Fallon, Montana Weather Forecast Discussion

482
FXUS65 KGGW 150820
AFDGGW
Area Forecast Discussion
National Weather Service Glasgow MT
220 AM MDT Mon Sep 15 2025
.DISCUSSION...
KEY MESSAGES:
1) Upper trough pattern will keep isolated to scattered
thunderstorms at times over the region today into Tuesday.
2) Fog is once again impacting eastern locations through late this
morning.
3) Drier weather conditions are expected for the second half of
the week with seasonable temperatures continuing.
WEATHER PATTERN OVERVIEW:
A broad trough with embedded low pressure centers will continue
impacting the region through Tuesday. These slow moving lows are
helping get another round of dense fog going in the east, with
moderate confidence of this fog making it into the Yellowstone and
Missouri River valleys through late this morning. Then two lows
will converge over the area and bring scattered thunderstorms to
the area. A Dense Fog Advisory has been issued for Sheridan County
On Wednesday, a dry, continental low will push down from the north
to keep weather more quiet. There is low confidence of the upper
trough retrograding back east to bring isolated showers and
thunderstorms to the eastern part of the area on Thursday and
Friday.
FORECAST CONFIDENCE & DEVIATIONS:
Main deviations are winds were mixed with NBM 90 for Day 1. PoPs
have been adjusted in Day 1 and 2 due to the NBM under forecasting
precipitation chances.
High confidence of dense fog remaining in Sheridan County through
at least 9 AM. There is low to moderate confidence of dense fog
forming along the Yellowstone and Missouri River valleys along the
eastern border. There is low confidence of the trough on Thursday
and Friday retrograding back into the eastern portion of the area
to bring showers and storms.
&&
.AVIATION...
LAST UPDATE: 0215Z
FLIGHT CAT RANGE: For KGGW and KGDV: VFR to MVFR. For KSDY and
KOLF: VFR to Airport Shutdown.
DISCUSSION: Dense FOG has set up over KPWD due to a slow moving
low pressure system in the east. There is moderate (50 percent)
confidence of KOLF and KSDY seeing dense fog through 16Z this
morning. There is moderate to high potential of KOLF reaching
airport shutdown in this time frame, and moderate potential for
KSDY. Then scattered thunderstorms after noon today will bring
potential for MVFR conditions.
WIND: For KGGW, southeast at 7 to 12 knots becoming light and
variable, becoming northwest at 8 to 15 knots after 18Z. For all
other sites, light and variable becoming northwest at 7 to 12
knots after 18Z.
EQUIPMENT: NOTAM comms issues with the KSDY observation remain.
AMD NOT SKED will remain in place until METARs are available.
&&
.GGW WATCHES/WARNINGS/ADVISORIES...
Dense Fog Advisory until 9 AM MDT this morning for Sheridan.
&&
$$
weather.gov/glasgow

NWS GGW Office Area Forecast Discussion