCELLULAR WIND PROFILE AND AN INITIALLY ISOLD EXPECTED STORM
MODE...THERE IS A 1-2 HR PERIOD IN WHICH A WEAK TORNADO CANNOT BE
RULED OUT AROUND DUSK AS TEMP/DEWPOINT SPREADS DECREASE WITHIN A
SUFFICIENTLY SHEARED LOW LEVEL ELY FLOW REGIME.

..SMITH/THOMPSON.. 06/08/2012

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

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

LAT...LON   48990837 48180897 47030915 46720858 46420771 46250541
            47430369 48430302 49010308 48990837

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 8, 2:52 PM MDT	Mesoscale Discussion	SPC	Blaine, Daniels, Fergus, Garfield, McCone, Musselshell and 3 more	53 min
Jun 8, 5:41 PM MDT	Severe Thunderstorm Watch	SPC	Custer, Daniels, Dawson, Fallon, Garfield, McCone and 10 more	9 hr

Nearby

Mesoscale Discussions in Montana, 2012 Mesoscale Discussions in North 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.