SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0226 AM CDT Mon Aug 19 2024 Valid 211200Z - 221200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN HIGH PLAINS... ...SUMMARY... Scattered thunderstorms, associated with large hail and severe wind gusts, will be possible on Wednesday across parts of the northern High Plains. Marginally severe storms will be possible westward into central Montana and southward into the central High Plains. ...Central and Northern High Plains... An upper-level ridge is forecast to move eastward across the northern Plains on Wednesday, as a mid-level shortwave trough moves northeastward across the northern Rockies. An axis of maximized low-level moisture is forecast from central Nebraska into central South Dakota and northwestward into northeast Montana, where surface dewpoints will likely be in the 60s F. Moderate to strong instability appears likely to develop along and near parts of the moist axis by afternoon. Both the NAM and ECMWF have MLCAPE peaking above 3000 J/kg in parts of the northern Plains, with the ECMWF showing an axis of strong instability by late afternoon. As the airmass destabilizes, isolated convective initiation will be possible near the moist axis. Additional storms will likely develop in the higher terrain of northern Wyoming and southern Montana. This convection is expected to move northeastward into the northern High Plains during the late afternoon and early evening as the shortwave trough approaches from the southwest. Forecast soundings over western North Dakota and far eastern Montana have 0-6 km shear in the 40 to 50 knot range, with steep low to mid-level lapse rates exceeding 8 C/km in some areas. The instability and shear would support supercells with isolated large hail and severe wind gusts. The models suggest that the severe threat would persist into the early to mid evening as the shortwave trough moves across the region. Further south in the central High Plains, isolated to scattered thunderstorms are expected to develop near the instability axis during the late afternoon. A potential for isolated large hail and severe wind gusts would be possible. However, deep-layer shear and large-ascent are forecast to be weaker in the central High Plains, suggesting any threat should remain marginal. ..Broyles.. 08/19/2024
