SAFETY, HEALTH AND ECONOMIC IMPACTS OF WEATHER AND CLIMATE IN THE URBAN ENVIRONMENT

Raymond J. BanThe Weather Channel, Inc.

MY MISSION TODAY

Provide an overview of certain weather/climate events that when occurring in urban environments produce unique challenges and impacts.

Selected Weather/Climate Events

• Winter Storm

• Heat Wave

• Flood

• Tropical Cyclone

• Wildfire

Urbanization results in:

- Increased threat for more damage and delays .

- Hundreds killed, tens of thousands injured in auto accidents.

- Millions marooned at home and work, disrupting commerce.

- Tremendous costs in road, rail and highway maintenance.

Implications for the forecaster:

– Small events (such as a dusting of snow or a light glaze) can have a huge over a short period of time – information must be collected and communicated rapidly.

– Large snow events can impact tens of millions of people for several days to a week or more

– forecast lead time is important for industry and emergency management.

– Icing can result in power outages affecting millions.

WINTER STORM

The Chicago heat wave of July 1995 caused somewhere between 465-739 deaths. It was exacerbated by the urban heat island which keeps night-time temps warmer.

Global Change Scenario:

– Very likely: More hot days.

– Very likely: Higher heat index.

– Likely: Higher night time temperatures.

– Likely: More heat waves.

HEAT WAVE

Chicago Heat WaveJuly 13-16, 1995

HIGH TEMP: 104° F (O’Hare)

DEW POINT: 75° TO 82°F

NIGHT-TIME TEMP: >75°U.S. WEATHER-RELATED DEATHS

AVERAGE PER YEAR (approx.)

Hurricanes 20

Tornadoes 60

Flooding 85

Lightning 70-100

HEAT WAVES 235

Heat waves are the #1 weather related killer and are likely to increase.

Urbanization results in:

- Reduced infiltration of rainfall.

- Accelerated runoff rates.

- Artificial flood-control channels with excessive rates of flow (where children sometimes play).

Implications for the forecaster:

- Reduced flash flood guidance values (lighter rain results in flooding).

- To have the desired warning lead time, sometimes must warn of flooding based upon rainfall in storms approaching area (before they arrive).

- In urban areas near mountains, must warn for rain falling over adjacent hills that will rush down streams and rivers (e.g., Las Vegas).

- Each new housing or business development changes the flood threshold and runoff characteristics of the urban watershed.

FLOOD

Urbanization results in: Implications for the forecaster:

– “Warning – Response” model is stressed.

– Increased difficulty in evacuation due to road constraints.

– A flood catastrophe to inland urban areas from a tropical storm or hurricane could be as costly as impacts at the coast (e.g. tropical storm Allison).

– Increased demand for safe shelters.

– More boats in the water make more people vulnerable to marine impacts.

TROPICAL CYCLONE

– Lead time

– Lead Time

– Lead Time

Urbanization results in:

- Increasingly expanding housing areas into hilly, wooded suburbs.

- Many communities in the West are in semi-arid environments, prone to long dry summer seasons and especially vulnerable to drought.

- Population growth outstripping water supply.

- Desire for trees near homes for shade and rural atmosphere as “escape” from the city.

Implications for the forecaster:

- Recognition of dangerous fire weather conditions is relatively easy.

- Prediction of in-fire weather conditions is VERY difficult.

- Scale of the wind phenomena usually smaller than observations or numerical models. Special mesoscale models now exist that integrate fires into models: e.g., Terry Clark, NCAR).

Urban Flooding

WILDFIRE

IN CLOSING….

TWC has large interest in this area.

70% of TWC viewing households are in urban environments.