Alert archive / Montana / Special Weather Statements in 2020

Special Weather Statement, NWS Great Falls, MT

July 4, 2020

NWS Great Falls, MT issued this special weather statement at Jul 4, 2020, 6:04 PM MDT. It was in force for 26 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 4, 2020, 6:04 PM MDT (00:04 UTC)
Expired: Jul 4, 2020, 6:30 PM MDT
In force: 26 min
Issued by: NWS Great Falls, MT

The radar

The Great Falls radar (KTFX), 61 km from the middle of the area, began a volume at 00:04 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, 0.1 hours before the alert went out and 91 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: -162 J/kg
Mixed-layer LCL: 2545 m above ground
0-6 km bulk shear: 48 kt
0-1 km storm-relative helicity: 169 m²/s²
0-3 km storm-relative helicity: 245 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 Great Falls, MT wrote its last area forecast discussion before this special weather statement went out at Jul 4, 6:02 PM MDT, 2 minutes earlier.

Area forecast discussion, Jul 4, 6:02 PM MDT, 2 minutes before

Area Forecast Discussion
National Weather Service Great Falls MT
602 PM MDT Sat Jul 4 2020

...AVIATION SECTION UPDATED...

.SYNOPSIS...

Showers and thunderstorms developing this afternoon over Southwest
Montana, will become more widespread across much of central Montana
this evening. Some of these thunderstorms may produce locally heavy
rain, large hail, and damaging winds. Skies clear overnight with
fair and cooler weather Sunday and Monday. The next round of
widespread showers and thunderstorms arrives Tuesday afternoon
into Wednesday.

&&

.DISCUSSION...

Satellite and radar imagery show numerous showers beginning to
develop over Southwest Montana as of about 1pm. At surface, we
note dewpoint temperatures in the low to mid 50s across the
region, and a light easterly wind across the Judith Basin into
southern portions of the Rocky Mountain Front. Mesoanalysis
reveals CAPE near or in excess of 2000 J/kg, with effective shear
exceeding 40 kts. Collectively, these ingredients highlight a
quickly destabilizing atmosphere. The timing of these developing
storms appears completely consistent with the suite of short term
convection allowing model guidance. Thus, expectations for a busy
afternoon and evening of convection remains on track. Independence
Day recreation and evening festivities are likely to be
interrupted by widespread showers and thunderstorms. Some of these
thunderstorms are expected to become strong to severe. The
stronger storms will be capable of producing large hail and
damaging wind gusts. Those outdoors should keep in mind this
potential for hazardous thunderstorms and have a plan to seek
shelter should a storm move near their location.

Individual storms will move from southwest to northeast at 30 to
40 mph. Training of storms is possible, producing some potential
for localized street flooding. Overall this activity will move
away to the east overnight. Generally fair and slightly cooler
weather follows on Sunday, although a few ordinary thunderstorms
will be possible over far Southwest MT Sunday afternoon. -PN

Monday through next Saturday...an unsettled and active pattern
will continue across the Northern Rockies for much of the upcoming
work week, with transient ridging moving across the region near
the end of the work week to bring a period of drier weather. High
temperatures to start the period will be near to slightly below
climatological norms, with most areas climbing above normal by the
end of the work week and into the weekend. An upper level trough
lifting northeast within southwesterly flow Tuesday through
Tuesday night will bring the next best shot at showers and
thunderstorms, especially to Central and North Central Montana.
- Moldan

&&

.AVIATION...
Updated 600 PM MDT Sat Jul 4 2020 (00Z TAF Period)

Showers/thunderstorms are currently situated over much of the region
with the most robust activity north and east of KLWT. Some storms
will continue to produce strong wind gusts, hail, and downpours of
rain. MVFR conditions and mountains obscuration can be expected
during periods of precipitation. Most shower/storm activity should
end by 6Z but may persist longer for KLWT. Scattered showers and
perhaps a thunderstorm may return to the southwest terminal sunday
afternoon. RCG

NOTE: Amendments not scheduled for Ennis (KEKS) due to ongoing
runway closure.

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  51  76  50  80 /  50  10  10  20
CTB  46  73  47  78 /  30   0   0  10
HLN  51  78  51  81 /  60  20  20  30
BZN  49  78  48  82 /  50  30  20  30
WYS  42  74  41  77 /  30  20  10  10
DLN  47  77  47  80 /  40  20  20  20
HVR  54  78  53  84 /  50  10   0  10
LWT  51  72  50  76 /  80  20  30  50

&&

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

http://www.weather.gov/greatfalls

In the hours before

Special weather statement, Jul 4, 5:39 PM MDT, 25 minutes before

Special Weather Statement
National Weather Service Great Falls MT
539 PM MDT Sat Jul 4 2020

MTZ012-049-050015-
Cascade-Eastern Teton-
539 PM MDT Sat Jul 4 2020

...A STRONG THUNDERSTORM WILL AFFECT SOUTH CENTRAL TETON AND
NORTHWESTERN CASCADE COUNTIES...

At 538 PM MDT, a strong thunderstorm was located near Fairfield, or
19 miles southeast of Choteau, moving northeast at 20 mph.

Winds in excess of 30 mph and pea size hail are possible with this
storm.

Locations impacted include...
Fairfield and Sun River.

This includes the following highways...
 Highway 200 between mile markers 138 and 139.
 Highway 89 between mile markers 9 and 25, and near mile marker 8.

When thunder roars, go indoors!

LAT...LON 4750 11204 4758 11204 4764 11198 4771 11185
      4753 11167
TIME...MOT...LOC 2338Z 239DEG 17KT 4756 11198

JAF

Special weather statement, Jul 4, 5:53 PM MDT, 11 minutes before

Special Weather Statement
National Weather Service Great Falls MT
553 PM MDT Sat Jul 4 2020

MTZ013-050030-
Chouteau-
553 PM MDT Sat Jul 4 2020

...A STRONG THUNDERSTORM WILL AFFECT NORTH CENTRAL CHOUTEAU COUNTY...

At 552 PM MDT, a strong thunderstorm was located 16 miles west of Big
Sandy, moving east at 30 mph.

Winds in excess of 30 mph and pea size hail are possible with this
storm.

Locations impacted include...
Virgelle and Kenilworth.

This includes Highway 87 between mile markers 56 and 76.

When thunder roars, go indoors!

LAT...LON 4800 11057 4820 11059 4830 11020 4793 11010
TIME...MOT...LOC 2352Z 267DEG 26KT 4808 11045

JAF

Local storm report, Jul 4, 5:55 PM MDT, 9 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
555 PM MDT SAT JUL 4 2020

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

0552 PM     HAIL             STANFORD                47.15N 110.22W
07/04/2020  E0.70 INCH       JUDITH BASIN       MT   PUBLIC

            SOCIAL MEDIA.

&&

ML

Special weather statement, Jul 4, 5:58 PM MDT, 6 minutes before

Special Weather Statement
National Weather Service Great Falls MT
558 PM MDT Sat Jul 4 2020

MTZ013-044-045-050030-
Chouteau-Liberty-Toole-
558 PM MDT Sat Jul 4 2020

...A STRONG THUNDERSTORM WILL AFFECT SOUTHERN LIBERTY...SOUTHEASTERN
TOOLE AND NORTHWESTERN CHOUTEAU COUNTIES...

At 557 PM MDT, a strong thunderstorm was located 12 miles north of
The Knees, or 25 miles southwest of Chester, moving northeast at 25
mph.

Winds in excess of 30 mph and pea size hail are possible with this
storm.

Locations impacted include...
Lothair and Tiber Dam.

This includes Highway 2 between mile markers 309 and 316.

When thunder roars, go indoors!

LAT...LON 4807 11127 4825 11141 4857 11117 4825 11077
TIME...MOT...LOC 2357Z 214DEG 21KT 4820 11127

JAF

Local storm report, Jul 4, 5:59 PM MDT, 5 minutes before

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE GREAT FALLS MT
559 PM MDT SAT JUL 4 2020

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

0558 PM     HAIL             STANFORD                47.15N 110.22W
07/04/2020  M1.00 INCH       JUDITH BASIN       MT   PUBLIC

            PICTURE VIA TWITTER OF HAILSTONE NEXT TO
            QUARTER.

&&

ML

Special weather statement, Jul 4, 6:04 PM MDT, 0 minutes before

Special Weather Statement
National Weather Service Great Falls MT
604 PM MDT Sat Jul 4 2020

MTZ013-044>046-049-050030-
Chouteau-Liberty-Eastern Teton-Eastern Pondera-Toole-
604 PM MDT Sat Jul 4 2020

...A STRONG THUNDERSTORM WILL AFFECT SOUTHEASTERN PONDERA...
SOUTHWESTERN LIBERTY...SOUTHEASTERN TOOLE...EAST CENTRAL TETON AND
WESTERN CHOUTEAU COUNTIES...

At 603 PM MDT, a strong thunderstorm was located 9 miles northeast of
Dutton, or 24 miles southeast of Conrad, moving northeast at 25 mph.

Winds in excess of 30 mph and pea size hail are possible with this
storm.

Locations impacted include...
The Knees.

When thunder roars, go indoors!

LAT...LON 4786 11149 4789 11163 4804 11174 4815 11162
      4825 11144 4794 11116
TIME...MOT...LOC 0003Z 233DEG 24KT 4794 11156

JAF

The office that day

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

Issued	Product	Office	Counties	Lasted
Jul 4, 6:05 PM MDT	Severe Thunderstorm Warning	TFX	Fergus	40 min
Jul 4, 6:16 PM MDT	Special Weather Statement	TFX	Hill	29 min
Jul 4, 6:53 PM MDT	Special Weather Statement	TFX	Blaine	22 min
Jul 4, 6:56 PM MDT	Special Weather Statement	TFX	Phillips	19 min
Jul 4, 7:00 PM MDT	Special Weather Statement	TFX	Blaine	30 min
Jul 4, 7:33 PM MDT	Special Weather Statement	TFX	Toole	27 min
Jul 4, 8:11 PM MDT	Special Weather Statement	TFX	Liberty	34 min
Jul 5, 5:05 PM MDT	Special Weather Statement	TFX	Gallatin	25 min
Jul 5, 5:24 PM MDT	Special Weather Statement	TFX	Broadwater	51 min

Nearby

Special Weather Statements in Montana, 2020 Every special weather statement in 2020

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.