Severe Thunderstorm Warning 151, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
805 PM MDT Wed Aug 24 2022

.SYNOPSIS...

Showers and thunderstorms will re-develop across much of
north-central and southwest Montana late this afternoon and evening
and continue through tonight across portions of north-central
Montana. A few strong to severe storms with hail and gusty winds are
possible through early this evening with the primary threat from
storms being locally heavy rain and lightning. Additional rounds of
showers and thunderstorms are expected through Friday before a
drying and warming trend develops this weekend through much of next
week.

&&

.UPDATE...

Numerous slow moving showers and thunderstorms continue to
propagate across Southwest Montana in a northeastward direction
into Central/North-central Montana, producing small hail,
frequent lightning, and heavy rainfall, and are expected to
continue through the overnight hours. Only alteration made to the
current grids was to increase PoPs coverage to account for the
aforementioned showers and thunderstorms. Otherwise, the forecast
describes the situation well. - Pierce

&&

.AVIATION...

520 PM MDT Wed Aug 24 2022 (25/00Z TAF period)

Scattered to numerous showers and thunderstorms will prevail over
much of the forecast area through the TAF period under a moist and
unstable weather regime. VFR conditions will largely prevail outside
of the shower/storm activity, with conditions possibly dropping as
low as IFR at times in heavier showers/storms. Gusty winds will be
most likely through this evening from KBZN south as there is more
dry air in the sub-cloud layer, at least initially.

&&

.PREV DISCUSSION...
/ISSUED 520 PM MDT Wed Aug 24 2022/

Regional satellite imagery early this afternoon shows an upper level
low centered across eastern WA with diffluent flow downstream across
the Northern Rockies and MT. Farther southwest another embedded
shortwave disturbance was moving into western NV. Widespread clouds
and isolated showers were ongoing across north-central MT early this
afternoon with mainly clear skies across SW MT and ID leading to
cumulus cloud initiation over the mountains. The overall forecast
has not changed significantly with the upper level low slowly moving
east across the Northern Rockies and MT through Friday with main
forecast concerns through the next several days revolving around
impacts from daily thunderstorm activity through Friday, including
the potential for some strong to isolated severe storms later this
afternoon and evening, and an ongoing risk for locally heavy rain
with some storms due to the anomalous moisture lingering across the
area.

Daytime heating across SW MT will lead to thunderstorm development
with moderate instability (CAPE 1000-2000J/kg) expected late this
afternoon across central and northern portions of SW MT. This in
combination with modest wind shear of around 30kts could support a
few strong to isolated severe thunderstorms across these areas
through early this evening. In addition to lightning and locally
heavy rainfall, hail and damaging wind gusts will be possible with
the isolated stronger storms. Further north, instability and shear
is weaker but will still support thunderstorms, likely with slower
movement and heavy rain potential, initially north along the
continental divide late this afternoon, shifting east across north-
central MT this evening and overnight. Locally heavy rain is likely
with any storms , with some areas along the Rocky Mtn front already
having received some significant precipitation in previous days
leading to higher susceptibility to impacts from additional rain and
a Flood Watch is in effect through tonight. Several hi-
res/convection allowing models are depicting a cluster of stronger
storms moving northeast across Jefferson, Broadwater, Lewis and
Clark and Meagher  counties this evening and this trend is noted on
several runs. With several susceptible burn scars in the Elkhorn and
Big Belt mountains from 2021 wildfires, will expand the Flood Watch
to these countries as well. Thunderstorm activity across central and
north-central MT will likely continue through tonight as additional
lifting arrives with the shortwave disturbance front NV lifting NE
across the area late tonight. Looking ahead through Thursday and
Friday, seasonal temperatures and daily thunderstorm chances
continue with primary concern being the potential for locally heavy
rain in addition to lightning with somewhat lesser thunderstorm
coverage. Hoenisch

Saturday and Sunday will be quieter for North Central Montana with a
chance of isolated showers for Southwest Montana as the weather
system moves out of our region. For Monday through Wednesday next
week, surface high pressure returns with upper level ridging
bringing dry conditions across our region. Above average
temperatures return through midweek with warm afternoon high
temperatures. Webb

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  56  80  55  81 /  70  60  60  40
CTB  55  73  52  79 /  70  80  60  30
HLN  59  83  56  83 /  80  70  50  40
BZN  55  84  51  81 /  60  50  50  30
WYS  45  76  41  74 /  80  50  40  30
DLN  51  83  49  79 /  70  60  30  20
HVR  58  80  57  83 /  40  70  70  40
LWT  55  76  52  78 /  60  50  70  50

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
&&

http://www.weather.gov/greatfalls

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Special Weather Statement
National Weather Service Great Falls MT
702 PM MDT Wed Aug 24 2022

MTZ015-052-250145-
Madison MT-Jefferson MT-
702 PM MDT Wed Aug 24 2022

...Strong thunderstorms will impact portions of northwestern Madison
and southwestern Jefferson Counties through 745 PM MDT...

At 702 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from 10 miles southeast of Divide to 11 miles
southwest of Silver Star to near Twin Bridges. Movement was northeast
at 20 mph.

HAZARD...Winds in excess of 30 mph and half inch hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Twin Bridges, Silver Star and Waterloo.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4570 11253 4576 11250 4574 11247 4575 11219
      4585 11243 4587 11241 4591 11242 4599 11235
      4558 11198 4537 11239 4565 11263
TIME...MOT...LOC 0102Z 208DEG 18KT 4568 11255 4561 11249 4547 11237

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

CMC

Special Weather Statement
National Weather Service Great Falls MT
708 PM MDT Wed Aug 24 2022

MTZ055-250145-
Gallatin MT-
708 PM MDT Wed Aug 24 2022

...A strong thunderstorm will impact portions of south central
Gallatin County through 745 PM MDT...

At 708 PM MDT, Doppler radar was tracking a strong thunderstorm near
West Yellowstone, moving northeast at 20 mph.

HAZARD...Winds in excess of 30 mph and pea size hail.

SOURCE...Radar indicated.

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

Locations impacted include...
West Yellowstone, Yellowstone Village and Targhee Pass.

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.

Persons in campgrounds should consider seeking sturdy shelter until
this storm passes.

&&

LAT...LON 4461 11124 4462 11122 4465 11127 4469 11128
      4495 11115 4493 11109 4461 11110 4457 11114
TIME...MOT...LOC 0108Z 208DEG 18KT 4468 11117

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...30 MPH

CMC

Special Weather Statement
National Weather Service Great Falls MT
718 PM MDT Wed Aug 24 2022

MTZ008-250200-
Beaverhead MT-
718 PM MDT Wed Aug 24 2022

...Strong thunderstorms will impact portions of northwestern
Beaverhead County through 800 PM MDT...

At 717 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from 14 miles west of Divide to 22 miles north of
Jackson to near Wisdom to near Gibbonsville. Movement was northeast
at 25 mph.

HAZARD...Winds in excess of 30 mph and pea size hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Wisdom, Dewey and Wise River.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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

Frequent cloud to ground lightning is occurring with these storms.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4581 11375 4588 11354 4594 11351 4580 11343
      4575 11336 4581 11333 4588 11318 4588 11310
      4581 11300 4577 11281 4576 11281 4553 11293
      4544 11377 4550 11376 4552 11383 4559 11380
      4563 11386
TIME...MOT...LOC 0117Z 202DEG 23KT 4569 11303 4568 11328 4562 11350
4549 11385

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...30 MPH

CMC

Special Weather Statement
National Weather Service Great Falls MT
738 PM MDT Wed Aug 24 2022

MTZ015-052-250230-
Madison MT-Jefferson MT-
738 PM MDT Wed Aug 24 2022

...A strong thunderstorm will impact portions of northwestern Madison
and southern Jefferson Counties through 830 PM MDT...

At 738 PM MDT, Doppler radar was tracking a strong thunderstorm over
Silver Star, or 18 miles north of Sheridan, moving north at 20 mph.

HAZARD...Winds in excess of 30 mph and half inch hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Whitehall, Silver Star, Cardwell and Waterloo.

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.

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.

&&

LAT...LON 4575 11246 4575 11219 4577 11226 4579 11228
      4583 11240 4585 11243 4587 11241 4591 11241
      4609 11237 4602 11167 4557 11213 4565 11248
TIME...MOT...LOC 0138Z 201DEG 19KT 4573 11227

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

CMC

Special Weather Statement
National Weather Service Great Falls MT
915 PM MDT Wed Aug 24 2022

MTZ053-055-250345-
Broadwater MT-Gallatin MT-
915 PM MDT Wed Aug 24 2022

...A strong thunderstorm will impact portions of southern Broadwater
and northwestern Gallatin Counties through 945 PM MDT...

At 915 PM MDT, Doppler radar was tracking a strong thunderstorm near
Three Forks, or 24 miles northwest of Bozeman, moving northeast at 25
mph.

HAZARD...Winds in excess of 30 mph and half inch hail.

SOURCE...Radar indicated.

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

Locations impacted include...
Three Forks, Manhattan, Logan, Trident, Menard, Madison Buffalo Jump
State Park and Missouri Headwaters State Park.

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.

&&

LAT...LON 4574 11146 4588 11164 4615 11130 4595 11104
TIME...MOT...LOC 0315Z 227DEG 23KT 4586 11147

MAX HAIL SIZE...0.50 IN
MAX WIND GUST...30 MPH

Moldan