We start the day with infrared satellite imagery that helps reveal how strong thunderstorms are across the Deep South today by measuring cloud peak heights through temperature. We see a complex of thunderstorms currently across the Ark-La-Tex region. What’s happening now is that this is being forced by a long, drooping fixed boundary that we see analyzed through Weather Center, and outlined in black below. It is this boundary that will catalyze repeated rounds of convection in the form of today and tomorrow’s training storms by providing low-level convergence. When we compare current observations with satellites, we can visually see why and how we have convection going on right now.
Let’s analyze why we will have very favorable factors for heavy rainfall and strong thunderstorm risk across the South. First, outlined is the forecast animation through the European HIRES model showing PWAT values above 1.5” on Thursday. This denotes an environment capable of producing heavy rainfall given the amount of moisture available there, and again note how this flows along the fixed boundary from above.
Next, we see that the instability caused by moisture accumulating along the boundary is not terrible. Water “holds” latent heat and there is plenty of water from the Gulf! So we combine a low-level humid atmosphere with instability and we have a “trigger” (forcing vertical movement) from the boundary to create an ideal environment that is capable of capable of generating heavy rain, flash floods and hurricanes.
Next, let’s take a look at both what hurricane motion can be and of course shear because extreme weather needs vertical wind shear because it determines the type of storm, while instability determines upflow intensity. We find that our 0-4 km (surface to ~13,000 ft) means vector oriented from west to east. Our boundary is also hanging in the same direction. When this is aligned in such a way, we will have slower storm motion because both want to try to cancel out (cloud motion and shear). We also have wind shear above 40 knots verbatim as this will also help organize convection leading to strong thunderstorms this afternoon and again further east into the Gulf Coast states from MS to GA.
As we watch how this plays out for the rest of today and into tomorrow, we initially see our convection complex moving over the southeast with new storms shooting out. from east TX this evening and merge. New storms, with separate cells possible tomorrow, occur late in the morning and into the afternoon with training convection emerging tomorrow before growing stronger and again merging . We will likely see some supercells along with thunderstorms capable of producing large hail and gusty winds.
In terms of cumulative precipitation, we are looking at total precipitation mostly at 2-5 inches, with higher localized precipitation from the Ark-La-TeX area to southern GA, especially with areas witnessed training storms continuously firing along the stalled forward boundary. This can also lead to local flash floods with excessive rainfall and areas where the soil is already saturated. Unfortunately, with the trend starting next week, we will see new threats to the area due to heavy rain and storms, so be prepared if you reside in this general area. !
About the author
Hello! My name is Armando Salvadore and I am a Mississippi State graduate with a Bachelor of Professional Meteorology and an Activity Meteorologist working in the Private Sector. Stay tuned if you like technical, exotic, and general weather tweets! Also big on long-range forecasting as well! Twitter: @KaptMands