476
FXUS65 KGGW 191839
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
1239 PM MDT Sat Sep 19 2026

.KEY MESSAGES...
 - A Flood Watch is in effect through tomorrow evening for
   Petroleum, Garfield, Prairie, Dawson and Wibaux Counties. There
   is a decent chance of moderate rain south of MT 200 from
   Winnett to Glendive as well as south of I-94 through Wibaux.
   Embedded thunderstorms are possible and can cause local heavier
   rainfall. Light rain is possible north of the Missouri River
   tonight into tomorrow morning.

- A moderately strong ridge is expected to move in on Monday,
  which will bring above average temperatures from Tuesday through
  Friday.





&&

.DISCUSSION...

SYNOPTIC SETUP:

A low pressure system over Idaho this morning is tracking east
across southern Montana and northern Wyoming for the rest of today
and tomorrow. This system is cutoff by a northern stream shallow
ridge in the Canadian Prairies which is leading to dry air cutting
off areas north of a line from Malta to Medicine Lake. There has
already been over an inch of rain in southern Garfield County.
This will in our awareness through tomorrow. There may even be an
extension to the Flood Advisory that is in effect there. Up to an
additional half inch of rain is expected for southern Garfield
County. This includes Prairie, Dawson, Wibaux, and the southern
half of Richland county through noon Sunday before the system
moves east.

A moderately strong ridge is expected to move in on Monday, and
temperatures are expected to rebound above average from Tuesday
through Friday. There may be a shortwave trough across the
southeast to bring a slight chance of precipitation on Wednesday
evening though.

FORECAST CONFIDENCE & DEVIATIONS:
The only deviation was to increase winds at high elevation
locations through tomorrow.

There is moderate to high confidence in rainfall amounts through
tomorrow evening.

There is high confidence of an upper ridge moving in on Monday,
and low confidence on accumulating precipitation moving in on
Wednesday evening.

&&

.AVIATION...
LAST UPDATED: 1830Z

FLIGHT CAT RANGE: For KOLF and KGGW, VFR becoming IFR after 07Z,
becoming LIFR after 12Z (near airport shutdown for ceilings),
becoming IFR after 21Z Sunday.

For KSDY and KGDV, MVFR/IFR becoming IFR/LIFR after 07Z (near
airport shutdown from 12Z to 18Z for ceilings).

DISCUSSION:

Scattered showers are occurring around KSDY and KGDV with mostly
low clouds in the area currently. The rain showers are expected to
progress northward over KGGW and KOLF by 06Z. There is moderate to
high (50 to 70 percent) confidence of IFR conditions occurring
(please refer to the timing above the DISCUSSION section). There
is low to moderate (30 to 50 percent) confidence of LIFR occurring
for all sites from 12Z to 18Z. There is low to moderate confidence
of moderate to heavy rain occurring from 06Z to 15Z for KSDY and
KGDV as well.

SFC Wind: Ranging from northeast at 7 to 17 knots with gusts to
22 knots becoming southeast after 18Z for all sites.

&&

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

&&

$$

weather.gov/glasgow