Special Weather Statement, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
1205 PM MDT Thu Aug 26 2021

...AVIATION SECTION UPDATED...

.UPDATE...

A few light rain showers are moving across N-central MT this
morning. Satellite imagery shows hazy skies from dispersed
wildfire smoke. Overall forecast describes the situation well, so
a mid-morning update will not be posted. We continue to monitor
for showers and thunderstorms to redevelop later this afternoon.

&&

.SYNOPSIS...
A stronger weather disturbance will move from west to east across
the region this afternoon. Expect another round of showers and
thunderstorms to accompany this disturbance. Some storms could be
severe today, especially east of a line from Havre to Stanford. A
few more passing showers are possible on Friday as well. Otherwise
afternoon temperatures will generally be seasonable through early
next week, with the exception of Friday, when temperatures will
average about 10 degrees below normal.

&&

.AVIATION...
1205 PM MDT Thu Aug 26 2021 (26/18Z TAF period)

Showers are approaching the Divide and will continue moving east
into the forecast area this afternoon. The showers/storms today will
be fairly quick moving, so they will not last long at any one point.
Still some brief MVFR conditions will be possible. Some stronger
storms may develop and possibly contain gusty winds/hail and brief
heavy downpours, mostly for areas south and east of a KHLN to KGTF
to KHVR line. Expect partial clearing behind the storms, generally
after 27/03z. Then a Pacific cold front moves through the region and
brings more scattered showers and west to northwesterly breezes on
Friday. -RCG

&&

.PREV DISCUSSION...
/ISSUED 405 AM MDT Thu Aug 26 2021/

Today and Friday...The main concern today will be a stronger upper
level disturbance moving through the region this afternoon and early
this evening. There is a chance for an isolated severe storm, mostly
east of a line from Havre to Stanford from mid afternoon until early
evening. The main threat from any severe storms today will be strong
winds and some hail. These storms will be quick moving, so any
thunderstorm activity should not last long at any one location.
Overall rainfall amounts will generally be less than 0.20 inches,
but a few isolated stronger storms could produce up to a half inch
of rainfall. On Friday, an upper level trof will move through the
area. As a result, expect much cooler temperatures, with afternoon
highs about 10 degrees below normal.
Additionally, rain showers look likely, especially over
Central/North Central MT. Overall rainfall amounts look light
again, with most areas receiving less than 0.25 inches of
rainfall.

Saturday through Monday...The GFS/EC have sped up the weather
system for Saturday into Friday, thus much of the weekend looks
dry along with a warming trend. A few light showers are possible
early Saturday, mainly north of Highway 2, otherwise dry
conditions should prevail. Afternoon temperatures are likely to be
above normal for most locations on Sunday/Monday.

Tuesday through Thursday...The GFS/EC models continue to differ
in terms of timing/amount of precipitation with the next trof
towards the middle of next week. The GFS is slower with the
approach of the trof, thus warmer with temperatures towards the
middle of next week. Overall the NBM's blend solution looks good
for this period. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  78  50  70  46 /  30  20  50  10
CTB  77  50  64  45 /  10  10  60  20
HLN  78  53  72  47 /  30  20  60  10
BZN  77  46  71  42 /  20  20  50  20
WYS  70  36  65  32 /  10  10  20  20
DLN  75  45  70  39 /  10  10  20  10
HVR  80  51  72  48 /  40  30  50  20
LWT  77  49  66  44 /  60  30  80  10

&&

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

http://www.weather.gov/greatfalls

Special Weather Statement
National Weather Service Great Falls MT
110 PM MDT Thu Aug 26 2021

MTZ014-048-261945-
Southern Rocky Mountain Front MT-
Central and Southern Lewis and Clark MT-
110 PM MDT Thu Aug 26 2021

...A strong thunderstorm will impact portions of central Lewis and
Clark County through 145 PM MDT...

At 109 PM MDT, Doppler radar was tracking a strong thunderstorm 15
miles south of Augusta, or 29 miles west of Cascade, moving northeast
at 10 mph.

HAZARD...Winds up to 40 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...
Bowmans Corner and Bean Lake.

This includes the following highways...
 Highway 200 between mile markers 100 and 115.
 Highway 287 between mile markers 16 and 32.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Cloud to ground lightning is possible with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4749 11228 4733 11205 4726 11205 4717 11233
      4726 11246
TIME...MOT...LOC 1909Z 224DEG 11KT 4727 11234

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

RCG

Special Weather Statement
National Weather Service Great Falls MT
146 PM MDT Thu Aug 26 2021

MTZ012-014-048-262015-
Cascade MT-Southern Rocky Mountain Front MT-
Central and Southern Lewis and Clark MT-
146 PM MDT Thu Aug 26 2021

...A strong thunderstorm will impact portions of northeastern Lewis
and Clark and western Cascade Counties through 215 PM MDT...

At 145 PM MDT, Doppler radar was tracking a strong thunderstorm 16
miles southeast of Augusta, or 21 miles west of Cascade, moving
northeast at 15 mph.

HAZARD...Winds up to 40 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...
Bowmans Corner.

This includes the following highways...
 Highway 200 between mile markers 104 and 123.
 Highway 287 between mile markers 16 and 27.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

Cloud to ground lightning is possible with this storm.
Lightning can strike 10 miles away from a thunderstorm. Seek a safe
shelter inside a building or vehicle.

&&

LAT...LON 4722 11221 4733 11232 4751 11204 4729 11180
TIME...MOT...LOC 1945Z 239DEG 12KT 4731 11215

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

RCG

Special Weather Statement
National Weather Service Great Falls MT
204 PM MDT Thu Aug 26 2021

MTZ054-262030-
Meagher MT-
204 PM MDT Thu Aug 26 2021

...A strong thunderstorm will impact portions of northwestern
Meagher County through 230 PM MDT...

At 203 PM MDT, Doppler radar was tracking a strong thunderstorm 31
miles northwest of White Sulphur Springs, moving east at 10 mph.

HAZARD...Winds up to 40 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.

This storm will remain over mainly rural areas of northwestern
Meagher and southeastern Cascade Counties.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

If outdoors, consider seeking shelter inside a building.

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 4700 11136 4701 11117 4709 11116 4709 11109
      4704 11108 4703 11111 4700 11104 4683 11097
      4684 11135 4699 11139
TIME...MOT...LOC 2003Z 260DEG 7KT 4693 11126

MAX HAIL SIZE...0.25 IN
MAX WIND GUST...40 MPH

RCG