textproduct: Glasgow

KEY MESSAGES

- More seasonable temperatures are expected Monday and Tuesday with mainly dry weather. There may be a lone stronger thunderstorm in the northeast each evening.

- A warming trend is likely through the week with triple digit temperatures potentially returning by Friday or Saturday.

DISCUSSION

WEATHER PATTERN OVERVIEW:

Upper ridging over the western and central portions of the U.S. extends into eastern Montana Monday and Tuesday. Given NE Montana will be on the northeast quadrant of the ridge under northwest flow aloft, weak embedded shortwaves may be enough to set off a few thunderstorms across the northeast zones Monday and/or Tuesday evening. It should be a fairly isolated but potentially strong storm via high res model guidance, so will keep patches of slight chance or silent pops in place.

As an aside, wind speeds may marginally support Lake Wind criteria for Fort Peck Lake this afternoon, especially near the dam. These breezy conditions are expected to be small in coverage and short in duration so have opted not to issue an advisory at this time.

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 with the diurnal heating and instability, and weak embedded disturbances. Most places however will remain dry this period.

The ridge axis will begin to slide downstream 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 may offer utility.

FORECAST CONFIDENCE & DEVIATIONS:

Ensemble consensus is fairly solid depicting upper ridging over the foreseeable future. This lends to above average confidence for hot and mostly dry weather through the week. Confidence is below average for specific timing and placement of thunderstorms through the next couple of days due to limited expected coverage. That said, its evolution is depicted in updraft helicity tracks among the high resolution model suite. Confidence is lower on convection during the mid to end of the week due to the later time scales.

AVIATION

LAST UPDATE: Monday July 20 at 0430Z.

FLIGHT CAT RANGE: VFR.

DISCUSSION: Upper ridging extending over the region will keep mostly dry weather conditions over area terminals through the taf period.

WIND: Light and variable winds this morning will become Northwest at 10 to 20 kts after 18Z.

GGW WATCHES/WARNINGS/ADVISORIES

None.