Flash Flood Warning 3, NWS Great Falls, MT

523 
WGUS75 KTFX 010510
FFSTFX

Flash Flood Statement
National Weather Service Great Falls MT
1110 PM MDT Thu Jul 31 2025

MTC007-049-010520-
/O.CAN.KTFX.FF.W.0003.000000T0000Z-250801T0600Z/
/00000.0.ER.000000T0000Z.000000T0000Z.000000T0000Z.OO/
Broadwater MT-Lewis and Clark MT-
1110 PM MDT Thu Jul 31 2025

...FLASH FLOOD WARNING FOR THE HORSE GULCH BURN SCAR IS CANCELLED 
FOR NORTHWESTERN BROADWATER AND SOUTHEASTERN LEWIS AND CLARK 
COUNTIES...

The heavy rain has ended. Flooding is no longer expected to pose a 
threat, but stream levels may remain elevated. Please continue to 
heed remaining road closures.

&&

LAT...LON 4670 11173 4670 11172 4671 11169 4673 11167
      4672 11164 4671 11161 4670 11161 4669 11159
      4668 11160 4666 11160 4665 11161 4665 11163
      4665 11164 4667 11169 4667 11172 4666 11173
      4668 11174 4669 11174

$$

Ludwig

Area Forecast Discussion
National Weather Service Great Falls MT
218 PM MDT Thu Jul 31 2025

.KEY MESSAGES...

 - Below normal temperatures will continue through the weekend
   thanks to an active and unsettled pattern over the Northern
   Rockies.

 - Daily chances for showers and thunderstorms exists across most
   locations through the weekend, with the potential for locally
   heavy rainfall beneath slower moving thunderstorms through
   Saturday.

 - A few thunderstorms through the evening hours tonight could
   produce damaging wind gusts and large hail, mainly along and
   south of the Montana Hwy 200 corridor.

&&

.DISCUSSION...

 - Meteorological Overview:

Convective initiation was underway early this afternoon over the
higher terrain of Southwest Montana, Northeast Idaho, and
Northwest Wyoming thanks to differential heating and the approach
of a upper level wave embedded within predominately southerly flow
aloft. This wave, which was moving over Idaho, will lift north
and over Southwest Montana through the remainder of the afternoon
and North Central Montana through Friday morning. Areal coverage
of showers and thunderstorms will continue to expand through the
remainder of the afternoon hours along and south of the US Hwy 12
corridor, with a rather continuous line of shower and
thunderstorms then lifting north into Central and North Central
Montana, generally along and west of a Judith Gap to Shelby line,
through the evening hours tonight. Additional shower and
thunderstorm development is then likely during the late evening
hours tonight/early morning hours on Friday east of the Judith Gap
to Shelby line, with these showers and thunderstorms lingering
through sunrise on Friday thanks to support from the nocturnal low
level jet and subsequent orographic lift over the island ranges.
- Moldan

Daily chances for showers and thunderstorms will help regulate
temperatures throughout the weekend and beginning of next week to
near to slightly below normal. This limbo pattern of southwest flow
aloft looks to continue well into next week, bringing daily chances
for precipitation. Though, moisture does decrease a bit after
Saturday, decreasing the heavy rainfall threat. Models hint towards
the second half of next week, southwest flow aloft weakens to more
of a zonal flow aloft pattern. However, it is uncertain if there is
finally a lull in precipitation or if the active period continues. -
Wilson

 - Forecast Confidence & Scenarios:

Severe Thunderstorms Today :

A marginal risk for severe thunderstorms exists along and southwest
of a Harlowton, to Neihart, to Great Falls, to Dutton, to Heart
Butte line; with a 5-15% chance for damaging winds and large hail
(albeit across a smaller portion of Southwest and Central Montana).
DCAPE values ranging from 1000 to nearly 1400J/kg, especially along
and south of the I-90 corridor, will help to support isolated
instances of damaging wind gusts in excess of 58 mph, especially
beneath initially collapsing cores. Mid-level lapse rates between 7-
8 degrees C/km and CAPE ~1,500 J/kg will also help to support hail
with thunderstorms; however, a lingering concern with respect to
overall hail size remains to be the higher freezing levels around
10000ft, which would help to lead to some melting. - Moldan/Wilson

Heavy Rainfall through Saturday :

Hi-Res models continue to show the best coverage of showers and
thunderstorms lifting north from Southwest and into portions of
North Central Montana through the early evening hours tonight, with
slow overall storm motions of between 15-25 mph. These slow storm
motions combined with increase PWATS to in excess of 0.75" north
of the I-90 corridor will help to set the stage for moderate to
locally heavy rainfall, which could lead to localized flooding in
poor drainage or urban areas and over recent burn scars. Primary
concern with respect to flooding continues to be the Horse Gulch
burn scar, where scattered convection in the region and lower
overall flash flood guidance with respect to surrounding terrain
will pose a threat for flash flooding and debris flow. For this
reason a Flash Flood Watch remains in effect until midnight
tonight. - Moldan/Wilson

Friday, the bulk of thunderstorms look to be across the Continental
Divide and North-Central MT plains. Models are struggling on the
placement of the heavier precipitation amounts.
Therefore I've held off on flood products for now. However,
scattered convection and high PWATs will pose another threat for
localized heavy rainfall. If the coverage of heavy rainfall
increases, then a flood watch may be needed in the future.
- Wilson

&&

.AVIATION...
31/18Z TAF Period

VFR conditions will prevail at all terminals during this TAF Period,
outside of during any thunderstorms. The primarily concern will be
showers and thunderstorms across North-central, Central, and
Southwestern Montana this afternoon and evening. These showers
and thunderstorms will produce heavy downpours, frequent
lightning, small hail, and gusty, erratic winds. At the KCTB and
KHVR terminals there is a 10 - 25% chance for showers and
thunderstorms between 01/02Z and the end of the TAF Period. There
will be periods of mountain obscuration during thunderstorms. -IG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  86  58  85  58 /  20  40  30  50
CTB  80  56  78  57 /  10  20  40  80
HLN  85  58  82  58 /  40  70  60  40
BZN  86  50  86  51 /  40  20  50  20
WYS  81  40  78  39 /  30  20  20  20
DLN  84  48  81  48 /  30  20  60  20
HVR  85  59  84  60 /  10  20  20  60
LWT  78  54  80  53 /  20  40  40  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...

Flash Flood Watch until midnight MDT tonight for Big Belt,
Bridger and Castle Mountains.

&&

http://www.weather.gov/greatfalls

Preliminary Local Storm Report
National Weather Service Great Falls MT
640 PM MDT Thu Jul 31 2025

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

0553 PM     Landspout        8 ENE Townsend          46.37N 111.36W
07/31/2025                   Broadwater         MT   Broadcast Media

            Media passed along a photo of what appears
            to be a landspout with defined circulation
            at the ground. Location estimated.

&&

ML

Special Weather Statement
National Weather Service Great Falls MT
647 PM MDT Thu Jul 31 2025

MTZ317-320-321-010115-
Little Belt and Highwood Mountains MT-
Big Belt, Bridger and Castle Mountains MT-Meagher County Valleys MT-
647 PM MDT Thu Jul 31 2025

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN LEWIS AND CLARK...
NORTHERN BROADWATER...NORTHWESTERN MEAGHER AND SOUTH CENTRAL CASCADE
COUNTIES THROUGH 715 PM MDT...

At 646 PM MDT, Doppler radar was tracking a strong thunderstorm 27
miles northwest of White Sulphur Springs, moving northwest at 20 mph.

HAZARD...Wind gusts up to 40 mph and nickel size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

This storm will remain over mainly rural areas of southeastern Lewis
and Clark, northern Broadwater, northwestern Meagher and south
central Cascade Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

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.

This storm 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 4683 11114 4667 11135 4691 11171 4711 11130
TIME...MOT...LOC 0046Z 135DEG 19KT 4682 11131

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...40 MPH

Ludwig

Special Weather Statement
National Weather Service Great Falls MT
711 PM MDT Thu Jul 31 2025

MTZ319-320-322-323-010215-
Helena Valley MT-Elkhorn and Boulder Mountains MT-
Big Belt, Bridger and Castle Mountains MT-Canyon Ferry Area MT-
711 PM MDT Thu Jul 31 2025

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN LEWIS AND CLARK...
NORTHWESTERN BROADWATER AND NORTHERN JEFFERSON COUNTIES THROUGH 815
PM MDT...

At 710 PM MDT, Doppler radar was tracking a strong thunderstorm 14
miles east of East Helena, or 16 miles north of Townsend, moving
northwest at 10 mph.

HAZARD...Nickel size hail.

SOURCE...Radar indicated.

IMPACT...Minor hail damage to vegetation is possible.

Locations impacted include...
Helena, East Helena, Winston, York, and Goose Bay. This storm may
also impact the Horse Gulch Burn Scar.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

This storm 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 4656 11146 4644 11165 4663 11207 4682 11164
TIME...MOT...LOC 0110Z 134DEG 7KT 4655 11162

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...<30 MPH

Ludwig

Special Weather Statement
National Weather Service Great Falls MT
713 PM MDT Thu Jul 31 2025

MTZ317-321-010215-
Little Belt and Highwood Mountains MT-Meagher County Valleys MT-
713 PM MDT Thu Jul 31 2025

...A STRONG THUNDERSTORM WILL IMPACT NORTH CENTRAL MEAGHER AND
SOUTHEASTERN CASCADE COUNTIES THROUGH 815 PM MDT...

At 713 PM MDT, Doppler radar was tracking a strong thunderstorm 12
miles northwest of White Sulphur Springs, moving north at 10 mph.

HAZARD...Nickel size hail.

SOURCE...Radar indicated.

IMPACT...Minor hail damage to vegetation is possible.

Locations impacted include...
Newlan Creek Reservoir.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4658 11090 4665 11116 4697 11117 4693 11077
TIME...MOT...LOC 0113Z 187DEG 9KT 4671 11102

MAX HAIL SIZE...0.88 IN
MAX WIND GUST...<30 MPH

Ludwig

Special Weather Statement
National Weather Service Great Falls MT
717 PM MDT Thu Jul 31 2025

MTZ305-310-311-010200-
Hill County MT-Western and Central Chouteau County MT-
Bears Paw Mountains and Southern Blaine MT-
717 PM MDT Thu Jul 31 2025

...A STRONG THUNDERSTORM WILL IMPACT SOUTHEASTERN HILL AND
NORTHEASTERN CHOUTEAU COUNTIES THROUGH 800 PM MDT...

At 717 PM MDT, Doppler radar was tracking a strong thunderstorm over
Box Elder, or 12 miles north of Big Sandy, moving northeast at 10
mph.

HAZARD...Wind gusts up to 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Gusty winds could knock down tree limbs and blow around
         unsecured objects. Minor hail damage to vegetation is
         possible.

Locations impacted include...
Box Elder, Azure, Sangrey, Boneau, Agency, and Laredo.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Torrential rainfall is also occurring with this storm and may lead to
localized flooding. Do not drive your vehicle through flooded
roadways.

&&

LAT...LON 4824 11009 4839 11020 4854 10986 4829 10969
TIME...MOT...LOC 0117Z 246DEG 7KT 4835 11004

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

Wilson

Preliminary Local Storm Report
National Weather Service Great Falls MT
720 PM MDT Thu Jul 31 2025

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

0719 PM     Hail             7 E Marysville          46.74N 112.16W
07/31/2025  E0.88 Inch       Lewis and Clark    MT   Trained Spotter

&&

ML