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KEY MESSAGES

- Yet another round of thunderstorms is expected late this afternoon into tonight. A few storms may be severe with 60 mph wind gusts, large hail, lightning, and brief heavy rain.

- An Extreme Heat Watch has been issued for Saturday morning through Saturday night with dangerously hot and humid conditions expected. - Temperatures will moderate early next week, but are expected to remain above average.

DISCUSSION

WEATHER PATTERN OVERVIEW:

Another round of thunderstorms is expected this afternoon into tonight. A few storms may be severe with wind gusts to 60 mph, large hail, lightning, and brief heavy rain.

A large upper ridge will become established over the western U.S. with the axis sliding east of the region this weekend. This will build hot and dry weather conditions into much of eastern Montana. An Extreme Heat Watch has been issued from Saturday morning through Sunday night. Highs on Saturday will be in the mid 90s to low 100s. Highs on Sunday will reach upper 90s to mid 100s with some ensemble means pointing to near 110 degrees in the Yellowstone River Valley. Look for limited overnight recoveries each night with lows in the upper 60s to low 70s.

Humidity will also be a concern. In the northeast zones this may lead to highs coming in below forecast expectations, but the trade off may be dew points in the 65 to 70 degree range. Elsewhere across NE Montana dew points will still range from the mid 40s to the mid 60s. The humidity combined with hot temperatures with low nighttime recoveries will add risk for heat related illnesses.

FORECAST CONFIDENCE & DEVIATIONS:

Minor adjustments were made to short term pops for collaboration and consistency. Otherwise, ensembles show decent consensus on track and evolution for storms this evening, with confidence increasing on extreme heat conditions unfolding this weekend. Heat impact levels are already showing warning criteria for most of the region by Sunday.

AVIATION

LAST UPDATED: Wednesday July 8 at 1915Z

FLIGHT CATEGORY: VFR to IFR.

DISCUSSION: Lingering low clouds this afternoon may lead to IFR ceilings at times. Otherwise look for VFR. Thunderstorms this afternoon into tonight will be fairly hit or miss but may reduce visibilities if passing directly over a taf site.

WIND: East to southeast winds will range 5 to 15 kts through 06Z before becoming light and variable. Look for gusty and shifting winds near any storms.

GGW WATCHES/WARNINGS/ADVISORIES

Extreme Heat Watch from Saturday morning through late Sunday night for Central and Southeast Phillips-Central and Southern Valley-Daniels-Dawson-Eastern Roosevelt-Garfield-McCone-Northern Phillips-Northern Valley-Petroleum-Prairie-Richland-Sheridan- Southwest Phillips-Western Roosevelt-Wibaux.