National Weather Service United States Department of Commerce

50 years ago, Hurricane Agnes was a tragedy for our area, and the Eastern U.S,. that caused billions in damage & 128 deaths - mostly from flooding. A retrospective look at Agnes, and improvements since then, can be found here.

50 years ago, Hurricane Agnes was a tragedy for our area, and the Eastern U.S., that caused billions in damage & 128 deaths - mostly from flooding. A retrospective look at Agnes, and improvements since then, can be found here. Read More >

  • Expected or Possible tornado

Biggest takeaway:
Whatever plan you base off a tornado warning, that NWS tornado warning needs to be received instantly, & your plan triggered and accomplished rapidly (within a few minutes) to be of value.

Warning/Trigger for Plan:
NWS Tornado Warning

Advance Notice/Time to Activate & Accomplish Your Planned Response:
Plan on 5-10 minutes of advance warning.
Allow options that there may be little/no advance warning, and it may be as much as 30 mins.

Frequency:
Average is 0-2/year for any one location in this region.

How Accurate Warnings?
 If a tornado occurs, it is highly likely that it was preceded by at least a few minutes by a NWS Tornado Warning. That said, with the current state of the science, more than half of NWS Tornado Warnings are false alarms. Furthermore, even when a tornado does occur within a warning area, it is less likely to hit your specific location.

 

  • How do you balance this uncertainty of a direct hit with the potentially deadly consequences if it does hit you?
  • Note: Any NWS Tornado Warning for your location will quickly activate the Wireless Emergency Alert system and will alert the cell phones of most of the people in your location. The message is very generic though, and only says "Tornado Warning in your area". That short message will likely impact their response and awareness, and needs to be taken into account in your planning.
  • Tornado winds could be just enough to cause downed trees & stripping off siding and shingles (>60 mph) [more common], or enough to cause catastrophic, structural damage (>120 mph) [rare]. However, it typically isn't known how strong the winds are while the storm is ongoing. Therefore, the best action is to treat all tornado threats the same - as a potential catastrophic threat.
  • Often the wind is not the direct threat - what is carried in the wind is. Consider that you may be able to stand against a 60 mph wind, but that wind may be carrying a 2x4, glass, or more.
  • Safest situation:
    • In a sturdy, enclosed structure – not a mobile home
      • Away from windows
      • Be as low as possible in the structure
        • Winds increase with height
        • If a tree falls into your structure, the upper levels will be most damaged
      • Put as much structure between you and the outside as possible
        • Homes: Typically the lowest level, interior room.
        • Buildings: Typically interior hallways or concrete staircases.
  • Safety References: