Severe thunderstorms will develop across the central and southern plains this afternoon and evening with the focused area of concern from South-central Nebraska to the Texas/Oklahoma Border. Very large hail (hail 2 inches and greater in diameter), damaging winds and tornadoes are a significant concern, especially with supercell thunderstorms. If you are in these areas, make sure you have a way to receive National Weather Service’s Watches and Warnings this afternoon and evening. Also know your safe places that you can reach quickly as thunderstorms will develop and move quickly.
Key Atmospheric Elements
A low pressure system in Eastern Colorado and associated warm front that extends across Kansas into Central Missouri will be one of the key players for the severe weather event in the Central and Southern Plains this afternoon and evening. Another player is the upper level system that will pivot across the Four Corners Region. The surface low and the upper level systems as well as very warm and moist conditions already in place to the south of the warm front and strong winds will come together to allow for thunderstorms to quickly develop this afternoon and evening in the Central and Southern Plains.
Finer Atmospheric Details and Timing
The high resolution weather models this morning are fairly consistent in showing thunderstorms with the potential of very large hail, damaging winds and tornadoes. The models however are struggling on the specific location and the timing. While the atmosphere becomes very unstable this afternoon with CAPEs of 3000 to 4000 J/kg, the fine detail trigger mechanisms and/or dry line are what the models are the elements still in question. (Note: Convective Available Potential Energy aka CAPE is the measure of how much energy is available once a thunderstorm develops and the higher the CAPE value the more explosive the potential development. Typically for the time of year, values in excess of 1500 to 2000 J/kg are decent. So with values in excess of 3000J/kg, there is a significant amount of energy in place to support thunderstorms.)
How quickly the dry line pushes east and provided a disturbance to initiate thunderstorm development (aka break the cap) is one of the questions impacting the timing and location.
Currently National Weather Service Storm Prediction Center has outlined areas from Southcentral Nebraska across Central Kansas and Oklahoma to the Oklahoma/Texas border as being the primary focus area with a Moderate Risk. A broader Enhanced Risk surrounds the Moderate Risk and extends along the warm front into Missouri and well into Central Texas.
The graphic below highlights the risk for Tornadoes where the area in yellow shows area of highest threat.
The graphic below identifies the area for hail. Areas outlined in magenta have a 45% risk. This coincides with the outline of the moderate risk.
For the risk of damaging winds, the 30% area in the graphic below outlines the highest risk areas.
For more insight on how the individual probability risk plays in to the identification of the NWS – SPC categorical risk, see the following graphic.
In addition to severe weather, rain will be heavy at times, especially in the more intense thunderstorms as well as for areas along and north of the warm front. Widespread amounts of 0.5 to ~ 2 inches can be expected from South Dakota, Nebraska, Iowa, Missouri, Oklahoma, Arkansas and Texas, as well as east into the Ohio River Valley through Wednesday Morning.
Remain weather aware today and have ways to receive notifications, such as a NOAA Weather Radio, if the National Weather Service issues Watches or Warning. If you will be out and about, know where your safe locations are in case you need to quickly take shelter. In addition, do not forget about the safety of your pets, if you will not away from home this afternoon/evening consider placing them in a safe area before you leave. Also move equipment, vehicles and other outdoor items inside. Again very large hail is a concern baseball hail 2+inch hail can do some serious damage.
The team at WxIntegrations will continue to provide relevant information and resources to help you better understand and prepare by incorporating weather impacts into your planning and response.