Providing Weather Forecast Uncertainty

Information to the Public

Julie Demuth, Rebecca Morss, & Jeff Lazo

NCAR Societal Impacts Program

USWRP

AMS Summer Community Meeting, Boulder, COAugust 11, 2008

AMS Summer Community Meeting, Boulder, COAugust 11, 2008

The forecast high temperature for Boulder

tomorrow is 88ºF.

a) 88ºFb) 87-89ºFc) 86-90ºFd) 83-93ºFe) 78-98ºF

What do you think the actual high temp will be?

Methodology• Nationwide controlled-access web survey of

public

Analysis based on N=1465 completed responsesAnalysis based on N=1465 completed responses

• Uncertainty-related research questions:• How much confidence do people have in different

types of weather forecasts?• Do people infer uncertainty into deterministic forecasts

and, if so, how much?• How do people interpret a type of uncertainty forecast

that is already commonly available and familiar: PoP?• To what extent do people prefer to receive forecasts

that are deterministic versus those that express uncertainty?

• What formats do people prefer for receiving forecast uncertainty information?

Suppose the forecast high temperature for tomorrow for your

area is 75°F.What do you think the actual high temperature will be?

0%

10%

20%

30%

40%

50%

75°F 74-76°F(± 1°F)

73-77°F(± 2°F)

70-80°F(± 5°F)

65-85°F(± 10°F)

Other

Per

cen

t o

f R

esp

on

den

ts

N=1465

0% 10% 20% 30% 40% 50%

Prefer Channel A(deterministic)

Prefer Channel B(uncertainty)

Like both channels

Like neither channel

I don't know

Percent of Respondents

Suppose you are watching the local evening news …

• The Channel A weather forecaster says the high temperature will be 76°F tomorrow

• The Channel B weather forecaster says the high temperature will be between 74°F and 78°F tomorrow.

N=1465

Broader implications• Interest in providing uncertainty

information…• …but limited understanding of how to do this

• Empirical knowledge about what weather forecast information people get, want, use, etc. is critical

• Provide people information that they actually want and use rather than what we think they do (or should) want and useSo much from social sciences (ideas,

methodologies, theoretical frameworks, etc.) to integrate!

So much from social sciences (ideas, methodologies, theoretical frameworks,

etc.) to integrate!