Special Weather Statement, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
1134 AM MDT Mon Aug 3 2020

...Updated Aviation Discussion...

.UPDATE...

The previous forecast appears to be mostly on track this morning.

A few high based showers have been developing along a line from
20 miles northwest of Havre to about 20 miles NNE of Lincoln. This
line is currently quite broken and weak, though a few cells along
this line W and SW of Great Falls have begun to develop into
thunderstorms. Overall, it appears that this line is well
represented in the POPs, so we're going to let those ride for now.
SPC maintains the marginal threat, and given this morning's
sounding, can see this line becoming capable of producing some
gusty downdraft winds and some hail later today.

Ludwig

&&

.SYNOPSIS...

Another warm day looks to be found across the area. A cold front
will bring scattered showers and thunderstorms today, some of
which may be severe with strong winds and large hail as the main
threats. Thunderstorms then diminish tonight, with a cooler and
dry day expected for Tuesday. A warming trend then returns mid
week, with perhaps a few thunderstorms on Thursday.

&&

.AVIATION...
Updated 1134 AM MDT Mon Aug 3 2020 (03/18Z TAF Period)

Showers and thunderstorms will continue across north-central Montana
through mid-afternoon. Additional showers and thunderstorms will
develop through mid- to late afternoon over central and southwest
Montana and will impact much of the region east of a KCTB-KHLN-KBTM
line through this evening. Gusty west winds will continue through
this afternoon behind the weather front for terminals KCTB and KHLN.
Predominant VFR conditions expected after 06z for all terminals as
the weather system departs the region.

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

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

&&

.PREV DISCUSSION...
/ISSUED 535 AM MDT Mon Aug 3 2020/

Today through Wednesday...Another warm day, with perhaps some
active weather, can be expected to start the work week today.
Upper level disturbance will approach the areas this morning. This
could perhaps set up a warm frontal type boundary across central
and northern portions bringing some morning thunderstorms for
areas with some elevated instability. Meanwhile temperatures will
warm into the 80s and 90s again today ahead of this approaching
disturbance. The mentioned disturbance will then push through this
afternoon and evening bringing through a cold front to the area.
With modest instability and decent amounts of shear strong to
severe storms will be possible. SPC currently puts much of central
and southern areas of the CWA in a marginal risk for isolated
strong to severe storms. Large hail, strong winds, and frequent
lightning will be the main threats to those outdoors today.
Thunderstorm activity then moves eastward and out of the area late
this evening. Mainly dry and temperatures cooling into the 80s
will then be found tonight and through Tuesday. Ridge of high
pressure then looks to build over the region on Wednesday. This
could warm temperatures back into the upper 80s to low 90s. Warm
and dry conditons, combined with some afternoon breezes could also
bring some increased fire danger for Wednesday. Ridge then shifts
east Wednesday night, with only a few isolated mountain
thunderstorms as a result. Anglin

Thursday through Monday...A shift to a more active and perhaps
cooler pattern may then be found to end the week. Ridge moves
east on Thursday with perhaps a weak disturbance found in
southwest flow. The result could be some scattered showers and
thunderstorms for Thursday. Generally dry zonal flow then looks to
bring dry and breezy conditions for Friday, with some increase
fire danger. A large trough then looks to move into the area this
coming weekend and perhaps into early next week. The result will
be cooler temperatures and perhaps some active weather at times.
Scattered showers and thunderstorms may be found for much of the
area Saturday and again Sunday, with activity diminishing Monday.
This drying trend for Monday could also lead to some fire weather
danger. High temperatures for this extended period start off warm
on Thursday with highs back in the 90s. Friday through the weekend
then looks to see temperatures cool back to near or perhaps
slightly below normal. Anglin

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  87  52  82  55 /  40  20   0   0
CTB  85  51  81  51 /  20  10  10   0
HLN  88  56  86  54 /  20  20   0   0
BZN  90  51  86  51 /  30  30   0   0
WYS  84  41  80  42 /  30  30  20  10
DLN  88  48  81  49 /  30  20   0   0
HVR  88  56  84  54 /  50  50  10  10
LWT  87  52  80  51 /  40  50  10   0

&&

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

http://www.weather.gov/greatfalls

Special Weather Statement
National Weather Service Great Falls MT
102 PM MDT Mon Aug 3 2020

MTZ050-051-031945-
Fergus MT-Judith Basin MT-
102 PM MDT Mon Aug 3 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN JUDITH BASIN AND
SOUTHWESTERN FERGUS COUNTIES UNTIL 145 PM MDT...

At 101 PM MDT, Doppler radar was tracking strong thunderstorms
across eastern Judith Basin County with the strongest cell near
Hobson, or 16 miles southeast of Stanford, moving northeast at 35
mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm, in addition to breif heavy rain.

Locations impacted include...
Lewistown, Stanford, Denton, Hobson, Moore, Windham, Moccasin, Ackley
Lake State Park, Glengarry, Utica, Danvers, Heath, Hilger and
Benchland.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4687 11012 4721 11030 4757 10957 4688 10903
TIME...MOT...LOC 1901Z 238DEG 31KT 4699 10995

BH

Special Weather Statement
National Weather Service Great Falls MT
140 PM MDT Mon Aug 3 2020

MTZ051-032045-
Fergus MT-
140 PM MDT Mon Aug 3 2020

...SIGNIFICANT WEATHER ADVISORY FOR CENTRAL FERGUS COUNTY UNTIL 245
PM MDT...

At 139 PM MDT, Doppler radar was tracking a strong thunderstorm over
Lewistown, moving northeast at 30 mph.

Half inch hail and winds in excess of 40 mph will be possible with
this storm, in addition to brief heavy rainfall.

Locations impacted include...
Lewistown, Grass Range, Roy, Fergus, Forestgrove, Giltedge, Heath and
Hilger.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4689 10939 4724 10968 4750 10866 4727 10863
      4727 10872 4719 10871 4718 10874 4710 10874
      4709 10861 4698 10860 4687 10861
TIME...MOT...LOC 1939Z 244DEG 26KT 4707 10940

BH

Special Weather Statement
National Weather Service Great Falls MT
216 PM MDT Mon Aug 3 2020

MTZ047-032100-
Blaine MT-
216 PM MDT Mon Aug 3 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHERN FERGUS AND SOUTHERN
BLAINE COUNTIES UNTIL 300 PM MDT...

At 216 PM MDT, Doppler radar was tracking a strong thunderstorm 14
miles south of Fort Belknap, or 26 miles northwest of Zortman, moving
northeast at 25 mph.

Pea size hail and wind gusts up to 50 mph will be possible with this
storm.

Locations impacted include...
Hays and Lodge Pole.

LAT...LON 4841 10841 4798 10843 4799 10860 4792 10864
      4792 10889 4779 10889 4777 10895 4779 10894
      4781 10899 4778 10913 4780 10927 4810 10929
      4833 10902 4844 10835
TIME...MOT...LOC 2016Z 244DEG 24KT 4827 10877

BH

Special Weather Statement
National Weather Service Great Falls MT
227 PM MDT Mon Aug 3 2020

MTZ051-032115-
Fergus MT-
227 PM MDT Mon Aug 3 2020

...SIGNIFICANT WEATHER ADVISORY FOR NORTHEASTERN FERGUS COUNTY UNTIL
315 PM MDT...

At 226 PM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from 35 miles southwest of Hays to 12 miles east of
Winifred to near Roy. Movement was northeast at 35 mph.

Half inch hail and wind gusts up to 50 mph will be possible with
these storms.

Locations impacted include...
Roy, Fergus and Fred Robinson Bridge.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy 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 4731 10859 4727 10860 4727 10871 4718 10874
      4719 10906 4749 10919 4772 10941 4780 10927
      4778 10913 4781 10898 4775 10892 4774 10895
      4772 10883 4765 10877 4761 10844 4758 10842
      4757 10832 4732 10831
TIME...MOT...LOC 2026Z 233DEG 32KT 4775 10932 4753 10912 4731 10902

BH

Special Weather Statement
National Weather Service Great Falls MT
227 PM MDT Mon Aug 3 2020

MTZ008-032100-
Beaverhead MT-
227 PM MDT Mon Aug 3 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTH CENTRAL BEAVERHEAD COUNTY
UNTIL 300 PM MDT...

At 226 PM MDT, Doppler radar was tracking strong thunderstorms 15
miles east of Gilmore, moving northeast at 10 mph.

Pea size hail and wind gusts up to 50 mph will be possible with
these storms.

Locations impacted include...
Lima, Bannack Pass and Snowline.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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.

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 4440 11289 4441 11294 4449 11303 4452 11301
      4478 11255 4454 11234 4448 11254 4450 11274
      4444 11283 4439 11282 4437 11288
TIME...MOT...LOC 2026Z 235DEG 10KT 4445 11295

RCG

Special Weather Statement
National Weather Service Great Falls MT
236 PM MDT Mon Aug 3 2020

MTZ008-015-032100-
Madison MT-Beaverhead MT-
236 PM MDT Mon Aug 3 2020

...SIGNIFICANT WEATHER ADVISORY FOR SOUTHEASTERN MADISON AND EASTERN
BEAVERHEAD COUNTIES UNTIL 300 PM MDT...

At 234 PM MDT, Doppler radar was tracking a strong thunderstorm 11
miles northwest of Henrys Lake, moving northeast at 40 mph.

Pea size hail and wind gusts up to 50 mph will be possible with
this storm.

Locations impacted include...
Raynolds Pass.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

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 4458 11167 4474 11181 4501 11139 4498 11137
      4476 11137 4471 11141 4472 11145 4470 11149
      4466 11147 4463 11152
TIME...MOT...LOC 2034Z 235DEG 33KT 4471 11162

RCG