193
FXUS65 KGGW 170803
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
203 AM MDT Sat Aug 17 2024

.DISCUSSION...

KEY MESSAGES:

 - A short-wave trough will bring thunderstorms at times this
   morning. Gusty winds, and brief heavy rain are possible.
   Additional storms are possible in the northeast corner of the
   state this afternoon and evening.


 - Several days of hot weather is expected starting on Sunday
   with highs in the 90s most of the time. A few locations could
   reach 100+. The probability of a 100 degree high is 30% or less
   between Sunday and Wednesday at this time.


WEATHER PATTERN OVERVIEW:

Upper lows/troughs will be on the Pacific Coast and over the Great
Lakes for the next several days with a blocking ridge over Rockies
and Great Plains in an Omega Block pattern.

A shortwave trough will move through eastern Montana this morning
with showers and thunderstorms at times. Another wave moves across
southern Saskatchewan in the late afternoon and this evening which
will bring a chance of showers and thunderstorms to the NE corner
of the state. These waves will flatten the ridge today.

The upper ridge rebounds over Montana over on Sunday with warmer
high temperatures mainly in the mid 90s from Sunday through
Wednesday. Weak disturbances moving through the ridge could bring
showers and thunderstorms at times each day.
FORECAST CONFIDENCE & DEVIATIONS:

Average to good confidence on the shower and thunderstorm chances
this morning. Low to average confidence on thunderstorm chances
beyond this morning.

With respect to high temperatures from Sunday onward, the
probability of reaching 100F for max temperatures is highest for
locations in lower elevations of adjacent river valleys, though
these probabilities of exceedance do not go above a 30% chance.
We will have to carefully monitor the trends for the 500 hPa high
pressure and how much heights increase in subsequent model runs
and to see if we creep back up to the 100s.


&&

.AVIATION...

UPDATED: 0800Z, Saturday morning, August 17th

FLIGHT CAT: Mainly VFR with occasional MVFR.

DISCUSSION: scattered showers/thunderstorms will move east across
the area this morning with mid and high clouds. Look for possible
gusty/erratic winds in the vicinity of them. Some daytime cumulus
is expected this afternoon. The NE corner of the state could have
an isolated thunderstorm this afternoon and evening. Skies will be
clear overnight.

Haze will linger this morning and clear during the day today.

WINDS: East, SE and south 5 to 10 knots this morning with
stronger and erratic winds near thunderstorms. Winds will be SE 10
to 15 knots this afternoon and east 5 to 10 knots tonight.

&&

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

$$

weather.gov/glasgow