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KEY MESSAGES

- Above average temperatures and high humidity are combining to make staying cool rather difficult this upcoming weekend. Poor cooling at night will also be part of the story, so make sure to find ways of keeping yourself cool. An Extreme Heat Warning has been issued for Saturday through Sunday night. - Temperatures will moderate early next week, but are expected to remain above average. Precipitation chances are expected to move back in by Tuesday.

DISCUSSION

WEATHER PATTERN OVERVIEW:

A large upper ridge is slowly building over the area. Southeast winds at low levels will help transport warm air northward into our area. The peak in intensity of the ridge is likely to be Sunday, with almost the entire area expected to be from around 98 to 110 degrees for a high temperature. The base NBM indicates lows staying above 65 degrees for Saturday night, Sunday night, and Monday night, so it will be difficult to stay cool enough to sleep comfortably. There are small wiggles in the upper level flow for various CAMs tomorrow afternoon and Sunday afternoon. Any forcing over the area would be enough to generate an intense storm since recent rainfall has helped keep high dewpoint air in place, especially in the east. We will keep an eye on this potential, but storm coverage is expected to be low at the very least. There is an extreme heat warning in place for Saturday and Sunday.

A mid level front is expected to move across the north tomorrow, so there is potential for a strong storm to move through there. There is a low (10 percent) chance of this scenario occurring. There is a similar event expected on Sunday, with this low chance being mostly in central Montana. One CAM suggests a severe gust or two there.

The latest GFS and ECMWF ensemble suggests a breakdown of the ridge by late Monday evening, so central Montana is expected to start to see precipitation chances again. A push into northeast is likely to occur by Tuesday evening, so shower and thunderstorms will need to be monitored for severe weather chances again.

FORECAST CONFIDENCE & DEVIATIONS: No deviations were made.

There is high confidence on temperatures exceeding 95 degrees for high temperatures and low temperatures struggling to drop below 65 degrees this weekend.

There is low confidence of storms holding off through Monday afternoon.

There is high confidence that fire weather will hold off for at least the next week. Recent rains are keeping the vegetation pretty green, so fire concerns are low.

There is high confidence of precipitation chances returning by Tuesday evening.

AVIATION

UPDATED: Friday July 10 at 18:15Z

FLIGHT CATEGORY: VFR

DISCUSSION: Mainly dry weather and mostly clear skies are expected over the TAF cycle as upper ridging begins to gain an influence. Hot temperatures with highs above 100 degrees this weekend may lead to equipment issues.

WIND: Mainly south at 8 to 15 knots, becoming mainly east southeast after 03Z, becoming southeast at 9 to 16 knots after 18Z Saturday.

LLWS: South around 40 knots from 05Z to 11Z for KSDY and KGDV.

GGW WATCHES/WARNINGS/ADVISORIES

Extreme Heat Warning from 6 AM Saturday to 6 AM MDT Monday 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.