Area Forecast Discussion

KEY MESSAGES

- Patchy fog still lingers this afternoon and will continue through at least tomorrow morning.

- Light rain will begin tomorrow afternoon lasting into into trick or treating hours.

- Precipitation chances will increase on Monday as a frontal system moves across the region.

DISCUSSION

Light rain will slowly move northeast into the region tomorrow afternoon and linger overnight as it pushes east. Most locations look to have a damp and chilly Halloween evening. Fog will continue to impact portions of the region again tonight into tomorrow morning. The most likely impacted areas will be along river valleys. Fog could become locally dense, reducing visibility in spots to 2 mile or less.

Meanwhile, as the upper ridge axis shifts northeast, a new Pacific trough will gain influence late in the weekend into early next week. Southwest flow aloft in advance of the trough with an approaching shortwave will lead to breezy winds and increased widespread precipitation chances late Sunday as surface low across Wyoming tracks into the Dakotas. Models continue to trend higher totals toward favoring southeast Montana, including Glendive and Sidney. No snow is expected at the time of this forecast update.

FORECAST CONFIDENCE & DEVIATIONS:

No changes to NBM this cycle.

A lot of uncertainty regarding fog overnight. There's very little model agreement in location, timing, and intensity. I have the most confidence in areas that saw fog last night/this morning seeing fog again overnight. Further more, model agreement after Wednesday is noticeably low.

AVIATION

LAST UPDATED: 1900Z

FLIGHT CAT RANGE: FR to IFR during patchy fog.

DISCUSSION: Lingering MVFR/IFR stratus will break during brief periods through the afternoon. Low stratus and patchy fog cannot be ruled out again overnight.

WIND: East winds 10 to 15 kt decreasing overnight. Light and variable thereafter.

GGW WATCHES / WARNINGS / ADVISORIES

None.