Somewhat unexpectedly, sea-surface temperatures across the eastern Pacific Ocean have warmed significantly during the past month. Some areas are running warmer than average by between 1 and 2 degrees.
Water temperatures across much of the rest of the equatorial Pacific also show signs of warming. These warming trends indicate that the La Nina is weakening and the ENSO phase is expected to become more neutral during the next month or two.
Beyond that, the current rapid warming over parts of the equatorial Pacific must be monitored to see if an El Nino phase is beginning to develop. A similar decline of a La Nina phase occurred around this same time in 2011.
As for April, warmer than average temperatures are forecast across parts of the Northeast, Midwest, Tennessee Valley and lower Mississippi Valley based on the weakening La Nina and a persistent positive North Atlantic Oscillation and past climate data. A surplus of early-season cooling degree-days of between 30 and 60 is expected across parts of the Deep South and lower Mississippi Valley.
Meanwhile, the Midwest, Ohio Valley and Northeast likely will see late-season heating degree-day deficits of between 30 and 60. Expect slightly cooler than average temperatures throughout the Pacific Northwest and northern Rockies.