3rd Year of La Nina Rainfall Climatology for North and South America

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Discussion: Forecasts for a 3rd consecutive La Nina year are confident. 3rd La Nina years are rare. Using the operational Nino index (ONI) for 1950-2022 yields 3 ENSO regimes (1956, 1975 and 2000) in which a 3rd consecutive La Nina year occurred (Table 1). In that 3rd year of La Nina, on average the U.S. experiences widespread dryness across the central and southern Great Plains to Texas and eastward to the Midwest States southeastward to Florida (Fig. 1). Nationally, the U.S. receives no regions of wet climate. In South America, the wet La Nina signal across the North Coast is more intense and compensated for by stronger subtropical high-pressure across central and southern Brazil that yields a dry climate (Fig. 2). The mid-latitude storm track is sufficiently active to bring above normal precipitation to parts of Argentina.

Fig. 1: U.S. precipitation anomalies for the 3rd year of a long-term La Nina regime.

Fig. 2: U.S. precipitation anomalies for the 3rd year of a long-term La Nina regime.

YearDJFJFMFMAMAMAMJMJJJJAJASASOSONONDNDJ
1950-1.5-1.3-1.2-1.2-1.1-0.9-0.5-0.4-0.4-0.4-0.6-0.8
1951-0.8-0.5-0.20.20.40.60.70.91.01.21.00.8
19520.50.40.30.30.20.0-0.10.00.20.10.00.1
19530.40.60.60.70.80.80.70.70.80.80.80.8
19540.80.50.0-0.4-0.5-0.5-0.6-0.8-0.9-0.8-0.7-0.7
1955-0.7-0.6-0.7-0.8-0.8-0.7-0.7-0.7-1.1-1.4-1.7-1.5
1956-1.1-0.8-0.6-0.5-0.5-0.5-0.6-0.6-0.5-0.4-0.4-0.4
1957-0.20.10.40.70.91.11.31.31.31.41.51.7
19581.81.71.30.90.70.60.60.40.40.40.50.6
19590.60.60.50.30.2-0.1-0.2-0.3-0.10.00.00.0
YearDJFJFMFMAMAMAMJMJJJJAJASASOSONONDNDJ
1960-0.1-0.1-0.10.00.00.00.10.20.30.20.10.1
19610.00.00.00.10.20.30.1-0.1-0.3-0.3-0.2-0.2
1962-0.2-0.2-0.2-0.3-0.3-0.20.0-0.1-0.1-0.2-0.3-0.4
1963-0.4-0.20.20.30.30.50.91.11.21.31.41.3
19641.10.60.1-0.3-0.6-0.6-0.6-0.7-0.8-0.8-0.8-0.8
1965-0.6-0.3-0.10.20.50.81.21.51.92.02.01.7
19661.41.21.00.70.40.20.20.1-0.1-0.1-0.2-0.3
1967-0.4-0.5-0.5-0.4-0.20.00.0-0.2-0.3-0.4-0.3-0.4
1968-0.6-0.7-0.6-0.40.00.30.60.50.40.50.71.0
19691.11.10.90.80.60.40.40.50.80.90.80.6
YearDJFJFMFMAMAMAMJMJJJJAJASASOSONONDNDJ
19700.50.30.30.20.0-0.3-0.6-0.8-0.8-0.7-0.9-1.1
1971-1.4-1.4-1.1-0.8-0.7-0.7-0.8-0.8-0.8-0.9-1.0-0.9
1972-0.7-0.40.10.40.70.91.11.41.61.82.12.1
19731.81.20.5-0.1-0.5-0.9-1.1-1.3-1.5-1.7-1.9-2.0
1974-1.8-1.6-1.2-1.0-0.9-0.8-0.5-0.4-0.4-0.6-0.8-0.6
1975-0.5-0.6-0.7-0.7-0.8-1.0-1.1-1.2-1.4-1.4-1.6-1.7
1976-1.6-1.2-0.7-0.5-0.30.00.20.40.60.80.90.8
19770.70.60.30.20.20.30.40.40.60.70.80.8
19780.70.40.1-0.2-0.3-0.3-0.4-0.4-0.4-0.3-0.10.0
19790.00.10.20.30.20.00.00.20.30.50.50.6
YearDJFJFMFMAMAMAMJMJJJJAJASASOSONONDNDJ
19800.60.50.30.40.50.50.30.0-0.10.00.10.0
1981-0.3-0.5-0.5-0.4-0.3-0.3-0.3-0.2-0.2-0.1-0.2-0.1
19820.00.10.20.50.70.70.81.11.62.02.22.2
19832.21.91.51.31.10.70.3-0.1-0.5-0.8-1.0-0.9
1984-0.6-0.4-0.3-0.4-0.5-0.4-0.3-0.2-0.2-0.6-0.9-1.1
1985-1.0-0.8-0.8-0.8-0.8-0.6-0.5-0.5-0.4-0.3-0.3-0.4
1986-0.5-0.5-0.3-0.2-0.10.00.20.40.70.91.11.2
19871.21.21.10.91.01.21.51.71.61.51.31.1
19880.80.50.1-0.3-0.9-1.3-1.3-1.1-1.2-1.5-1.8-1.8
1989-1.7-1.4-1.1-0.8-0.6-0.4-0.3-0.3-0.2-0.2-0.2-0.1
YearDJFJFMFMAMAMAMJMJJJJAJASASOSONONDNDJ
19900.10.20.30.30.30.30.30.40.40.30.40.4
19910.40.30.20.30.50.60.70.60.60.81.21.5
19921.71.61.51.31.10.70.40.1-0.1-0.2-0.3-0.1
19930.10.30.50.70.70.60.30.30.20.10.00.1
19940.10.10.20.30.40.40.40.40.60.71.01.1
19951.00.70.50.30.10.0-0.2-0.5-0.8-1.0-1.0-1.0
1996-0.9-0.8-0.6-0.4-0.3-0.3-0.3-0.3-0.4-0.4-0.4-0.5
1997-0.5-0.4-0.10.30.81.21.61.92.12.32.42.4
19982.21.91.41.00.5-0.1-0.8-1.1-1.3-1.4-1.5-1.6
1999-1.5-1.3-1.1-1.0-1.0-1.0-1.1-1.1-1.2-1.3-1.5-1.7
YearDJFJFMFMAMAMAMJMJJJJAJASASOSONONDNDJ
2000-1.7-1.4-1.1-0.8-0.7-0.6-0.6-0.5-0.5-0.6-0.7-0.7
2001-0.7-0.5-0.4-0.3-0.3-0.1-0.1-0.1-0.2-0.3-0.3-0.3
2002-0.10.00.10.20.40.70.80.91.01.21.31.1
20030.90.60.40.0-0.3-0.20.10.20.30.30.40.4
20040.40.30.20.20.20.30.50.60.70.70.70.7
20050.60.60.40.40.30.1-0.1-0.1-0.1-0.3-0.6-0.8
2006-0.9-0.8-0.6-0.4-0.10.00.10.30.50.80.90.9
20070.70.2-0.1-0.3-0.4-0.5-0.6-0.8-1.1-1.3-1.5-1.6
2008-1.6-1.5-1.3-1.0-0.8-0.6-0.4-0.2-0.2-0.4-0.6-0.7
2009-0.8-0.8-0.6-0.30.00.30.50.60.71.01.41.6
YearDJFJFMFMAMAMAMJMJJJJAJASASOSONONDNDJ
20101.51.20.80.4-0.2-0.7-1.0-1.3-1.6-1.6-1.6-1.6
2011-1.4-1.2-0.9-0.7-0.6-0.4-0.5-0.6-0.8-1.0-1.1-1.0
2012-0.9-0.7-0.6-0.5-0.30.00.20.40.40.30.1-0.2
2013-0.4-0.4-0.3-0.3-0.4-0.4-0.4-0.3-0.3-0.2-0.2-0.3
2014-0.4-0.5-0.30.00.20.20.00.10.20.50.60.7
20150.50.50.50.70.91.21.51.92.22.42.62.6
20162.52.11.60.90.4-0.1-0.4-0.5-0.6-0.7-0.7-0.6
2017-0.3-0.20.10.20.30.30.1-0.1-0.4-0.7-0.8-1.0
2018-0.9-0.9-0.7-0.5-0.20.00.10.20.50.80.90.8
20190.70.70.70.70.50.50.30.10.20.30.50.5
YearDJFJFMFMAMAMAMJMJJJJAJASASOSONONDNDJ
20200.50.50.40.2-0.1-0.3-0.4-0.6-0.9-1.2-1.3-1.2
2021-1.0-0.9-0.8-0.7-0.5-0.4-0.4-0.5-0.7-0.8-1.0-1.0
2022-1.0-0.9-1.0-1.1-1.0

Table 1: The operational Nino index for 1950-2022 identifies 3 ENSO regimes in which a 3rd year of La Nina developed.