textproduct: Glasgow

KEY MESSAGES

- Isolated showers will drift across northeast Montana today as winds begin to pick up ahead of a major pattern shift.

- Thursday and Friday will see cooler and wetter conditions. Over a 48 hour period, many locations could see over of an inch of accumulated rainfall.

- Precipitation chances don't completely go away this weekend and into early next week, but overall conditions will trend towards drier and warmer.

DISCUSSION

WEATHER PATTERN OVERVIEW:

Today and tonight, the flow aloft will transition from an upper ridge to SW flow aloft across Montana. Meanwhile, an upper trough move into the Canadian Rockies and Pacific NW. The pattern change will lead to increasing daily chances for showers and thunderstorms, with heavy rain potential as some southwestern monsoonal moisture does transport its way this far north.

There will be chances for showers and thunderstorms at times today. Chances for showers and thunderstorms increase tonight with widespread rain expected between Thursday, Thursday night and Friday morning with heavy rain possible at times. The current probability for one inch or more rain between tonight and Friday is 40 - 90 percent across NE Montana with higher confidence the more east you go. The probability for 2 or more inches of rain between tonight and Friday is between 10 and 50 percent, especially east of Fort Peck Lake. If more than 2 inches of rain occurs, flooding could become a possibility depending on how quickly the rain falls in a given location. A marginal risk of excessive rainfall for NE Montana today, and a slight risk Thursday, and another marginal for Friday. Will hold off on any Flood Watches for now given that the ground is dry and rainfall has been light over the last 4 weeks.

Flow aloft Friday night and Saturday turns into a drier WSW aloft as the upper trough moves east across the Canadian Prairies. Rain chances diminish Friday afternoon and Friday night and Saturday look mainly dry with isolated showers possible.

Frequent waves moving across eastern Montana will bring shower and thunderstorm chances at times early next week.

FORECAST CONFIDENCE & DEVIATIONS:

Increased PoPs for the first 8 hours to better capture AM showers. No changes to NBM otherwise.

Low confidence in shower and thunderstorm chances today. Confidence in precipitation chances increase tonight and Thursday and are high Thursday night and Friday morning. High confidence in many areas getting an inch or more rain overall but low confidence possibility of amounts higher than an inch.

AVIATION

LAST UPDATE: 1900Z.

FLIGHT CAT RANGE: VFR - MVFR after 18Z Thursday.

DISCUSSION: Skies will vary from broken mid and high clouds today with isolated showers and thunderstorms possible. Mid level clouds and chances for showers and thunderstorms will increase tonight with low clouds moving in from the west after 09z Thursday.

WIND: NE 5 to 15 kts becoming E 5 to 10 kts tomorrow morning.

GGW WATCHES/WARNINGS/ADVISORIES

None.