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KEY MESSAGES

- Dangerously hot temperatures will continue this weekend with highs today near 100 and lows tonight in the mid 60s to mid 70s.

- Hot, dry, and windy conditions will cause high fire danger this weekend.

- Southeast winds today switching to the west northwest on Sunday will cause impacts to recreation on Fort Peck Lake. A Lake Wind Advisory is in effect until 6 PM Sunday.

DISCUSSION

WEATHER PATTERN OVERVIEW:

A dominant upper level ridge axis will translate east this afternoon into tonight with the arrival of an initial cold front. This ridge will provide hot and dry conditions to NE Montana today with slightly lower temperatures on Sunday as winds turn west to northwest. Extreme heat headlines continue into Sunday given highs today near 100 with low overnight recoveries by Sunday morning. Hot and dry weather will also make for high fire danger so will keep the red flag going into Sunday as well. Finally, as west to northwest winds ramp up on Sunday, ranging 15 to 25 mph, gusting to 35 mph, will maintain the Lake Wind Advisory for Fort Peck Lake. Smoke and haze will also secondarily create visibility reductions at times into tonight, and those sensitive to respiratory symptoms should continue monitoring conditions into tonight.

A second cold front will arrive Sunday night into Monday as an upper low moves over the region, flattening the departing ridge as it moves east. This will usher in cooler temperatures for early next week offering a relief from the heat and fire weather concerns. There may be an isolated to scattered shower or thunderstorm Sunday night with this, but otherwise look for mostly dry weather into the first part of next week.

Longer term, ensembles begin to show the trough moving downstream as a new ridge becomes established over the Pacific Northwest. This will extend height rises over eastern Montana with northwest flow aloft and moderating temperature toward seasonable averages late week.

FORECAST CONFIDENCE & DEVIATIONS:

While NBM handled the big picture well across the forecast, a blend with NBM90 was used for near term winds this weekend in line with the expected windy conditions supporting the Red Flag and Lake Wind headlines in effect. Pops were also adjusted for Sunday evening in collaboration with surrounding offices. Confidence is high on hot and dry conditions this weekend, but more moderate for showers and thunderstorms on Sunday evening given expected spotty coverage. Having said that, there is a fairly strong emerging consensus among the placement and timing along a southwest to northeast axis Sunday night among the high resolution models.

AVIATION

UPDATED: 2300Z

FLIGHT CAT RANGE: VFR - MVFR

DISCUSSION: Overall expect quiet weather today into tonight with the exception of haze from upstream wildfire smoke. This smoke may concentrate enough to bring MVFR visibilities to area starting around 15Z as current HRRR Smoke plumes reach the terminals around this time.

LLWS: Low level wind shear will develop due to a low level jet tonight aroiun 06Z and last through about 15Z or sunrise when the LLJ shuts off.

WIND: SE at 10 to 20 kts will become W to NW on Sunday, ranging from 10 to 20 kts with gusts to 25 kts.

DENSITY ALTITUDE: Will be a concern this afternoon with temperatures near or over 100. Extra power and longer runway will be needed for takeoffs.

/GAH

GGW WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning until noon MDT Sunday for Central and Southeast Phillips-Central and Southern Valley-Garfield-Northern Phillips-Northern Valley-Petroleum-Southwest Phillips.

Red Flag Warning until 9 PM MDT Sunday for Dawson/McCone/Prairie/Richland/Wibaux Counties-Fort Peck Reservation and Daniels/Roosevelt/Sheridan Counties-Northern Valley and Northern Phillips Counties-Southern Petroleum and Southern Garfield Counties-The Little Rockies-The Lower Missouri River Breaks including the Charles M Russell National Wildlife Refuge.

Lake Wind Advisory until 6 PM MDT Sunday for Central and Southeast Phillips-Central and Southern Valley-Garfield-McCone- Petroleum.

Extreme Heat Warning until 6 PM MDT Sunday for Daniels-Dawson- Eastern Roosevelt-McCone-Prairie-Richland-Sheridan-Western Roosevelt-Wibaux.