SPC 0600Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1256 AM CDT Wed Aug 09 2023 Valid 101200Z - 111200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS THE CENTRAL AND EASTERN CAROLINAS... ...SUMMARY... Strong to severe thunderstorms are possible across parts of the northern Plains, and from the Tennessee Valley to the coastal Carolinas/southeast Virginia on Thursday. Highest severe thunderstorm coverage is expected across the central and eastern Carolinas. ..TN Valley into the Carolinas/Mid-Atlantic... Showers and thunderstorms will likely be ongoing from the middle/upper OH Valley southwestward through the TN Valley early Thursday morning, ahead of shortwave trough moving through the OH and TN Valleys. This broad area of showers and thunderstorms is expected to gradually shift eastward as the shortwave trough continues eastward throughout the day. These showers and thunderstorm should limit destabilization across the Upper OH Valley and northern Mid-Atlantic, but some potential for destabilization exists farther south from eastern TN and northern AL/GA into the Carolinas and southern VA. Thunderstorm development would be likely in this area as the approaching cold front interacts with the destabilized air mass. Strong mid-level flow supports the potential for organized storms, with a bowing/line segment mode most likely. One caveat regarding that scenario is the potential for early period showers and thunderstorms to linger and limit destabilization. Additionally, there is also some potential for the early storms to be strong enough to overturn the airmass. Despite these uncertainties, strong deep-layer shear suggests any robust convection could be severe, and 15% wind probabilities were introduced across the central and eastern Carolinas where highest confidence in storms exists. Less buoyancy is anticipated with northern extent into VA, but strong wind fields merit a northward expansion of the 5% wind probabilities. ...Northern Plains... Low 60s dewpoints will likely be in place across eastern NE and into southeast/south-central SD by Thursday afternoon, ahead of a shortwave trough and its associated surface low and cold front. The combination of 60s dewpoints and steep mid-level lapse rates will result in moderate buoyancy, and thunderstorm development is anticipated as the cold front interacts with this buoyant airmass. Initially isolated thunderstorm coverage is anticipated during the late afternoon, with environmental conditions supporting supercells capable of large hail and damaging gusts. Strengthening low-level flow could aid in upscale growth, with the resulting convective line likely tracking southeastward into IA. However, overall confidence in upscale growth is currently low, largely as a result of likely isolated severe coverage. Warm-air advection thunderstorms are also possible across IA Thursday night, with an attendant risk for severe hail. 5% hail probabilities were expanded eastward to cover this threat. ...Southern New England... A pair of shortwave troughs are forecast to move eastward through the broadly cyclonic flow over the eastern CONUS south of the mid-latitude cyclone over Ontario and Quebec. This evolution will encourage the deepening of a surface low moving ahead of these waves northeastward across the northern Mid-Atlantic into southern New England. Current expectation is for the low to move fairly close to the coast, with some potential for the warm sector to move inland from eastern Long Island and eastern MA/Cape Cod. Strong, veering wind profiles could support a few more organized thunderstorms capable of damaging gusts and/or a tornado or two. ..Mosier.. 08/09/2023
