textproduct: Glasgow

KEY MESSAGES

- A cold front today will bring scattered showers and thunderstorms. Strong to severe thunderstorms are possible in the far east this evening.

- A Lake Wind Advisory is in effect from 3 PM to 9 PM this evening. - Monday will be dry before an upper trough brings cool and partially wet weather through the end of the work week.

DISCUSSION

WEATHER PATTERN OVERVIEW: An upper trough continues to remain just off to the west, so this is providing upper level support for organized thunderstorms. This activity is mostly going to be focused east of a line from Scobey to Terry. Severe weather is most likely going to be in the far southeast if it occurs, with isolated gusts up to 80 mph and 1 inch hail possible. Wibaux county is the closest to this worst case scenario. Most models suggest severe weather will stay to the south though. Any severe weather reports would be greatly appreciated if storms move through your area. When it comes to hail size, references to things that are consistently the same round diameter, such as coin sizes, are the most helpful. A cold front will swing through the area 3 PM today, so temperatures will begin dropping before sunset. This front will also bring a brief period of showers and wind to the western two thirds of the area. Skies are expected to clear after midnight and a dry day on Monday is in store. One other nice thing is the northeast part of the area got some rain over the past few days, and hopefully will get a bit more tonight and Monday night so that fire conditions stay quiet.

On early Tuesday morning, the upper trough will still be pivoting and cycling above the area, so this will aid in getting a low level jet going at 850 millibars. This will start pushing a plume of low level moisture into the southeast, so scattered thunderstorms are forecast by a few models from 1 AM Tuesday through 6 AM. There will be weak instability by the afternoon, so below severe thunderstorms and showers are expected to develop for various locations in the area.

Beyond Tuesday, the upper low will continue to stay overhead. The GFS ensemble suggests this low will be effecting the area through June 13th, so scattered showers and storms will continue to be part of the story through at least the end of the work week.

FORECAST CONFIDENCE & DEVIATIONS: No deviations were made.

There is low to moderate confidence in severe thunderstorms impacting the far east this evening. There is moderate confidence in accumulating rain showers occurring for the remainder of the area. There is high confidence in the Lake Wind Advisory for this evening.

There is moderate confidence in showers and thunderstorms occurring on Tuesday in the southeast during the morning, and similar confidence in the afternoon. A few storms may be strong.

There is high confidence in slightly below normal temperatures and scattered showers and storms occurring through the end of the work week.

AVIATION

FLIGHT CAT RANGE: VFR - MVFR. IFR possible from 23Z to 03Z for KSDY and KGDV.

DISCUSSION: There will be low and mid level clouds today with a low pressure system still centered in western North Dakota. KGDV and KSDY are the closest TAF sites to the possible severe weather today. A shortwave trough is expected to move through, and a few models indicate storms gusting as high as 80 mph. Most models have this activity southeast of the Yellowstone Valley, but wanted to mention it in case the storms start a bit further west. There is therefore moderate confidence of MVFR conditions, and low confidence of IFR conditions occurring from 23Z through 03Z Monday. There is moderate confidence that low clouds will reduce CIGS to MVFR levels at times from 03Z to 06Z. A cold front will then swing through and clear things out after midnight.

WINDS: For KOLF and KGGW, northwest at 10 to 15 knots, increasing to 17 to 22 knots with gusts to 35 knots after 2 PM, becoming west southwest at 8 to 14 knots after 09Z. For KSDY and KGDV, northeast at 6 to 12 knots, becoming northwest at 13 to 18 knots after 21Z, increasing to 18 to 23 with gusts to 35 knots after 00Z, becoming west southwest at 8 to 13 knots after 07Z.

GGW WATCHES/WARNINGS/ADVISORIES

Lake Wind Advisory from 3 PM this afternoon to 9 PM MDT this evening for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone-Petroleum.