213
FXUS65 KTFX 121833
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1233 PM MDT Fri Jul 12 2024

.SYNOPSIS...

The extended period of very warm to hot and dry weather will
persist through the weekend into next week. Weak weather systems
will maintain breezy to windy conditions at times and there will
be a daily slight chance for shower and thunderstorm activity with
little to no rainfall.

&&

.UPDATE...

As of this time the only update is to fire weather products. The
Fire Weather Watch for Fire Weather Zone 118 has been upgraded to
a Red Flag Warning. Additionally, a Red Flag Warning has been
issued for Fire Weather Zone 117. Both warnings are valid from
Saturday at 2 PM to Saturday night at midnight.
- Fogleman

&&

.AVIATION...
12/12Z TAF Period

A weak cold front will slowly move southward and bring a northerly
wind shift, most notably over the plains. VFR conditions will
generally prevail aside from some low VFR clouds along the Rocky
Mountain Front and northern high plains (KCTB area) this morning and
periods of hazy conditions impacting slantwise visibility at times
throughout the period. There will also another round of isolated
shower and thunderstorm activity this afternoon and evening, mostly
over Southwestern Montana and to a lesser degree near and east of
KHVR. - RCG

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

&&

.PREV DISCUSSION...
/ISSUED 529 AM MDT Fri Jul 12 2024/

A weak cold front is approaching the Canadian border and will
slowly continue southward throughout the day and bring a northerly
wind shift and slightly cooler temperatures, most notably over
the plains. Passing shortwave disturbances will dampen the upper
level ridge some through Sunday, resulting in breezy to windy
conditions at times while moisture aloft combined with diurnal
instability maintains slight chances of mostly afternoon and
evening showers and thunderstorms. The primary thunderstorm
concerns will generally be gusty and erratic winds and a few
lightning strikes in the presence of little or no rainfall.

Saturday looks to be the most active day weatherwise with breezy
to windy and dry conditions expected for most locations. There
will also be a bit more instability and moisture for a few
stronger thunderstorms, mostly over Hill and Blaine Counties.
Forecast soundings are starting to show longer hodographs
favorable for at least a short opportunity for marginally severe
weather Saturday afternoon. Otherwise, the focus will mostly be on
the gusty winds and potential red flag conditions over Southwest
and portions of Central Montana where fuels are the driest and
fire activity is already being observed. Many of these locations
have over a 70% chance for 20 mph sustained winds and a 30 to 50%
chance for wind gusts over 40 mph. This in combination with
expected RHs in the lower teens continues to warrant the Fire
Weather Watch already in place. I continued to hold off on adding
fire zone 117 to the watch area with it looking to be a shorter
period of gusty winds and lower RHs, though this area will still
need to be monitored by upcoming shifts for any changes.

Winds diminish Saturday night before picking up once again on
Sunday as another shortwave moves from the northwest. While winds
will be on the gustier side throughout the entire forecast area,
winds don`t appear to be quite as strong for as long of a period
of time over the southwest and northern areas will see slightly
cooler temperatures and higher RHs move in by the afternoon hours.

Lighter winds are expected for much of next week as westerly flow
weakens and the ridge begins to slowly become more amplified.
Still weak perturbations moving within the ridge look to maintain
daily isolated shower and thunder activity. Temperatures will
mostly stay in the upper 80s and lower 90s until the end of the
week when peak amplification of the ridge pushes temperatures back
into the 90s to near 100 again. - RCG

&&

.FIRE WEATHER...

Very warm to hot temperatures and low humidity 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, localized gusty and erratic
winds are possible near any high-based showers and isolated
thunderstorms along with occasional lightning strikes.

On Saturday the combination of deep afternoon mixing and stronger
westerly flow aloft may lead to more widespread gusty westerly
winds, especially across the Central Montana fire districts where
deepest mixing is expected. A Red Flag Warning is valid from
Saturday at 2 PM through Saturday and midnight for Fire Weather
Zones 117 and 118.
- RCG/Fogleman

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  59  95  58  94 /   0   0   0   0
CTB  56  90  55  88 /   0  10   0   0
HLN  62 100  61  98 /  10   0   0   0
BZN  56  97  58  96 /  20   0   0   0
WYS  44  87  47  85 /  20  10   0  10
DLN  54  94  57  91 /  20   0   0  10
HVR  60  93  59  91 /  10  20   0   0
LWT  58  91  57  89 /  10  20   0   0

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Red Flag Warning from 2 PM Saturday to midnight MDT Saturday
night for Central and Eastern Lewis and Clark National Forest
Areas-Helena and Townsend Ranger Districts of the Helena
National Forest.

&&

$$

http://www.weather.gov/greatfalls