Brief Outlook:
A severe weather outbreak is expected across the Carolinas on Friday, September 27, 2024. Cities including Charlotte, Raleigh, Greensboro, and Columbia are at risk for severe thunderstorms capable of producing damaging winds, and isolated tornadoes. Counties such as Mecklenburg, Wake, Guilford, and Richland should prepare for significant weather impacts.
Upper-Level Forecast:
A strong mid-level trough is forecasted to move eastward across the Mississippi Valley into the Southeast. This system will bring enhanced wind speeds in the upper levels, creating significant wind shear conducive to severe thunderstorm development. A pronounced jet streak at 250 mb will enhance divergence aloft, promoting vigorous upward motion. Additionally, a shortwave trough embedded within the larger system will provide extra lift, increasing the potential for organized convection.
Surface Forecast Conditions:
At the surface, a cold front is expected to advance into the region, interacting with a warm and moist air mass from the Gulf of Mexico. Instability values (CAPE) are projected to reach between 2000-2500 J/kg by the afternoon, indicating a highly unstable atmosphere. Effective shear values are anticipated to be around 40-50 knots, with low-level shear near 25 knots, supporting the development of supercell thunderstorms. Mid-level lapse rates are expected to be around 7.0°C/km, which is sufficient for large hail formation. The storms are likely to initiate as discrete cells but may evolve into a linear system as the evening progresses.