1. North American Impacts of El Nino Jon M Schrage

2. r(-SOI 3mrm,OLR’), r(-SOI 3mrm,  ’@200), r(-SOI 3mrm,winds@ 200)

3. 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.

4. PNA PATTERN

6. The following slides are composites from January 1998. http://www.cdc.noaa.gov/cgi-bin/Composites/printpage.pl

7. 500mb heights

9. 1000mb T

11. OLR

13. Precip

15. Sea Level Pressure

17. 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

18. Changnon Losses during El Nino: –Rain in the southeast (including Florida) Unusual tornadoes Crop damage by rain Reduced tourism Direct damage from storms

19. Changnon Losses during El Nino: –Storms: October, 1997 in Midwest January, 1998 in New England April, 1998 in Ohio Valley

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

21. 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

22. Changnon Benefits of El Nino: –No landfalling hurricanes 13 lives, $5 billion, saved

23. Changnon Benefits of El Nino: –Difficult to quantify: Improvement in lifestyle Recharging reservoirs

24. Changnon Losses: –Human lives lost: 189 –Economic costs:$4.2 billion Benefits: –Human lives saved: 850 –Economic gains: $19.6 billion

25. 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.”

26. Changnon Lessons: –“News… writers tend to approach “local” experts for interpretations of the events… [resulting] in widely different interpretations…”

27. Changnon Lessons: –“…all weather conditions produce winners and losers”

28. 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.”