ZCZC SPCSWOMCD ALL ACUS11 KWNS 272244 SPC MCD 272244 MTZ000-280015- Mesoscale Discussion 1276 NWS Storm Prediction Center Norman OK 0544 PM CDT Thu Jun 27 2019 Areas affected...Parts of central and southeastern Montana Concerning...Severe Thunderstorm Watch 454... Valid 272244Z - 280015Z The severe weather threat for Severe Thunderstorm Watch 454 continues. SUMMARY...An evolving cluster of storms likely will pose an increasing risk for severe wind gusts across much of north central Montana, including areas near and between Lewistown and Havre, through 6-8 PM MDT. Trends are being monitored for increasing severe weather potential that may require an additional watch east of severe thunderstorm watch 454 within the next few hours. DISCUSSION...Convection has become fairly widespread across and northeast of the Montana Rockies, aided by forcing associated with orography, and a focused area of high-level divergence which is forecast to turn eastward along the vicinity of the central Montana international border area through this evening. This activity has generated substantial outflow, and a large surface cold pool encompassing the Cut Bank, Butte, Helena and now Great Falls vicinities, with the leading edge likely to advance northeastward and eastward across the Havre and Lewistown areas through 28/00-02Z. The most vigorous storms, exhibiting the most substantive recent intensification, may be focused along the gust front, east through southeast of Great Falls, aided by inflow of moderately unstable boundary layer air characterized by CAPE of 1500-2000+ J/kg. Given the large easterly component to the near surface flow ahead of the activity, beneath moderate to strong, south to southwesterly mid/high-level flow, deep layer shear is strong. This environment appears conducive to considerable further upscale convective growth and organization of convection into the evening hours, which seems likely to be accompanied by increasing potential for severe surface gusts. The development of discrete storms ahead of advancing cold pool may still not be entirely out of the question and, if this occurs, may include supercells posing a risk for large hail and at least some potential for a tornado. ..Kerr.. 06/27/2019 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...BYZ...GGW...TFX... LAT...LON 48941040 49130885 48730747 47580733 46770816 46520945 47120976 47511023 47761050 48941040 NNNN