944
FXUS65 KTFX 181701
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1101 AM MDT Sat May 18 2024

Aviation and Forecast section updated

.SYNOPSIS...
Today is forecast to be dry, mild and on the cool side, with
periods of breezy to gusty winds. Daily isolated afternoon and
evening thunderstorms are forecast through the early part of next
week. For the next several days, temperatures remain cooler than
normal, with periods of gusty winds and an active weather pattern
that favors periods of rain and high elevation snow.

&&

.UPDATE...
No Updates planned for this mornings forecast. Mostly sunny skies
prevail over the CWA this morning. Winds are increasing and could
gust near 40 mph at times today. A few showers/thunderstorms could
develop by late afternoon in the Cut Bank area, as a weak upper
level disturbance moves through that area. Otherwise, the rest of
the forecast is on track. Brusda

&&

.AVIATION...
18/18Z TAF Period

VFR conditions will prevail across much of the CWA through
tonight. The exception will be in the Northern Rockies and the
Cut Bank area where a passing shower/thunderstorm could move
through late this afternoon/evening. Surface winds will gust near
35 knots at times this afternoon over Central and North Central
MT. On Sunday morning, showers will become more widespread over
Central and Southwest MT with low IFR ceilings possible at times.
Mountains/passes will become obscured at times this afternoon over
the Northern Rockies and tomorrow morning over Central/Southwest
MT. Brusda

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

&&

.PREV DISCUSSION...
/ISSUED 529 AM MDT Sat May 18 2024/

Note: The forecast area for the National Weather Service Great
Falls Weather Forecast Office includes north central, central and
southwest Montana.

Today...A broad upper level trof stretches across the Canadian
Provinces of British Columbia, Alberta and Saskatchewan. Within,
closed upper level areas of lower heights rotate through this
trof. To our south, a weak upper level ridge resides over the
Four Corners region. Off of the southern California/Baja Peninsula
west coast resides a closed upper area of lower heights, and just
upstream of that trof lies a strong upper level ridge. As a
result, a westerly cross-barrier flow develops across The Rocky
Mountain Front, favoring widespread non-warning criteria gusty
winds. A few rumbles of thunder may be heard along The Northern
Rocky Mountain Front, this afternoon and evening. Aside from gusty
winds and maybe a few thunderstorms, today is forecast to be dry,
mild and on the cool side.

Sunday through next Saturday...Sunday, as one of the Canadian
minor shortwave trofs rotates through the main trof, removing mass
from the broad upper level trof, the wave begins to feel the
upper level closed area of lower heights off of the southern
US/Baja Peninsula west coast, causing the upper level trof to
deepen. Afternoon and evening thunderstorm activity is forecast
through Monday. Numerical Weather Prediction models are in
agreement that this deep trof remains the dominant upper level
feature over The Treasure State through Thursday. The best chance
of receiving an inch or more of precipitation in a 24-hr period,
is forecast for Thursday, when north central and central Montana
has a 20% or less chance of receiving one or more inches of
moisture in 24 hours. Beyond Thursday, numerical model solutions
become divergent, with some favoring the development of an upper
level ridge over our area, while others continue to include upper
level trofing as the dominant feature. The National Blend of
Models is favoring and active weather pattern, at least, through
next Saturday. The resultant weather, throughout this period,
includes cooler than normal temperatures, periods of gusty winds,
as well as, periods of rain and high elevation snow.
- Fogleman

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  62  39  56  38 /  10  20  80  50
CTB  58  33  55  35 /  20  20  80  40
HLN  66  42  58  39 /   0  30  70  30
BZN  66  35  55  33 /  10  20  80  20
WYS  58  35  52  27 /   0  30  50  20
DLN  65  34  54  32 /   0  10  40  10
HVR  63  38  60  39 /  10  10  70  30
LWT  59  37  53  34 /   0  20  80  30

&&

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

&&

$$

http://www.weather.gov/greatfalls