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

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

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

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

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

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

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

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

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 http://water.usgs.gov/osw/lins/streamflowtrends.html 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

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!

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.

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

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

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

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

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.

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

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

Ohio Corn Production Historical Yield Data, 1930-2007

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

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

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

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

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

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

Water Resources Outlooks http://www.erh.noaa.gov/ohrfc/WRO.shtml

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: http://www.erh.noaa.gov/ohrfc/WRO.shtml Subscribe: https://public.govdelivery.com/accounts/USNWS/subscriber/new?topic_id=USNWS_1048 Discussion: http://www.erh.noaa.gov/ohrfc/HAS/text/wro.txt

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.

Summary Even though risk for extreme events may be less overall in 2012 than 2011, “RISK” will be elevated for at least the next 10-20 years overall.

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