140
FXUS65 KTFX 010555
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1155 PM MDT Sun Jun 30 2024

Aviation Section Updated

.SYNOPSIS...
The upcoming week looks to be on the cooler side of average, with
daily opportunities for showers and thunderstorms through July 4th.
Looking toward next weekend, warmer and drier conditions are favored.

&&

.UPDATE...
Showers and thunderstorms will continue this evening and through the
overnight hours across Southwestern Montana. These showers and
thunderstorms have a low chance of being severe. As a result the
Severe Thunderstorm Watch has expired. Some isolated showers and
thunderstorms will make it into North-central and Central Montana
this evening and continue until around midnight. As a result Pops,
QPF, and Sky cover were increased and adjusted across North-central,
Central, and Southwestern Montana to better reflect radar and hi-res
model trends. Minor changes were made to hourly temperatures, winds,
and wind gusts. The rest of the forecast is on track. -IG


&&

.AVIATION...
01/06Z TAF Period

Just a few showers will affect mostly Southwest MT overnight,
otherwise expect increasing chances for showers on Monday afternoon
over much of the CWA. Held of thunder at the terminals for now, but
there will be thunder at times over the CWA. Additionally, northwest
winds will increase at the surface for most terminal sites by late
Monday morning. Expect decreasing showers and lowering wind speeds
on Monday evening. Mountains/passes will be obscured at times across
the CWA through the period. Brusda

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

&&

.PREV DISCUSSION...
/ISSUED 557 PM MDT Sun Jun 30 2024/

The rest of today and tonight... The leading wave within an
approaching upper level trough is passing across the region this
afternoon. This wave has helped initiate showers and thunderstorms
near Monida Pass that will shift northeastward through the
evening. Relatively deep inverted-V soundings, modest instability,
and long straight hodographs will foster a strong wind gust and
hail threat, though the former is the main concern today. These
showers and thunderstorms exit eastern portions of Central Montana
this evening.

Although the most favorable area for ascent will exit eastward
tonight, the broad upper trough across the region will still allow
for showers and thunderstorms to develop across Southwest Montana
tonight, with impacts being much more limited.

Monday... The broad troughing will remain in place across the
northern Rockies, allowing for scattered showers and thunderstorms,
mainly in the afternoon and evening. At this point, these
thunderstorms look to be more of a run-of-the-mill variety. -AM

Tuesday through the 4th of July...Expect a slow cooling trend for
temperatures during this period, with the 4th of July looking like
the coolest day for most areas. The airmass will remain unstable,
with daily chances for showers/thunderstorms, especially for areas
north of I-90 from Butte to Bozeman. At this time, it looks like the
showers/storms will exit much of the CWA by late in the afternoon on
July 4th, resulting in mostly dry conditions for the 4th of July
evening hours. Overall, the threat for any severe storms early next
week looks to be less than 10 percent.

Friday through Sunday...The GFS and EC differ in terms of how strong
an upper level trof will be over MT for next weekend. Right now
there is only about a 20 percent chance from the cluster analysis
that the GFS is right. Thus, I will continue to use the warmer and
drier NBM solution for next weekend, as there is an 80 percent
chance for this solution to pan out. Brusda

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  53  76  52  75 /  40  30  40  50
CTB  51  71  50  73 /  20  60  30  60
HLN  54  79  54  81 /  50  30  30  30
BZN  50  74  47  76 /  70  60  60  20
WYS  44  65  37  67 /  60  80  80  20
DLN  48  71  43  73 /  50  60  40   0
HVR  55  76  54  77 /  40  40  30  70
LWT  49  72  48  71 /  80  20  20  70

&&

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

&&

$$

http://www.weather.gov/greatfalls