619
FXUS65 KGGW 140656
AFDGGW

Area Forecast Discussion
National Weather Service Glasgow MT
1256 AM MDT Mon Sep 14 2026

.KEY MESSAGES...
- Accumulating rain showers and embedded thunderstorms at times
  going through 9 PM this evening beside low amounts in Petroleum
  and southwest Phillips counties.

- Winds will reach Lake Wind Advisory Criteria today. Wave heights
  will have the potential to reach 4 to 5 ft with localized areas
  to 6 feet on the widest parts of Fort Peck Lake.

- Slight chances for rain showers are possible Tuesday night and
  again Thursday night into the weekend.



&&

.DISCUSSION...
A low pressure system is on its way into the area, and rain
showers with weak thunderstorms have started moving into the west
and southeast parts of the area. This activity is expected to
increase and persist through 16Z, and moderate to heavy rain is
expected at times. As the system pivots northeastward, a break in
the rain is expected briefly before scattered showers and weak
storms move back in after 12 PM. This activity is expected to
leave the area after 8 PM. Winds will also come up after 8 AM this
morning. These west to northwest winds have potential to gust to
around 45 to 55 mph through about 8 PM before they gradually
decrease in the late evening.

The best chance for rain is through noon today, and the highest
amounts are expected on a line from Malta to Jordan. Up to 9
tenths of an inch is possible in the northeast, and two tenths to
a half inch in the southeast part of the area. The wind will make
the rain do some sideways action, so an extremely sturdy umbrella
will be needed. Maybe an umbrella made out of titanium or
something.

This system will move out late tomorrow evening, but a splitting
upper trough over the western CONUS will remain. This will
contribute to a chance of showers moving into the northwest and
southeast parts of the area. There is indication that any rain
amounts will remain below a wetting rain (one tenth of an inch of
accumulation).

Weak ridging is expected to move in on Wednesday and last through
Thursday afternoon before the next trough tries to move in from
the south on Thursday evening. There is moderate to high uncertainty
on the strength of the trough, so rainfall amounts are not
reliable enough to talk about in this forecast update.

FORECAST CONFIDENCE & DEVIATIONS:

The main deviation was to increase PoPs at various times through
9 PM this evening.

There is high confidence in winds across the area, and moderate
confidence in rainfall amounts through 9 PM today.

There is high confidence in timing of the next ridge, and low to
moderate confidence on the next trough.

&&

.AVIATION...
LAST UPDATED: 0630Z

FLIGHT CAT RANGE: VFR through 09Z, then a mix of MVFR and IFR.

DISCUSSION: A low pressure system is moving in and is already
bringing scattered showers and weak thunderstorms to KSDY and
KGDV. There is moderate to high (50 to 70 percent) confidence of
visibility dropping to 2 miles in heavy showers between 10Z and
15Z. There is low to moderate confidence of visibility lingering
around 6 miles for KOLF and KGGW after 15Z, and for showers to
linger for all sites between 19Z and 02Z.

SFC WIND: Southeast at 8 to 16 knots becoming west at 10 to 20
knots with gusts to 30 knots after 14Z, increasing to 20 to 30
knots with gusts to 45 knots after 18Z.

LLWS: There is low confidence of southerly low level wind shear
with gusts to 40 knots through 09Z for KSDY and KGDV.

&&

.GGW WATCHES/WARNINGS/ADVISORIES...
Lake Wind Advisory until midnight MDT tonight for Central and
Southeast Phillips-Central and Southern Valley-Garfield-McCone-
Petroleum.

&&

$$

weather.gov/glasgow