995
FXUS65 KTFX 032034
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
234 PM MDT Wed Jul 3 2024

.SYNOPSIS...

Shower and thunderstorm chances will linger through the remainder
of the work week, most notably over Central and North Central
Montana. The best chance for showers and thunderstorms over the
Independence Day holiday will be during the afternoon hours, with
decreasing chances through the evening hours. Below to near normal
temperatures will continue through the weekend, with hot
temperatures arriving by the middle of the next work week.

&&

.DISCUSSION...

Rest of today through tonight...Strong shortwave currently moving
overhead, which was within a moist and unstable northwest flow
regime, will depart to the southeast of the Northern Rockies through
midnight tonight. This will lead to a gradual decrease in the
coverage of precipitation through the evening hours, but before
then, scattered to numerous showers and thunderstorms will continue
across much of North Central through Southwest Montana. Isolated
showers and thunderstorms will remain possible beyond midnight
tonight northeast of a Bozeman to Helena line as a weak embedded
wave within the overall flow dives southeast. A few of the storms
through this evening hours could become strong and produce wind
gusts of between 45-55 mph, small hail, and even a cold air funnel
(mainly during the afternoon hours). Additionally, while PWATs are
not anomalously high, slow storm motions of generally 10-20 mph
could lead to periods of moderate to heavy rainfall. This could lead
to ponding of water in low lying and poor drainage areas.

Independence Day through Friday...moist, unstable northwest flow
aloft with embedded shortwaves diving southeast within the flow will
help to maintain chances for showers/thunderstorms and below, albeit
slightly warmer than the prior day, normal temperatures. Best chances
for showers and storms on Thursday look to be be during the
afternoon hours northeast of a Bozeman to Helena line, with
decreasing chances through the evening hours. As has been the case
for the previous two days, slow storm motions will lead to brief
heavy downpours beneath relatively small showers and storms.

Saturday through Monday...ensemble clusters favor the upper level
ridge axis remaining just west of the Northern Rockies through the
weekend before shifting east towards the Northern Rockies on Monday.
This would keep Southwest through North Central Montana beneath
continued northwest flow aloft, which would help to keep chances for
precipitation and near normal temperatures for the weekend before
drying and warming conditions arrive on Monday. Leading mode(s) of
uncertainty through the weekend and early next week will be the
exact position and/or timing of the ridge axis, with any deviation
east of the ridge axis by ~200-400 mile having a totally different
outcome (i.e. much warmer and drier), especially on Saturday and
Sunday. None-the-less, NBM trends over the past several days with
respect to temperatures have been for "cooler", near normal highs vs
the previously above normal highs.

Tuesday through next Wednesday...ensemble clusters strongly favor
upper level ridging over the Northern Rockies through the period and
beyond, with the leading mode(s) of uncertainty on Tuesday and
Wednesday being the position and/or timing of the ridge. This will
ultimately affect when the hot temperatures arrive to the Northern
Rockies; however, confidence is high that well above normal
temperatures of at least 10 degrees will occur by the middle to end
of next (work) week, with normal high temperatures at Cut Bank
(CTB), Havre (HVR), Great Falls (GTF), Lewistown (LWT), Helena
(HLN), Bozeman (BZN) and Dillon (DLN) ranging from the upper 70s to
mid-80s. NBM probabilities for temperatures of 95 degrees or warmer
at the aforementioned sites range from 15% (CTB), 20% (HVR), 20%
(GTF), 5% (LWT), 70% (HLN), 30% (BZN), 10% (DLN) on Tuesday and 25%,
30%, 40%, 10%, 85%, 55%, 20% on Wednesday respectively, with these
probabilities increasing further for Thursday and Friday. It is not
out of the realm of possibilities that some sites by the middle to
end of the upcoming work week may string together multiple
consecutive days of 100-105 degree high temperatures. People,
especially those with medical conditions exacerbated by hot
temperatures, should begin to prepare for this heatwave. - Moldan

&&

.AVIATION...
03/18Z TAF Period

Unsettled weather is expected to continue through around 04/02Z
before tapering off. During this time, expect intermittent showers
and thunderstorms, periods of mountain obscuration, and periods of
low-VFR to MVFR conditions. By later in the afternoon clouds are
expected to break for KEKS, KWYS, KHLN, and KCTB while lingering mid
to high level clouds will persist for all other sites through the
rest of the period.

-thor

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  47  74  47  77 /  40  30  20  20
CTB  46  72  45  77 /  30  40  20  20
HLN  50  79  50  85 /  50  20  10  10
BZN  42  73  45  80 /  60  20  10  10
WYS  33  67  33  73 /  20  20  20  10
DLN  39  73  42  79 /  20  10  10   0
HVR  50  74  50  79 /  20  40  20  40
LWT  44  68  45  73 /  40  50  20  40

&&

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

$$

http://www.weather.gov/greatfalls