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000
FXUS65 KTFX 241151
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
550 AM MDT Thu Jun 24 2021

...UPDATED AVIATION SECTION...

...Scattered showers and thunderstorms today through this
evening...
...Hot and dry conditions starting this weekend...

.SYNOPSIS...

A passing Canadian cold front will bring gusty northerly winds
with scattered showers and thunderstorms to much of the region,
mainly this afternoon and evening. Some storms may become strong,
producing erratic wind gusts, frequent lightning, small hail, and
brief heavy downpours. Clouds, storms, and winds will diminish
later this evening and overnight, which may allow patchy fog to
form. An overall warming and drying trend is then expected through
this weekend into early next week, which should bring the warmest
temperatures of the year so far.

&&

.DISCUSSION...

Today through Friday...A shortwave trough with an associated cold
front remains on track to bring scattered showers and
thunderstorms to much of the area, mainly this afternoon and
evening. As of early this morning, the cold front is parked over
the Hi-Line and the disturbance will move southeast out of
southwest Canada today to push the front through the area. The
shortwave will help provide the instability necessary to create
the storms. The front will move through north central Montana
through this afternoon, providing a focus for potentially strong
thunderstorms that could produce erratic wind gusts, lightning,
and hail. The cooler and more moist air behind the front will
mostly spread over north central Montana today, keeping
temperatures there near to slightly below normal and provide a
chance for brief heavy downpours. Behind the front, winds will
become more northerly and gusty, and the resulting upslope effect
will focus the better chance for heavier rain showers along the
east- and north-facing slopes of the plains. The front will not
move into southwest Montana until later this afternoon into early
this evening, which will help allow temperatures to warm above
normal once again. This warmer and drier air ahead of the front
will give thunderstorms a better chance for strong wind gusts with
less of a chance of heavy rain. The system will exit the area to
the southeast later this evening and overnight, allowing showers,
storms, and winds to decrease. Skies will also partially clear
overnight, which may cause patchy fog to form, especially over
the plains. There may be enough lingering moisture in the
northerly flow aloft in the wake of this system on Friday to allow
a few showers and thunderstorms to form over the mountains of
central and southwest Montana during the afternoon, but any
showers/storms should be fairly weak. The northerly flow will also
keep daytime highs mostly in the 70s.

Saturday through next Thursday...Forecast models continue to bring
an area of high pressure into the Pacific Northwest Saturday into
Sunday, which will help dry out the area and warm daytime
temperatures up to 10 degrees warmer than normal by Sunday.
However, there is a slight change for the remainder of the
forecast from prior issuances, at least as of early Thursday
morning. The strong upper level high pressure ridge that was
previously forecast to settle in over the area along and west of
the Rockies is now forecast to remain more so over the Pacific
Northwest and Great Basin. This westward shift in the ridge axis
will keep the brunt of the expected extremely hot temperatures
over that area. Montana will generally remain very warm and dry
Monday through next Thursday, especially from Tuesday onward, but
extreme heat is becoming less likely; the consensus blend of
models has trended up to 5 degrees cooler than previous runs.
Although this is not a significant drop in temperatures, it does
hint at a potential trend if the positioning of the ridge
continues to trend westward away from Montana. Again, this
decrease is slight as of now, and the temperature trend continues
to indicate the potential for Heat Advisories at least over the
plains for the middle of next week. Stay tuned for updates.
-Coulston

&&

.AVIATION...
550 AM MDT Thu Jun 24 2021 (24/12Z TAF period)

VFR conditions will continue across most of the area through at
least 18Z. A disturbance with an associated cold front will move
south through the area through 21Z, and lower mid level cloudiness
will spread over the area behind it, along with gusty northerly
winds. Scattered showers and thunderstorms with periods of MVFR
conditions will then move south from the Canadian border around 15Z
through 00Z into southwest Montana. Erratic winds gusts, brief heavy
downpours, and mainly small hail will be the primary threats. Storms
will decrease from the north after 21Z through around 06Z, but low
VFR/high MVFR ceilings will linger for 2 to 3 hours after the end of
them. Partial clearing and decreasing winds overnight will likely
allow patchy fog to form. -Coulston

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  79  48  78  53 /  70  40  10   0
CTB  69  46  77  53 /  80  10   0   0
HLN  86  55  81  56 /  50  50  10   0
BZN  85  49  79  49 /  20  50  20   0
WYS  76  40  71  38 /  40  40  30   0
DLN  82  48  77  49 /  10  20  10   0
HVR  77  48  80  55 /  60  30   0   0
LWT  79  48  73  50 /  70  50  20   0

&&

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

$$

http://www.weather.gov/greatfalls