Alert archive / Montana / Mesoscale Discussions in 2011

Mesoscale Discussion 1441

June 29, 20114 counties in Idaho; 27 counties in Montana

The Storm Prediction Center issued this mesoscale discussion at Jun 29, 2011, 11:35 AM PDT for 4 counties in Idaho; 27 counties in Montana. It was in force for 115 min.

The area

The outline as issued.

The facts

Issued
Jun 29, 2011, 11:35 AM PDT (18:35 UTC)
Expired
Jun 29, 2011, 1:30 PM PDT
In force
115 min
Issued by
the Storm Prediction Center
All 31 counties

Clearwater County, ID, Idaho County, ID, Lemhi County, ID, Valley County, ID, Beaverhead County, MT, Blaine County, MT, Broadwater County, MT, Cascade County, MT, Chouteau County, MT, Deer Lodge County, MT, Fergus County, MT, Gallatin County, MT, Granite County, MT, Hill County, MT, Jefferson County, MT, Judith Basin County, MT, Lake County, MT, Lewis and Clark County, MT, Liberty County, MT, Madison County, MT, Meagher County, MT, Mineral County, MT, Missoula County, MT, Phillips County, MT, Pondera County, MT, Powell County, MT, Ravalli County, MT, Silver Bow County, MT, Teton County, MT, Toole County, MT, Wheatland County, MT

The radar

The Great Falls radar (KTFX), 70 km from the middle of the area, began a volume at 18:38 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.

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 6.6 hours before the alert went out and 119 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-pSkew-T log-p diagram, Great_falls, MT at 12:00Z on 2011-06-29Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 23 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Great_falls, MT at 12:00Z on 2011-06-29The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -15 square meters per square second.1939587897Sfc1 km3 km6 km9 kmRMLM
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
23 J/kg
Mixed-layer CIN
-499 J/kg
Mixed-layer LCL
2376 m above ground
0-6 km bulk shear
35 kt
0-1 km storm-relative helicity
-15 m²/s²
0-3 km storm-relative helicity
106 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.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 29, 12:41 PM PDTMesoscale DiscussionSPCBear Lake, Caribou, Franklin2 hr
Jun 29, 2:46 PM PDTSevere Thunderstorm WatchSPCBlaine, Cascade, Chouteau, Fergus, Garfield, Golden Valley and 9 more5 hr

Nearby

Mesoscale Discussions in Montana, 2011Mesoscale Discussions in Idaho, 2011Every mesoscale discussion in 2011

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.