785
FXUS65 KTFX 112104
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
304 PM MDT Thu Jul 11 2024

.SYNOPSIS...

Hot and dry weather prevails across the region into next week
beneath a strong upper level ridge of high pressure in place
across the inter-mountain Western United States. Isolate shower
and thunderstorm development is possible each afternoon with
little to no measurable precipitation expected.

&&

.DISCUSSION...

Isolated showers and thunderstorms will continue to pop up over
the rest of the afternoon into the evening hours. Very little to
no measurable precipitation is expected with these showers,
however, there is a risk for gusty winds and cloud to ground
lightning which will increase fire weather concerns heading into
the weekend. For a more in-depth outlook at upcoming fire weather
concerns, see the FIRE WEATHER section. -thor

The weak disturbance moving over the ridge today results in some
very minor cooling on Friday, mostly focused across north-central MT
as weak surface high pressure temporarily moves across southern
AB/SK, shifting winds to more northerly across the Plains. Heat will
re-intensify across the area on Saturday as the upper level ridge
strengthens a bit and becomes centered across the eastern Great
Basin and central Rockies. A belt of stronger winds aloft also
moves over the ridge Saturday, which will lead to at least breezy
conditions, while an associated disturbance potentially supports
some isolated high-based showers/thunderstorms across the
central/SW MT mountains late Saturday and Saturday night.
-Hoenisch

Next week hot and dry conditions will continue from the strong
ridge moving in from the west. High temperatures will be above
average in the mid 90s, and overnight lows will remain in the 60s
providing some relief from the high temperatures during the day.
Opportunities for showers and thunderstorms will continue in
Southwest Montana. Fire weather concerns will increase as fuels
continue to dry out, and drier thunderstorms are also a risk
because of the lightning and winds. -Kiffle


&&

.AVIATION...
11/18Z TAF Period

Note: The NWS Great Falls Weather Forecast Office manages the
following TAFs: KCTB, KHVR, KGTF, KLWT, KHLN, KBZN, KEKS and KWYS.

VFR conditions prevail at all airfields for the duration of this
11/18Z forecast period. Having said this, high based convective
activity develops, producing some showery precipitation and
scattered thunderstorms. There is a less than 25% chance of these
storms impacting the airfields 10 mile aerodromes. For this reason,
thunderstorm has not been included in these TAFs. Virga should be
expected. Some thunderstorms may become severe, particularly across
portions of north central Montana. Aside from convective activity,
the strongest winds are forecast to occur, this afternoon, along The
Northern Rocky Mountain Front, when/where winds gust to as high as
30KT. Considering observed and forecast temperatures, density
altitude impacts are a given.
- Fogleman

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

&&

.FIRE WEATHER...

Near record heat and low humidity will continue to rapidly dry fuels
and increase fire danger across the area with several fire weather
concerns over the next several days. In addition to the heat and
dryness today, localized gusty and erratic winds are possible this
afternoon near any high-based showers and isolated thunderstorms
along with the potential for isolated lightning. Hoenisch

The next concern for fire weather will be on Saturday. Well above
normal temperatures in combination with strong westerly flow aloft
will create critical fire weather conditions across portions of
central and southwestern Montana. Sustained winds over 15 mph are
expected for much of fire weather zone 118 with a widespread 15 to
25% chance of sustained winds over 20 mph. Wind gusts over 25 mph
are generally expected for most of the zone with a 15 to 25% chance
of wind gusts over 35 mph, particularly for the southern portion of
the zone. Minimum RH values are expected to range from 10 to 15% for
most of the zone.

It is worth mentioning that there are some concerning fire weather
signatures for zone 117 on Saturday. However, from discussing fuel
conditions and recent precipitation with fire weather partners, it
sounds like most of the zone is about a week away from reaching
critical conditions. Some parts of Meagher county in zone 117 will
be of concern for potential fire growth and spread. But given the
locality of these concerns in relation to the size of the zone, the
decision was made to hold off on issuing a fire weather watch for
zone 117.

Looking further out in time, Sunday is expected to be much more
marginal in terms of the fire weather setup. Low RH and warm
temperatures will continue. However, winds are expected to be a
little lighter and will pose less of a threat to fire suppression.
The next time period to watch will be Monday and Tuesday afternoon
for dry thunderstorms across central and southwestern Montana. There
is still some model disagreement on the specifics with the dry
thunderstorm potential but it will be something to watch in the
coming days.

-thor

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  59  90  59  95 /   0   0   0   0
CTB  57  85  56  90 /   0   0   0   0
HLN  62  98  62 100 /   0   0   0   0
BZN  57  96  56  97 /  10   0   0  10
WYS  46  86  44  87 /  10  10   0  10
DLN  54  93  54  94 /   0  10   0  10
HVR  61  91  60  93 /   0   0   0  10
LWT  59  87  58  91 /  20   0  10  10

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Fire Weather Watch from Saturday afternoon through Saturday
evening for Helena and Townsend Ranger Districts of the Helena
National Forest.

&&

$$

http://www.weather.gov/greatfalls