272
FXUS65 KGGW 111951
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
151 PM MDT Sun Aug 11 2024

.DISCUSSION...

KEY MESSAGES:

- Scattered showers and isolated thunderstorms through this
  afternoon, mainly south of the Missouri River.

- Temperatures will gradually climb to slightly above average over
  the next few days.

- Another system will help bring scattered showers and storms to
  the area throughout the week, with strong storms Tuesday into
  Tuesday night in eastern Montana.

WEATHER PATTERN OVERVIEW:
The low pressure center over the southeastern part of the GGW CWA
spawned a few more thunderstorms than CAMs were indicating in
Richland County. However, this activity will the last through late
this afternoon before pushing into ND. The Yellowstone River
Valley has the best opportunity for fog tonight due to higher
dewpoints from today`s rainfall. A reduction in visibility is
expected where fog does develop, and there is moderate (40
percent) confidence of this fog diminishing by 10 AM Monday.

With capping in place across the low elevations of northeast MT on
Monday evening, storm activity will be inhibited for the most
part. However, there is moderate (50 percent) confidence of a few
dying storms to impact the western portion of the CWA.

Then Tuesday, a shortwave trough ahead of an oncoming trough in
the Pacific northwest will make its way into northeast MT.
Temperatures will be above average ahead of this shortwave. With
moisture advection of upper 50s to mid 60s dewpoints along with
daytime heating ahead of this disturbance, breaking the cap will
be much easier on Tuesday than it has been for much of August.
Although confidence is low on exact location and timing, current
CAMs such as NAM NEST and HRW FV3 indicate that storms may
initiate on a line from Saco to Jordan before transitioning
eastward.

Wednesday onward will feature occasional shortwave troughs passing
through the region. However, there is low confidence on timing and
location of these disturbances. Temperatures are expected to
remain near average.

FORECAST CONFIDENCE & DEVIATIONS:

There is high confidence in a warming trend through Tuesday before
temperatures moderate after Tuesday. There is moderate to high
confidence of strong thunderstorms occurring on a line from Saco
to Jordan eastward on Tuesday. Although there is moderate to high
confidence in at least isolated convection each day after Tuesday,
there remains low confidence on total accumulation.

-Zanker/Stoinskers


&&

.AVIATION...

LAST UPDATED: 2045Z

FLIGHT CAT: VFR, MVFR for KGDV from 09Z to 16Z. Isolated IFR in
thunderstorms.

DISCUSSION: A weak low pressure system is expected to continue
influencing KSDY and KGDV through 02Z, with brief reductions to
IFR in scattered thunderstorms. Although VFR will be the main
flight category for TAF sites, there is low to moderate (30 to 50
percent) confidence of fog developing near KGDV tonight, which
may drop the category down to MVFR in the morning.

WINDS: Southeast at 7 to 15 knots. Erratic winds near
thunderstorms.



&&

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

$$

weather.gov/glasgow