145
FXUS65 KTFX 140247
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
847 PM MDT Sat Jul 13 2024

.SYNOPSIS...

Critical fire weather conditions across much of southwestern and
central Montana will continue through the rest of the afternoon
and early evening. Further north, the threat of severe weather
will continue through the evening hours before tapering off.
Winds and storms will decrease overnight, but another hot and dry
day is forecasted on Sunday.

&&

.UPDATE...

The Severe Thunderstorm Watch for Hill and Blaine Counties has
been cancelled. Showers and thunderstorms will continue in eastern
Beaverhead, Madison, and Gallatin Counties for the next couple of
hours. Otherwise for North-central, Central, and Southwestern
Montana it will be dry for tonight through Sunday. Critical Fire
Weather conditions continue for the higher elevations of fire
weather zones 118 and 117, so the Red Flag Warning remains in
effect for those zones until midnight tonight. See the FIRE
WEATHER Section below for more details.

For tonight`s update low temperatures and hourly temperatures
across North-central and Central Montana were decreased to better
reflect current observations and trends. Dewpoints and relative
humidities across portions of North-central and Central Montana
were increased to better reflect current trends. Pops across
eastern Beaverhead, Madison, and Gallatin Counties were increased
for the next couple of hours to better match current radar trends.
The rest of the forecast is on track. -IG

&&

.AVIATION...
14/00Z TAF Period

VFR conditions will prevail across all terminals during this TAF
period. Smoke and haze will be around the KBZN, KEKS, and KWYS
terminals this evening from wildfires burning across the Western US.
No visibility reductions are expected from it. Smoke and Haze will
be around the KHLN terminal Sunday afternoon through the end of the
TAF period from wildfires burning across the Western US. No
visibility reductions are expected from it. Tonight through sunset
it will remain hot and it will be hot Sunday late morning through
the end of the TAF period. During those time periods there will be
density altitude concerns. For the KBZN, KGTF, and KLWT terminals
winds will be light and variable during this TAF period until they
increase at the very end of it. For the KWYS and KEKS terminals
winds will be stronger at the beginning of this TAF period and then
die down for the rest of the TAF period. -IG

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

&&

.FIRE WEATHER...

The Red Flag Warning remains in effect from 2 pm today through
midnight tonight for Fire Weather Zones 117 and 118 due to hot
temperatures, low humidity, and gusty winds.

The forecast remains on track with keeping the main focus for
critical fire weather conditions today over portions of Southwest
and Central Montana (including Fire Weather Zones 117 and 118).
Significantly dry fuels will combine with increasing westerly
winds (gusting mostly to 35 mph at times) and continued low
afternoon humidity (as low as 10 percent). The area of most
concern in Zone 117 is Meagher County, as fuels in areas farther
north in the Zone (including Cascade and Judith Basin Counties)
have not dried out as much.

Similarly hot and dry conditions are forecast for Sunday, but
winds are not forecast to be quite as strong. After a brief and
minor cooldown on Monday, hot and dry conditions are forecast to
return for at least the next week after that.
-Coulston

&&

.PREV DISCUSSION...
/ISSUED 548 PM MDT Sat Jul 13 2024/

Today and Tonight... Thunderstorms are already underway along Hill
and Blaine counties. The severe weather threat for these two
counties is higher with up to 2 inch hail and over 60 mph gusts
possible. These storms will continue to push east with more storms
coming down from Canada over the next few hours. The thunderstorm
threat is expected to diminish after 7 PM.

The other main threat for this afternoon will be critical fire
weather conditions in southwestern Montana with gusty winds and
low relative humidity that will make fires hard to contain. The
winds will start to taper off after sunset but poor recovery
overnight will lead to near-critical fire weather conditions
tomorrow afternoon. Despite the near-critical environment, the
duration of the highest winds is quite narrow and winds are
generally expected to be lighter Sunday than today. However, it
will be something to watch in case conditions deteriorated
further. -thor

Sunday through Monday... A high pressure ridge is forecast to
build back into the forecast area on Sunday, maintaining the hot
and dry conditions. However, it will also help decrease winds
aloft, which will in turn keep winds from becoming quite as strong
as those today. Weak energy in the resulting flow aloft may bring
a few weak thunderstorms to the Hi-Line and to the Southwest
Montana mountains once again during the afternoon. A shortwave
trough is then forecast to move southeast on the leading edge of
the ridge across southern Saskatchewan Sunday night through
Monday, which will swing a Canadian cold front south over at
least the plains of Montana. An overall lack of moisture will
limit the possibility of thunderstorm activity, but a few storms
cannot be ruled out. The main impact of this frontal passage will
be to cool temperatures back closer to seasonal averages with a
shift to more northerly winds, at least over the plains.

Tuesday through next Saturday... The ridge is forecast to remain
unusually strong over the Western United States through this
period, as indicated by good agreement among model ensemble
clusters. This will likely result in a return to widespread much
above normal temperatures through this period, with most lower
elevations continuing to have high temperatures in the 90s and
possibly over 100 degrees. The chance for afternoon and evening
thunderstorms will mainly be focused over the mountainous area of
Southwest Montana. However, the heat will likely be the greater
threat, so prepare for it now if you need to. -Coulston

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  56  95  57  89 /   0   0   0   0
CTB  55  90  52  87 /   0   0   0   0
HLN  62  98  60  95 /   0   0   0   0
BZN  57  96  56  91 /  10  10  10  10
WYS  47  83  46  82 /  10  10  20  30
DLN  56  92  55  88 /  10  10   0  10
HVR  58  93  56  86 /  10   0  10   0
LWT  55  89  54  84 /   0   0   0  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning until midnight MDT tonight for Central and
Eastern Lewis and Clark National Forest Areas.

Red Flag Warning until midnight MDT tonight for Helena and
Townsend Ranger Districts of the Helena National Forest.

&&

$$

http://www.weather.gov/greatfalls