004
FXUS65 KGGW 172045
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
245 PM MDT Sat Aug 17 2024

.DISCUSSION...

KEY MESSAGES:

 - A few additional thunderstorms are possible in the northeast
   corner of the state this afternoon and evening.

 - Several days of hot weather are expected starting on Sunday
   with highs in the mid 90s most of the time. A few locations
   could approach 100 degrees. The current probability of a 100
   degree high is 30% or less between from Sunday through
   Wednesday.

WEATHER PATTERN OVERVIEW:

For the big pictures, 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.

Closer to home, another embedded wave or slight disturbance moves
across southern Saskatchewan later this afternoon and evening,
which will bring a chance of showers and thunderstorms to the NE
corner of the state. The overall effect is to flatten out the
blocked ridge of high pressure a bit.

By Sunday, the upper ridge rebounds over Montana, 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, but seem more likely
by Monday evening, especially near and east of MT-Highway 24.

FORECAST CONFIDENCE & DEVIATIONS:

Average to low to average confidence on thunderstorm chances in
the northeast corner of the state this afternoon and evening. Low
confidence in the exact timing and placement of thunderstorms
Sunday afternoon and evening. Average to better than average
confidence in more widespread precipitation arriving by Monday
evening.

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: 2045Z, Saturday afternoon, August 17th

FLIGHT CAT: VFR throughout.

DISCUSSION: a few daytime low and mid level cumulus clouds are
expected this afternoon and evening. The NE corner of the state
could have an isolated thunderstorm this afternoon and evening,
but are not expected to impact any NE MT TAF sites. Skies will be
clear overnight.

WINDS: Winds will either be from the ESE around 10 kts or near
calm.


&&

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

$$

weather.gov/glasgow