Peoria, Ill. (WMBD) — When it comes to severe weather, from tornadoes to hail and damaging winds to floods, Central Illinois sees it all. As severe weather season approaches its important to understand the threats that can impact Central Illinois and the types of watches and warnings that are issued in the area.
Watch vs Warning
Watch: Be prepared, severe weather is possible
Conditions are right for severe weather. These are issued by the Storm Prediction Center before severe weather occurs, covering numerous counties and sometimes states. These are usually in effect for several hours.
Warning: Take action, seek shelter immediately
Severe weather is occurring or imminent. These are issued by your local NWS Office and typically include portions of counties. These are usually in effect for 20 minutes to an hour.
Types of Severe Weather Watches and Warnings
Severe Thunderstorm Watch: Be Prepared!
A Severe Thunderstorm Watch is issued when conditions are right for severe thunderstorms to develop. While not everyone in a watch area will experience a severe thunderstorms, storms that develop will be capable of producing damaging winds, large hail and or tornadoes.
Severe Thunderstorm Warning: Take Action!
A Severe Thunderstorm Warning is issued when severe weather is occurring or imminent. These warnings are typically issued for storms capable of producing damaging wind gusts over 58 mph and/or 1.0″ diameter hail. Sometimes severe thunderstorms will produce tornadoes before a tornado warning can be issued. It’s important to note that warnings are not issued for lightning.
Tornado Watch: Be Prepared!
A Tornado Watch is issued when severe thunderstorms capable of tornadoes are likely. Storms will also be capable of large hail and damaging winds.
Tornado Warning: Take Action!
A Tornado Warning is issued when a tornado is occurring or imminent. These warnings are issued when strong rotation is observed on radar or when spotters observe one. When a warning is issued you should seek shelter immediately by getting to an interior room of the lowest floor in the building you are in.
Tornado Emergency: Take Action!
This is an enhanced version of the typical Tornado Warning. While it’s not a new type of warning, Tornado Emergencies are issued when significant tornadoes are moving through populated areas. If a Tornado Emergency is issued it means widespread damage and numerous fatalities are expected with a large, strong to violent tornado.
Flash Flood Watch: Be Prepared!
A Flash Flood Watch is issued when conditions are right for flash flooding to occur. While not everyone in the watch area will experience flash flooding, heavy rain producing thunderstorms capable of causing flash flooding will be possible…even in areas that typically don’t flood. These could also be issued along rivers where dam breaks could lead to a flash flood.
Flash Flood Warning: Take Action!
A Flash Flood Warning is issued when flash flooding occurring or imminent. Be sure to avoid flooded roads and watch for sudden rises along area creeks and river beds. If you are in area that is seeing flooding, you need to get to higher ground immediately. Keep an eye on sump pumps in your basement to make sure they are not overwhelmed. Remember, even if you are in area that doesn’t experience flooding often, flash flooding is still possible.
Severe Storm Terminology
While we try to keep the weather jargon to a minimum, you may hear some unfamiliar terminology during our severe weather coverage. So here’s a list of terms you may soon hear…
Supercell – A thunderstorm with a rotating updraft. Storms with rotating updrafts produce large hail, damaging winds and, if the rotation is tight enough, tornadoes.
Hook Echo – The radar signature associated with a rotating thunderstorm.
Gust Front – Leading edge of a line of gusty winds blowing out and away from a thunderstorm, what we call outflow winds. These often occur on the back edge of a supercell as cold upper-level winds are brought to the surface but can occasionally happen on the leading edge of the cell.
Tornadic Vortex Signature (TVS) – An area of strong rotation identified by doppler radar. While a storm may show a TVS on radar it doesn’t necessarily mean that the storm is tornadic. Meteorologists will analyze the placement of the TVS and factor in the surrounding environment before issuing a Tornado Warning.
Tornado Debris Signature (TDS) – Commonly referred to as a Debris Ball, a TDS is an area of higher reflectivity on radar caused by debris being lofted into the air. We often verify the presence of a TDS by using a dual-pol radar product called correlation coefficient, or what we call VIPIR Debris.