897
FXUS65 KTFX 301557 RRA
AFDTFX

Area Forecast Discussion
National Weather Service Great Falls MT
1000 AM MDT Tue Apr 30 2024

.SYNOPSIS...

A slow moving Pacific storm system will bring breezy to windy
conditions, below average temperatures and periods of rain and
snow through much of this week with more widespread precipitation
and periods of wintry conditions across portions of north-
central and central Montana Wednesday through Thursday.
Temperatures moderate some heading towards the weekend, but the
typically active spring weather pattern will persist for the
foreseeable future.

&&

.UPDATE...

Forecast is performing well; therefore, no updates are made, at this
time.
- Fogleman

&&


.DISCUSSION...

Satellite imagery this morning reveals a complex upper level low
taking shape over SW Canada with several notable shortwaves pivoting
around it, including a stronger wave approaching the Pacific NW and
weaker waves lifting out of the Northern Rockies and MT along the
International Border. While we spend most of today in between these
disturbances, cold/unstable westerly flow aloft and the arrival of
additional moisture ahead of the disturbance moving into the Pacific
NW will support the development of showers this afternoon, across
the western and southwest MT mountains. Areas near Glacier NP will
also see an increase in snow showers this afternoon as one of the
embedded disturbances within the larger scale low moves east along
the MT/AB border. Otherwise, breezy to windy and cooler conditions
will be noticeable with afternoon temperatures around 10 degrees
below seasonal averages and westerly winds with gusts 30-40 mph.
Highest winds speeds today will be near the Rocky Mtn Front and
central MT mountain ranges where a few gusts may exceed 45 mph,
particularly for a period late this morning through mid-day with the
passage of an embedded wind maximum.

The larger scale closed upper level low moves east of the Rockies
tonight with its circulation shifting slowly across MT/AB/SK through
Thursday. Models are in general agreement and continue to trend
somewhat slower with the arrival of more widespread precipitation
circulating into the forecast area. Widespread precipitation
develops across southern AB/SK in association with a TROWAL (trough
of warm air aloft) and shifts southwest into areas along the east
side of Glacier NP by Wednesday morning. Colder air aloft wraps into
the circulation Wednesday with widespread precipitation expanding
south and east across much of north- central MT by Wednesday
afternoon with moist/cyclonic NW flow now forecast to linger across
the area through at least Thursday afternoon. This has shifted the
more impactful period of winter precipitation for portions of
central MT to late Wednesday through Thursday, though precipitation
amounts have not changed significantly.

Winter storm warnings and advisories for The Glacier NP/Rocky Mtn
Front vicinity begin at midnight tonight with areas near the AB
border being initially impacted tonight before precipitation spreads
south on Wednesday. Winter weather advisories were added for the Big
Belt/Bridger and Snowy mountain ranges beginning Wednesday afternoon
with the Winter Storm Watch for the Little Belts continuing while
these highlights were extended through Thursday afternoon. There is
some potential for additional winter weather highlights across
portions of central MT adjacent to the Little Belts but considerable
uncertainty exists at these lower elevations due to marginal
temperatures with melting and compaction likely to limit
accumulation and impacts to roads. Still, the later onset of
precipitation towards Wednesday night and Thursday could allow for
some overnight accumulation and minor winter weather impacts to the
Thursday morning commute that will need to be watched.

Models continue to delay the exit of troughing from the area through
Friday though the bulk of the widespread precipitation should be
ending Thursday night. A brief period of ridging is possible early
this weekend before the next round of troughing arrives late this
weekend into early next week with models suggesting temperatures
remaining closer to seasonal averages for  this period. Hoenisch

&&

.AVIATION...
515 AM MDT Tue Apr 30 2024 (30/12Z TAF Period)

A somewhat moist and unstable westerly flow aloft persists across
the region today. Scattered showers exist near KHVR early this
morning with scattered shower development expected this afternoon
across much of southwest Montana. Mainly VFR conditions prevail with
some brief MVFR and mountain obscuration possible near early morning
and afternoon shower activity. Westerly surface winds with gusts 25-
35 kts develop at most terminals late this morning and continue
through this afternoon before diminishing this evening. Hoenisch

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

&&

.PRELIMINARY POINT TEMPS/POPS...
GTF  51  31  47  32 /  20  30  70  80
CTB  47  31  43  32 /  50  50  80  80
HLN  51  31  50  36 /  30  10  60  60
BZN  49  24  48  29 /  40  40  40  40
WYS  42  20  40  19 /  60  70  60  30
DLN  47  24  45  28 /  30  30  30  20
HVR  54  32  50  33 /  30  40  70  70
LWT  48  27  46  28 /  10  10  60  60

&&

.TFX WATCHES/WARNINGS/ADVISORIES...
Winter Storm Warning from midnight tonight to noon MDT Thursday
for East Glacier Park Region.

Winter Weather Advisory from midnight tonight to noon MDT
Thursday for Northern High Plains-Southern Rocky Mountain Front.

Winter Storm Watch from Wednesday morning through Thursday
afternoon for Little Belt and Highwood Mountains.

Winter Weather Advisory from noon Wednesday to 6 PM MDT Thursday
for Big Belt, Bridger and Castle Mountains-Snowy and Judith
Mountains.

&&

$$

http://www.weather.gov/greatfalls