Alert archive / Montana / Mesoscale Discussions in 2015

Mesoscale Discussion 1683

August 14, 20156 counties in Montana

The Storm Prediction Center issued this mesoscale discussion at Aug 14, 2015, 4:40 PM MDT for 6 counties in Montana. It was in force for 35 min.

The area

The outline as issued.

The facts

Issued
Aug 14, 2015, 4:40 PM MDT (22:40 UTC)
Expired
Aug 14, 2015, 5:15 PM MDT
In force
35 min
Issued by
the Storm Prediction Center

Counties Broadwater County, MT, Cascade County, MT, Jefferson County, MT, Lewis and Clark County, MT, Meagher County, MT, Powell County, MT

The radar

The Great Falls radar (KTFX), 101 km from the middle of the area, began a volume at 22:42 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, 10.7 hours before the alert went out and 140 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 2015-08-14Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 11 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 2015-08-14The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 12 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
11 J/kg
Mixed-layer CIN
-316 J/kg
Mixed-layer LCL
3444 m above ground
0-6 km bulk shear
26 kt
0-1 km storm-relative helicity
12 m²/s²
0-3 km storm-relative helicity
23 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
Aug 14, 12:30 PM MDTMesoscale DiscussionSPCFergus, Garfield, Petroleum, Phillips2 hr
Aug 14, 1:35 PM MDTMesoscale DiscussionSPCBeaverhead, Broadwater, Cascade, Chouteau, Deer Lodge, Gallatin and 13 more2 hr
Aug 14, 2:23 PM MDTSevere Thunderstorm WatchSPCBeaverhead, Blaine, Broadwater, Cascade, Chouteau, Deer Lodge and 18 more7 hr

Nearby

Mesoscale Discussions in Montana, 2015Every mesoscale discussion in 2015

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.