•El Nino: Warm Event
•La Nina: Cold Event
•“Therefore, a persistent cold (warm) ENSO from winter to summer does not create favorable conditions for drought (wet spells) to persist over the Southeast. While cold ENSO events are more likely to initiate droughts, droughts are likely to persist if the cold (warm) ENSO winter is followed by an ENSO neutral summer.” (Mo)
•ENSO influence on precipitation is seasonally dependent
•Conditions for drought: cold SSTAs in tropical Pacific in winter and neutral ENSO summer w/ warm SSTAs over west coast of US and in N. Atlantic (Mo)
•Conditions for wet spell: warm ENSO winter pattern w/ positive SSTAs in tropical Pacific and negative SSTAs in N. Atlantic…weakening of warm ENSO in summer w/ weaker SSTAs in eastern Pacific (Mo)
•During a cold ENSO event the atmospheric response to tropical SSTAs is a Pacific North American wave train. (Mo)
–Negative height anomalies over western-central US
–Positive height anomalies over SE