The 4 main ingredients for severe weather development with a possibility of isolated tornadoes are:
MOISTURE, INSTABILITY, LIFT and WIND SHEAR. This Thursday we will have all in place.
You may have already notice it’s a bit muggier outside. Well, we are just getting started. Dewpoints on Wednesday are approaching 50°. Thursday, dewpoints will hit the 60s. That is the moisture part of this severe weather equation. Below are the dewpoints expected for Thursday. The bluish-gray colors are dewpoints in the 60s.
The warm and moist air rushing in from the Gulf will provide the warm and humid air at the surface, aka moisture. The cooler and dryer air moving in with the front to out west along with the dry air working its way into the center of a strong area of low pressure will provide the instability needed to fuel strong thunderstorms. Below is the GFS model for temperatures on Thursday. The orange areas are temps in the 70s and 80s.
There will be lots of lift happening Thursday. It will mostly be the warm moist air running into the colder denser air of the cold front. Also, the low pressure nearby, the warm moist air at the surface and the jet stream overhead will also provide a source of lift. The strong winds of the jet move air away, encouraging air from below to move up and replace the void.
The winds on Thursday will be feeding into the approaching area of low pressure. These strong surface winds will be mainly out of the southeast. The area of low pressure will be pulling in air from the west and northwest at higher levels. The jet stream will also focus winds from the southwest to the northeast. Below is the jet stream position for Thursday.
These differential winds, from SE at the surface to NW aloft, will encourage rotation in the strong storms. These strong storms will be ingesting warm humid air. Aloft that air will cool and come rushing back to the surface. This downdraft of air can pull the rotating column of air to the ground, resulting in a tornado.
As you can see, we have all the ingredients for a severe weather outbreak, including the possibility of an isolated tornado. A severe thunderstorm is one that produces 1” diameter hail and winds of 58 mph or greater. That large hail created by strong updrafts and that severe wind and tornado threat created by the updraft and downdraft of Thursday’s storm. Stay Sky Aware.