Alert archive / Montana / Mesoscale Discussions in 2007

Mesoscale Discussion 1012

June 5, 200719 counties in Montana

The Storm Prediction Center issued this mesoscale discussion at Jun 5, 2007, 1:08 PM MDT for 19 counties in Montana. It was in force for 97 min.

The area

The outline as issued.

The facts

Issued: Jun 5, 2007, 1:08 PM MDT (19:08 UTC)
Expired: Jun 5, 2007, 2:45 PM MDT
In force: 97 min
Issued by: the Storm Prediction Center

Counties Big Horn County, MT, Carbon County, MT, Cascade County, MT, Chouteau County, MT, Fergus County, MT, Glacier County, MT, Golden Valley County, MT, Judith Basin County, MT, Lewis and Clark County, MT, Liberty County, MT, Meagher County, MT, Musselshell County, MT, Pondera County, MT, Stillwater County, MT, Sweet Grass County, MT, Teton County, MT, Toole County, MT, Wheatland County, MT, Yellowstone County, MT

The radar

The Great Falls radar (KTFX), 112 km from the middle of the area, began a volume at 19:08 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 350Jun 5, 1:40 PM MDT

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 7.1 hours before the alert went out and 87 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: 1792 m above ground
0-6 km bulk shear: 14 kt
0-1 km storm-relative helicity: 55 m²/s²
0-3 km storm-relative helicity: 46 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.

000 
ACUS11 KWNS 051908
SWOMCD
SPC MCD 051908 
MTZ000-052045-

MESOSCALE DISCUSSION 1012
NWS STORM PREDICTION CENTER NORMAN OK
0208 PM CDT TUE JUN 05 2007

AREAS AFFECTED...SWRN/CNTRL MT

CONCERNING...SEVERE POTENTIAL...WATCH POSSIBLE 

VALID 051908Z - 052045Z

CURRENT WATER VAPOR IMAGERY SHOWS MODERATELY STRONG UPPER TROUGH
ALONG PAC NW COAST IS CONTINUING ITS SLOW EWD MOVEMENT. WITH THE
MIDLEVEL DIFFLUENT FLOW EXTENDING OVER THE NRN ROCKIES AND EXIT
REGION OF UPPER JET /100-110 KTS AT 250 MB PER LATEST RUC/ NOW INTO
SRN ID...A BROAD REGION OF SYNOPTIC SCALE ASCENT OCCURRING FROM THE
COLUMBIA BASIN INTO THE WRN ROCKIES. LATE MORNING/EARLY AFTERNOON IR
IMAGERY TRENDS INDICATIVE OF THE BROAD SYNOPTIC ASCENT WITH
EXPANDING/COOLING CLOUD TOPS WELL INTO SWRN MT.

APPEARS THE BEST THREAT OF STRONG/SEVERE CONVECTION WILL BE IN THE
AXIS OF INSTABILITY THAT HAS DEVELOPED ALONG/EAST OF DIFFERENTIAL
CLOUD/HEATING BOUNDARY PRESENTLY EXTENDING FROM TETON COUNTY SEWD
INTO WRN BIG HORN COUNTY. AS THE MIDLEVEL FLOW INCREASES DURING THE
AFTERNOON AND ONGOING DIURNAL HEATING CONTINUES...THE LARGE SCALE
ENVIRONMENT IS BECOMING INCREASINGLY FAVORABLE FOR ORGANIZED
CONVECTION. CURRENT SURFACE TEMPERATURES ARE NOW IN THE MID 70S AND
DEW POINTS IN THE LOWER 50S...PRODUCING MLCAPE AROUND 1500 J/KG WITH
AN EFFECTIVE SHEAR APPROACHING 35 KTS. THE BOUNDARY LAYER IS
GENERALLY DEEP AND WELL MIXED /DCAPE ABOUT 750 J/KG/ WITH STRONGER
STORMS CAPABLE OF DAMAGING DOWNBURST WINDS IN ADDITION TO LARGE HAIL
.

THE AREA WILL CONTINUE TO BE MONITORED FOR POSSIBLE WATCH.

..BRIGHT.. 06/05/2007

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

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

46681158 46901240 47361285 48181339 48931296 48541084
47590916 45830733 45260735 45180791 45070890 45240958
46131048

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Jun 5, 1:39 PM MDT	Severe Thunderstorm Watch	SPC	Big Horn, Broadwater, Carbon, Cascade, Chouteau, Fergus and 21 more	7 hr

Nearby

Mesoscale Discussions in Montana, 2007 Every mesoscale discussion in 2007

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.