Severe Thunderstorm Warning 11, NWS Great Falls, MT

Area Forecast Discussion
National Weather Service Great Falls MT
1235 AM MDT Thu May 28 2026

.KEY MESSAGES...

 - Daily thunderstorm chances continue through Saturday, with the
   potential for some storms to be strong to severe.

 - Increased temperatures continue today and tomorrow, with a cold front
   on Saturday cooling temperatures down this weekend through
   Tuesday.

 - Widespread precipitation is expected this weekend across the
   region.

&&

.DISCUSSION...

 - Meteorological Overview:

A closed low continues to spin over California today and tomorrow,
causing southerly flow aloft. This will advect warm moist air into
the region, continuing the trend of warmer temperatures and daily
convection for the next two days. Highs will be in the upper 80s to
low 90s across the region today, remaining the same tomorrow with
the exception of Southwest MT seeing slightly lower highs in the low
to mid 80s. At this time, the strongest convection looks to occur
tomorrow afternoon/evening, with chances for thunderstorms tapering
off after Saturday.

On Saturday, the axis of the closed low moves northeast towards MT.
At the same time, a small upper level trough moves into the
Intermountain West, phasing with the closed low on Sunday. This
pattern will bring ample moisture, with PWATs of 3-4 inches. As a
result, widespread precipitation is expected this weekend across the
region. A cold front on Saturday will also cool down temperatures
through Tuesday, before weak upper level ridging on Wednesday brings
them back up. -Dzomba

 - Forecast Confidence & Scenarios:

Thunderstorms Today through Saturday

The models are showing 1,000-1,500 J/kg of CAPE across the region
this afternoon, with the Euro and Canadian showing pockets of higher
CAPE in Central MT. However, with dewpoints generally only reaching
the low 50s in Central/North-Central MT, moisture will be a limiting
factor in the strength of these storms. Overall, the thunderstorms
this afternoon are not expected to be severe. However, some
soundings are still showing a strong inverted V profile indicative
of a dry surface layer, creating the potential for an isolated
severe wind gust or two to occur. Storm motions may be a little bit
slower towards Central MT which can increase the risk slightly for
localized flash flooding over burn scars. Better instability and
shear increases Friday, which will increase chances for marginal
severe wind gusts and large hail. PWATs nearing an inch will bring a
minor threat for localized flash flooding particular in burn scar
areas/urban areas. Saturday's thunderstorm threat will mostly be
focused to the Hill/Blaine/Fergus County areas.

Precipitation this Weekend

There is increased confidence with the precipitation this weekend,
as the spread between models thins. Saturday through Sunday, there
is an 85 to 95% chance for at least 0.25" of precipitation and an 80
to 90% chance for at least 0.5". However, there are still some
slight differences for how the closed low phases with the new
incoming trough, leading to an increased spread in the probabilities
for higher amounts. There is a 60 to 80% chance for at least 1" of
precipitation, and a 15% to 60% chance for 2" inches. Snow levels
look to drop to above pass level, which can bring light, slushy snow
accumulations to the higher peaks. -Wilson and Dzomba

&&

.AVIATION...
28/06Z TAF Period

VFR conditions will prevail across all terminals during this TAF
Period. Thursday afternoon and evening there will be very
isolated showers and thunderstorms across North-central, Central,
and Southwestern Montana. At the KBZN, KHLN, KGTF, and KHVR
terminals there is a 15% chance for showers and thunderstorms
between 28/21Z and 29/06Z. At the KCTB and KLWT terminals there is
a 20 - 40% chance for showers between 28/18Z and 29/06Z and a 15
- 25% chance for thunderstorms between 28/21Z and 29/06Z. All
thunderstorms will produce frequent lightning and gusty, erratic
winds. -IG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  91  57  90  55 /  20  30  20  60
CTB  88  53  86  52 /  20  40  20  40
HLN  90  54  87  52 /  20  20  30  60
BZN  89  48  86  46 /  20  20  30  50
WYS  82  40  78  38 /  10   0  20  40
DLN  84  46  80  45 /  10   0  10  50
HVR  97  57  96  55 /  20  20  20  40
LWT  89  53  88  50 /  20  20  40  50

&&

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

http://www.weather.gov/greatfalls

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