Brockton, Montana Weather Forecast Discussion

278
FXUS65 KGGW 180802
AFDGGW
Area Forecast Discussion
National Weather Service Glasgow MT
202 AM MDT Thu Sep 18 2025
.DISCUSSION...
KEY MESSAGES:
- Isolated patchy fog may be possible in the far northeast this
  morning.
- A weak lift zone associated with exiting low pressure will
  generate isolated to scattered showers and thunderstorms
  throughout the day today.
- Dry and warming conditions are expected Friday through Sunday.
WEATHER PATTERN OVERVIEW:
Today: The low pressure complex is starting to finally morph into
one single circulation, the center of which is now moving
southeastward through central South Dakota. A NW outer band of
isolated thunderstorms is moving westward along the hi-line early
this mronign and is expected to drop south into Phillips and
Garfield cloouty this afternoon. With peak diurnal heating this
lift zone will expand in size, but overall rainfall totals under
these small cells will likely be under a wetting rain(0.10") for
most locations that do get hit before it exits to the southeast
tonight.
Early morning fog is hinted at by GLAMP data in patchy locations
over the big sheep tops and along the Big Muddy and Missouri River
Valley bottoms. THis activity should disappear by about 9-10 AM.
Saturday through Monday, a new western states ridge of high
pressure will moving into our region, bringing warmer than average
temperatures and much drier conditions through Sunday. It will be
wise to monitor early next week for marginal fire weather
conditions. Afterward, the ridge will topple over by a cold front
Sunday night and Monday, which could bring scattered showers and
thunderstorms along with slightly stronger winds behind it.
MOnday night onward: Once the cold air associated with the cold
front moves through the area the ridge to the swoyuthwest looks
like it will begin to build again bringing more warming and dry
conditions.
FORECAST CONFIDENCE & DEVIATIONS:
Deviations were genereated today over northern Valley county into
northern Garfield county in the hourly PoPs to account for the
low pressure exterior lift zone that is generating a few
thunderstorms on radar and NLDN data early this morning. This lift
zone was not adequately captured by the NBM with near zero PoPs
until it moves over southern Phillips and northern Garfield later
this afternoon. Therefore, had to raise PoPs to account for this
migration and bridge radar trends from this morning to the larger
area of coverage this afternoon.
Confidence is average for precipitation timing, and amounts.
Confidence is high for the temperature forecast.
GAH
&&
.AVIATION...
UPDATE: 0800Z
FLIGHT CAT RANGE: VFR - IFR
DISCUSSION: The entire region remains under the influence of a
migrating low pressure system which is exiting to the southeast.
Expect low clouds and isolated precipitation to encroach westward
from North Dakota into NE Montana this morning and then blossom
into scattered showers and thunderstorms this afternoon and
evening. IFR level FOG will be possible near the KOLF and KSDY
terminals from 11 to 16Z this morning.
WIND: E to SE and under 10 kts this morning. rising to 5 to 15 kts
after sunrise through the day. Calming to less than 10 kts after
midnight/06Z through the remainder of the cycle.
EQUIPMENT: Comms issues with the KSDY observation remain. AMD NOT
SKED will remain in place until METARs are available.
&&
.GGW WATCHES/WARNINGS/ADVISORIES...
None.
&&
$$
weather.gov/glasgow

NWS GGW Office Area Forecast Discussion