SPC 1630Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1128 AM CDT Wed May 14 2025 Valid 141630Z - 151200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN/CENTRAL PLAINS... ...SUMMARY... Scattered strong to severe thunderstorms should occur over parts of the Dakotas and Nebraska this afternoon and evening, and far western Iowa and southwest Minnesota overnight. Very large hail, severe wind gusts, and a couple of tornadoes all appear possible. ...Northern/Central Plains... An upper trough over the western states will pivot eastward today while gradually acquiring a negative tilt over the northern/central Plains by late tonight. At the surface, a front extending over the Dakotas should stall in a nearly north-south orientation later today. Shallow low-level moisture will continue to stream northward this afternoon ahead of the primary surface low, which is forecast to consolidate over western KS/southwest NE by early evening. A dryline will extend southward from this low over much of the central/southern Plains, but strong capping should generally limit convective development with southward extent through much of the day. Daytime heating of the modestly moist low-level airmass, combined with somewhat steepened mid-level lapse rates, will encourage around 1500-3000 J/kg of MLCAPE by mid afternoon. Stronger instability will likely exist with southward extent into NE, where slightly greater low-level moisture should be present. Mainly unidirectional/ southerly wind profiles along/near the front this afternoon suggest that initial convective development will be messy, with numerous updraft and outflow interactions. Still, the strongest of these initial cores should pose some risk for hail and wind gusts. Initially high-based convection is also forecast to develop across the central High Plains (northeast CO vicinity) by late afternoon/early evening, and spread northeastward across NE. A greater threat for sustained supercells remains apparent with southward extent across NE this evening, where stronger deep-layer shear somewhat more orthogonal to the surface boundaries should be present. Isolated very large hail (up to 2-3 inches in diameter) will be possible with any discrete cells, while severe wind gusts should become an increasing concern as convection grows upscale into a bowing cluster through the evening and early overnight hours. There should also be a narrow spatial/temporal window for a couple of tornadoes this evening across parts of NE as a low-level jet modestly strengthens and 0-1 km SRH increases. ...Southeast and Southern Mid-Atlantic into the Ohio Valley... A weak mid/upper trough will drift eastward today from the Appalachians towards the Carolinas and Mid-Atlantic. While mid-level winds and related effective bulk shear are expected to remain rather weak, some clustering/modest organization may occur with convection that will further develop this afternoon across NC into parts of southern VA. Occasional damaging winds should be the main threat with this activity as low-level lapse rates gradually steepen with continued diurnal heating. But, some hail may also occur. See Mesoscale Discussion 776 for more details on the short-term severe threat across this area. Across parts of the OH Valley, mainly elevated thunderstorms are forecast to develop this evening/overnight in a low-level warm advection regime. Sufficient MUCAPE and deep-layer shear is forecast to support an isolated threat for mainly large hail with this activity. ..Gleason/Wendt.. 05/14/2025