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Weather and Society Watch
From the Director

Forecasting Impacts
by Jeff Lazo*

The following is part of a Wind Advisory issued May 5, 2010 by the Los Angeles/Oxnard, CA National Weather Service (NWS) Weather Forecast Office (WFO).

This is not at all unusual for an advisory issued by an NWS WFO. It seems obvious and reasonable to advise or warn that strong gusty winds may cause driving problems. It seems responsible to provide information about the potential impacts from severe weather events.

But then . . . why not advise that blowing dust and strong winds are related to soil erosion and farmers should take necessary precautions? Why not tell people with respiratory sensitivities that blowing dust may irritate their bronchial passages? Why not advise the folks at the Antelope Valley California Poppy Reserve that high winds may wipe out the remaining poppy blooms and that they should thus update their website ( in case you are wondering).

In keeping with its mission of " of life and property and the enhancement of the national economy," the NWS provides weather forecasts to assist organizations and the public to make better decisions. It seems reasonable that providing information about weather impacts will lead to even better decisions to protect life and property. This is consistent with what I've heard at recent meetings I've attended where National Weather Service folks have talked of moving from a paradigm of forecasting the weather to forecasting impacts.

But what impacts should the NWS warn the public about? And, how qualified is the National Weather Service to determine the impacts of weather events? It seems obvious that gusting winds may cause "vehicle loss of control." But is this the most important or immediate impact of concern? Maybe for gusting winds in the desert it is. In many areas the folks in the WFO may have a good sense of what the primary impacts are of different weather events. Perhaps impacts can be forecast based on this local knowledge. Perhaps...

But what about something like forecasting impacts of an extreme cold event on the 18 million plus people in the New York City urban area? What impacts should the NWS warn about? About potential frost-bite, freezing water pipes, slippery roads, increased mortality and morbidity, increased energy demand, decreased consumer expenditures on ice cream cones, death of trees and plants, increased stress on diesel engines due to gelling of the fuel, psychological impacts on shut-ins, and a multitude of other impacts on 18 million people? And then what about tornado warnings, hurricane warnings, severe thunderstorm warnings, flash flood warnings, flood warnings, winter storm warnings, special marine warnings, non precipitation warnings, tsunami warnings, and even space weather warnings? And what about all the different conditions in the 122 WFOs around the country serving multitude concerns and needs of the 309,205,896 people of the U.S. (as of 15:19 UTC on May 05, 2010.

I do not know what the context and plans are within the National Weather Service for moving from forecasting weather to forecasting impacts , but the potential does raise a number of issues. The NWS does an amazing job forecasting the weather, but I wonder what it means by "impacts." If purely focusing on purely physical impacts (reduced visibility, high river flow, increased avalanche potential) that may not be a far reach from current NWS physical science-based capabilities. If moving from forecasting physical impacts to forecasting societal impacts (e.g., reduced driving speeds, increased health problems, changes in energy demand) the NWS is moving from its core competency to a whole new paradigm - one that (1) requires a significant investment to develop a social science competency, and (2) may well start to test the private-public divide.

It will be interesting to see if a move from forecasting weather to forecasting impacts is really planned in the NWS, what it means to the people advocating the change and also to those making it happen, and whether or not it is well thought out or is it perhaps just "buzz words"? How far can the science-based NWS go down the societal path?

*Jeff Lazo ( is the director of the Societal Impacts Program (SIP) at NCAR.

Figure information:

Figure 1: Example of National Weather Service Wind Advisory

Figure 2. Ficticious NWS Impacts Advisory


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