535
FXUS65 KTFX 181130
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
530 AM MDT Thu Jul 18 2024

...AVIATION SECTION UPDATED...

.SYNOPSIS...
A passing weather system will bring an increased chance for
widely scattered showers and thunderstorms today. A few storms may
be on the stronger side with brief strong, gusty winds,
lightning, and downpours, especially in Central and North-central
Montana. Otherwise, the hot and mostly dry weather pattern looks
to continue through the weekend and beyond.

&&

.DISCUSSION...

Showers and embedded thunderstorms are approaching the
Continental Divide this morning while the responsible shortwave
centered over E WA continues to trek eastward toward the Northern
Rockies. This initial area of convection looks to reach the Rocky
Mountain Front an hour or two early, but will still follow the
overall expected path through the North-central plains through the
morning hours. This shouldn`t be too impactful, but there will be
an additional round of widely scattered showers and storms for
this afternoon and evening.

The boundary layer is still relatively dry, so there`s an
expectation for a mix of wet and dry storms with the best chance
for drier storms south of a Helena to Lewistown line. The
combination of higher PWATs approaching the 0.75 to 1 inch mark,
with ML CAPE values around 500 to 1,000 J/kg and inverted V
profiles may result in at least a few storms becoming strong to
severe with strong, gusty winds, brief downpours, and even some
hail. Of course the occurrences of rain and hail, if any, look to
be reserved to the Central/North-central areas, particularly areas
east of I15. Since southwestern areas will have less available
moisture, gusty winds and lightning in the presence of little
rainfall will be more of a concern.

Most shower and storm activity will begin to diminish during the
evening hours, though at least some showers and storms lingering
into the overnight hours can be expected, mostly for Hill, Blaine,
Fergus, and eastern Chouteau counties. These same locations may
be become susceptible to patchy fog development once things do
partially clear out late tonight into Friday morning.

Despite all the talk of today`s moisture, ridging will still be
strong enough to warm most lower elevations in the 90s this
afternoon and the overall hot and dry pattern will persist through
the weekend into next week. Once today`s shortwave exits the
region later tonight, instances of showers and thunderstorms look
to become much more isolated again, but won`t completely go away.
The latest 3 to 7 day cluster analysis shows some ridge
amplification early next week before becoming dampened some by
troughing late in the week. Temperatures will roughly follow this
pattern by rising a few degrees Tuesday and Wednesday and then
dropping off a little again on Thursday. - RCG

&&

.AVIATION...
18/12Z TAF Period

An area of light showers/virga and a few embedded thunderstorms will
move through the Rocky Mountain Front and portions of Central/North-
central MT this morning. Then widely scattered showers and
thunderstorms are expected area wide this afternoon and evening. A
few storms may be on the stronger side with strong, gusty winds,
lightning, and brief downpours. Hazy skies will continue to impact
slantwise visibility and hot afternoon temperatures will impact
density altitude. - RCG

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  92  59  93  61 /  30  20   0   0
CTB  89  54  92  58 /  30  20   0  10
HLN  97  61  97  63 /  20  10   0   0
BZN  94  56  93  56 /  30  30   0   0
WYS  85  44  84  43 /  50  40  20  10
DLN  90  54  89  54 /  30  10  10   0
HVR  93  59  94  62 /  50  50   0  10
LWT  90  55  87  58 /  40  50  10   0

&&

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

$$

http://www.weather.gov/greatfalls