569
FXUS65 KTFX 252132 CCA
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
332 PM MDT Sat May 25 2024

.SYNOPSIS...

Shower and isolated thunderstorm activity slowly diminishes from
west to east tonight. Breezy to windy conditions are expected on
Sunday with shower chances mostly confined to the Hi-Line. Much
Drier and warmer weather is expected for Memorial Day and most of
Tuesday before shower and thunderstorm chances return later Tuesday
into Wednesday.

&&

.DISCUSSION...

Tonight through Monday... Scattered showers and thunderstorms will
persist through the rest of the afternoon across most of central
and southwestern Montana. Overall, the threat for severe weather
is minimal, however, a gust or two up to 50 mph and some pea-sized
hail is possible. Showers will quickly taper off after sunset for
north-central and central Montana. Some lingering showers will
remain for southwestern Montana through around 3 AM before
tapering off.

For tonight, model soundings are still split on fog developing
around Bozeman. There is just enough confidence and potential for
fog developing after the last of the showers move through early
tomorrow morning that a 20% chance for patchy fog was added to the
Gallatin Valley and portions of far southwestern Montana.
Widespread dense fog is not expected but it would not be
surprising for a couple isolated places to reach a quarter of a
mile in visibility at times.

Otherwise, as the shortwave continues east there will be another
chance for isolated showers and thunderstorms along the hi-line
Sunday afternoon. Memorial Day will be warmer and drier across the
region with generally light winds and partly cloudy skies except
along the northern Rocky Mountain front.  -thor


Tuesday through Saturday... An upper level ridge will be over the
area on Tuesday morning, which will quickly break down by Tuesday
afternoon, as an upper level trof approaches from the west.
Tuesday will likely be the warmest day over the next week, but I
did lower NBM guidance a few degrees for Tuesday afternoon, as it
might be too warm. Otherwise, the main concern Tuesday is for the
potential for severe storms Tuesday afternoon/evening. With the
flow aloft becoming southwest, it will be unstable by late
afternoon. However, it is not that unstable, thus the potential
for widespread severe storms looks low at this time. On
Wednesday, the main cold front moves though. Temperatures will
start to cool a bit, as well as the potential for heavy rainfall
over Central MT. Right now there is about a 30 percent chance for
locations between Great Falls and Lewistown to receive 0.50 inches
of rainfall. This would be convective rainfall, thus portions of
Central MT are in a marginal risk for excessive rainfall during
this period. It does remain unsettled for Thus/Fri with scattered
showers continuing and afternoon temperatures just a few degrees
below normal. Brusda

&&

.AVIATION...
25/18Z TAF Period

Mid-level clouds and showers will continue to increase and spread
east across remaining portions of north-central MT this afternoon
ahead of upper level weather disturbance crossing the Northern
Rockies. Scattered thunderstorms develop and track east across the
area this afternoon with 50-60% probabilities for thunderstorms
at/near KBZN, KEKS and KWYS and 30-50% probabilities for KGTF, KHVR
and KLWT. Gusty winds will accompany most showers and thunderstorms
this afternoon wish some small hail possible in isolated/more intense
cells. Otherwise some brief MVFR and mountain obscuration is expected
in the vicinity of showers/thunderstorms this afternoon and evening
with showers and clouds decreasing as the system exits overnight.
Some patchy fog is possible in KBZN area late tonight as clouds
decrease following the showers. Westerly surface winds increase this
afternoon and evening with the passage of the weather disturbance
with breezy to locally windy conditions likely to develop at most
terminals on Sunday. Hoenisch

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  41  63  40  73 /  40  10   0   0
CTB  40  60  39  70 /  10  10   0   0
HLN  42  64  43  76 /  20  10   0   0
BZN  36  62  36  71 /  70  10   0   0
WYS  33  55  30  64 /  80  20   0   0
DLN  35  63  36  71 /  50   0   0   0
HVR  44  65  43  73 /  40  30  10   0
LWT  38  58  37  67 /  80  10   0   0

&&

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

$$

http://www.weather.gov/greatfalls