South America Precipitation Forecast for Q4/2019 & Q1/2020 Using Regional SSTA Forecasts (Rather than ENSO) Discussion: Research has shown that in North America the U.S. agriculture belts summertime precipitation patterns are often-related to the middle latitude SSTA patterns especially if ENSO is weak or neutral. The most common set of circumstances to produce increased drought risk is anomalous warmth of the northeast Pacific (positive phase of the Pacific decadal oscillation) and North Atlantic (positive phase of the Atlantic multi-decadal oscillation). The +PDO/+AMO was generally present this past summer season and seasonal soil moisture trends responded as the seasonal soil moisture change was dry just-about everywhere in the U.S. except the northern Great Plains (Fig. 1). The same non-tropical SSTA-based (forecast) approach can be used to project the South America rainfall patterns for the next 3-6 months. Currently, regional SSTA off the west coast of South America is cool while off the east coast of the continent the SSTA pattern is averaging neutral. The NMME global SSTA forecast for OCT/NOV/DEC 2019 indicates the cool anomaly off the west coast remains (and may be stronger than indicated) while SSTA east of South America is warming (Fig. 2). The cool off the west coast/warm off the east coast trend continues for JAN/FEB/MAR 2020 (Fig. 3). The SSTA-based climate forecast for Q4/2019 and Q1/2020 across South America is in a large part driven by the relationship of these differing regional SSTA patterns. In the modern climate era (since the late 1990’s when long-term cycles of ENSO, PDO and AMO changed phase) there are 4 analog years with similar SSTA patterns projected by the NMME model for late 2019 and early 2020. They are 2014-15, 2010-11, 2007-08 and 2001-02. Based on these analog years the rainfall anomaly forecast across South America for OCT/NOV/DEC 2019 maintains a currently well-established dry pattern across central and northern Argentina and eastern Brazil (Fig. 4). Roughly the same SSTA pattern, a little warmer east of South America causes a near reversal in the pattern to wetter than normal for northern Argentina to southwest Brazil during JAN/FEB/MAR 2020 (Fig. 5). The implications are dryness across central and eastern Argentina plus central and eastern Brazil crop areas is likely to worsen during Q4/2019 and recover during Q1/2020. The forecast is not ENSO-based mainly due to a lack of strong ENSO signal. Instead the SSTA patterns either side of South America which will mirror the strength of summertime subtropical high pressure ridging are used to project the rainfall patterns. Fig. 1: +PDO/+AMO (warm mid-latitude oceans) historically increases drought risk during summer in the U.S. The seasonal soil moisture TREND identifies the +PDO/+AMO inspired drier soils across the U.S. Fig. 2: The NMME global SSTA forecast for OCT/NOV/DEC 2019. Fig. 3: The NMME global SSTA forecast for JAN/FEB/MAR 2020. Fig. 4: The regional SSTA forecast based analog forecast of anomalous rainfall for quarter 4 of 2019 across South America. Fig. 5: The regional SSTA forecast based analog forecast of anomalous rainfall for quarter 1 of 2020 across South America.