Written by Denys Khrulov and Allison Sousa
General Outline:
A large-scale severe weather event is projected to strike much of the central United States on Friday, March 31st. A trough ejection from the eastern Rockies will advect into the central Plains throughout the day, allowing to set up for a very broad zone of severe weather in the warm sector of a developing robust low pressure system. With more than ample enough of upper-level wind shear overlapped with a strong low-level jet transporting moisture from the Gulf of Mexico into the northern Plains will allow for this threat to be maximized across a very large region. The highest threat for the most widespread severe weather will lie in the moderate (level 4 out of 5) and enhanced (level 3 out of 5) risk zone areas. In these particular areas, the threats may include for long-track tornadoes, damaging wind gusts in excess of 70mph, and very large hail. For those under the slight (level 2 out of 5) and marginal (level 1 out of 5) risk areas, the threat for severe weather cannot be completely ignored. The potential will still exist for isolated tornadoes, damaging wind gusts in excess of 60 mph, and large hail. The best way to prepare for this severe weather event is having an adequate shelter to take cover in when the storms strike and having multiple ways of receiving severe weather alerts. Please do not rely off of outside tornado sirens. Having a source with your local NWS office and/or local TV meteorologist to receive alerts will be the best and most effective way to be prepared.
Iowa, Illinois, Missouri, Southern Wisconsin Zones (including MDT Risk Northern Zone):
A rapidly-strengthening low pressure system will move into northwestern Iowa during the early-afternoon hours, which will allow the warm sector to surge northward, advecting higher dew points of the low-60s into much of central and eastern Iowa. There is the possibility of some convection to fire between 12 – 2 PM, which may put a slight damper to some of the destabilization process, especially across far northern Missouri and eastern Iowa. After these showers and thunderstorms clear the state, enough clearing in the sky will allow for the atmosphere to fully destabilize, with potential CAPE values into the 2000-2500 J/kg range, more than enough for additional thunderstorm development. As the cold front begins to sweep through Iowa and Missouri, expect explosive convection between 3 – 5 PM, beginning in central Iowa and Missouri and push east. Some of these initial thunderstorms will take form as supercells, which will bring an heightened tornado risk. A couple strong tornadoes cannot be ruled out, especially in eastern Iowa. As these storms progress eastward, they will transition more into a linear (squall-like) mode, which will then allow for the damaging wind threat to ramp up in the later afternoon hours and into the early evening hours, primarily across the state of Illinois and in southern Wisconsin and then later into the overnight hours in Indiana. The threat for brief spin-up tornadoes within squall segments cannot be ruled out as well. Damaging wind gusts may exceed 70 MPH in the strongest linear segments. The threat will diminish as the front passes through, with much colder air wrapping around on the backside.
Arkansas, Tennessee, Missouri, Kentucky, Southern Ohio Zones (including MDT Risk Southern Zone):
Rain associated with a low pressure system centered in the northern plains will extend into the southern United States bringing a risk for severe weather. Scattered showers throughout the day on Friday will become a line of steady rain and thunderstorms in the afternoon and evening. The greatest risk for severe weather includes northeastern Arkansas, western Tennessee, and a small portion of southeast Missouri. There is a threat for strong winds, large hail, and tornadoes associated with this line of storms. Thunderstorms will move through here between 3pm and 6pm. Tornadoes spawned by these supercells have the potential to stay on the ground for a long time and may impact several communities. As these supercells progress eastward, the storm mode will turn more linear, allowing for the damaging wind threat to be greater. However, the threat for isolated tornadoes will continue within the squall segments. These thunderstorms will move into the eastern half of Tennessee, Kentucky, and southern Ohio overnight on Friday between 12am and 2am. If you live in these areas, make sure to have a plan to seek shelter, check for weather alerts during the day, and keep your phone on overnight. Be prepared for power outages and damage due to wind, hail, and possibly tornadoes.
Preparedness & Actions:
As always, the best way to protect yourself ahead of severe weather is to be adequately prepared. Make sure you have a safe place to take shelter in, preferably the most-central room or the basement of your building. Absolutely do not take shelter from severe weather in a vehicle or mobile home, as these objects may be tossed in the event of a tornado. If you reside in a mobile home, plan to have access to a more sturdy structure throughout the day in case of severe weather. The best way to receive these weather alerts will be either from your phone or through your local NWS/TV meteorologist. Make sure NOAA Weather Alerts are enabled in your settings. Do not rely off of outdoor tornado sirens as they are only meant to be a warning for those caught outdoors. Make sure to stay safe and keep your eyes to the sky throughout the day on Friday!
