218
FXUS65 KGGW 132124
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
324 PM MDT Thu Jun 13 2024

.DISCUSSION...

KEY MESSAGES:

- Showers and thunderstorms possible Friday afternoon and evening
  with a marginal chance for severe storms from Glendive
  southward.

- Widespread rain possible on Monday and Tuesday along with
  cooler temperatures.

WEATHER PATTERN OVERVIEW:

Slight upper ridging over the region today as large low in the
Gulf of Alaska begins to drift toward the Pacific Northwest. Quasi
closed low over southern California will phase with a weak impulse
out of the north Pacific low to cross the Rockies on Friday,
spawning thunderstorms along the entire Front Range. Across
Montana, development of a lee surface trof and strengthening low
level jet, will bring boundary layer moisture north across the
plains. With forcing from the shortwave, and daytime instability,
potential for strong thunderstorms high enough for a marginal risk
area from SPC to extend into the southeast zones.

Sporadic storms will continue through the weekend with the upper
trof moving onshore and through the northwest states into the
middle of next week. The prolonged period of rain will be due to a
splitting of the upper low as it moves across the Pacific
Northwest. The first portion will lift into the Canadian Prairies
over the weekend, with the second portion digging southward before
moving east early next week. The digging trof will also pull
colder air into the region, pushing temperatures below normal for
next week.

FORECAST CONFIDENCE and DEVIATIONS:

There is a moderate to high (50-80%) probability for a wetting
rain (0.10") across much of the region with the weekend system
with the highest chances in the northeast corner of the state.

For the Monday/Tuesday system, QPF amounts are higher, with a
probability around 70% for at least 0.25", around 60% for 0.50",
and around 30% for 1".


&&

.AVIATION...
VFR. Clear to partly cloudy skies through tonight. Clouds will
increase from the west early Friday morning with the approach of a
frontal system along with an increase in southeast winds.
Thunderstorms are possible as early as mid Friday afternoon, with
stronger storms possible around KGDV in the evening.

EQUIPMENT: METARs are missing for KSDY, thus AMD NOT SKED.



&&

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

$$

weather.gov/glasgow