Scientific Forecaster Discussion
fxus65 kmso 262003
Area forecast discussion
National Weather Service Missoula Montana
203 PM MDT Fri may 26 2017
Discussion...a weak cutt-off low pressure system will continue
spinning over east-central Idaho through the day today. Wrap
around moisture, in terms of light rain and clouds, will continue
for most of Lemhi County today. Elsewhere across western Montana
and north-central Idaho, afternoon scattered showers and
thunderstorms will develop, with areas along and south of
Interstate 90. Lightning will be the main threat with these
A ridge of high pressure will begin to build over the northern
rockies overnight, that will allow for a very nice Memorial Day
weekend. Though, there will be enough moisture and instability
for a few showers and thunderstorms to develop over the terrain
along the Continental Divide, and the Montana/Idaho border.
Temperatures will generally run 5 to 10 degrees above normal for
this time of year with upper 70s to low 80s for most valleys.
Temperatures will continue to rise next week for all of western
Montana and north-central Idaho, with highs in the 80s for the
majority of the valleys across the region. The ridge will begin to
break down mid week, allowing for a shortwave trough to move over
the area. With the combination of the trough with, a moist
unstable southwesterly flow, the threat for thunderstorms will
return for Wednesday evening and Thursday. It's too far out to
get really detailed, but the flow pattern is favorable for some
thunderstorms to be quite strong.
The threat for afternoon and evening thunderstorms will remain for
the rest of the week, along with above normal temperatures.
Area rivers and streams will continue to run high and fast through
the weekend and into next week. Use caution when venturing near
swift moving water.
Aviation...a few showers and perhaps an isolated thunderstorm
will develop this afternoon, mainly for locations south and west
of the Interstate 90 corridor. Gusty winds and lightning will be
the primary threat. Most of these showers and thunderstorms will
remain over the terrain, however there is the possibility they
could drift over area terminals, such as kmso and kbtm. Timing for
convective activity will be now through sunset this evening.