729
FXUS65 KGGW 200650
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
1250 AM MDT Sun Sep 20 2026

.KEY MESSAGES...

- Flood Watch remains in effect for Dawson, Garfield, Petroleum,
  Prairie, and Wibaux counties through 6PM with additional rain
  totals between 0.25" and 0.5", most of it in the early morning
  hours today.

- Above average temperatures beginning Tuesday as upper riding
  builds. Highs peak near the end of the work week.


&&

.DISCUSSION...

- Synoptic Setup:

A low pressure system over Idaho continues tracking east across
northern Wyoming. As this exits east, high pressure moves into the
region. A much drier pattern will build through the end work week
and as southwest flow dominates. As the trough builds off of the
west coast, upper riding strengthens over the Northern Rockies
bringing above normal temperatures through Friday. A shortwave
trough pushing across the southeast on Wednesday may bring a
slight chance for some precipitation. Towards the end of the week
an upper level trough deepening over the PNW and pushing east
over the Rockies will push temperatures down closer to normal as
well as the next likely chance for precipitation.

The Flood Watch remains in effect for Dawson, Garfield, Petroleum,
Prairie, and Wibaux counties through 6PM with additional rain
totals between 0.25" and 0.5", most of it in the early morning
hours today. Low clouds presenting as patchy fog may drop
visibility to 2 miles in localized areas of higher terrain until
noon today, especially along HWY 200, 200S, and 253.

FORECAST CONFIDENCE & DEVIATIONS:
Blended 6 hours of SREF to better match PoPs with neighbors. No
change to NBM otherwise.

Low confidence in additional rain totals exceeding 0.5" as of 6Z.

&&

.AVIATION...
LAST UPDATED: 0530Z

FLIGHT CAT RANGE: KOLF and KGGW, MVFR becoming IFR after 10Z.
KSDY and KGDV, IFR/LIFR.

DISCUSSION: Scattered showers continue over KSDY and KGDV
progressing northward over KGGW and KOLF after 6Z. LIFR ceilings
over KGDV lower to near airport shutdown between 6Z and 16Z, KSDY
between 10Z and 16Z.

WIND: East at 5 to 15 kts with gusts to 22 kts, becoming
southeast at 5 to 10 kts after 6Z for all sites.

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Flood Watch through this afternoon for Dawson-Garfield-Petroleum-
Prairie-Wibaux.

&&

$$

weather.gov/glasgow