Weekly ENSO Diagnostics Report: La Nina Strenghtening

Highlight: La Nina continues to strengthen.

Fig. 1: The subsurface upper ocean heat index for the equatorial Pacific during the past 12 months.

Discussion: The coolest upper ocean heat index in the equatorial East Pacific since September 2010 occurred during October 2021 (Fig. 1). The subsurface chill provides ample strength for a cool La Nina event to unfold. Last week, Nino34 SSTA dipped to -1.1C and represents presence of a moderate-strength La Nina (Fig. 2). The latest NCEP CFS V2 forecast indicates La Nina continues to strengthen and is more intense than the 2020-21 La Nina event peaking in December (Fig. 3). In the U.S., a La Nina winter favors a northern U.S. storm track strongest in the Northwest while the southern states are generally drier than normal. Modern-day La Nina tends to produce warm winters in the South and East.

Fig. 2: The 12-week Nino SSTA regime indicates La Nina continues to strengthen.

Fig. 3: The latest NCEP CFS V2 Nino34 SSTA forecast reveals an intensifying La Nina peaking by late 2021.