1. Jim Noel Service Coordination Hydrologist March 2, 2012
NOAA/NWS Ohio River Forecast Center Climate Trends, Risk and Impacts on the Ohio Valley Ohio State University Severe Weather Symposium
Jim Noel
Service Coordination Hydrologist
March 2, 2012

2. Climate Trends – Annually and Seasonally
Today’s Discussion
Climate Trends – Annually and Seasonally
Risk from Cyclone Frequency ENSO, NAO
Climate Impacts on Ohio
2012 Seasonal Outlook
Questions/Comments

3. Temperature/Rainfall Annual Trends
Trend in Ohio has been for warming from 1976 to recently
Trend in Rainfall has been for increased rainfall from 1976 to recently
Much of the increase has been in late summer through autumn

4. Temperature/Rainfall Winter Trends
Most significant warming has occurred in the winter season
Only minor increases in winter precipitation

5. Temperature/Rainfall Spring Trends
Some warming in spring in Ohio
Only slight increase in peak flood season rains

6. Temperature/Rainfall Summer Trends
Little change in overall summer temperatures
Some increase in summer rainfall

7. Temperature/Rainfall Autumn Trends
No change in autumn temperatures
Most significant increase have come in fall low flow season and harvest season

8. Temperature/Rainfall Autumn Trends
Ohio fits composite of United States generally
Greatest warming in cool season
Greatest increase in rainfall in autumn

9. Climate Trends in Hydrology
Most trends are up especially from Deep South to Ohio Valley and Northeast.
For Ohio, streamflows trends are up in 2-3 of the 4 seasons for minimum and median flows, especially autumn and late summer
Little change to all seasons in Ohio for maximum flows
USGS Median Daily Flows
Just as temperatures and rainfall has been increasing across much of the U.S. the last 20 years, so too are streamflows. All categories are showing increases except the peak category which has seen a small decline. Regionally, most areas have increased but some have seen decreases.
USGS Maximum Daily Flows
Credit: USGS

10. Cyclone Frequency Trends and Risk
Natural variability in the system does account for some of the change, climate system is always changing, but we can’t explain all the change through natural processes
1900 to 1950s was very active then less active period from 1960s to 1990s
We have now returned to a more active period with INCREASED RISK!

11. Climate Impacts on Ohio – La Nina Risk
La Nina is the cooling of the eastern Pacific Ocean waters near the equator
Thunderstorms in the western Pacific Ocean create downstream impacts into North America
Commonly wet in Ohio Valley
La Nina is the cooling of the eastern Pacific Ocean equatorial waters shifting climate patterns and favoring wet weather in Ohio Valley and Kentucky.

12. Climate Impacts on Ohio – La Nina Risk
Typically La Nina events have their best relationship during the winter and early spring
The stronger the La Nina the better the relationship
Heavy rain along the Ohio River and adjacent areas is common

13. Climate Impacts on Ohio – El Nino Risk
Typically El Nino events have their best relationship during the winter and early spring
The stronger the El Nino the better the relationship
It tends to be drier in Ohio

14. Climate Impacts on Ohio – NAO Risk
North Atlantic Oscillation – relationship between low pressure near Greenland and high pressure in the Atlantic
Positive phase tends to be warm and wet winters
Negative phase is colder, not as wet but snowier
NAO has been more negative since early 2000s
Credit: Columbia University

15. Climate Impacts on Ohio – NAO Risk
Typically late winter and spring are wet with a positive NAO
Typically late winter and spring are drier with a negative NAO
Hard to predict NAO past 2-4 weeks but climate models are getting better

16. 2011 Rainfall – La Nina, NAO Risk
There was a significant La Nina in early 2011
The risk was > 1.5 times the normal for extreme rainfall events in the big La Nina events
North Atlantic Oscillation switched from negative (colder/dry) phase in winter to positive (warmer/wet phase in spring
Many other reasons too as climate/weather is quite complex
North Atlantic Oscillation
Much weaker La Nina this winter means more influence by other climate factors like NAO.

17. Current NAO Strong Negative NAO fall and early winter 2010/2011
Strong Positive NAO fall and early winter 2011/2012
Generally staying neutral to positive for rest of January supporting
If NAO stays positive it supports warmer weather through spring then near normal for summer still warmer in western corn belt

18. Climate Impacts on Ohio - Example
NAO a Factor
Positive NAO at least a contributing factor in warm weather in the East.

19. Ohio Corn Production Historical Yield Data, 1930-2007

20. Climate Impacts on Ohio - Example
When NAO is negative, corn yields 10% below normal in Ohio
When NAO is positive, corn yields up 8% above normal in Ohio
NAO does change over time and is influenced by many factors
Research: Joint Ohio State University and NOAA/NWS/Ohio River Forecast Center

21. Climate Impacts on Ohio - Example
Crop yields fall typically 10-12% below normal when a La Nina or El Nino event occurs in the Pacific Ocean.
More fluctuations in our climate will yield greater fluctuations in ENSO which will have an impact on Ohio agriculture
Research: Joint Ohio State University and NOAA/NWS/Ohio River Forecast Center

22. U.S. Climate Forecasting System Temperatures
Warm winter linger into spring with temperatures trending to normal by later spring and summer

23. U.S. Climate Forecasting System Rainfall
Wet winter lingers into part of spring then turning drier than normal by June and summer

24. Japan Climate Forecasting System
Winter
Spring
Summer
Goal from climate models is can we gather an overall risk. Not from individual events!

25. Positive NAO
NAO
Winter
PDO
Spring
La Nina
Summer
NAO forecast to remain positive, La Nina to end, PDO to remain negative. Look for trends and need to know biases

26. Water Resources Outlooks

27. Water Resources Outlooks
Subscribe to the Ohio River Forecast Center Water Resources Outlook
Monthly Outlook talking about flood and drought risk and rainfall and temperature risks
Probability maps
Website:
Subscribe:
Discussion:

28. Summary Climate System is complex (no silver bullet)
ENSO and NAO impact our weather, more so when events are strong
Many other climate regimes impact the weather as well
2012 will be different than 2011,likely fewer extreme events
It is all about risk management! What is the risk of events occurring!
The risk appears to shift from active to inactive from spring into summer.

29. Summary
Even though risk for extreme events may be less overall in 2012 than 2011, “RISK” will be elevated for at least the next years overall.

30. Questions! James.Noel@noaa.gov NOAA/NWS/Ohio River Forecast Center
Service Coordination Hydrologist
THANKS!