We have an interesting situation setting up with good potential for a severe outbreak in the Southeast, including North Carolina. A trough with a strong jet streak upstream is becoming negatively tilted. In layman's terms, that means that it is increasing in strength rapidly and gaining atmospheric potential to unwind in a severe way.
Here's the situation: Storms will be forming and rolling through around dinner time. These storms, for central North Carolina, will more likely be our normal thunderstorms than not. The main event will come in the wee hours of Thursday morning and last into the morning commute (3:00 a.m. until 7:00 a.m.), making anything severe that much more dangerous due to the lack of available light for observation. Soundings indicate the possibility for a Linear Convective System to establish itself prior to moving eastnortheastward across the state, with growing potential for isolated supercell formation and tornadoes.
|A Supercell Thunderstorm is one in which the main core involves a lower, rotating mass of clouds called a mesolow. This rotation allows for super strong updrafts capable of creating and maintaining hail stones larger than golf balls and in some cases larger than tennis balls, and if the conditions are right and the rotation persists, a tornado can form. There are many more factors involved in tornado formation which I will not go into at this point.|
Threats:
The imposing danger is split into 3 different parts.
1. Strong Winds: This not including tornadoes... Atmospheric sounding profiles would suggest that throughout the event, 850 and 700 mb wind speeds would produce non-insignificant damage if mixed down to the surface, and currently it looks as though with high equivalent potential temperature (theta-e) air will be mixed into the system by the Gulf with southerly winds ahead of the line. This high theta-e air mixed into the middle of the atmospheric profile will provide instability (even though the surface instability from surface heating will not due to the time of day), and mixing to the surface could occur, producing surface instability and atmospheric mixing. These winds, when mixed down, could blow at a rate of 50 or 60 mph, a speed capable of toppling trees and power lines.
2. Hail: The hail danger is fairly straight forward. If hail forms, it will likely cause damage. If it's large enough, it could cause window breakage and crop damage in addition to dents in the roofs and hoods of cars.
3. Tornadoes: Tornadoes can form in two of the aforemention situations... either in the isolated supercell thunderstorms, or in a piece of a multicell line that accelerates due to strong winds from aloft. One piece I did not mention about those strong winds in point 1, is that if they mix down they can aid the advancement of a piece of the line of t-storms ahead of the rest of the line. In this case, the northern portion of that advancing segment could wrap around and allow for tornadic formation. The other situation is within a supercell thunderstorm, where the rotation found in the mesocyclone (aforementioned "mesolow") extends down to the surface.
Keep all forms of social media and warning prepared for tonight, as these storms will be arriving while most everyone is asleep, increasing the danger which exists with already dangerous storms. I will be retweeting from @miscan5000 and sharing by miscan5000 on Facebook overnight to help keep updates coming. Have an awesome day everyone! Keep your eyes to the sky!
