Severe Thunderstorm Warning 50, 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

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Special Weather Statement
National Weather Service Great Falls MT
1059 AM MDT Mon Aug 3 2020

MTZ013-031745-
Chouteau MT-
1059 AM MDT Mon Aug 3 2020

...Several Thunderstorms continuing to track east across central
Chouteau County through 1145 AM..

At 1057 AM MDT, Doppler radar was tracking strong thunderstorms along
a line extending from Fort Benton to 11 miles west of Highwood.
Movement was northeast at 25 mph.

Half inch hail and winds in excess of 30 mph will be possible with
these storms.

Locations impacted include...
Fort Benton, Big Sandy, Carter, Floweree, Loma, Kenilworth and
Virgelle.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Localized heavy rainfall may also occurring with these storms, and
may lead to localized flooding, especially in areas that receive
multiple rounds of thunderstorm activity. 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 4800 10971 4786 11036 4759 11103 4762 11105
      4769 11099 4770 11109 4780 11115 4831 11029
      4831 11002
TIME...MOT...LOC 1657Z 242DEG 22KT 4784 11064 4763 11101

BH

Special Weather Statement
National Weather Service Great Falls MT
1148 AM MDT Mon Aug 3 2020

MTZ013-047-051-031845-
Chouteau MT-Fergus MT-Blaine MT-
1148 AM MDT Mon Aug 3 2020

...SPECIAL WEATHER STATEMENT...

At 1143 AM MDT, Doppler radar was tracking strong thunderstorms from
near Fort Benton east across eastern Chouteau and northwest Fergus
Counties. These cells were moving east at 30 mph.

Half inch hail and winds in excess of 30 mph will be possible with
some of these storms.

Locations impacted include...
Winifred, Judith Landing, Cleveland and Iliad.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Heavy rainfall is also occurring with some of these 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.

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 4745 10890 4766 11034 4787 11057 4814 10974
      4814 10954 4821 10953 4841 10888
TIME...MOT...LOC 1743Z 251DEG 28KT 4782 11040

BH