466
FXUS65 KTFX 122330
AFDTFX

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

...Updated Aviation Section...


.SYNOPSIS...

Today`s cold front brings a northerly wind shift, and some
relatively cooler temperatures to the region. Tomorrow, hot, dry
and windy conditions return. Additionally, isolated afternoon and
evening thunderstorm activity is forecast.

&&

.DISCUSSION...

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

Today, a cold front entering our region from the north, brings a
northerly wind shift and some relatively cooler temperatures to
the region. Sufficient atmospheric instability exists to allow for
some isolated afternoon and evening thunderstorms. An upper level
trof removes mass from the dominant upper level ridge, favoring a
tighter upper level height gradient with some gusty surface winds
at times, for the weekend ahead. Considering tomorrow`s hot, dry
and windy conditions, a Red Flag Warning has been issued for
portions of central and southwest Montana, valid from tomorrow
afternoon through tomorrow evening. For the most current Fire
Weather Discussion, please, scroll down toward the bottom of this
document.
 - Fogleman

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

&&

.AVIATION...
13/00Z 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 when they will
increase. Due to being under an upper-level ridge mostly few to
scattered hi-level clouds will be around all terminals with hot
temperatures Saturday late morning through the end of the TAF
period. Due to the hot-temperatures there will be density altitude
concerns primarily Saturday afternoon through the end of the TAF
period. Wildfire smoke will be around the KEKS and KBZN terminals
tonight through Saturday morning. This smoke has a low chance of
local visibility reductions. Tonight at the KEKS, KBZN, and KWYS
terminals there is a 20% chance for a isolated thunderstorm. As a
result of the low probability a mention of thunderstorms is not
included in those TAFs excluding the KEKS TAF. There is currently a
thunderstorm near the KEKS terminal which will move out of the area
in the next hour. At the KHVR terminal there is a 20% chance for a
isolated thunderstorm. As a result of the low probability a mention
of thunderstorms is not included in that TAF. -IG

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

&&

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