Alert archive / Montana / Severe Thunderstorm Warnings in 2011

Severe Thunderstorm Warning 26, NWS Great Falls, MT

July 13, 2011Lewis and Clark County, Montana

NWS Great Falls, MT issued this severe thunderstorm warning at Jul 13, 2011, 1:38 PM MDT for Lewis and Clark County, Montana. It was in force for 35 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 13, 2011, 1:38 PM MDT (19:38 UTC)
Expired: Jul 13, 2011, 2:13 PM MDT
In force: 35 min
Issued by: NWS Great Falls, MT
Area: Storm-based polygon

County Lewis and Clark County, MT

The radar

The Great Falls radar (KTFX), 104 km from the middle of the area, began a volume at 19:39 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 13, 1:40 PM MDT	HAIL 1	13 S Marysville, MT

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 2 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 nearest sounding before it

Great_falls, MT (KTFX), launched 12:00Z, 7.6 hours before the alert went out and 147 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: 6 J/kg
Mixed-layer CIN: -325 J/kg
Mixed-layer LCL: 1669 m above ground
0-6 km bulk shear: 17 kt
0-1 km storm-relative helicity: -16 m²/s²
0-3 km storm-relative helicity: 16 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.

217 
WUUS55 KTFX 131938
SVRTFX
MTC049-132030-
/O.NEW.KTFX.SV.W.0026.110713T1938Z-110713T2030Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE GREAT FALLS MT
138 PM MDT WED JUL 13 2011

THE NATIONAL WEATHER SERVICE IN GREAT FALLS HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  SOUTH CENTRAL LEWIS AND CLARK COUNTY IN WEST CENTRAL MONTANA...

* UNTIL 230 PM MDT

* AT 135 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED 
  A SEVERE THUNDERSTORM 11 MILES WEST OF HELENA MOR NEAR MACDONALD 
  PASS...MOVING NORTHEAST AT 15 MPH.

* THE SEVERE THUNDERSTORM WILL GENERALLY REMAIN OVER RURAL AREAS OF
  SOUTH CENTRAL LEWIS AND CLARK COUNTY.

HAIL TO THE SIZE OF QUARTERS AND WIND GUSTS TO 60 MPH ARE LIKELY WITH
THIS STORM.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

DOPPLER RADAR HAS INDICATED SOME WEAK ROTATION WITHIN THIS STORM.
WHILE NOT IMMEDIATELY LIKELY...A TORNADO MAY STILL DEVELOP. IF A
TORNADO IS SPOTTED...ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A
STURDY STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

&&

LAT...LON 4694 11215 4671 11181 4651 11222 4657 11233
      4661 11230 4665 11235
TIME...MOT...LOC 1937Z 212DEG 11KT 4659 11224

$$

1 follow-up statement

283 
WWUS55 KTFX 132013
SVSTFX

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
213 PM MDT WED JUL 13 2011

MTC049-132024-
/O.CAN.KTFX.SV.W.0026.000000T0000Z-110713T2030Z/
LEWIS AND CLARK MT-
213 PM MDT WED JUL 13 2011

...THE SEVERE THUNDERSTORM WARNING FOR SOUTH CENTRAL LEWIS AND CLARK
COUNTY IS CANCELLED...

NATIONAL WEATHER SERVICE RADAR INDICATED THAT THE SEVERE THUNDERSTORM
THAT PROMPTED THE WARNING HAD WEAKENED AND WAS NO LONGER SEVERE...
THUS THE WARNING HAS BEEN CANCELLED.

LAT...LON 4694 11215 4671 11181 4651 11222 4657 11233
      4661 11230 4665 11235
TIME...MOT...LOC 2014Z 212DEG 11KT 4669 11215

$$

HOENISCH

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 Great Falls, MT wrote its last area forecast discussion before this severe thunderstorm warning went out at Jul 13, 1:12 PM MDT, 26 minutes earlier.

Area forecast discussion, Jul 13, 1:12 PM MDT, 26 minutes before

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE GREAT FALLS MT
112 PM MDT WED JUL 13 2011

.DISCUSSION...

TONIGHT THROUGH FRIDAY...RAIN AND THUNDERSTORMS WILL CONTINUE TO
DEVELOP THIS AFTERNOON AS A MOIST AND UNSTABLE AIRMASS WITH
DIFFLUENT FLOW ALOFT CONTINUES TO RESIDE OVER THE REGION. THE BIGGEST
THREATS WILL BE HEAVY RAINFALL WITH FLASH FLOODING POTENTIAL ALONG
WITH STRONG AND GUSTY WINDS. ACTIVITY WILL DIMINISH LATE THIS
EVENING WITH PARTLY CLOUDY SKIES OVERNIGHT. ON
THURSDAY...SOUTHWEST FLOW ALOFT AND INSTABILITY WILL RESULT IN A
SIMILAR SCENARIO WITH AFTERNOON CONVECTION LIKELY WITH THE
GREATEST THREAT OVER SOUTHWEST AND PARTS OF CENTRAL MONTANA.
HOWEVER...MORE CLOUDS MAY KEEP HIGH TEMPERATURES COOLER WHICH MAY
LOWER THE SEVERE POTENTIAL. BY FRIDAY...THE CHANCES FOR AFTERNOON
THUNDERSTORMS WILL DECREASE AS THE UPPER-LEVEL LOW THAT HAS BEEN
OVER THE PACIFIC NORTHWEST SHIFTS NORTHWARD INTO SOUTHERN ALBERTA.
HAVE THUS LOWERED POPS TO SLIGHT CHANCE AND CHANCE ACROSS THE
AREA. MLS

FRIDAY NIGHT THROUGH WEDNESDAY...EXPECT A FEW SHOWERS/THUNDERSTORMS
TO CONTINUE TO AFFECT THE REGION INTO THE START OF THE WEEKEND...AS
A WEAK UPPER LEVEL DISTURBANCE MOVES NORTHEAST THROUGH THE AREA ON
SATURDAY. HOWEVER...THE CHANCES FOR PRECIPITATION WILL GENERALLY BE
DIMINISHING BY THE EVENING HOURS. THEN FOR SUNDAY THROUGH
TUESDAY...THE REGION WILL GENERALLY BE UNDER THE INFLUENCE OF AN
UPPER LEVEL RIDGE OF HIGH PRESSURE. LITTLE TO NO PRECIPITATION IS
EXPECTED OVER THE PLAINS...WITH A SMALL CHANCE FOR AN ISOLATED
MOUNTAIN THUNDERSTORM CONTINUING. FOR NEXT WEDNESDAY...THE GFS/EC
HAVE FAIRLY OPPOSITE SOLUTIONS...WITH THE GFS BEING WARM/MOSTLY
DRY...WHILE THE EC HAS A TROF OF LOW PRESSURE OVER THE
REGION...RESULTING IN COOLER WEATHER AND A GOOD CHANCE FOR RAIN. FOR
NOW...WENT WITH THE DRY/WARM GFS...AS A SUMMER TIME UPPER LEVEL
RIDGE IS USUALLY SLOW TO BREAK DOWN. IN TERMS OF
TEMPERATURES...EXPECT A SEASONABLE DAY ON SATURDAY...THEN A GRADUAL
WARMING TREND CAN BE EXPECTED FROM SUNDAY THROUGH TUESDAY. BY
TUESDAY...AFTERNOON TEMPERATURES WILL AVERAGE BETWEEN 5 AND 10
DEGREES ABOVE NORMAL. THE WARM TEMPERATURES ARE EXPECTED TO CONTINUE
INTO NEXT WEDNESDAY. BRUSDA

&&

.AVIATION...
UPDATED 1730Z.
VFR CONDITIONS SHOULD PREVAIL AT ALL TAF SITES FOR A MAJORITY OF THE
FORECAST PERIOD. A RELATIVELY MOIST AND UNSTABLE AIRMASS WILL SLOWLY
MOVE ACROSS THE AREA THROUGH THE PERIOD. EXPECT A FEW ISOLATED
THUNDERSTORMS OVER THE AREA BEFORE 20Z...WITH THE
THUNDERSTORM ACTIVITY BECOMING MORE WIDESPREAD AFTER 22Z TODAY.
EXPECT ABOUT 1/2 HOUR PERIODS OF MODERATE TO HEAVY RAINFALL AND
REDUCED VISIBILITIES IN HEAVIER STORMS. THE STORMS WILL START TO
EXIT NORTH CENTRAL MONTANA BY 8Z THURSDAY. BRIEF IFR/MVFR CONDITIONS
WILL BE LIKELY IN/NEAR ANY THUNDERSTORMS. SUK

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  56  78  53  82 /  60  30  30  10
CTB  55  76  49  77 /  60  30  20  10
HLN  56  79  53  83 /  50  30  20  20
BZN  52  82  49  84 /  30  30  20  20
WEY  45  74  40  74 /  30  20  10  20
DLN  51  77  49  79 /  30  30  30  20
HVR  60  82  55  84 /  60  30  30  10
LWT  56  80  52  80 /  40  30  30  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

WEATHER.GOV/GREATFALLS

Hazardous weather outlook, Jul 13, 5:01 AM MDT, 8 hours 37 minutes before

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE GREAT FALLS MT
501 AM MDT WED JUL 13 2011

MTZ008>015-044>055-141115-
BEAVERHEAD-NORTHERN ROCKY MOUNTAIN FRONT-EASTERN GLACIER-HILL-
CASCADE-CHOUTEAU-CENTRAL AND SOUTHERN LEWIS AND CLARK-MADISON-
TOOLE-LIBERTY-EASTERN PONDERA-BLAINE-
SOUTHERN ROCKY MOUNTAIN FRONT-EASTERN TETON-JUDITH BASIN-FERGUS-
JEFFERSON-BROADWATER-MEAGHER-GALLATIN-
501 AM MDT WED JUL 13 2011

THIS HAZARDOUS WEATHER OUTLOOK IS FOR PORTIONS OF CENTRAL
MONTANA...NORTH CENTRAL MONTANA AND SOUTHWEST MONTANA.

.DAY ONE...TODAY AND TONIGHT

THUNDERSTORMS WILL DEVELOP THIS AFTERNOON AND EVENING ACROSS THE
REGION. A FEW STORMS MAY BECOME STRONG TO SEVERE WITH LOCALLY
HEAVY RAINFALL...SMALL HAIL...AND GUSTY OUTFLOW WINDS.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

THUNDERSTORMS ARE EXPECTED TO OCCUR AGAIN ON THURSDAY WITH A
CHANCE FOR ISOLATED STRONG TO SEVERE STORMS.

.SPOTTER INFORMATION STATEMENT...

SPOTTERS ARE ENCOURAGED TO RELAY TIMELY REPORTS OF ANY HAIL...GUSTY
OR DAMAGING WINDS OR FLASH FLOODING TO THE NATIONAL WEATHER SERVICE
OFFICE IN GREAT FALLS.

In the hours before

Local storm report, Jul 13, 8:21 AM MDT, 5 hours 17 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
821 AM MDT WED JUL 13 2011

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

0800 PM     HEAVY RAIN       5 SSE GRANT             44.94N 113.03W
07/12/2011  M0.82 INCH       BEAVERHEAD         MT   CO-OP OBSERVER

            0.82 INCHES OF RAIN FELL IN A 4 HOUR PERIOD.

&&

WILLIAMSON

Special weather statement, Jul 13, 1:06 PM MDT, 32 minutes before

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE GREAT FALLS MT
106 PM MDT WED JUL 13 2011

MTZ048-131945-
SOUTHERN ROCKY MOUNTAIN FRONT MT-
106 PM MDT WED JUL 13 2011

...SIGNIFICANT WEATHER ADVISORY FOR NORTHWESTERN LEWIS AND CLARK AND
WESTERN TETON COUNTIES UNTIL 145 PM MDT...

AT 104 PM MDT...NATIONAL WEATHER SERVICE DOPPLER RADAR WAS TRACKING A
STRONG THUNDERSTORM 17 MILES WEST OF AUGUSTA...OR 31 MILES SOUTHWEST
OF CHOTEAU...NEAR THE GIBSON DAM AREA...MOVING NORTHEAST AT 20 MPH.

HAIL UP TO THE SIZE OF PENNIES AND WIND GUSTS UP TO 40 MPH ARE
EXPECTED WITH THIS STORM...ALONG WITH HEAVY RAIN AND FREQUENT
DANGEROUS LIGHTNING.

* LOCATIONS IMPACTED INCLUDE...
  RURAL NORTHERN LEWIS AND CLARK COUNTY...
  RURAL SOUTHWESTERN TETON COUNTY...
  RURAL WESTERN TETON COUNTY...

IF THREATENING WEATHER APPROACHES YOUR AREA...TAKE SHELTER IN A
STURDY BUILDING.

LAT...LON 4795 11265 4780 11227 4747 11274 4754 11291
TIME...MOT...LOC 1906Z 214DEG 19KT 4757 11272

SUK

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 12, 6:48 PM MDT	Special Weather Statement	TFX	Blaine	57 min
Jul 12, 7:15 PM MDT	Special Weather Statement	TFX	Hill	45 min
Jul 12, 7:39 PM MDT	Special Weather Statement	TFX	Hill	51 min
Jul 12, 8:23 PM MDT	Special Weather Statement	TFX	Beaverhead	37 min
Jul 13, 12:26 AM MDT	Special Weather Statement	TFX	Fergus	49 min
Jul 13, 1:06 PM MDT	Special Weather Statement	TFX	Teton	39 min
Jul 13, 1:28 PM MDT	Severe Thunderstorm Warning	TFX	Lewis and Clark, Teton	62 min
Jul 13, 1:33 PM MDT	Flash Flood Watch	TFX		10 hr
Jul 13, 2:18 PM MDT	Special Weather Statement	TFX	Glacier	42 min
Jul 13, 2:25 PM MDT	Special Weather Statement	TFX	Teton	50 min
Jul 13, 2:27 PM MDT	Special Weather Statement	TFX	Lewis and Clark	48 min
Jul 13, 2:32 PM MDT	Severe Thunderstorm Warning	TFX	Lewis and Clark	18 min
Jul 13, 2:40 PM MDT	Special Weather Statement	TFX	Cascade	50 min
Jul 13, 2:42 PM MDT	Special Weather Statement	TFX		48 min
Jul 13, 2:51 PM MDT	Special Weather Statement	TFX	Glacier	39 min
Jul 13, 3:02 PM MDT	Severe Thunderstorm Warning	TFX	Glacier	43 min
Jul 13, 3:32 PM MDT	Special Weather Statement	TFX	Judith Basin	43 min
Jul 13, 3:32 PM MDT	Severe Thunderstorm Warning	TFX	Lewis and Clark	43 min
Jul 13, 3:47 PM MDT	Flash Flood Warning	TFX	Judith Basin	3 hr
Jul 13, 3:51 PM MDT	Special Weather Statement	TFX	Cascade	39 min
Jul 13, 3:56 PM MDT	Severe Thunderstorm Warning	TFX	Cascade	49 min
Jul 13, 4:06 PM MDT	Special Weather Statement	TFX	Toole	39 min
Jul 13, 4:08 PM MDT	Severe Thunderstorm Warning	TFX	Liberty, Toole	52 min
Jul 13, 4:11 PM MDT	Severe Thunderstorm Warning	TFX	Lewis and Clark	49 min
Jul 13, 4:36 PM MDT	Special Weather Statement	TFX	Judith Basin	39 min
Jul 13, 4:39 PM MDT	Severe Thunderstorm Warning	TFX	Cascade, Lewis and Clark, Meagher	66 min
Jul 13, 4:55 PM MDT	Special Weather Statement	TFX	Fergus	65 min
Jul 13, 5:00 PM MDT	Severe Thunderstorm Warning	TFX	Cascade, Chouteau, Judith Basin	45 min
Jul 13, 5:16 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	44 min
Jul 13, 5:27 PM MDT	Areal Flood Advisory	TFX	Jefferson, Lewis and Clark	2 hr
Jul 13, 5:38 PM MDT	Severe Thunderstorm Warning	TFX	Cascade, Judith Basin, Meagher	52 min
Jul 13, 5:39 PM MDT	Special Weather Statement	TFX	Blaine	51 min

Nearby

Severe Thunderstorm Warnings in Montana, 2011 Every severe thunderstorm warning in 2011

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.