North American Impacts of El Nino

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North American Impacts of El Nino

• Jon M Schrage

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r(-SOI3mrm,OLR), r(-SOI3mrm,?_at_200),
r(-SOI3mrm,winds_at_ 200)
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Rossby Wave Source

• Conservation of Absolute Vorticity
• The twin anticyclones aloft are what initially
  displaces the air parcels.
• Results in a pattern of troughs and ridges far
  downstream.

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PNA PATTERN
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PNA PATTERN
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The following slides are composites from January
1998.
http//www.cdc.noaa.gov/cgi-bin/Composites/printpa
ge.pl
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500mb heights
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1000mb T
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1000mb T
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OLR
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OLR
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Precip
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Precip
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Sea Level Pressure
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Sea Level Pressure
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Changnon

• What counted as an impact of El Nino?
• The general monthly and seasonal temperature and
  precipitation conditions
• The lack of Atlantic hurricanes
• Snowstorms?
• An event attributed to El Nino by a NOAA employee
  speaking in an official capacity

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Changnon

• Losses during El Nino
• Rain in the southeast (including Florida)
• Unusual tornadoes
• Crop damage by rain
• Reduced tourism
• Direct damage from storms

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Changnon

• Losses during El Nino
• Storms
• October, 1997 in Midwest
• January, 1998 in New England
• April, 1998 in Ohio Valley

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Changnon

• Losses during El Nino
• Drought in Hawaii
• Ski resorts in Midwest
• Producers of salt, natural gas, snowmobiles, etc.
• Fires in Florida

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Changnon

• Benefits during El Nino
• Mild Winter in Midwest
• Few lives lost (13 vs. 757!)
• Lower fuel costs (10 nationally!)
• Fewer airline and shipping delays
• Longer construction season
• Snow removal costs

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Changnon

• Benefits of El Nino
• No landfalling hurricanes
• 13 lives, 5 billion, saved

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Changnon

• Benefits of El Nino
• Difficult to quantify
• Improvement in lifestyle
• Recharging reservoirs

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Changnon

• Losses
• Human lives lost 189
• Economic costs 4.2 billion
• Benefits
• Human lives saved 850
• Economic gains 19.6 billion

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Changnon

• Lessons
• the need to focus on both the good and bad
  impacts of predicted weather conditions. The
  media tends to focus only on the negative
  outcomes.

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Changnon

• Lessons
• News writers tend to approach local experts
  for interpretations of the events resulting in
  widely different interpretations

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Changnon

• Lessons
• all weather conditions produce winners and
  losers

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Changnon

• Lessons
• predicting future impacts on lives and the
  economy due to expected weather is likely as
  difficult as making accurate long range weather
  predictions.

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