textproduct: Missoula

DISCUSSION

KEY MESSAGES:

- Warmest temperatures of the summer continue today and Monday. Elevated heat risk for those sensitive to heat, especially those without cooling or hydration.

- Low relative humidity and strong winds will result in elevated fire weather concerns today in southwest Montana.

- A surge of summer moisture will bring clouds, showers, and thunderstorms by late Monday and into Tuesday.

An upper-level ridge positioned just east of the Northern Rockies remains the dominant weather feature this morning. The ridge is maintaining dry and hot conditions throughout the region. High temperatures today and Monday will climb into the low to mid 90s in western Montana, while the lower valleys of north-central Idaho will approach triple digits. The position of the ridge is keeping a strong upper level jet streak over the northwestern U.S., resulting in strong winds mixing down to the surface. The combination of strong winds, high temperatures, and relative humidity dropping into the low teens to single digits will keep concerns for critical fire weather conditions in the forecast for southwest Montana and Lemhi County.

A surge of moisture is still expected to move into the region from the south, elevating the risk for showers and thunderstorms across western Montana and north-central Idaho on Monday, bringing relief from the hot and dry weekend conditions. The initial shower and thunderstorm activity will bring mostly cloudy skies and erratic, gusty winds due to the very dry air at the surface. By Tuesday evening, the atmosphere will moisten enough for rain to reach the ground.

Atmospheric conditions are becoming more favorable for the potential of a few severe thunderstorms by Wednesday and into Thursday. If you have outdoor plans through mid-week, please plan accordingly.

AVIATION

VFR conditions will prevail across western Montana and north-central Idaho through the forecast period. High density altitudes across all terminals (KMSO, KGPI, KHRF, KBTM, KSMN) will continue today as temperatures remain well above normal under a ridge of high pressure. High winds will also be a concern today as a strong upper level jet streak becomes position over the Pacific Northwest. Expect sustained surface winds increasing this afternoon to 15-20 knots across regional terminals through 03Z, with localized gusts up to 35 knots at KBTM and KSMN.

MSO WATCHES/WARNINGS/ADVISORIES

MT... Red Flag Warning from noon to 9 PM MDT Sunday for East Beaverhead.

ID...Heat Advisory until 9 PM MDT /8 PM PDT/ Sunday for Eastern Lemhi County...Lower Hells Canyon/Salmon River Region...Southern Clearwater Mountains...Western Lemhi County.