Alert archive / Montana / Special Weather Statements in 2017

Special Weather Statement, NWS Great Falls, MT

August 9, 2017Beaverhead County, Montana

NWS Great Falls, MT issued this special weather statement at Aug 9, 2017, 5:53 PM MDT for Beaverhead County, Montana. It was in force for 37 min. No storm report in the archive falls inside the area while it was in force.

The area

The outline as issued.

The facts

Issued
Aug 9, 2017, 5:53 PM MDT (23:53 UTC)
Expired
Aug 9, 2017, 6:30 PM MDT
In force
37 min
Issued by
NWS Great Falls, MT

County Beaverhead County, MT

The radar

The Pocatello radar (KSFX), 195 km from the middle of the area, began a volume at 23:55 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

Boise Airport, ID (KBOI), launched 12:00Z, 11.9 hours before the alert went out and 303 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, Boise Airport, ID at 12:00Z on 2017-08-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 26 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, Boise Airport, ID at 12:00Z on 2017-08-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 15 square meters per square second.1939Sfc1 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
26 J/kg
Mixed-layer CIN
-369 J/kg
Mixed-layer LCL
2501 m above ground
0-6 km bulk shear
11 kt
0-1 km storm-relative helicity
15 m²/s²
0-3 km storm-relative helicity
82 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

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What forecasters said that day

The local office's own words before this special weather statement went out, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.

NWS Great Falls, MT wrote its last area forecast discussion before this special weather statement went out at Aug 9, 5:26 PM MDT, 27 minutes earlier.

Area forecast discussion, Aug 9, 5:26 PM MDT, 27 minutes before
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In the hours before

Special weather statement, Aug 9, 5:08 PM MDT, 45 minutes before
Special Weather Statement
National Weather Service Great Falls MT
508 PM MDT WED AUG 9 2017

MTZ008-092345-
Beaverhead-
508 PM MDT WED AUG 9 2017

...A STRONG THUNDERSTORM WILL AFFECT CENTRAL BEAVERHEAD COUNTY...

At 508 PM MDT, a strong thunderstorm was located 14 miles west of
Dillon, moving southeast at 10 mph.

Winds in excess of 30 mph and brief heavy rain are possible with
this storm.

Locations impacted include...
Dillon, Bannack, Beaverhead Rock State Park, Clark Canyon and Bannack
State Park.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 4517 11313 4536 11292 4522 11254 4495 11285
TIME...MOT...LOC 2308Z 309DEG 10KT 4522 11293

Coulston
Special weather statement, Aug 9, 5:13 PM MDT, 40 minutes before
Special Weather Statement
National Weather Service Great Falls MT
513 PM MDT WED AUG 9 2017

MTZ053-054-092345-
Broadwater-Meagher-
513 PM MDT WED AUG 9 2017

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT NORTHEASTERN
BROADWATER AND SOUTHWESTERN MEAGHER COUNTIES THROUGH 545 PM MDT...

At 511 PM MDT, radar indicated strong thunderstorms were located
along a line extending from 16 miles northeast of East Helena to 20
miles east of Toston, or over the Big Belt Mountains. These storms
were nearly stationary.

Winds in excess of 30 mph and brief heavy rain are possible with
these storms.

Locations impacted include...
Goose Bay.

Frequent cloud to ground lightning is occurring with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

LAT...LON 4679 11159 4682 11162 4686 11161 4681 11154
      4681 11158 4680 11159 4677 11156 4677 11149
      4632 11090 4619 11104 4619 11112 4660 11165
      4674 11164
TIME...MOT...LOC 2311Z 344DEG 7KT 4673 11165 4619 11100

Coulston
Special weather statement, Aug 9, 5:19 PM MDT, 34 minutes before
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Special weather statement, Aug 9, 5:44 PM MDT, 9 minutes before
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Special weather statement, Aug 9, 5:48 PM MDT, 5 minutes before
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Special weather statement, Aug 9, 5:53 PM MDT, 0 minutes before
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The office that day

Everything else NWS Great Falls, MT issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 9, 3:16 PM MDTSpecial Weather StatementTFXJefferson29 min
Aug 9, 3:40 PM MDTSpecial Weather StatementTFXLewis and Clark50 min
Aug 9, 4:04 PM MDTSpecial Weather StatementTFXJefferson26 min
Aug 9, 4:17 PM MDTSpecial Weather StatementTFXMeagher28 min
Aug 9, 4:22 PM MDTSpecial Weather StatementTFXMadison23 min
Aug 9, 4:35 PM MDTSpecial Weather StatementTFXJefferson25 min
Aug 9, 5:06 PM MDTSpecial Weather StatementTFXJefferson24 min
Aug 9, 5:08 PM MDTSpecial Weather StatementTFXBeaverhead37 min
Aug 9, 5:13 PM MDTSpecial Weather StatementTFXBroadwater32 min
Aug 9, 5:19 PM MDTSpecial Weather StatementTFXJefferson26 min
Aug 9, 5:44 PM MDTSpecial Weather StatementTFXBroadwater31 min
Aug 9, 5:48 PM MDTSpecial Weather StatementTFXBroadwater27 min
Aug 9, 5:57 PM MDTSpecial Weather StatementTFXJefferson33 min

Nearby

Special Weather Statements in Montana, 2017Every special weather statement in 2017

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.