SPC Mesoscale Discussion: Severe Thunderstorm Watch 418…

SUMMARY…A damaging bow echo will continue to shift east/southeast this evening. A new severe thunderstorm watch will be needed across parts of northeast AR into TN, perhaps replacing portions of WW 418.

DISCUSSION…A well defined damaging bow echo continue to shift southeast into far southeast MO toward northeast AR, western KY and eventually western TN. Most recently, Poplar Bluff measured a severe gust of 51 kt and Cape Girardeau measured 63 kt. Multiple mPING reports of wind damage have also been noted over the past 30 minutes across Cape Girardeau and Scott Counties in MO and Union County in far southern IL. Regional VAD wind profile data show an intense rear-inflow jet with 50+ kt winds around 1.5-4 km ARL from the PAH, SGX and LSX radars. This descending rear-inflow jet is aiding in producing these damaging gusts, and is evident in reflectivity data where low returns are noted behind the initial line of convection. Downstream of the bow echo, outflow from another long-lived bow echo moving east/southeast toward central KY arcs westward into the apex of the southeast MO bow echo. There has been re-invigoration of the convection at this intersection with increasing reflectivity noted in 5 and 7 km CAPPI. Recent track on this bow gives a motion toward the east/southeast at nearly 60 kt, which will bring the system to the edge of WW 418 between 00-01z. The southeastern flank of the bow now shifting into northeast AR is a little less organized and not progressing as quickly as the apex region further north/northeast. However, given extreme instability and a very warm/moist downstream environment with surface dewpoints in the mid 70s, a severe threat will persist into the evening hours to the west of WW 418. As a result, a new watch will likely be needed across parts of northeast AR eastward into TN.

Tags: MesoScaleDiscussion

Category: ALL POSTS, MescoScale Discussions