This relative lull in the weather pattern so far this week will be coming to a screeching halt come next week. A dynamic storm system is forecast to affect much of the Lower 48 east of the Rocky Mountains on Monday and Tuesday. For this particular blog entry, we will be focusing on the severe weather potential for Tuesday. Areas from far southern Ohio to the Louisiana/Mississippi Gulf Coast are at risk.
One of the first basics we look at is the dewpoint temperature. Plenty of moisture will be available Tuesday afternoon and evening across Dixie Alley. Dewpoint temperatures and the actual air temperatures are forecast to be only separated by about five to seven degrees Tuesday afternoon and evening.
As a result, the Lifted Condensation Levels are forecast to be plenty low across Mississippi Tuesday afternoon. This is forecast to move into Alabama by Tuesday evening. When the LCL heights are forecast to be this low, tornado formation is more likely.
The Surface Based Convective Available Potential Energy (SBCAPE) Tuesday afternoon is forecast to peg just below 1,000 J/kg across much of western Mississippi. At first, you would think it is not that much. Given this is the Winter season, it is more than enough for any thunderstorm development to feed off of.
Notice the wind direction at the surface (south to southeast), at 850 mb (5,000 ft. above ground level) (southwest), and at 500 mb (18,000 ft. above ground level) (west to southwest). Winds in this instance are backed at the surface. That is one favorable factor for tornadic supercell development. In addition, the winds at 850 and 500 are screaming.
Pay attention to these two arrows here. These two arrows represent a difluent wind pattern. When this occurs, it is a strong indicator that tornado activity is a definite possibility. That will allow thunderstorm development to be rather explosive.
The amount of helicity in the lowest three kilometers on Tuesday will be more than enough for supercell thunderstorm development across Dixie Alley. Values in excess of 200 units are quite prevalent across Dixie Alley.
The Energy Helicity Index values Tuesday afternoon are pegging over one unit across much of Mississippi. This will transition into Alabama during the later afternoon and evening hours. Those values would represent a tornadic supercell threat.
IN SUMMARY : A very active severe weather day on Tuesday looks likely across much of Mississippi and Alabama. Make sure you have multiple ways of receiving warnings in case your area is affected by severe thunderstorms.