The Storm Prediction Center issues daily outlooks denoting the risk for severe weather and wildfires for specific regions in the United States. For severe weather, which includes the risk for thunderstorms, tornadoes,

hail Hail is a form of solid precipitation. It is distinct from ice pellets (American English "sleet"), though the two are often confused. It consists of balls or irregular lumps of ice, each of which is called a hailstone. Ice pellets generally fal ...

, and straight-line winds, there are five risk levels indicating the probability for these hazards: ''marginal'', ''slight'', ''enhanced'', ''moderate'', and ''high''. For wildfires, there are three risk levels: ''marginal'', ''critical'', and ''extremely critical''. Although outlooks issued by the Storm Prediction Center indicate the severity of a

convective Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convect ...

or wildfire threat, they do not always come to fruition. There have been many instances where a high risk outlook did not verify and only a few tornadoes occurred. Conversely, there have been days where a lower risk level was issued and a major

tornado outbreak __NOTOC__ A tornado outbreak is the occurrence of multiple tornadoes spawned by the same synoptic scale weather system. The number of tornadoes required to qualify as an outbreak typically are at least six to ten, with at least two rotational l ...

occurred. Some of the deadliest severe weather and wildfire days in recent history did not have a high risk or extremely critical outlook issued. For example, the

2011 Joplin tornado A devastating EF5-rated multiple-vortex tornado struck Joplin, Missouri on the evening of Sunday, May 22, 2011. Part of a larger late-May tornado outbreak, the tornado touched down just west of Joplin and intensified very quickly, reaching a ...

, which killed 158 people occurred on a moderate risk day,Storm Prediction Center May 22, 2011 2000 UTC Day 1 Convective Outlook
/ref> as did the tornado outbreak of December 10–11, 2021, which killed 89 people.Storm Prediction Center December 10, 2021 2000 UTC Day 1 Convective Outlook
/ref> Furthermore, the October 2017 Northern California wildfires, which killed 44 people occurred under a critical fire weather outlook.Storm Prediction Center October 8, 2017 0657 UTC Day 1 Fire Weather Outlook
/ref> The following are lists of the deadliest days in which various risk levels were issued for severe weather and wildfires.

Deadliest severe weather outlooks

''Note: Only direct tornadic fatalities are included, unless otherwise noted.''

Slight risk days

Enhanced risk days

''Note: Enhanced risks have only been issued since October 22, 2014.''

Moderate risk days

High risk days

Deadliest fire weather outlooks

Critical days

Extremely critical days

Notes

References

{{reflist, 30em Storm Prediction Center days by death toll Lists of tornadoes in the United States National Weather Service Tornado-related lists United States environment-related lists Weather-related lists Weather warnings and advisories Wildfires in the United States