384
FXUS65 KGGW 280901
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
301 AM MDT Sun Apr 28 2024

.DISCUSSION...
KEY MESSAGES:

1) For the 24-hour period ending at 6 AM Tuesday, there is a
80-90% chance of a wetting rain (at least 0.1 in) for most of
northeast Montana. The chance for at least 0.25 in and 0.5 inches
of rainfall for the same period maxes out at 50-70% and 20-40%
chance, respectively.

2) Winds pick on Tuesday, with gusts as high as 45 to 50 mph
possible.

3) Tuesday and Wednesday, area of precipitation moves north of the
Missouri River as high pressure builds across southern Montana in
the wake of the surface low pressure system passage.


WEATHER PATTERN OVERVIEW:

A shortwave trough moving through this morning will provide
chances for precipitation in our western zones, but diminish as
this area moves west through the day. Then, an upper level trough
moves in across the areas, bringing chances for precipitation
through at least Tuesday for northeast Tuesday, as described
probabilistically above.

From Tuesday, a shortwave ridge aloft builds and moves across
southeast MT, resulting in surface high pressure moving areas of
precipitation generally north of MT Hwy 200. As the high pressure
builds to the south, a tight pressure gradient develops from
northwest MT into eastern Montana. This increases winds speed,
mainly south of the Missouri River, with a medium to high chance
for at least 40 mph gusts, but low chance (<20%) for gusts in
excess of 55 mph. Given this, not issuing any wind headlines at
this moment, but will discuss with the next shift as we could
likely issue the Lake Wind Advisory on their shift. Discussion
regarding fire weather headlines is provided in the Fire Weather
Forecast. Chances for precipitation shifts north thanks to this
surface high pressure influence from the south. The chances for at
least 0.25 inches for the period from Tuesday through Wednesday
ranges from 30 to 50% for areas north of the Hi-Line.

From Thursday, the trough fills and moves into the Great Plains,
placing the region in northwest flow aloft, resulting in chances
for daily afternoon showers.


CONFIDENCE AND POTENTIAL DEVIATIONS FROM BASE FORECAST:

NBM has tended to underestimate the last few wind events across
the region, so will have to monitor the next run to see if the
winds for Tuesday increase. This will dictate headline decisions.

-Enriquez



&&

.AVIATION...
LAST UPDATED: 0900Z

FLIGHT CAT RANGE: VFR (MVFR in isolated shower) today. MVFR from
Monday morning

DISCUSSION: Morning showers along the island ranges of central and
eastern Montana will move east this morning, diminishing as they
do so. Monday, rain showers move in from south central Montana
moving northeastward through the day.

-Enriquez

&&

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

$$

weather.gov/glasgow