The Superstorm of March 1993

1
The Superstorm of March 1993

• A Case Study of the Storm of the Century

2
March 12-14 1993

• Formation and storm events
• Forecasts and dissemination
• Human, economic and environmental impacts

3
Synoptic Overview of the Storm

• Friday March 12 Development
• Thunderstorm development along Texas/Mexico
  border
• Rapidly intensifying low pressure system over
  Gulf of Mexico
• 984 mb low pressure by Friday evening
• Hurricane force winds reported in Gulf of Mexico

4
Synoptic Overview of the Storm

• Saturday, March 13 Strengthening
• Low pressure system moving across Gulf of Mexico
• Squall line forms ahead of cold front in eastern
  Gulf
• Widespread snow falling over southern
  Appalachians
• Florida and Cuba hit hard by severe
  thunderstorms, tornadoes, and coastal flooding
• Low pressure of 971 mb over Georgia in the
  morning, falls to 966 mb over North Carolina by
  afternoon
• Heavy snows over much of the eastern United States

5
Synoptic Overview of the Storm

• Sunday, March 14 Exiting
• Lowest pressure of 960 mb overnight
• Storm tracks west of urban corridor
• Storm filling and central low pressure rising
• Blizzard conditions west of low pressure center
• Exits U.S. by Sunday evening

6
Forecasts and Dissemination

• Models Successes and Failures
• Medium Range Forecasts for March 13-14 were
  excellent from March 8 forward
• Track and intensity of storm along East Coast
  were well predicted by several models
• Forecasts of initial formation and rapid
  strengthening over Gulf of Mexico were poor
• Little model forecasting of squall line forming
  over Gulf of Mexico
• Reasons for poor model forecasts over the Gulf of
  Mexico

7
Forecasts and Dissemination

• Forecasters Successes and Failures
• Forecasters failed to predict the rapid deepening
  of the storm in the Gulf of Mexico
• Warning signs of error
• Accounting for model errors, and correcting
  forecasts
• Excellent forecasts for urban corridor and
  northeast

8
Forecasts and Dissemination

• Dissemination Public Awareness
• NWS forecasters issued statements about storm
  starting March 11 Unusually Severe Perhaps
  Record Breaking
• Hurricane Hotline
• Florida Failures
• Long Watch and Warning lead times
• Winter Storm Warning 40 hours before event,
  Blizzard Warnings 10-24 hours before snow started
  falling
• State of Emergency in many states

9
Impacts

• Wind and Rain
• Severe thunderstorms, tornadoes, and coastal
  flooding in Florida
• Coastal flooding from Gulf Coast to Outer Banks
  and up to New York
• Power outages widespread due to winds

10
Impacts

• Snowfall
• Heavy snowfall was widespread, reached from
  Georgia and Alabama up to Maine
• Transportation paralyzed for days
• Schools and businesses closed due to impassible
  roads
• Extensive clean up costs for snow and ice removal

11
Impacts

• Storm Totals
• 100 directly related deaths (47 in Florida
• 2 billion in damage (1.6 in Florida)
• Record low sea level pressures
• 90 million people with 1 inches of snow
• Record low temperatures across southern states
• Every major airport on east coast closed at least
  once
• 25 of flights nationwide canceled

12
Summary and Questions