014
FXUS65 KGGW 191951
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
151 PM MDT Sun May 19 2024

.DISCUSSION...

KEY MESSAGES:

- A low pressure system moving across southeast MT will continue
  to bring rain showers, with isolated thunderstorms for Prairie,
  Dawson, and Wibaux counties, through midnight tonight before
  ending.

- Unsettled pattern continues with daily rain and thunderstorm
  chances especially in afternoon and evenings for the upcoming
  week.

WEATHER PATTERN OVERVIEW:

A dreary day is occurring across much of the area in response to a
low pressure system passing south of northeast MT, with much below
average temperatures occurring across central MT. However, Prairie,
Dawson, and Wibaux counties are seeing some sunshine closer to the
surface low, which is providing enough daytime heating to
destabilize the atmosphere this afternoon. Therefore, there is low
to moderate (20 to 40 percent) confidence of a thunderstorm
producing severe wind gusts and hail in these counties between 4
PM and 6 PM.

A brief dry period is in store during the morning hours Monday
before more shower opportunities in the afternoon. There is high
(80 percent) confidence of rainfall remaining below a tenth of an
inch of accumulation on Monday.

The next reasonable opportunity for showers, thunderstorms, and
accumulation rainfall is on Wednesday and continues through Friday
night. Temperatures are expected to remain at or slightly below
normal through the end of the work week. In other words, there is
moderate to high (50 to 70 percent) confidence of a Canadian
trough affecting the area through Friday.

The GFS ensemble is suggesting a pattern change after next
weekend, with high (60 percent) confidence of temperatures staying
near normal to slightly above normal.


CONFIDENCE LEVEL and POTENTIAL DEVIATIONS FROM BASE FORECAST:

There is low (30 percent) confidence in thunderstorm strength on
Wednesday and beyond based on low surface-based CAPE values in
the GFS ensemble. Total rainfall amounts from Wednesday through
Friday night have been fluctuating quite a bit the past two days,
so there is low (30 percent) confidence on QPF amounts.

-GAH/Stoinskers

&&

.AVIATION...

LAST UPDATED: 2000Z

FLIGHT CONDITIONS: VFR - MVFR

DISCUSSION: A low pressure system moving through southeast Montana
is influencing northeast MT enough to bring in scattered rain
showers that are expected to last through midnight, with low to
moderate (20 to 50 percent) confidence of thunderstorms impacting
KSDY and KGDV. There is moderate (50 percent) confidence of MVFR
ceilings occurring after 21Z Monday within rain showers and
thunderstorms. Although precipitation will end by midnight, this
same confidence exists for MVFR ceilings lasting through 15Z
Monday.

WINDS: For KGGW, northwest at 10 to 15 knots. For KOLF, northeast
at 8 to 13 knots. For KSDY and KGDV, east northeast at 10 to 15
knots, becoming northwest. For all TAF sites, light and variable
winds after 03Z becoming northwest at 5 to 10 knots by 16Z.

-Stoinskers


&&

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

$$

weather.gov/glasgow