850
FXUS65 KTFX 152029
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
229 PM MDT Mon Jul 15 2024

.SYNOPSIS...
Sunny skies and very warm temperatures will be the common weather
theme through the rest of the work week and into the weekend.
There will be small chances for an isolated thunderstorm this
evening and on Tuesday along the U.S. Canadian border north of
Havre and along the MT Idaho border between Monida Pass and West
Yellowstone.

&&

.DISCUSSION...
Tonight through Tuesday... Light showers continue to move across
the southern Montana/Idaho border. In general most of the moisture
does not appear to be reaching the ground based on area webcams.
Regarding the potential for storms this afternoon, a disturbance
in the flow will keep the threat for mainly afternoon and evening
thunderstorms along the highway 2 corridor from Havre to Harlem,
and over the mountains of Southwest Montana. Relatively weak
instability, lift, and upper level dynamics will likely hinder any
strong thunderstorm development, but the warm and dry air at the
surface will make erratic wind gusts from any storms the main
concern. Some stronger winds have started mixing down with gusts
up to 30 mph being observed across portions of central and north-
central Montana. Some isolated gusts up to 35 mph are possible but
updated model guidance has continued to point towards less than a
40 percent chance of wind gusts over 30 mph across the broader
region.

-Coulston/thor

Wednesday through next Monday... Forecast model ensembles continue
to predict a very warm and dry period into early next week. They
indicate that the high pressure ridge will remain fairly strong for
this time of year as it lingers over the Four Corners region,
extending north into Montana. This shift of the ridge axis to just
east of the region sets up the potential that at least some
monsoonal moisture could be drawn into the area. As of now, guidance
keeps the chance for thunderstorms at less than 40 percent and
focused over the mountains of Southwest and Central Montana, but
we`ll monitor the situation for potentially higher chances.
Temperature-wise, current NBM guidance keeps high temperatures well
into the 90s through this period at lower elevations (10 to 15
degrees above normal), with some ensemble guidance hinting at some
locations potentially exceeding 100 degrees over the weekend into
early next week. This could threaten daily record highs for some
locations. Also, despite the relatively dry air in place, this kind
of a prolonged hot period may limit how much overnight cooling will
occur. This may require excessive heat highlights if models start to
forecast warmer temperatures, but highlight-worthy temperatures are
not being forecast at this time.
-Coulston

&&

.AVIATION...
15/18Z TAF Period

VFR conditions will prevail throughout the duration of the 1518/1618
TAF period; however, isolated to scattered thunderstorms along the
Idaho border may bring gusty and erratic winds to the KWYS terminal,
mainly this afternoon. Otherwise, another round of showers and
thunderstorms is possible along and north of a KCTB to KHVR line
through 06z Tuesday, but confidence in any one shower or storm
impacting the KCTB and KHVR terminals was too low to mention in this
TAF issuance. Slantwise visibility reductions upon ascent/descent
will continue due to smoke/haze across portions of Central and
Southwest Montana (i.e. KHLN, KBZN, KEKS, and KWYS).

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

&&

.FIRE WEATHER...
Overall, expect above normal afternoon temperatures to continue
for at least the next week. Afternoon humidity will be low each
day as well. As of now, no fire highlights are planned for, as
wind speeds generally remain on the light side. Do expect fuels
to continue to dry each day as well. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  57  90  60  94 /   0   0   0  10
CTB  54  87  56  92 /  10  10   0   0
HLN  58  94  59  97 /   0   0   0  10
BZN  52  91  54  94 /   0   0   0  10
WYS  42  83  41  85 /  10  20  10  30
DLN  50  88  51  90 /   0   0   0  10
HVR  58  88  59  94 /  10  10   0   0
LWT  54  84  55  89 /   0  10   0   0

&&

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

&&

$$

http://www.weather.gov/greatfalls