Monday, July 17, 2017

It struck without warning!

A recent fatal flash flood incident has led me to think over the topic of media coverage of weather-related incidents.  We in the "tornado community" frequently hear interviews with the public to the effect that tornadoes have hit somewhere "without warning" when the facts are that the National Weather Service (NWS) has indeed issued a warning.  Clearly, what this statement by some victim reflects is that she/he didn't hear that warning (or ignored it!) and then was unfortunate enough to be in the tornado's path.  I suppose they think that it was someone's responsibility to notify them personally that they were going to be hit.  First of all, it's not the responsibility of the NWS to notify personally everyone in danger.  Second, it's a fact that although technology might eventually make personal warnings possible, but at the moment, it's pretty much impossible to notify everyone who will be affected (and no one else).  The NWS might have the means to contact individuals with warning information, but the state of the art of forecasting simply doesn't permit 100% accuracy regarding who will and who won't be in the damage path of a tornado.

Most fatality-producing tornadoes these days have warnings issued at least a few minutes before someone is struck, and sometimes the lead times can be as much as an hour!  Is an hour's lead time too long?  This is a debate within the tornado community that's not yet settled and clearly requires the involvement of social scientists.  But just for the sake of the argument, let's consider some things about how warnings can be effective in reducing casualties:  for an issued warning to be effective, it requires a chain of events.  The user must

1. receive the warning by some means
2. understand what information the warning provides
3. know what to do with the warning information
4. believe the warning is relevant to him/her
5. take effective action based on the warning

All of the links in that chain must be met, or the warning will not be effective.  In the case of the recent flash flood, the people in the path of the flood evidently did not receive the warning.  It hadn't even rained at the location where the fatalities occurred - the rainfall was miles away upstream.  This is not uncommon when hiking and camping in the wild, away from TV and cell phone coverage.  If  people are to recognize the danger signs without benefit of hearing the warning, they must have experienced one or more similar events (unlikely) or have been given training in heavy rainfall situation awareness (also unlikely).  Flash floods have a special handicap relative to tornadoes:  most everyone has experienced heavy rainfall without a flash flood, whereas most people have never been hit by a tornado.  Rain seems "normal" and not very threatening, whereas a tornado is "exotic" and would automatically be seen as a threat.

A more extensive treatment of the chain of events needed for weather warnings to be effective can be found here.  There are many ways for this chain to be broken, often leading people to think that the event struck them without warning.  In the interest of their own safety, weather warning recipients should make it their personal business to learn situation awareness with respect to potential weather hazards.  The unfortunate part is that many users won't take the relatively simple steps necessary for their own safety, and seem to expect that it's solely someone else's responsibility to protect them from weather hazards.

And the fact that some particular hazard is relatively rare where the user lives and works and recreates, doesn't mean the threat is non-existent.  Tornadoes are infrequent in New England, for example, but violent tornadoes can and do occur there.  Though the danger is not high most of the time, sometimes violent tornadoes happen in New England.  Thinking it could never happen to you is the first step toward a personal disaster.  The weather is not malevolent or evil;  it's just indifferent to what we puny humans do or don't do.  At times, we find ourselves in the path of a potentially fatal hazard  Being prepared is a personal choice;  it's no one's responsibility but your own.  The NWS does its best, but there are still times when they fail to issue a warning, or issue the warning too late to be of much use to at least some people.  That's the state of the art and it should not require much to understand that a warning may not be issued sometimes.  Then, public safety depends on good luck and proper situation awareness;  i.e., recognition of danger signs even in the absence of a warning.

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