261
FXUS65 KGGW 211051
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
451 AM MDT Tue May 21 2024

.DISCUSSION...

KEY MESSAGES:

- A more widespread chance for showers and thunderstorms will
begin late Wednesday through Friday. Unsettled weather will remain
likely at times into the upcoming weekend.

WEATHER PATTERN OVERVIEW:

An upper trough will prevail across the western CONUS this week
with occasional shortwaves helping produce enough lift and
instability for daily shower and thunderstorm chances.

A more organized low pressure system will track through the
northern Rockies for the second half of this week with a more
widespread opportunity for wetting rains from showers and
thunderstorms. This unsettled weather pattern looks to linger
into the upcoming weekend.

CONFIDENCE LEVEL and POTENTIAL DEVIATIONS FROM BASE FORECAST:

Confidence is high that a wetter weather pattern is set to unfold
for the second half of this week with ensembles showing strong
consensus for a broad trough pattern and low pressure system
pushing through the region. Confidence is lower on exact
precipitation amounts and precise location given the convective
nature of expected precipitation, but in general, expecting
greater QPF to the southwest and lesser to the northeast.

For now, have decided to remain close to the base forecast given
that the NBM lines up with consensus view of a cool but wet
pattern unfolding and the above average confidence. As the event
works its way into the short term and human detail gains greater
input value, some deviations become increasingly likely to better
capture mesoscale details and placement of precipitation.


&&

.AVIATION...
VFR conditions. Mid level clouds are expected across the north
with a few shower along the Canadian border this morning.

DISCUSSION: Mainly clear skies are expected tonight while
isolated showers over north-central Montana mainly move into
southern Sask tonight.

Isolated to scattered showers will develop SW of the terminals
this afternoon and evening.


&&

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

$$

weather.gov/glasgow