Area Forecast Discussion Issued by NWS Great Falls, MT
000
FXUS65 KTFX 261114
AFDTFX
Area Forecast Discussion
National Weather Service Great Falls MT
515 AM MDT Tue Mar 26 2024
Updated Aviation Discussion
.SYNOPSIS...
Scattered light snow showers will become more numerous this
afternoon, especially across central and southwest Montana.
Breezy and milder conditions move in mid- week before another
series of weather systems bring cooler temperatures and areas
precipitation for the second half of the week.
&&
.DISCUSSION...
Montana remains under a cyclonic northwest flow aloft on the
southwest periphery of an upper level trough over central Canada.
Meanwhile, a narrow upper level ridge extends north through BC
with several shortwave disturbances and some associated moisture
moving over a broad ridge in the eastern Pacific and undercutting
the BC ridge before tracking southeast across the Northern Rockies
and MT through tonight. Moist low level easterly flow across the
plains is supporting some low cloud development this morning with
potential for some areas of fog as well.
Scattered snow showers will become more numerous this afternoon,
especially south and west of a line from Cut Bank to Great Falls
to Judith Gap where modest low level instability is expected to
develop with daytime heating. High resolution models indicate some
banding of snow showers is possible as well this afternoon with
the main impact being quickly changing conditions for those
encountering snow showers, but these should be very brief with
little or no accumulation at lower elevations. NW flow pattern
favors better chances for repetitive snow showers across the
Little/Big Belts, Bridger and Gallatin ranges this afternoon where
there is a 50-60% probability of snow accumulation around an inch
at Bozeman pass and similar probability for 2 inches over Deep
Creek Pass and Kings Hill.
Upper level ridging then shifts east across the Rockies Tuesday
night and Wednesday for a drier period with temperatures warming
back to seasonal levels. The shift to westerly flow will bring
some increased winds, initially along the Rocky Mtn Front, but
spreading to most of the area by Wednesday afternoon. Strong winds
are not anticipated but there is a 60% or higher probability for
gusts in excess of 40 mph along areas adjacent to the Rocky Mtn
Front as well as through the Madison River Valley through Three
Forks. Any drifting snow impacts should be minimal and confined to
the onset of winds early Wednesday.
The drier period is short-lived with the next Pacific upper trough
approaching the west coast by Thursday. Southwest flow ahead of
the trough will bring an initial wave of moisture with an embedded
Pacific cold front moving across the region Thursday. This is a
fairly quick moving system with probabilities for precipitation
amounts of 0.25” or more ranging from 20% or less at lower
elevations to around 60-70% across some of the southwest MT
mountain ranges. Snow accumulations of 2 inches or more are
similarly likely (>50% chance) across the southwest MT mountains
with the passage of this system. Medium range model ensembles are
in agreement to split the offshore trough with a closed low
tracking southeast toward CA by the weekend. Further north there
is some spread in the degree of northern stream troughing to
affect the northern Rockies and MT. This would still provide a
cooler and unsettled pattern for the upcoming weekend with still
some uncertainty regarding precipitation. Hoenisch
&&
.AVIATION...
515 AM MDT Tue Mar 26 2024 (26/12Z TAF Period)
A moist NW flow aloft with embedded disturbances will maintain
widespread mid level clouds and some mountain obscuration across the
region today with widely scattered snow showers across mainly
central and southwest MT this morning increasing in coverage this
afternoon. Areas of low clouds and patchy fog will impact some north-
central MT terminals as well as the Helena area this morning with
some local IFR/LIFR, mainly for ceilings. Showers this afternoon
will likely be brief in duration but could bring some quick
reductions to MVFR cigs/vis at times, primarily across SW MT
terminals. Surface winds remain light and variable at most north-
central MT terminals with a period of breezy west/northwest winds
likely this afternoon at SW MT terminals. Hoenisch
Refer to weather.gov/zlc for more detailed regional aviation
weather and hazard information.
&&
.PRELIMINARY POINT TEMPS/POPS...
GTF 37 24 47 31 / 20 10 0 0
CTB 34 21 44 25 / 10 10 0 0
HLN 45 28 52 33 / 50 20 0 10
BZN 43 21 49 30 / 50 30 0 10
WYS 37 14 37 25 / 70 40 10 60
DLN 42 23 47 31 / 40 20 0 20
HVR 26 13 41 24 / 10 0 0 0
LWT 34 20 47 29 / 40 10 0 0
&&
.TFX WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
http://www.weather.gov/greatfalls