Alert archive / Montana / Special Weather Statements in 2021

Special Weather Statement, NWS Great Falls, MT

July 7, 2021Petroleum County, Montana

NWS Great Falls, MT issued this special weather statement at Jul 7, 2021, 6:56 PM MDT for Petroleum County, Montana. It was in force for 34 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 7, 2021, 6:56 PM MDT (00:56 UTC)
Expired: Jul 7, 2021, 7:30 PM MDT
In force: 34 min
Issued by: NWS Great Falls, MT

County Petroleum County, MT

The radar

The Glasgow radar (KGGW), 156 km from the middle of the area, began a volume at 00:58 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

Glasgow Intl Airport, MT (KGGW), launched 00:00Z, 0.9 hours before the alert went out and 158 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: 201 J/kg
Mixed-layer CIN: -154 J/kg
Mixed-layer LCL: 2168 m above ground
0-6 km bulk shear: 41 kt
0-1 km storm-relative helicity: 107 m²/s²
0-3 km storm-relative helicity: 209 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 1.8

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 Jul 7, 5:40 PM MDT, 1 hour 16 minutes earlier.

Area forecast discussion, Jul 7, 5:40 PM MDT, 1 hour 16 minutes before

Area Forecast Discussion
National Weather Service Great Falls MT
540 PM MDT Wed Jul 7 2021

...AVIATION SECTION UPDATED...

.SYNOPSIS...

Scattered strong to potentially severe thunderstorms move through
the region through this evening. On its heels, a cold front moves
through the region tonight into Thursday. Temperatures lower back
into the 80s through Friday. Hot and dry conditions return for the
weekend.

&&

.DISCUSSION...

Upper ridging moves east through the remainder of the afternoon and
evening as a vigorous upper disturbance approaches from the west
later today and tonight. First round of showers and isolated
thunderstorms continues to fall apart as it moves into the upper
ridging to the east of the Continental Divide. Additional rounds of
showers and thunderstorms will have better dynamic and thermodynamic
conditions to work with and should be considerably stronger and more
persistent. Main threats from storms will be the potential for a few
to reach severe levels with damaging winds the primary threat,
followed by quarter-size hail, lightning, and heavy rain with
localized flooding the secondary threats. Lightning strikes will
continue to be capable of producing new wildfire starts. Fast storm
movements, despite a fairly moist environment, will dampen rainfall
amounts at any one location unless there are multiple storms moving
across the area.

Today's thunderstorm activity is expected to dissipate and clear to
the east by late evening in eastern areas. A cool front associated
with the upper level shortwave trough passing through Canada will
move into North-central Montana overnight into Thursday. Thus,
breezy and gradually cooler weather follows through Friday. Another
shortwave system moves through the region on Friday afternoon,
producing chances for widespread showers and non-severe
thunderstorms.

Large scale ridging amplifies over the weekend, leading to another
period of dry and hot weather. The ridge flattens into early next
week, with some uncertainty regarding the position and strength of
shortwave disturbances passing through the westerly flow.

&&

.AVIATION...
540 PM MDT Wed Jul 7 2021 (08/00Z TAF period)

Shower and thunderstorm chances continue through 4Z, especially over
the southwest and the eastern portions of North-central MT. Some of
the storms could become strong to severe, with damaging winds and
hail, mostly for KLWT over the next hour or so. Otherwise, gusty
erratic winds, vicinity lightning, and brief downpours can be
expected from any storm. VFR conditions are generally expected, but
some brief MVFR conditions are possible during the heavier activity.
Drier weather can be expected for tonight and Thursday, with
westerly surface breezes picking up after 08/16Z as a closed upper
level low moves eastward along the Canadian border. -RCG

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.

&&

.FIRE WEATHER...

Elevated fire weather conditions are expected today and Thursday as
a disturbance passes through the area. Expect a mix of wet and dry
thunderstorms today, with the potential for drier storms more south
and west toward the Dillon area. Thursday will see a brief period of
low RH values and post-frontal wind gusts in the 20 to 30 mph range,
but cooler with improving humidity recovery, which will reduce fire
weather concerns a bit on Thursday. Thus no fire weather highlights
are planned for at this time in our area.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  55  88  54  83 /  40   0  10  30
CTB  51  81  51  82 /  30  20  10  20
HLN  58  92  59  86 /  40   0  20  20
BZN  52  93  52  86 /  40   0  10  20
WYS  43  84  41  80 /  40  10   0  10
DLN  52  90  51  85 /  30  10  10  10
HVR  57  87  56  86 /  40  20  10  30
LWT  55  87  54  80 /  70  10  20  40

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&

http://www.weather.gov/greatfalls

In the hours before

Local storm report, Jul 7, 5:06 PM MDT, 1 hour 50 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
506 PM MDT WED JUL 7 2021

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

0434 PM     TSTM WND GST     8 NE BELGRADE           45.88N 111.08W
07/07/2021  E60 MPH          GALLATIN           MT   TRAINED SPOTTER

            ALSO REPORTED PEA SIZE HAIL.

&&

HART

Special weather statement, Jul 7, 5:12 PM MDT, 1 hour 44 minutes before

Special Weather Statement
National Weather Service Great Falls MT
512 PM MDT Wed Jul 7 2021

MTZ050-054-080000-
Judith Basin-Meagher-
512 PM MDT Wed Jul 7 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT EAST CENTRAL MEAGHER
AND JUDITH BASIN COUNTIES...

At 510 PM MDT, radar indicated strong thunderstorms were located
along a line extending from 8 miles southeast of Geyser to 23 miles
southwest of Stanford to 20 miles northeast of White Sulphur Springs.
Movement was east at 30 mph.

Winds in excess of 40 mph and half inch hail are possible with these
storms.

Locations impacted include...
Stanford, Hobson, Geyser, Windham, Moccasin, Ackley Lake State Park,
Sapphire Village, Utica, Buffalo and Benchland.

This includes the following highways...
 Highway 200 between Geyser and Hobson.

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.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 4680 10982 4680 10979 4673 10992 4675 11005
      4671 11015 4672 11027 4665 11028 4670 11081
      4686 11058 4728 11050 4729 11013 4727 11012
      4727 11000 4723 10999 4723 10988 4719 10987
      4718 10976 4690 10976
TIME...MOT...LOC 2310Z 271DEG 28KT 4718 11040 4686 11046 4676 11061

Kredensor

Special weather statement, Jul 7, 5:13 PM MDT, 1 hour 43 minutes before

Special Weather Statement
National Weather Service Great Falls MT
513 PM MDT Wed Jul 7 2021

MTZ047-080015-
Blaine-
513 PM MDT Wed Jul 7 2021

...STRONG THUNDERSTORMS WILL AFFECT SOUTHWESTERN BLAINE AND
SOUTHEASTERN HILL COUNTIES...

At 513 PM MDT, radar indicated strong thunderstorms were located
along a line extending from near Chinook to 26 miles southeast of
Parker School. Movement was east at 25 mph.

Winds in excess of 40 mph and half inch hail are possible with these
storms.

Locations impacted include...
Chinook, Harlem, Lohman, Lloyd, Cleveland and Zurich.

This includes Highway 2 between mile markers 392 and 424.

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.

These storms may intensify, so be certain to monitor local radio
stations and available television stations for additional information
and possible warnings from the National Weather Service.

LAT...LON 4793 10890 4788 10951 4846 10950 4846 10946
      4852 10946 4853 10949 4865 10949 4866 10877
TIME...MOT...LOC 2313Z 257DEG 14KT 4853 10923 4797 10935

CMC

Special weather statement, Jul 7, 5:56 PM MDT, 1 hour before

Special Weather Statement
National Weather Service Great Falls MT
556 PM MDT Wed Jul 7 2021

MTZ047-080030-
Blaine-
556 PM MDT Wed Jul 7 2021

...A LINE OF STRONG THUNDERSTORMS WILL AFFECT EAST CENTRAL BLAINE
COUNTY...

At 555 PM MDT, radar indicated strong thunderstorms were located
along a line extending from near Harlem to 18 miles south of Fort
Belknap. Movement was east at 40 mph.

Winds in excess of 40 mph and half inch hail are possible with these
storms.

Locations impacted include...
Harlem and Fort Belknap.

This includes Highway 2 between mile markers 417 and 445.

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.

To report severe weather, contact your nearest law enforcement
agency. They can relay your report to the National Weather Service
office in Great Falls.

LAT...LON 4856 10835 4844 10835 4844 10842 4823 10842
      4812 10844 4814 10896 4857 10897 4867 10832
      4858 10831
TIME...MOT...LOC 2355Z 265DEG 35KT 4851 10889 4822 10888

Kredensor

Special weather statement, Jul 7, 6:36 PM MDT, 20 minutes before

Special Weather Statement
National Weather Service Great Falls MT
636 PM MDT Wed Jul 7 2021

MTZ051-080100-
Fergus-
636 PM MDT Wed Jul 7 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN FERGUS COUNTY...

At 635 PM MDT, a strong thunderstorm was located 22 miles north of
Roy, or 23 miles southwest of Zortman, moving east at 25 mph.

Wind gusts up to 50 mph and penny size hail are possible with this
storm.

This storm will remain over mainly rural areas of northeastern Fergus
County.

This includes Highway 191 between mile markers 80 and 87.

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.

To report severe weather, contact your nearest law enforcement
agency. They can relay your report to the National Weather Service
office in Great Falls.

Persons in the James Kipp Recreation Area should consider seeking
sturdy shelter until this storm passes.

LAT...LON 4746 10855 4758 10893 4773 10887 4772 10883
      4768 10878 4765 10877 4764 10872 4762 10868
      4763 10861 4761 10857 4761 10851
TIME...MOT...LOC 0035Z 281DEG 17KT 4764 10879

Kredensor

Special weather statement, Jul 7, 6:56 PM MDT, 0 minutes before

Special Weather Statement
National Weather Service Great Falls MT
656 PM MDT Wed Jul 7 2021

MTZ051-080130-
Fergus-
656 PM MDT Wed Jul 7 2021

...A STRONG THUNDERSTORM WILL AFFECT NORTHEASTERN FERGUS COUNTY...

At 655 PM MDT, a strong thunderstorm was located 20 miles south of
Zortman, moving southeast at 25 mph.

Wind gusts up to 50 mph and half inch hail are possible with this
storm.

This storm will remain over mainly rural areas of northeastern Fergus
County.

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.

To report severe weather, contact your nearest law enforcement
agency. They can relay your report to the National Weather Service
office in Great Falls.

LAT...LON 4760 10869 4762 10866 4763 10861 4761 10857
      4762 10851 4760 10850 4761 10844 4758 10842
      4760 10840 4757 10834 4758 10831 4735 10832
TIME...MOT...LOC 0055Z 308DEG 23KT 4763 10848

Kredensor

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 7, 6:10 PM MDT	Severe Thunderstorm Warning	TFX	Fergus, Judith Basin	35 min
Jul 7, 6:36 PM MDT	Special Weather Statement	TFX		24 min
Jul 7, 8:02 PM MDT	Special Weather Statement	TFX	Glacier	28 min
Jul 7, 8:48 PM MDT	Special Weather Statement	TFX	Glacier	27 min
Jul 7, 9:33 PM MDT	Special Weather Statement	TFX	Glacier	27 min
Jul 8, 11:48 AM MDT	Special Weather Statement	TFX	Blaine	42 min

Nearby

Special Weather Statements in Montana, 2021 Every special weather statement in 2021

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.