Alert archive / Montana / Mesoscale Discussions in 2012

Mesoscale Discussion 1102

June 8, 201216 counties in Montana

The Storm Prediction Center issued this mesoscale discussion at Jun 8, 2012, 10:38 PM MDT for 16 counties in Montana. It was in force for 67 min.

The area

The outline as issued.

The facts

Issued: Jun 8, 2012, 10:38 PM MDT (04:38 UTC)
Expired: Jun 8, 2012, 11:45 PM MDT
In force: 67 min
Issued by: the Storm Prediction Center

Counties Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, Garfield County, MT, McCone County, MT, Musselshell County, MT, Petroleum County, MT, Phillips County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Rosebud County, MT, Sheridan County, MT, Valley County, MT, Wibaux County, MT

The radar

The Billings radar (KBLX), 161 km from the middle of the area, began a volume at 04:41 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

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 4.6 hours before the alert went out and 175 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: 31 J/kg
Mixed-layer CIN: -91 J/kg
Mixed-layer LCL: 2081 m above ground
0-6 km bulk shear: 51 kt
0-1 km storm-relative helicity: 111 m²/s²
0-3 km storm-relative helicity: 131 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.6

Open this sounding in Storm Lab

The text

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

489 
ACUS11 KWNS 090438
SWOMCD
SPC MCD 090438 
NDZ000-SDZ000-MTZ000-090545-

MESOSCALE DISCUSSION 1102
NWS STORM PREDICTION CENTER NORMAN OK
1138 PM CDT FRI JUN 08 2012

AREAS AFFECTED...EAST CENTRAL AND NERN MT

CONCERNING...SEVERE THUNDERSTORM WATCH 363...

VALID 090438Z - 090545Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 363
CONTINUES.

SUMMARY...SEVERE STORMS CAPABLE OF PRODUCING LARGE HAIL...SOME VERY
LARGE /EXCEEDING 2 INCH DIAMETER/...AND STRONG DAMAGING WINDS WILL
REMAIN A THREAT INTO THE EARLY OVERNIGHT PERIOD ACROSS EAST CENTRAL
AND NERN MT.  NEWD TRACK OF STORMS ALONG AND JUST EAST OF A COLD
FRONT...AND TIMING OF THE FRONT TO NEAR THE MT/ND BORDER BETWEEN
09-12Z SUGGEST THE SEVERE WEATHER THREAT WILL REMAIN CONTAINED
WITHIN WW 363 THROUGH 07Z.

DISCUSSION...REGIONAL RADAR IMAGERY ACROSS THE HIGH PLAINS OF ERN MT
SHOWED ACTIVITY INCREASED IN COVERAGE AND INTENSITY AS HEIGHT FALLS
HAVE OCCURRED OVER WW 363 WITH THE APPROACH OF A SHORTWAVE TROUGH
MOVING INTO MT AND ATTENDANT 50-60 KT SWLY JET TRACKING INTO
CENTRAL/ERN MT. THE CONTINUED INFLUX OF LOW LEVEL MOISTURE PER
STRENGTHENING SELY LLJ NE OF NERN WY SURFACE LOW HAS OFFSET COOLING
SURFACE TEMPERATURES TO MAINTAIN MODERATE INSTABILITY EAST OF THE
COLD FRONT. AT 0430Z...THE COLD FRONT EXTENDED FROM INVOF GGW NWWD
TO THE INTERNATIONAL BORDER AND SSWWD TO JUST EAST OF JDN TO NORTH
CENTRAL AND SWRN WY.

AS FORCING FOR ASCENT CONTINUES ACROSS ERN MT OVERNIGHT...STORMS
WILL CONTINUE TO DEVELOP ALONG THE FRONT AS IT ADVANCES INTO THE
MODERATELY UNSTABLE AIR MASS.  EFFECTIVE BULK SHEAR EXCEEDING 50 KT
AND ORIENTED ACROSS THE BOUNDARY INTO THE WARM SECTOR WILL FAVOR
DISCRETE STORMS...SOME HAVING SUPERCELL STRUCTURES. MEANWHILE...
SHEAR VECTORS ORIENTED MORE PARALLEL TO THE FRONT WILL FAVOR FAST
MOVING LINE SEGMENTS IN THE POST FRONTAL ENVIRONMENT. THUS...
LOCATIONS TO THE W OF THE FRONT WILL HAVE SOME SEVERE THREAT...AT
LEAST IN THE SHORT TERM.

..PETERS.. 06/09/2012

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

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

LAT...LON   46130848 46450883 47350857 47880878 48080836 49020819
            49030578 49000403 46120402 45910400 45920470 45790500
            45690617 45200631 45180671 45660699 46290707 46410728
            46390794 46150844 46130848

Nearby

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.