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12/19/2018, 7:13 am EST

South America Season 1-3 Ahead Outlook

JAN/FEB 2019 are forecast wetter in Southeast Brazil Executive Summary: The recent dry pattern emerging in eastern Paraguay and to the east across Southeast Brazil is forecast to reverse wetter-than-normal in early 2019 as the influence on climate by a strengthening El Nino increases. Northeast Argentina is also wetter than normal during JAN/FEB 2019. The Climate Impact Company season 1-3 ahead forecast for South America is based on weak-to-moderate El Nino through quarter 1 of 2019. But ENSO phase/intensity is more uncertain for the remainder of 2019 leading to below average forecast confidence. Climate Impact Co. Constructed Analog Rainfall Anomalies JAN/FEB 2019 Climate discussion:  During December the prevailing late spring precipitation pattern across South America went from a widespread wetter-than-normal regime (Fig. 1) to an aggressively dry signature in and east of Paraguay (Fig. 2). The result has been to produce a sudden dry soil region centered on Santa Catarina and Parana (Fig. 3). The precipitation pattern change is driven by a tighter consolidation of upper trough(s) both west and east of South America at the northern Argentina latitude supporting sometimes heavy precipitation events in northern Argentina while the central and southern Brazil climate has been produced by a strengthening subtropical ridge. As the core of the warm season is approaching the weak-to-moderate El Nino in the equatorial East Pacific will gain control of the climate pattern. The Climate Impact Company ENSO analog forecast emphasizes lack of strength to this warm ENSO event with the most recent analogs (2007 and 2010) weighted most heavily. Forecast confidence is excellent on weak-to-moderate El Nino for Q1 of 2019 (Fig. 4) but diverting forecasts (sustained El Nino or a trend toward La Nina) appear for the remainder of 2019. The Bureau of Meteorology/Australia maintains El Nino well into 2019 (Fig. 5). Fig. 1-2: The past 45 days and past 15 days rainfall anomalies across South America identify a rapidly developing dry zone east of Paraguay.   Fig. 3: The 0 to 10 CM depth soil moisture anomaly analysis across South America indicates a dry zone developing in and east of Paraguay. Fig. 4: The Climate Impact Company ENSO analog forecast. Fig. 5: The Bureau of Meteorology/Australia Nino34 SSTA forecast reveals moderate El Nino ahead which dominates South America climate. Seasonal climate outlooks: The outlooks are adjusted for an increasing influence of warm ENSO developing during quarter 1 of 2019. Extra weight of recent analog years (compared to older analog years) is made given climate change. The outlooks extend to winter 2019 and are compared with last month’s forecasts. DEC/JAN/FEB 2018-19: Despite the drier regime in and east of Paraguay developing in December a wetter pattern is expected to return for early in the New Year. The wetter pattern should reverse current emerging drought concerns. The wetter forecast is reliant on the influence of El Nino increasing. Northeast Argentina is adjusted wetter (also). Conversely, the wet pattern across north/northeast Brazil in late 2018 driven by cross equatorial trade wind flow as identified by the positive phase of the Atlantic meridional mode (AMM) should ease. Warm ENSO climatology in this zone is dry therefore a drier pattern change should emerge early in 2019. The temperature anomaly forecast indicates lack of important heat in Argentina while anomalous heat is most likely to occur in Southeast Brazil. Fig. 6-7: The Climate Impact Company temperature and precipitation anomaly outlook for DEC/JAN/FEB 2018-19. The previous forecast is below. MAR/APR/MAY 2019: Uncertain is whether the El Nino climate will persist. Analogs are split between continued El Nino (and dynamic models agree) while more recent analogs end El Nino. The forecast is based on a consensus of the 2 possibilities therefore forecast confidence is below average. A dry regime is forecast in Brazil while southeast Brazil and northeast Argentina are wetter than normal. Argentina maintains a thermal pattern doubting any anomalous warmth. Fig. 8-9: The Climate Impact Company temperature and precipitation anomaly outlook for MAR/APR/MAY 2019. The previous forecast is below. JUN/JUL/AUG 2019: The winter 2019 outlook is adjusted somewhat cooler over Argentina. Brazil is on the warm side. Dryness is forecast across southwest Brazil while a small wet anomaly appears in southeast Brazil. The ENSO forecast for next winter is uncertain leading to below average forecast confidence. Fig. 10-11: The preliminary Climate Impact Company temperature and precipitation anomaly outlook for JUN/JUL/AUG 2019.