Alert archive / Montana / Severe Thunderstorm Warnings in 2013

Severe Thunderstorm Warning 22, NWS Missoula, MT

July 17, 2013Powell County, Montana

NWS Missoula, MT issued this severe thunderstorm warning at Jul 17, 2013, 4:12 PM MDT for Powell County, Montana. It was in force for 33 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: Jul 17, 2013, 4:12 PM MDT (22:12 UTC)
Expired: Jul 17, 2013, 4:45 PM MDT
In force: 33 min
Issued by: NWS Missoula, MT
Area: Storm-based polygon

County Powell County, MT

The radar

The Great Falls radar (KTFX), 121 km from the middle of the area, began a volume at 22:12 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.

What was reported inside it

Time	Report	Where	Remark
Jul 17, 4:16 PM MDT	HAIL 1.5	6 Nne Avon, MT	FOUR TO FIVE FOOT TALL HAY CROP DECIMATED BY HAIL.

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

Did it verify

Verified. The Iowa Environmental Mesonet's Cow matched one storm report to this severe thunderstorm warning; the first came 4 minutes after it went out.

Cow counts a report within 15 km of the polygon while the warning was in force: a tornado for a tornado warning; hail of 1 inch or more, a gust of 58 mph or more or wind damage for a severe thunderstorm warning; a flash flood report for a flash flood warning.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
Jul 17, 2:48 PM MDT	Severe Thunderstorm Watch	SPC	7 hr

The nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 10.2 hours before the alert went out and 166 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: 1289 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: -6 m²/s²
0-3 km storm-relative helicity: -14 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.

852 
WUUS55 KMSO 172212
SVRMSO
MTC077-172245-
/O.NEW.KMSO.SV.W.0022.130717T2212Z-130717T2245Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE MISSOULA MT
412 PM MDT WED JUL 17 2013

THE NATIONAL WEATHER SERVICE IN MISSOULA HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  EASTERN POWELL COUNTY IN WEST CENTRAL MONTANA...

* UNTIL 445 PM MDT.

* AT 406 PM MDT...DOPPLER RADAR INDICATED A SEVERE THUNDERSTORM      
  CAPABLE OF PRODUCING PING PONG SIZE HAIL...AND DAMAGING WINDS IN   
  EXCESS OF 60 MPH.  THIS STORM WAS LOCATED NEAR AVON...OR ABOUT     
  17 MILES NORTHEAST OF DEER LODGE...AND WAS MOVING EAST AT 30 MPH.

* LOCATIONS IMPACTED INCLUDE...AVON...BLOSSBURG AND ELLISTON.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

LARGE HAIL IS LIKELY WITH THIS SEVERE THUNDERSTORM. DAMAGING WINDS
ARE POSSIBLE...ALONG WITH FREQUENT LIGHTNING AND HEAVY RAIN. FOR YOUR
PROTECTION...GO INDOORS AND STAY AWAY FROM WINDOWS. IF YOU ARE CAUGHT
OUTSIDE...MOVE TO A WELL PROTECTED AREA.

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM MDT
WEDNESDAY EVENING FOR EAST CENTRAL IDAHO AND NORTHWESTERN MONTANA.

&&

LAT...LON 4653 11230 4653 11265 4671 11267 4672 11252
      4670 11252 4671 11242 4670 11240 4666 11240
      4667 11233 4662 11229
TIME...MOT...LOC 2212Z 267DEG 27KT 4662 11253

$$

ZUMPFE

1 follow-up statement

644 
WWUS55 KMSO 172232
SVSMSO

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE MISSOULA MT
432 PM MDT WED JUL 17 2013

MTC077-172242-
/O.CAN.KMSO.SV.W.0022.000000T0000Z-130717T2245Z/
POWELL MT-
432 PM MDT WED JUL 17 2013

...THE SEVERE THUNDERSTORM WARNING FOR EASTERN POWELL COUNTY IS
CANCELLED...

A SEVERE THUNDERSTORM WATCH REMAINS IN EFFECT UNTIL 1000 PM MDT
WEDNESDAY EVENING FOR EAST CENTRAL IDAHO AND NORTHWESTERN MONTANA.

LAT...LON 4653 11230 4653 11265 4671 11267 4672 11252
      4670 11252 4671 11242 4670 11240 4666 11240
      4667 11233 4662 11229
TIME...MOT...LOC 2232Z 267DEG 27KT 4661 11231

$$

ZUMPFE

What forecasters said that day

The local office's own words before this severe thunderstorm warning 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 severe thunderstorm warning went out at Jul 17, 2:13 PM MDT, 1 hour 59 minutes earlier.

Area forecast discussion, Jul 17, 2:13 PM MDT, 1 hour 59 minutes before

Area Forecast Discussion
National Weather Service Missoula MT
213 PM MDT Wed Jul 17 2013

...Very HOT and Dry conditions Thursday through Monday...

.DISCUSSION...Thunderstorms are developing over the region with a
weak storm system moving over northwest Montana. Some of these
thunderstorms may produce local heavy rain, hail and wind gusts to
50 mph. Check out our twitter feed for real-time information of
location and intensity of storms. Convection will end later this
evening as a drier airmass and high pressure move into the region.

Thursday through Sunday...High pressure will persist through the
weekend resulting in very hot temperatures and dry conditions.

Forecast highs:
Thursday and Friday...Mid 90s
Saturday and Sunday...Mid and upper 90s.

90 plus degree weather will continue through the middle of next
week. One possible change to the region may be a brief flattening
of the ridge on Monday or Tuesday which could increase west winds
and pose a potential fire weather impact. Confidence is low right
now for this scenario as little agreement exists among the current
weather models.

&&

.AVIATION...Thunderstorms, some possibly severe, developing over
the region may produce hail, gusty winds and locally heavy rain.
All Northern Rockies terminals have a potential for thunderstorms
through 18/0300z.

&&

.Climate...The overnight low Wednesday morning was 70 degrees. This
makes it only the third time in the history of Missoula weather the
overnight low has been 70 or higher.

&&

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

Nester

Follow us on Facebook and Twitter!
https://www.facebook.com/US.NationalWeatherService.Missoula.gov
https://www.twitter.com/NWSMissoula

In the hours before

Local storm report, Jul 17, 3:40 PM MDT, 32 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
340 PM MDT WED JUL 17 2013

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0330 PM     HAIL             8 N EUREKA              49.00N 115.06W
07/17/2013  E0.25 INCH       LINCOLN            MT   LAW ENFORCEMENT

&&

IRIS SYSTEM

Local storm report, Jul 17, 3:56 PM MDT, 16 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
356 PM MDT WED JUL 17 2013

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0318 PM     HAIL             4 NNE REXFORD           48.95N 115.15W
07/17/2013  M1.00 INCH       LINCOLN            MT   PUBLIC

            HAIL ACCUMULATED TO 12 INCHES. HAIL STRIPPED
            TREE LEAVES. SPOTTER WILL BE SENDING PHOTOS.

&&

IRIS SYSTEM

Local storm report, Jul 17, 3:57 PM MDT, 15 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
357 PM MDT WED JUL 17 2013

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0318 PM     TSTM WND DMG     4 NNE REXFORD           48.96N 115.15W
07/17/2013                   LINCOLN            MT   PUBLIC

            30 FOOT TALL WILLOW TREE BLOWN DOWN.

&&

IRIS SYSTEM

Local storm report, Jul 17, 4:03 PM MDT, 9 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
403 PM MDT WED JUL 17 2013

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0351 PM     HAIL             2 SSE SEELEY LAKE       47.15N 113.47W
07/17/2013  E0.50 INCH       MISSOULA           MT   TRAINED SPOTTER

            HAIL DURATION 5 MINUTES OBSERVER LOCATION 2
            MI S OF SEELEY LAKE

&&

IRIS SYSTEM

Local storm report, Jul 17, 4:08 PM MDT, 4 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
408 PM MDT WED JUL 17 2013

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0255 PM     HAIL             1 SE MARION             48.10N 114.65W
07/17/2013  M0.25 INCH       FLATHEAD           MT   COCORAHS

            HAIL DURATION 15 MINUTES

&&

IRIS SYSTEM

Local storm report, Jul 17, 4:09 PM MDT, 3 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE MISSOULA MT
409 PM MDT WED JUL 17 2013

...TIME...  ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
...DATE...  ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0400 PM     HAIL             6 SE SEELEY LAKE        47.12N 113.38W
07/17/2013  M0.50 INCH       MISSOULA           MT   TRAINED SPOTTER

&&

IRIS SYSTEM

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 17, 2:21 PM MDT	Special Weather Statement	MSO	Lincoln	39 min
Jul 17, 2:36 PM MDT	Special Weather Statement	MSO	Missoula	24 min
Jul 17, 2:42 PM MDT	Special Weather Statement	MSO	Flathead	33 min
Jul 17, 2:49 PM MDT	Special Weather Statement	MSO		41 min
Jul 17, 2:53 PM MDT	Special Weather Statement	MSO	Powell	52 min
Jul 17, 2:56 PM MDT	Severe Thunderstorm Warning	MSO	Flathead	49 min
Jul 17, 3:02 PM MDT	Severe Thunderstorm Warning	MSO	Missoula	43 min
Jul 17, 3:06 PM MDT	Special Weather Statement	MSO	Lake	24 min
Jul 17, 3:08 PM MDT	Severe Thunderstorm Warning	MSO	Lincoln	37 min
Jul 17, 3:26 PM MDT	Severe Thunderstorm Warning	MSO	Flathead, Lake	49 min
Jul 17, 3:28 PM MDT	Special Weather Statement	MSO		32 min
Jul 17, 3:32 PM MDT	Severe Thunderstorm Warning	MSO	Granite, Powell	43 min
Jul 17, 3:42 PM MDT	Severe Thunderstorm Warning	MSO	Missoula, Powell	63 min
Jul 17, 3:43 PM MDT	Severe Thunderstorm Warning	MSO	Flathead	47 min
Jul 17, 4:00 PM MDT	Severe Thunderstorm Warning	MSO	Flathead	30 min
Jul 17, 5:20 PM MDT	Special Weather Statement	MSO	Deer Lodge	40 min
Jul 17, 5:39 PM MDT	Special Weather Statement	MSO	Missoula	51 min

Nearby

Severe Thunderstorm Warnings in Montana, 2013 Every severe thunderstorm warning in 2013

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.