Besides our winter storm that we'll be dealing with here in the Upper Midwest, there is another big weather event that looks to occur later today down south. The ingredients are coming together for a potentially significant severe weather outbreak thanks to a strong low pressure system, favorable winds, and ample moisture. Portions of the Mississippi River Valley and southern Ohio River Valley are under a moderate risk for severe weather as seen by the map below from the Storms Prediction Center. This is quite rare to see this kind of a risk in January.
The storms that fire later today along a cold front that will be moving through the area could produce large hail, damaging straight line winds, and tornadoes.
Above is the outlook for hail with this storms. The percentages refer to chance of hail of one inch diameter or greater. However, the larger risks appear to be for straight-line winds and tornadoes. Below is the outlook for damaging winds producing 50 knots. The hatched area refers to an area where thunderstorms could produce winds greater than 65 knots.
What is most troubling about this event is when you look at the outlook for tornadoes. Below the image shows the percentage of a tornado. You may think well 15% seems like a very small chance. However, a tornado is a very rare event to pinpoint for one specific location. So really, 15% is a significant chance to at least see several tornadoes within this area. The hatched area is the area where there is a 10% that an EF-2 to EF-5 tornado could development. Given these numbers along with the atmospheric conditions, we very well could have several tornadoes develop later today with maybe a couple significant ones.
Models are forecasting initiation of the storms to begin around 6 or 7pm this evening from Missouri down to Louisiana. Eventually the storms will merge into one large line later in the evening. At that point the biggest threat will be damaging winds. Given the late initiation time and the early sunsets this time of year, tornadoes that form will be night tornadoes, especially, dangerous. People down south will have to monitor the forecast closely the rest of the day. Fortunately, the risk for severe weather is quiet once we get through this evening and tonight.