Eastern North American Sea-level Pressure Dipole Pattern


As shown by Schulte et al. (2017), the ENA pattern is related to eastern equatorial Pacific SST anomalies during the winter and spring. Temporal changes in extreme eastern equatorial Pacific SST anomalies can be measured using the NINO 1+2 index. Schulte et al. (2017) showed that the relationship between the ENA and Nino 1+2 indices is strongest in the January-March and February-April seasons. Consistently, the Marches and Februaries following the super strong 1982-1983, 1997-1998, and 2015-2016 EL Ninos featured positive ENA phases. In fact, a prominent positive ENA event- perhaps the strongest event on record based on daily NCEP reanalysis- occurred in February 2016. This event featured widespread severe weather across the eastern United States. The Northeast U.S was also quite wet in February 2016 (https://www.ncdc.noaa.gov/sotc/national/201602), consistent with how the February ENA index is positively correlated with February precipitation anomalies across the Northeast U.S as shown here.

Correlation between the ENA and Nino 1+2 Indices for the 1979-2017 Period

Correlation between ENA Index and Nino 1.2 Index
Current sea surface temperature anomalies
LIM forecasts of SST anomalies
CFSv2 Seasonal Climate Forecasts