946
FXUS65 KTFX 301522
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
922 AM MDT Sun Jun 30 2024

.SYNOPSIS...
Showers and thunderstorms will move from west to east across the
area today. Some storms could be severe this afternoon or early
this evening. Overall, a cooling trend will be occur with
afternoon temperatures over the next few days, with the 4th of
July likely being the coolest day of the week for most areas.
Expect scattered showers or thunderstorms most days through the
4th of July afternoon, with clearing skies on the evening of the
4th of July.

&&

.UPDATE...

No significant tweaks were needed with the update this morning.

Confidence is increasing that there will be strong to severe
thunderstorms across eastern portions of Southwest through Central
Montana this afternoon and early evening. Satellite and radar
this morning are still showing a few showers across Southwest
Montana, but with clearing skies moving in from the south, this
will set the stage for increasing instability heading into the
afternoon. Forecast soundings for this afternoon across Southwest
into Central MT show long straight hodographs, with relatively
deep inverted-V profiles. This suggests both strong wind gusts and
hail will be a concern with the most robust storms, though
stronger wind gusts appear to the most prolific threat at this
time. These look to initially form across Southwest MT early to
mid afternoon, spreading northeastward with time through the
evening. Those recreating today are urged to be weather aware and
have a plan for thunderstorms. -AM

&&

.AVIATION...
30/12Z TAF Period

Aside from a few isolated SHRA this morning, expect VFR conditions
to continue through 18z. Instability increases this morning and
afternoon, especially across SW MT, which will result in widely
scattered to widespread showers and thunderstorms, some of which may
bring hail and gusty winds in addition to IFR conditions. TSRA and
SHRA move eastward after sunset. Ludwig

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

&&

.PREV DISCUSSION...
/ISSUED 550 AM MDT Sun Jun 30 2024/
Today through Monday...An upper level trof is approaching from the
west this morning. A few isolated thunderstorms have developed
west of Monida Pass this morning. Thus low pops have been placed
over the western half of the CWA this morning. The main trof/front
move eastward through the CWA this afternoon. There is the
potential for isolated severe storms over the western portions of
the CWA, but as the disturbance approaches the eastern portions of
the CWA, particularly the Lewistown area, there is a higher
potential for severe storms. The HREF progs a convective band of
60 mph wind gusts through Fergus County as the boundary moves
through between 4 and 7 PM. Overall, most areas east of a line
from Lincoln to Havre are in a Marginal Risk for severe storms,
while the Judith Gap, Lewistown and Grass Range areas are in a
Slight Risk. There is also the potential for large hail with the
stronger storms as well today. I did lower afternoon temperatures
just a few degrees, as cloud cover today will limit max temp rises
a bit. Expect most showers/thunderstorms to exit the eastern
portions of the CWA this evening, but another round of
showers/thunderstorms is expected on Monday, especially over
Southwest MT. At this time, no severe storms are expected on
Monday.

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  77  53  77  53 /  40  30  20  30
CTB  72  51  72  50 /  70  10  50  30
HLN  79  55  80  54 /  60  50  30  30
BZN  80  50  75  46 /  80  60  60  50
WYS  79  44  67  37 /  40  70  80  80
DLN  77  48  73  42 /  70  50  50  40
HVR  78  55  78  54 /  20  40  40  30
LWT  79  50  73  49 /  30  60  20  20

&&

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

$$

http://www.weather.gov/greatfalls