textproduct: Glasgow

KEY MESSAGES

- Slightly cooler temperatures today with a warming trend through the week bringing triple digit temperatures by Friday or Saturday.

- Daily rounds of isolated showers and thunderstorms in the afternoons and evenings by mid week.

- Drier and windier conditions this weekend will increase fire weather concerns.

DISCUSSION

WEATHER PATTERN OVERVIEW: Upper ridging over the western and central portions of the U.S. extends into eastern Montana through the beginning of the week, continuing the warm, but seasonally average, temperatures. Given NE Montana will be on the northeast quadrant of the ridge under northwest flow aloft, a weak embedded shortwave may be enough to set off a few isolated showers around mid-day today.

For Wednesday into Friday, upper ridging amplifies as the ridge axis pushes across central Montana and adjacent Canada with a warming trend resuming. Conditions will largely be dry save for an isolated thunderstorm forming over the central Montana mountains in the afternoon with the diurnal heating and instability, and the weak embedded disturbances that might drag it across northeast Montana in the evening hours. Most places however will remain dry through this period. As of now monsoonal moisture looks to remain just south of the region across southern Montana, giving an overall drier setup.

The ridge axis will begin to slide east Into the region on Friday into the weekend, lending to a return to triple digit heat across the area as well as a continuation of thunderstorm chances at times. If the current ensemble means hold, eventual heat related products will be necessary. Some ensemble members begin to slide the ridge axis farther east into North Dakota Sunday night through Tuesday which should open up higher chance for monsoonal showers across the region and may drop temps a little into early next week. But confidence in this ridge axis slide is low.

Haze from smoke across Washington and Oregon has thankfully not quite reduced visibility below 10 SM, and therefore has not yet become nuisance enough to place in the grids directly. So, Big Sky Country may have to wait awhile longer to get its namesake back.

FORECAST CONFIDENCE & DEVIATIONS: Changed hourly default NBM PPI01 PoPs with a CAMs Blend of NPoPs for mentionable mid-day shower chances today. Ensemble consensus is fairly solid depicting upper ridging over the foreseeable future. No changes to NBM otherwise.

GAH

AVIATION

LAST UPDATE: 0530Z

FLIGHT CAT RANGE: VFR

DISCUSSION: Upper ridging extending over the region will keep mostly clear skies and dry weather over area terminals through the TAF period. Some virga with downdrafts may be possible just south of the terminals mid-day Wednesday.

WIND: N to E and 10 kts or less tonight through Tuesday afternoon. Becoming all E Tuesday evening thorugh the night.

DENSITY ALTITUDE issues will begin to return to the terminals Friday through the Weekend.

/GAH

GGW WATCHES/WARNINGS/ADVISORIES

None.