Weekly ENSO Diagnostics Report: La Nina Strenghtening

-WPO/-EPO Lead The Charge On A Colder 6-10-Day Central U.S. Forecast!
10/27/2021, 5:51 pm EDT
Unusually Dynamic Global SSTA Pattern October 2021
11/04/2021, 5:06 am EDT
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Upper ocean heat in the eastern equatorial Pacific plunges to the lowest level since September 2010. Indicated is plenty of fuel to allow La Nina to intensify which it will likely to peak in December.

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.