2PM Day 1 Convective Outlook for Friday, February 20. NO SEVERE THUNDERSTORM AREAS FORECAST
SUMMARY
A few damaging gusts are possible across eastern North Carolina this afternoon.
20z Update
The Marginal Risk across North Carolina was removed with this update. Convection is moving offshore this hour, with minimal development expected through the rest of the afternoon.
See previous discussion for more information on potential for thunderstorm development overnight across MS/AL/GA.
Synopsis and Discussion
Recent satellite imagery shows several cyclones and shortwave troughs within the upper pattern across the CONUS this morning. The most prominent is the cyclone currently over the southern Lake Michigan vicinity. Surface analysis places the surface low associated with system in the same location, revealing the stacked and mature character of this system. An occluded front extends southeastward from this low across southern Lower MI into northwest PA before arcing more southward across western PA, central WV, and far western VA. Here it intersects the stationary wedge front over far northeast NC before transitioning to a cold front and continuing southwestward/west-southwestward through Southeast states.
Carolinas into the Southeast
General expectation is for the northern portion of this cold front to continue eastward/southeastward throughout the day as its parent cyclone shifts eastward as well. This will take the front off the Mid-Atlantic Coast later tonight. Isolated thunderstorms are anticipated along and ahead of this front across the eastern Carolinas. Despite favorable low-level moisture (i.e. dewpoints in mid 60s), warm temperatures aloft will mitigate the overall buoyancy, likely tempering updraft strength and persistence. Even so, the moderate to strong deep-layer western flow may still support a few damaging gusts, particularly across northeast NC where some additional lift may be provided by interaction with the stationary wedge front.
Farther south, the front is expected to stall later this afternoon/evening from southern GA west-southwestward into southern LA. Some strengthening of the low-level flow is anticipated in the vicinity of this boundary ahead of another shortwave progressing eastward across the central Plains. Resulting warm-air advection amid the modestly moist and buoyant environment will foster isolated to widely scattered thunderstorm development overnight. Moderate to strong mid to upper-level southwesterlies will be in place, supporting sufficient vertical shear for organized updrafts. However, thermodynamic profiles should be relatively warm, limiting buoyancy and likely tempering the overall severe potential. While a couple of strong storms could occur tonight, current thinking remains that the potential for severe storms should remain low/conditional.
Northwest PA and Southwestern NY
Low-topped convection is anticipated along the occluded front across northwest PA and western NY this afternoon. This convection may not even be deep enough for lightning but a few stronger, convectively aided gusts are possible.