Alert archive / Montana / Mesoscale Discussions in 2012

Mesoscale Discussion 1077

June 5, 201212 counties in Montana

The Storm Prediction Center issued this mesoscale discussion at Jun 5, 2012, 4:48 PM MDT for 12 counties in Montana. It was in force for 87 min.

The area

The outline as issued.

The facts

Issued: Jun 5, 2012, 4:48 PM MDT (22:48 UTC)
Expired: Jun 5, 2012, 6:15 PM MDT
In force: 87 min
Issued by: the Storm Prediction Center

Counties Cascade County, MT, Chouteau County, MT, Fergus County, MT, Glacier County, MT, Golden Valley County, MT, Judith Basin County, MT, Liberty County, MT, Meagher County, MT, Pondera County, MT, Teton County, MT, Toole County, MT, Wheatland County, MT

The radar

The Great Falls radar (KTFX), 42 km from the middle of the area, began a volume at 22:48 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

Great_falls, MT (KTFX), launched 12:00Z, 10.8 hours before the alert went out and 22 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: 111 J/kg
Mixed-layer CIN: -628 J/kg
Mixed-layer LCL: 1113 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 234 m²/s²
0-3 km storm-relative helicity: 311 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.

623 
ACUS11 KWNS 052248
SWOMCD
SPC MCD 052248 
MTZ000-060015-

MESOSCALE DISCUSSION 1077
NWS STORM PREDICTION CENTER NORMAN OK
0548 PM CDT TUE JUN 05 2012

AREAS AFFECTED...N-CNTRL MT

CONCERNING...TORNADO WATCH 360...

VALID 052248Z - 060015Z

THE SEVERE WEATHER THREAT FOR TORNADO WATCH 360 CONTINUES.

SUMMARY...TRAINING SUPERCELLS EXPECTED TO SHIFT NWD ACROSS WW 360
THIS EVENING WITH RISKS FOR VERY LARGE HAIL...AND ISOLATED
TORNADOES/DAMAGING WINDS. LEFT-SPLITS MAY GRAZE THE ADJACENT HIGH
TERRAIN NEAR THE CONTINENTAL DIVIDE WITH A THREAT FOR SEVERE HAIL.

DISCUSSION...PERSISTENT SUPERCELL STRUCTURES HAVE BEEN NOTED WITH
TRAINING CELLS CURRENTLY IN A NW TO SE ORIENTATION FROM TETON TO
WHEATLAND COUNTIES. WITH 55 TO 60 DEG F SURFACE DEW POINTS N OF THE
LITTLE BELT MTNS ACROSS ALL OF NRN MT TO THE HIGH TERRAIN NEAR THE
CONTINENTAL DIVIDE...THERMODYNAMIC ENVIRONMENT APPEARS TO BE RATHER
UNSTABLE. MODIFIED 19Z TFX RAOB AND OLDER GENERATION RUC-BASED
OBJECTIVE ANALYSIS SUGGESTS MLCAPE OF 1500-2000 J/KG IS PREVALENT IN
MOST OF WW 360.

ALTHOUGH THE STRENGTH OF LOW-LEVEL FLOW IN TFX VWP DATA IS LACKING
AT PRESENT...MUCH STRONGER LOW-LEVEL SLYS WERE SAMPLED IN MSO/PIH
VWP DATA. AS THE NEGATIVELY-TILTED SHORT WAVE IMPULSE ALONG THE SWRN
MT/ERN ID BORDER SHIFTS NWD THIS EVENING...GUIDANCE IS CONSISTENT IN
STRENGTHENING LOW-LEVEL WINDS IN N-CNTRL MT. THIS SHOULD YIELD AN
INCREASING SEVERE THREAT GIVEN THE FAVORABLE THERMODYNAMIC
ENVIRONMENT.

..GRAMS.. 06/05/2012

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

ATTN...WFO...BYZ...GGW...TFX...MSO...

LAT...LON   48290988 47470852 47030844 46530871 46260912 46281005
            46381084 47091216 47801305 48121357 48471359 48981306
            48861098 48290988

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 4, 6:02 PM MDT	Tornado Watch	SPC	Blaine, Cascade, Chouteau, Fergus, Glacier, Hill and 6 more	7 hr
Jun 4, 7:42 PM MDT	Mesoscale Discussion	SPC	Granite, Lake, Lincoln, Mineral, Missoula, Ravalli and 1 more	93 min
Jun 4, 8:22 PM MDT	Mesoscale Discussion	SPC	Blaine, Chouteau, Fergus, Hill, Petroleum, Phillips and 1 more	83 min
Jun 4, 10:08 PM MDT	Mesoscale Discussion	SPC	Lake, Lincoln, Mineral, Sanders	67 min
Jun 4, 10:48 PM MDT	Mesoscale Discussion	SPC	Liberty, Pondera, Teton, Toole	57 min
Jun 5, 12:54 PM MDT	Mesoscale Discussion	SPC	Broadwater, Carbon, Gallatin, Golden Valley, Madison, Meagher and 6 more	2 hr
Jun 5, 1:37 PM MDT	Severe Thunderstorm Watch	SPC	Broadwater, Carbon, Gallatin, Golden Valley, Jefferson, Madison and 5 more	7 hr
Jun 5, 1:56 PM MDT	Mesoscale Discussion	SPC	Blaine, Cascade, Chouteau, Fergus, Glacier, Hill and 8 more	2 hr
Jun 5, 2:37 PM MDT	Tornado Watch	SPC	Blaine, Cascade, Chouteau, Fergus, Glacier, Hill and 6 more	8 hr
Jun 5, 4:21 PM MDT	Mesoscale Discussion	SPC	Broadwater, Golden Valley, Meagher, Stillwater, Sweet Grass, Wheatland	84 min

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.