691
FXUS65 KGGW 120823
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
223 AM MDT Wed Mar 12 2025

.DISCUSSION...

KEY MESSAGES:

- A warming trend continues into Thursday. There is potential to
  challenge record highs in the afternoon.

- Colder conditions following a cold front will bring unsettled
  weather on Thursday and Friday.

WEATHER PATTERN OVERVIEW:

An upper ridge will be building along the front range, which will
allow warm air advection to occur today and tomorrow. With a
stationary boundary and weak ascent over the area, there are
multiple CAMs indicating sprinkles and flurries this evening into
the early overnight. By Thursday a deep, Pacific trough will move
onshore, and a low pressure system will develop over southern
Alberta/north central Montana. As the upper trough continues
eastward it is expected to develop a split, which will pull the
surface low southward until a deep closed low develops over the
southern plains Thursday night.

As the surface low moves south across Montana on Thursday
night into Friday, a band of precipitation will slide through the
region. The precipitation is expected to start as rain, then
transition to snow as colder air moves in from the north. There is
100 to 300 J/kg surface based CAPE forecast by the HRW FV3, HRRR,
and NamNest on Thursday afternoon, so any thunderstorms that
develop will be on the weak side.

There is moderate to high confidence of a ridge beginning to build
on Sunday. There is low confidence this will be followed by a
trough early next week.

FORECAST CONFIDENCE & DEVIATIONS:
For deviations, blended GFS 1 hour and NamNest to get a better
representation of POPs early this morning and for the sprinkles
and flurries this evening. Used NBM90 for winds for day 1 and 2 of
the forecast.

There is moderate confidence of light precipitation occurring this
evening. There is high confidence of a band of precipitation
moving in on Thursday afternoon into Friday. There is low to
moderate confidence of precipitation exceeding one tenth of an
inch with the entire system. There is low to moderate confidence
of thunderstorms developing in central Montana on Thursday
afternoon. There is high confidence of a ridge moving in on
Sunday, with low confidence on a trough moving in early next week.
There is low to moderate potential for icing conditions with
temperatures dropping to around or below freezing on Friday
morning.

&&

.AVIATION...

LAST UPDATED: 0900Z

FLIGHT CAT RANGE: VFR.

DISCUSSION: There is an isolated opportunity for light rain and
snow showers before 12Z with a break during the day expected.
There is low to moderate confidence of scattered rain and snow
showers moving through late in the afternoon and evening. This
activity is expected to end after midnight tonight.

WIND: Light south winds, becoming south southwest at 8 to 17
knots after 16Z, becoming southeast after 00Z Thursday.
OUTLOOK: The next cold front to move through will be late
Thursday as south winds turn to the west then increase from the NW
Friday. There is low confidence of thunderstorms occurring closer
to central Montana with this disturbance on Thursday afternoon
These storms are not expected to move into the TAF sites at this
time.

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&

$$

weather.gov/glasgow