842
FXUS65 KGGW 170908
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
308 AM MDT Sat May 17 2025

.DISCUSSION...

KEY MESSAGES:

- Lows tonight will be near freezing along the ND and parts of the
  Canadian border.

- A Lake Wind Advisory has been issued for gusty east winds from
  this evening through Sunday evening.

- The next low pressure system looks to bring rain opportunities
  from Sunday afternoon through early next week.


WEATHER PATTERN OVERVIEW:
A weak stationary front is allowing light rain showers to move
through the central portion of the area, with high confidence of
accumulation remaining below 0.05 inches through noon. There is
moderate (40 percent) confidence of temperatures reaching the
freezing mark north of the Hi-line, as well as on a line from
Wolf Point to Terry eastward.

An oncoming upper trough and surface low pressure system will move
in on Sunday afternoon. East to southeast winds will crank up this
evening, with gusts to 40 mph likely in many locations going into
Sunday. There is high confidence of little to no rain
accumulation occurring through 6 AM Sunday. Then the system will
push northward from the intermountain west into central Montana.
Beside the wetter conditions that occurred along the North Dakota,
there are still drought conditions across much of the area. This
is the justification for reducing the total rainfall forecast for
Sunday and Monday. There is high confidence in central Montana
receiving more rainfall than eastern Montana with this system.
There is low (30 percent) confidence of rainfall amounts, but what
can be said is that there is high (80 percent) confidence of
greater than a tenth of inch of rainfall occurring west of line
from Jordan to Saco on Sunday through 6 PM Monday.

An active pattern will remain in place after Monday night, but
there is low confidence on timing and placement of shortwave
troughs, as well as on precipitation amounts during the week.

FORECAST CONFIDENCE & DEVIATIONS:
Overall, confidence is high on precipitation remaining below 0.05
inches through 6 AM Sunday. There is high confidence of
precipitation accumulating more in central Montana than in eastern
Montana from Sunday into Monday. There is low to moderate
confidence of fog occurring this morning over the eastern zones
given the recent rainfall, light winds, and partly cloudy skies.

For deviations, dropped the QPF for Sunday into Monday a decent
amount due to drought conditions remaining in place across much of
the area.


&&

.AVIATION...

UPDATED: 0900Z

FLIGHT CAT RANGE: VFR - MVFR

With recent rainfall near KGDV and KSDY, there is enough moisture
to help with fog potential this morning. There is low to moderate
(20 to 40 percent) confidence of fog bringing MVFR ceilings and
visibilities through 12Z this morning. There is moderate to high
(40 to 60 percent) confidence of this clearing off after 12Z. VFR
conditions are expected afterward.

WINDS: For KGGW, southeast at 6 to 15 knots increasing to 15 to 20
knots after 21Z. For all other sites, light and variable, becoming
southeast at 5 to 10 knots after 15Z, increasing to 10 to 15 knots
after 18Z.

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory from 6 PM this evening to midnight MDT Sunday
night for Central and Southeast Phillips-Central and Southern
Valley-Garfield-McCone-Petroleum.

&&

$$

weather.gov/glasgow