Posted: May 25, 2013 4:58 PM by Jason Laird - MTN News
BILLINGS - The South Eastern half of the state is primed and could potentially become active this afternoon into the evening. Cloud cover delayed heating today thus deepening convection. This has left the atmosphere heavily unstable with plenty of up draft and wind shear over the SE portion of the state.
Today and Tonight...A Low level jet setting up over southeast Montana and will advect low level moisture into the area. Dew point temperatures will increase through the day and will be in the mid to upper 50s by afternoon from Forsyth East to Baker.
Afternoon heating will allow surface based capes to range from 1500 to 2500 j/kc this afternoon and evening with lifted index values of a -7c. Bufkit soundings indicate strong directional and speed shear across southeast Montana. 0 to 6 km effective shear progged at 35 to 40 kt.
Models are indicating several short waves to move across the region this afternoon and tonight. Upper jet will also bring qg forcing over the forecast area. Forecast models are also indicating preciptable waters over the southeast today will reach around 1 inch. Upper air sounding in Rapid City had 0.75 pwat`s at 00z last evening.
The area most likely to see severe weather this afternoon and tonight will be along and east of line from Miles City to Broadus and have increased pops to high scattered for Custer and powder river counties and likely for Fallon and Carter.
The main threat from these storms will be large hail...damaging winds and very heavy rain. Cannot rule out an isolated tornado given the strong wind shear over the area.