Alert archive / Montana / Severe Thunderstorm Watches in 2012

Severe Thunderstorm Watch 449

July 1, 201219 counties in Montana; 11 counties in North Dakota; Harding County, South Dakota

The Storm Prediction Center issued this severe thunderstorm watch at Jul 1, 2012, 4:04 PM MDT for 19 counties in Montana; 11 counties in North Dakota; Harding County, South Dakota. It was in force for 9 hr.

The area

The outline as issued.

The facts

Issued
Jul 1, 2012, 4:04 PM MDT (22:04 UTC)
Expired
Jul 2, 2012, 1:00 AM MDT
In force
9 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
65 kt
All 31 counties

Big Horn County, MT, Carter County, MT, Custer County, MT, Daniels County, MT, Dawson County, MT, Fallon County, MT, Garfield County, MT, McCone County, MT, Petroleum County, MT, Phillips County, MT, Powder River County, MT, Prairie County, MT, Richland County, MT, Roosevelt County, MT, Rosebud County, MT, Sheridan County, MT, Treasure County, MT, Valley County, MT, Wibaux County, MT, Adams County, ND, Billings County, ND, Bowman County, ND, Divide County, ND, Dunn County, ND, Golden Valley County, ND, Hettinger County, ND, McKenzie County, ND, Slope County, ND, Stark County, ND, Williams County, ND, Harding County, SD

The radar

The Glasgow radar (KGGW), 192 km from the middle of the area, began a volume at 22:07 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 SPC expected

The probabilities SPC published with the watch, for the watch area over its life.

Two or more tornadoes
10%
One or more EF2 to EF5 tornadoes
5%
Ten or more severe wind reports
30%
One or more gusts of 65 knots or more
30%
Ten or more severe hail reports
20%
One or more hailstones of 2 inches or more
20%
Six or more combined severe hail and wind reports
70%

Warnings issued inside it

10 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

IssuedProductOfficeCountiesLasted
Jul 1, 4:58 PM MDTSevere Thunderstorm WarningBYZCarter, Custer, Fallon62 min
Jul 1, 5:46 PM MDTSevere Thunderstorm WarningBYZCarter, Fallon59 min
Jul 1, 6:47 PM MDTSevere Thunderstorm WarningBISGolden Valley43 min
Jul 1, 7:11 PM MDTSevere Thunderstorm WarningBISBillings49 min
Jul 1, 7:33 PM MDTSevere Thunderstorm WarningBISBowman, Slope40 min
Jul 1, 7:54 PM MDTSevere Thunderstorm WarningUNRHarding66 min
Jul 1, 9:00 PM MDTSevere Thunderstorm WarningUNRHarding, Perkins60 min
Jul 1, 10:46 PM MDTSevere Thunderstorm WarningGGWGarfield, McCone, Phillips, Valley59 min
Jul 1, 11:40 PM MDTSevere Thunderstorm WarningGGWDaniels, Garfield, McCone, Roosevelt, Valley65 min
Jul 2, 12:43 AM MDTSevere Thunderstorm WarningGGWDaniels, McCone, Roosevelt, Sheridan, Valley62 min

Discussions around it

SPC mesoscale discussions over the same counties from four hours before the watch to its end.

The nearest sounding before it

Glasgow Intl Airport, MT (KGGW), launched 12:00Z, 10.1 hours before the alert went out and 193 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, Glasgow Intl Airport, MT at 12:00Z on 2012-07-01Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 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, Glasgow Intl Airport, MT at 12:00Z on 2012-07-01The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 145 square meters per square second.193958Sfc1 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
0 J/kg
Mixed-layer CIN
No buoyant parcel
Mixed-layer LCL
2044 m above ground
0-6 km bulk shear
38 kt
0-1 km storm-relative helicity
145 m²/s²
0-3 km storm-relative helicity
212 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.

198 
WWUS20 KWNS 012206
SEL9
SPC WW 012206
MTZ000-NDZ000-SDZ000-020500-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 449
NWS STORM PREDICTION CENTER NORMAN OK
405 PM MDT SUN JUL 1 2012

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

       EASTERN MONTANA
       WESTERN NORTH DAKOTA
       NORTHWESTERN SOUTH DAKOTA

EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 405 PM UNTIL
1100 PM MDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 75
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 120
STATUTE MILES EAST AND WEST OF A LINE FROM 35 MILES SOUTH OF
BROADUS MONTANA TO 60 MILES NORTH OF WOLF POINT MONTANA.  FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU9).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

OTHER WATCH INFORMATION...CONTINUE...WW 442...WW 443...WW
444...WW 445...WW 446...WW 447...WW 448...

DISCUSSION...SVR POTENTIAL INCREASING OVER AREA E OF SFC COLD FRONT
AND ON BOTH SIDES OF DRYLINE/WARM FRONT...INCLUDING INCREASING
THREAT FOR A FEW HIGH-BASED SUPERCELLS AND EVENTUAL UPSCALE
GROWTH/INTENSIFICATION OF CONVECTION.  SEE SPC MESOSCALE DISCUSSION
1342 FOR DETAILS. DAMAGING DOWNDRAFTS AND OCNL LARGE HAIL ARE
LIKELY.

AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 65
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 500. MEAN STORM
MOTION VECTOR 25030.


...EDWARDS

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Jun 30, 8:33 PM MDTMesoscale DiscussionSPCFlathead, Lake, Lincoln, Mineral, Missoula, Sanders2 hr
Jul 1, 2:40 PM MDTMesoscale DiscussionSPCCarter, Custer, Daniels, Dawson, Fallon, Garfield and 10 more2 hr
Jul 1, 4:34 PM MDTMesoscale DiscussionSPCBeaverhead, Blaine, Broadwater, Carbon, Cascade, Chouteau and 19 more86 min
Jul 1, 5:04 PM MDTSevere Thunderstorm WatchSPCBeaverhead, Blaine, Broadwater, Carbon, Cascade, Chouteau and 18 more6 hr
Jun 30, 6:19 PM MDTMesoscale DiscussionSPCEmmons, Kidder, Logan, Sioux, Stutsman86 min
Jul 1, 4:49 PM MDTSevere Thunderstorm WatchSPCButte, Custer, Fall River, Harding, Lawrence, Meade and 2 more6 hr

Nearby

Severe Thunderstorm Watches in Montana, 2012Severe Thunderstorm Watches in North Dakota, 2012Severe Thunderstorm Watches in South Dakota, 2012Every severe thunderstorm watch in 2012

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.