Alert archive / Montana / Special Weather Statements in 2017

Special Weather Statement, NWS Missoula, MT

July 9, 2017Powell County, Montana

NWS Missoula, MT issued this special weather statement at Jul 9, 2017, 6:14 PM MDT for Powell County, Montana. It was in force for 46 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: Jul 9, 2017, 6:14 PM MDT (00:14 UTC)
Expired: Jul 9, 2017, 7:00 PM MDT
In force: 46 min
Issued by: NWS Missoula, MT

County Powell County, MT

The radar

The Missoula radar (KMSX), 95 km from the middle of the area, began a volume at 00:17 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 00:00Z, 0.2 hours before the alert went out and 210 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: 56 J/kg
Mixed-layer CIN: -199 J/kg
Mixed-layer LCL: 3424 m above ground
0-6 km bulk shear: 37 kt
0-1 km storm-relative helicity: 104 m²/s²
0-3 km storm-relative helicity: 240 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 Missoula, MT wrote its last area forecast discussion before this special weather statement went out at Jul 9, 2:37 PM MDT, 3 hours 37 minutes earlier.

Area forecast discussion, Jul 9, 2:37 PM MDT, 3 hours 37 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
237 PM MDT Sun Jul 9 2017

.DISCUSSION...The ridge axis has shifted slightly to the east
today putting the Northern Rockies more under a southwesterly flow
pattern. A plume of moisture has traversed under the ridge and is
interacting with an unstable atmosphere from Lemhi county into
southwest Montana. This interaction will allow for the development
of fairly strong thunderstorms. Due to the extremely dry low
levels, the main threat will be gusty and potentially damaging
winds. Temperatures today will once again be hot, but should not
quite reach daily record levels.

A weak disturbance will be moving through the Pacific Northwest
tonight into Monday. This feature will knock down the ridge
causing the upper level flow to become more westerly. A weak cold
front associated with the disturbance will cool temperatures to
seasonal readings. The front appears to become the focal point for
convection during the afternoon/evening hours across southwest
Montana.

The westerly flow persists into Tuesday with temperatures
remaining near normal. Then the models are depicting another
extraordinary ridge of high pressure building over the region for
the remainder of the work week into the weekend. Temperatures
appear to be in the upper 90s to low 100s by Thursday through at
least Sunday.

&&

.AVIATION...Scattered showers and thunderstorms are developing
across Lemhi county into southwest Montana this afternoon. KBTM
and KSMN will be impacted gusty winds and potentially brief heavy
rain between 09/21z-10/00z. The convection will diminish after
sunset this evening. On Monday, westerly winds will be on the
increase during the afternoon with a few showers and thunderstorms
along the Divide.

&&

.MSO WATCHES/WARNINGS/ADVISORIES...
MT...None.
ID...None.
&&

In the hours before

Special weather statement, Jul 9, 3:41 PM MDT, 2 hours 33 minutes before

Special Weather Statement
National Weather Service Missoula MT
341 PM MDT SUN JUL 9 2017

IDZ009-010-092215-
Eastern Lemhi County ID-Western Lemhi County ID-
341 PM MDT SUN JUL 9 2017

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL LEMHI COUNTY UNTIL 415 PM
MDT...

At 341 PM MDT, Doppler radar was tracking a strong thunderstorm over
Salmon, moving east at 20 mph.

Dime size hail and wind gusts up to 50 mph will be possible with this
storm.

Locations impacted include...
Salmon, Carmen, Leesburg and Baker.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4523 11412 4539 11374 4533 11374 4528 11368
      4526 11369 4518 11359 4516 11359 4515 11357
      4513 11357 4511 11355 4511 11352 4509 11352
      4508 11349 4502 11402
TIME...MOT...LOC 2141Z 253DEG 20KT 4519 11391

Special weather statement, Jul 9, 4:46 PM MDT, 1 hour 28 minutes before

Special Weather Statement
National Weather Service Missoula MT
446 PM MDT SUN JUL 9 2017

IDZ009-010-MTZ005-006-092330-
Eastern Lemhi County ID-Western Lemhi County ID-
Bitterroot/Sapphire Mountains MT-Missoula/Bitterroot Valleys MT-
446 PM MDT SUN JUL 9 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN LEMHI AND SOUTHWESTERN
RAVALLI COUNTIES UNTIL 530 PM MDT...

At 446 PM MDT, Doppler radar was tracking a strong thunderstorm 20
miles southwest of Conner, or 39 miles northwest of Salmon, moving
northeast at 25 mph.

Half inch hail and wind gusts up to 50 mph will be possible with this
storm.

Locations impacted include...
Sula and Lost Trail Pass.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4575 11384 4578 11387 4575 11391 4570 11391
      4570 11394 4566 11392 4555 11435 4570 11449
      4599 11401 4576 11380
TIME...MOT...LOC 2246Z 237DEG 23KT 4567 11433

Special weather statement, Jul 9, 5:18 PM MDT, 56 minutes before

Special Weather Statement
National Weather Service Missoula MT
518 PM MDT SUN JUL 9 2017

MTZ006-007-043-100000-
Bitterroot/Sapphire Mountains MT-Butte/Blackfoot Region MT-
Potomac/Seeley Lake Region MT-
518 PM MDT SUN JUL 9 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN GRANITE COUNTY UNTIL
600 PM MDT...

At 517 PM MDT, Doppler radar was tracking a strong thunderstorm 17
miles east of Stevensville, or 27 miles southeast of Missoula, moving
east at 25 mph.

Half inch hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Quigley...Rock Creek.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4642 11382 4652 11383 4661 11378 4670 11337
      4643 11333
TIME...MOT...LOC 2317Z 261DEG 23KT 4653 11372

Special weather statement, Jul 9, 5:31 PM MDT, 43 minutes before

Special Weather Statement
National Weather Service Missoula MT
531 PM MDT SUN JUL 9 2017

MTZ005-006-100015-
Bitterroot/Sapphire Mountains MT-Missoula/Bitterroot Valleys MT-
531 PM MDT SUN JUL 9 2017

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL RAVALLI COUNTY UNTIL 615
PM MDT...

At 531 PM MDT, Doppler radar was tracking a strong thunderstorm near
Conner, or 25 miles south of Hamilton, moving northeast at 25 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm.

Locations impacted include...
Conner and Sula.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4576 11402 4593 11425 4617 11388 4611 11380
      4603 11381 4602 11374 4591 11357
TIME...MOT...LOC 2331Z 228DEG 23KT 4589 11403

Special weather statement, Jul 9, 5:49 PM MDT, 25 minutes before

Special Weather Statement
National Weather Service Missoula MT
549 PM MDT SUN JUL 9 2017

MTZ006-007-100015-
Bitterroot/Sapphire Mountains MT-Butte/Blackfoot Region MT-
549 PM MDT SUN JUL 9 2017

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN GRANITE AND SOUTH
CENTRAL POWELL COUNTIES UNTIL 615 PM MDT...

At 549 PM MDT, Doppler radar was tracking a strong thunderstorm near
Drummond, moving east at 35 mph.

Pea size hail and winds in excess of 30 mph will be possible with
this storm.

Locations impacted include...
Drummond, Garrison, Maxville, Jens, Brock Creek, New Chicago,
Goldcreek and Hall.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4645 11334 4666 11337 4681 11286 4645 11277
TIME...MOT...LOC 2349Z 260DEG 30KT 4658 11321

Special weather statement, Jul 9, 6:14 PM MDT, 0 minutes before

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The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 9, 6:46 PM MDT	Special Weather Statement	MSO	Powell	44 min
Jul 9, 7:06 PM MDT	Special Weather Statement	MSO	Ravalli	39 min
Jul 9, 7:46 PM MDT	Special Weather Statement	MSO	Ravalli	44 min
Jul 9, 8:37 PM MDT	Special Weather Statement	MSO	Deer Lodge	38 min
Jul 9, 9:34 PM MDT	Special Weather Statement	MSO		41 min
Jul 9, 10:17 PM MDT	Special Weather Statement	MSO	Ravalli	43 min
Jul 10, 1:29 PM MDT	Special Weather Statement	MSO	Silver Bow	46 min
Jul 10, 3:12 PM MDT	Severe Thunderstorm Warning	MSO	Silver Bow	33 min
Jul 10, 3:40 PM MDT	Special Weather Statement	MSO	Deer Lodge	35 min
Jul 10, 4:12 PM MDT	Special Weather Statement	MSO	Deer Lodge	33 min
Jul 10, 4:16 PM MDT	Severe Thunderstorm Warning	MSO	Deer Lodge, Powell, Silver Bow	29 min
Jul 10, 4:20 PM MDT	Special Weather Statement	MSO	Silver Bow	25 min
Jul 10, 4:22 PM MDT	Severe Thunderstorm Warning	MSO	Silver Bow	23 min
Jul 10, 4:51 PM MDT	Special Weather Statement	MSO	Deer Lodge	24 min
Jul 10, 5:04 PM MDT	Special Weather Statement	MSO	Ravalli	26 min
Jul 10, 5:38 PM MDT	Special Weather Statement	MSO	Powell	37 min
Jul 10, 5:45 PM MDT	Special Weather Statement	MSO	Granite	45 min

Nearby

Special Weather Statements in Montana, 2017 Every 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.