Posted: Jul 16, 2013 2:24 PM by Meteorologist Mike Heard
Updated: Jul 16, 2013 2:42 PM
Severe thunderstorms are possible across Montana Wednesday afternoon especially along and north of I-90 (see graphic).
Timing of severe thunderstorms will be between 3 and 9 p.m. Wednesday but could develop earlier west of the divide in the Butte area beginning around noon.
Some of the developing thunderstorms could produce hail an inch or larger in diameter, wind gusts up to or over 60 mph, brief heavy rain and deadly lightning.
Impacts of this event: damage to structures-vehicles-tree-crops due to large hail and strong winds. Poor visibilities in areas of heavy rain, debris flows in burn scars receiving heavy rain. Fire starts from lightning strikes associated with thunderstorms containing little rainfall.
An exceptionally moist airmass will move up into Montana from the south producing a very unstable atmosphere into Wednesday afternoon and early evening. Storm motion is expected to be very slow (10-15 mph) and slowing further along the steep mountain terrain can lead to localized flash flooding. Flash flood watches are up for Yellowstone National Park and central Idaho.
High pressure ridge should re-build over Montana by the end of the week and with it a warming and drying trend into the weekend. Temperatures could rise into the upper 80's to mid 90's.