429
FXUS65 KTFX 102335
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
535 PM MDT Wed Jul 10 2024

...Aviation Section Updated...

.SYNOPSIS...

Hot and dry conditions prevail across north central, central and
southwest Montana. Breezy westerly winds develop tomorrow, with
the strongest winds forecast across The Northern Rocky Mountain
Front and the adjacent plains. A few thunderstorms may develop,
tomorrow afternoon and evening. Hot and mostly dry conditions
continue through the weekend, with some breezy winds on Saturday.

&&

.DISCUSSION...

Note: The forecast area for the National Weather Service Great
Falls Weather Forecast Office includes north central, central and
southwest Montana.

Today and Tomorrow...Upper level ridging continues to dominate the
Treasure State, favoring ongoing hot and dry conditions.
Considering overnight recovery with cooling in the 60s, will
continue to hold off on issuing heat products. Although fire
weather concerns are ramping up, no fire weather highlights are
issued, at this time, due to the state of the fuels.

There is a slight chance for a few thunderstorms to develop
tomorrow afternoon and evening across portions of southwest and
central Montana. Lightning and erratic gusty winds are the
greatest concern from these storms. These storms are forecast
produce very little moisture.
- Fogleman

Friday into next week... Although upper level ridging looks to
continue to dominate across the west over the timeframe, there is
still a bit of uncertainty, especially for Friday across the plains.
Model consensus is for a slightly cooler, but more moist airmass to
drop south from Canada late Thursday night into Friday. Confidence
decreases in just how much moisture is pulled southward however,
which leaves quite a few questions with respect to any shower or
thunderstorm chances for the afternoon Friday. Less aggressive
guidance brings marginally higher dew points, and largely mixes them
out by early Friday afternoon. This leaves little in way of
instability but does result in a slightly cooler day across the
plains. More aggressive guidance brings considerably more moist air
southward within a slightly cooler airmass across the plains and
somewhat maintains the higher dew points through the day Friday.
Relatively warm temperatures aloft still bring questions as to how
much instability will be generated, and if it will even be
accessible by a surface-based parcel (Concerns for a capping
inversion at the top of the boundary layer). Regardless, the best
parameter space for instability looks to be near the Canadian border
and adjacent areas by Friday afternoon, with the caveat that a
capping inversion may inhibit convection altogether. For now I have
left the chance for any precipitation across the region Friday at
or below 10%.

Areas where confidence in the forecast is higher will be across the
valleys of Central and Southwest Montana. The hot temperatures will
stick around in these areas, with non-negligible opportunities for a
shower or isolated thunderstorm across Southwest Montana terrain
Friday.

Looking toward this weekend, the theme of hot will return/continue,
depending on where you are across the region. Opportunities for
mostly dry afternoon showers and isolated thunderstorms will
continue across Southwest Montana terrain.

Heading into next week, the upper level ridging overall looks to
persist, but moisture aloft rounding the western side of the ridge
does look to work its way toward the Northern Rockies. The main
takeaway is for more of the same: Above average temperatures and
daily opportunities for isolated showers and thunderstorms across
Southwest Montana. Fire weather concerns will be increasing through
the next week as drying of fuels occurs. Dry thunderstorms that form
over the next week will also start to raise concerns for lightning
starts. -AM

&&

.AVIATION...
11/00Z TAF Period

VFR conditions will prevail across all terminals during this TAF
period. Winds will be light and variable for most of the TAF period
excluding the first few hours and the last few hours of the TAF
period. Due to being under an upper-level ridge mostly few to
scattered hi-level clouds will be around all terminals with hot
temperatures Wednesday evening and Thursday late morning through the
end of the TAF period. Due to the hot-temperatures there will be
density altitude concerns primarily Thursday afternoon through the
end of the TAF period. Wildfire smoke will be around all terminals
Thursday morning through the end of the TAF period. This smoke has a
low chance of local visibility reductions. -IG

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

&&


.PRELIMINARY POINT TEMPS/POPS...
GTF  63  97  59  90 /   0  20   0   0
CTB  61  94  57  84 /   0   0   0   0
HLN  66 100  62  98 /   0   0   0   0
BZN  60  97  57  95 /   0  10   0   0
WYS  46  87  45  87 /   0   0   0   0
DLN  58  92  56  93 /   0   0   0   0
HVR  64 100  60  91 /  10   0  10  10
LWT  61  92  59  87 /  10  20  20   0

&&

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

$$

http://www.weather.gov/greatfalls