NOAA/NWS Ohio River Forecast Center Climate Trends, Risk and Impacts on the Ohio Valley Ohio State University Severe Weather Symposium

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NOAA/NWS Ohio River Forecast CenterClimate
Trends, Risk and Impacts on the Ohio ValleyOhio
State University Severe Weather Symposium

• Jim Noel
• Service Coordination Hydrologist
• March 2, 2012

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Todays Discussion

• Climate Trends Annually and Seasonally
• Risk from Cyclone Frequency ENSO, NAO
• Climate Impacts on Ohio
• 2012 Seasonal Outlook
• Questions/Comments

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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

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Temperature/Rainfall Winter Trends

• Most significant warming has occurred in the
  winter season
• Only minor increases in winter precipitation

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Temperature/Rainfall Spring Trends

• Some warming in spring in Ohio
• Only slight increase in peak flood season rains

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Temperature/Rainfall Summer Trends

• Little change in overall summer temperatures
• Some increase in summer rainfall

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Temperature/Rainfall Autumn Trends

• No change in autumn temperatures
• Most significant increase have come in fall low
  flow season and harvest season

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Temperature/Rainfall Autumn Trends

• Ohio fits composite of United States generally
• Greatest warming in cool season
• Greatest increase in rainfall in autumn

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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
USGS Maximum Daily Flows
Credit USGS
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Cyclone Frequency Trends and Risk

• Natural variability in the system does account
  for some of the change, climate system is always
  changing, but we cant 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!

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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

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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

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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

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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
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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

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2011 Rainfall La Nina, NAO Risk

• La Nina

• There was a significant La Nina in early 2011
• The risk was gt 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
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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

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Climate Impacts on Ohio - Example

• NAO a Factor
• Positive NAO at least a contributing factor in
  warm weather in the East.

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Ohio Corn Production Historical Yield Data,
1930-2007
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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
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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
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U.S. Climate Forecasting System Temperatures

• Warm winter linger into spring with temperatures
  trending to normal by later spring and summer

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U.S. Climate Forecasting System Rainfall

• Wet winter lingers into part of spring then
  turning drier than normal by June and summer

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Japan Climate Forecasting System

• Winter

• Spring

• Summer

• Goal from climate models is can we gather an
  overall risk. Not from individual events!

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Positive NAO

• NAO

• Winter

• Spring

PDO
La Nina

• Summer

• NAO forecast to remain positive, La Nina to end,
  PDO to remain negative. Look for trends and need
  to know biases

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Water Resources Outlooks
http//www.erh.noaa.gov/ohrfc/WRO.shtml
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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_idUSNWS_1048 Discuss
ion http//www.erh.noaa.gov/ohrfc/HAS/text/wro.tx
t
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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.

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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.

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Questions!

• James.Noel_at_noaa.gov
• NOAA/NWS/Ohio River Forecast Center
• Service Coordination Hydrologist
• THANKS!