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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS65 KTFX 181124
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
525 AM MDT Thu Apr 18 2024

.SYNOPSIS...

A lingering northwesterly flow aloft will keep temperatures up to
15 degrees below normal through Friday, with a chance of isolated
afternoon snow showers, mainly near and over the mountains. Weak
high pressure ridging will help warm temperatures back close to
normal through the weekend, but a Pacific disturbance will bring a
chance of showers back to the area for Sunday into Monday.
Continued warming is then expected into the middle of next week.

&&

.DISCUSSION...

Today through Friday... An east-to-west oriented low pressure
trough along the Canadian Border will keep North Central,
Central, and Southwest Montana under a cool northwesterly flow
aloft through Friday. Temperatures should remain 10 to 15 degrees
below normal through the period, with widespread teens and 20s
for overnight lows likely causing a frost, if not a freeze, after
a stretch of highs in the 60s to lower 70s that ended just a few
days ago. The cyclonic nature of the northwesterly flow aloft
will likely combine with weak afternoon instability to cause a
few snow showers to form each day, especially over and near the
mountains. However, these showers are only expected to cause
minor measurable accumulation, if any at all. Surface high
pressure building south out of Canada will mostly cause lingering
breezy northwest winds to decrease and shift more northeasterly
tonight into Friday. However, that shift will likely cause winds
to become gusty through north-south oriented valleys of Southwest
Montana, including the Twin Bridges, Dillon, and Ennis areas.

Saturday through next Thursday... Weak high pressure ridging is
forecast to develop over the western United States for much of
this period Saturday through Monday, warming temperatures to near
seasonal averages. However, a low pressure trough off the Pacific
coast of North America is also forecast to eject a shortwave
trough over Montana Sunday into Monday, bringing at least a
chance of precipitation to much of the area. Right now, though,
probabilistic guidance is giving less than a 20 percent chance of
4 inches of snow accumulation in the mountains through this
period. Forecast models then indicate that the high pressure ridge
will start to amplify Tuesday into Wednesday, which should help
warm temperatures to around 10 degrees above normal through mid-
week. Mostly dry conditions are also expected on Tuesday, but the
low pressure trough is forecast to deepen off the Pacific coast
Wednesday into Thursday. This would shift the flow aloft more
southwesterly and unsettled, for an increasing chance of showers.
-Coulston

&&

.AVIATION...
-- Changed Discussion --
525 AM MDT Thu Apr 18 2024 (18/12Z TAF Period)

Expect mostly VFR conditions across the area through the day today
as incoming high pressure gradually clears the remaining clouds.
Main concern today will be some gusty winds to 15-25 kts across the
plains, especially KGTF, KHVR, and KLWT, and a few isolated snow
showers across SW MT that could cause brief MVFR to IFR conditions.
Ludwig

Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.
-- End Changed Discussion --

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  39  18  38  20 /  10  10  10   0
CTB  36  17  36  20 /   0   0  10   0
HLN  42  22  43  24 /  10  10   0   0
BZN  42  19  44  19 /  10  10  10   0
WYS  36  10  42  12 /  10  10  10   0
DLN  41  19  43  22 /  10  10  10   0
HVR  39  21  40  20 /   0  10  10   0
LWT  35  15  34  17 /   0  10  10   0

&&

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

$$

http://www.weather.gov/greatfalls