209
FXUS65 KTFX 141142
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
542 AM MDT Sun Jul 14 2024

...AVIATION SECTION UPDATED...

.SYNOPSIS...

A passing weather system will bring a period of gusty winds,
along with isolated to scattered showers and thunderstorms this
afternoon and evening. The strongest storm potential will be along
the Hi- Line. Temperatures hold steady or even cool a few degrees
during the first half of next week before heating back up mid-
week and beyond. Daily chances for isolated scattered shower and
thunderstorm activity with little rainfall will persist for much
of the week.

&&

.DISCUSSION...

Shortwave energy and a cold front will bring a round of west to
northwesterly breezes and isolated shower and thunderstorm chances
later this afternoon and evening. The winds actually look to
expand in coverage, including much of North-central MT, but wind
speeds will generally be less and there will be a shorter temporal
opportunity for the windier conditions, mostly around 3 to 4
hours or less. Regardless, this will create difficulties for those
working on containment of ongoing wildfires given the combination
of the winds with the continued hot and dry weather.

Today`s shower and thunderstorm activity looks most widespread
along the Hi-Line and then over the southwest and central areas
south of the highway 200 corridor. Moisture, instability, and
shear along the Canadian border will be favorable for a few
stronger to possibly severe storms with forecast soundings
highlighting ML CAPE values around 1,000 to 1,500 J/kg, PWATS
approaching 1 inch, and bulk shear north of 30 kts. Primary
thunderstorm hazards from the stronger storms will be gusty winds,
hail, and brief heavy downpours in addition to lightning. The
storms farther south will be weaker and mostly an isolated gusty
wind and lightning threat. Activity decreases later this evening,
but a few showers and storms may linger into the overnight hours.

Temperatures cool down by a few degrees on Monday in the wake of
the passing weather system, but many locations will be breezy with
minimum relative humidities dipping critically low again.
Isolated shower thunderstorm activity with little rainfall relief
can also be expected. The latest 3 to 7 day cluster analysis still
favors the upper level ridge amplifying mid- late week, yielding
more hot and dry conditions while lingering moisture bring daily
chances for isolated to scattered showers and storms. - RCG

&&

.AVIATION...
14/12Z TAF Period

A passing weather system will bring west to northwesterly breezes
this afternoon and evening, along with isolated to scattered showers
and thunderstorms. Shower/thunder activity will be mostly
concentrated over Southwestern MT and along the Hi-Line (KCTB,
KHVR). The storms along the Hi-Line will have the potential to be
the strongest, but any shower or storm may initiate brief periods of
gusty, erratic winds and isolated lightning. Overall, VFR conditions
are expected for this TAF period save for patchy fog development
over the river valleys near KHVR through 15Z, periods of mostly mid-
and higher level cloudiness associated with any shower/thunder
activity, and lastly hazy skies impacting slantwise visibility over
the southwest. Very warm to hot afternoon temperatures will continue
to cause density altitude concerns. - RCG

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

&&

.FIRE WEATHER...

A passing weather disturbance will bring increased northwesterly
winds, hot temperatures, and critically low relative humidity this
afternoon and evening. There will also be isolated to scattered
shower and thunderstorm activity generally offering little in the
way of rainfall while initiating isolated instances of gusty,
erratic winds in the presence of a few lightning strikes. Even
without the thunderstorm wind gusts, the northwesterly breezes may
gust up to the 25 to 30 mph range for a short period this
afternoon while relative humidity is critically low.

looking ahead, the overall very warm to hot and dry pattern looks
to persist into next week with little to no relief from daily
chances for scattered showers and storms. These conditions will
increase the risk for new wildfires. Be mindful of the
deteriorating conditions and avoid activities involving sparks or
open flames. - RCG

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  94  57  92  58 /  10  10   0   0
CTB  91  52  89  54 /  40  30   0   0
HLN  98  60  96  60 /  10  10   0   0
BZN  95  56  92  55 /  20  20   0   0
WYS  85  46  82  44 /  40  40  30  20
DLN  91  55  89  53 /  20  20  10   0
HVR  92  56  88  58 /  20  40   0   0
LWT  89  54  85  55 /  10  10  10   0

&&

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

$$

http://www.weather.gov/greatfalls