News
02/08/2022, 8:17 am EST

AG Climate Research: New Factors Causing Hostile Argentina/Brazil Climate Regime of Summer 2021-22 So Far

Executive summary: Adverse climate affecting crop production is often blamed on the ENSO regime. La Nina is in-place now and cited for causing the harsh hot/dry warm season climate across Paraguay and Northern Argentina while Brazil has observed unrelenting rainfall. La Nina has certainly continued to these climate regimes. However, a relatively new aspect of global ocean climate and influence on the upper atmosphere which leads to sensible weather patterns is likely a larger catalyst to the Argentina/Paraguay/Brazil hostile climate regime rather than La Nina. Specifically, the emergence in recent years of large anomalous warm SSTA regions mostly in the middle latitudes and referred to by climate scientists as “warm blobs” are leading to regional weather patterns that can cause extremes and are not necessarily related to ENSO. The Argentina/Paraguay/Brazil extreme climate of the 2021-22 warm season is mostly shaped by this new phenomenon. Discussion: The meteorological summer 2021-22 climate across Argentina to Brazil has produced harsh extremes adversely affecting crops. During the summer season so far, anomalous heat has accelerated dry soils in Paraguay, northern Argentina to far southeastern Brazil (Fig. 1). Most of summer has featured very dry climate in this region (Fig. 2). Conversely, excessive rainfall beginning last spring has persisted over much of central and eastern Brazil. The second of two La Nina events emerged last September (according to NOAA) and continues in early 2022 and is generally blamed for the climate pattern described. However, the climate pattern has unique characteristics related to other aspects of climate (somewhat unique to recent years) and possibly a larger contributor to the Argentina/Brazil summer climate of 2021-22 (so far) than La Nina. The wet pattern in Brazil is due mostly to a semi-permanent upper-level low-pressure trough just southeast of Brazil present since last spring (Fig. 3). The upper trough has a northwestward extension into Brazil causing the consistent instability to drive heavy rains. Meanwhile, to the south of the upper trough, a semi-permanent upper-level high-pressure system is in-place also extending northwestward (at times) to enhance the Paraguay/Argentina dryness. Helping to enhance the Brazil precipitation is a very warm Tropical South Atlantic (TSA) index which was at historic warm levels JUL/AUG/SEP last year and although not as strong certainly lingering into early summer 2021-22. Across the warm South Atlantic tropics, trade winds have carried above normal low atmospheric moisture into the Brazil trough pattern to make the observed rainfall more extreme. The atmosphere is constantly in a state of compensation. The heavy convective rains in Brazil caused the compensating atmospheric subsidence to the south across Paraguay and Argentina to induce hot temperatures, lack of rainfall and drought. This phenomenon is separate from La Nina. The climate pattern described is well-correlated to the 90-day global SSTA analysis (Fig. 4). La Nina is well-established. But note a relatively new phenomenon, extremely warm SSTA regions in the mid-latitudes of both hemispheres sometimes referred to by climate scientists as “warm blobs”. Across these regions of warm SSTA semi-permanent upper-level high-pressure ridge areas are common as previously identified across Southern Argentina extending east (and westward). These upper-level features are independent of ENSO and can induce other upper- level features to compensate for the strength of the high-pressure ridge. In this case, the upper trough southeast of Brazil. Again, this phenomenon is not necessarily related to La Nina. All La Nina climate regimes are not the same. However, the past 10 years during DEC/JAN when La Nina was present has (on average) produced a South America climate with a hot bias in Northeast Brazil and the central coast of Argentina while the precipitation bias has been very wet over northwest continent (Fig 5-6). The DEC/JAN 2021-22 climate pattern is unique and possibly more related to the mid-latitude SSTA pattern(s) and their influence on the persistent upper air features driving the UNIQUE climate of summer 2021-22 (so far) across South America. Summary: An unusually hostile climate pattern has emerged in South America during the 2021-22 warm season. Anomalous heat and dryness have propelled a drought in Paraguay to Southeast Brazil to Northern Argentina while excessive rains have plagued Brazil. While La Nina has contributed to this pattern, the more likely specific catalyst is the semi-permanent upper-level low-pressure trough southeast of Brazil extending northwestward into Brazil to cause convective rains compensated for by subsidence on the back side of that rainfall and centered on Paraguay and Argentina to cause just-the-opposite climate pattern – dryness and heat to accelerate drought. The South Atlantic SSTA pattern reveals a “warm blob” east of Argentina where an upper-level high-pressure ridge persists and to compensate for that ridge, the upper trough southeast of Brazil has formed. Up until recently, the entrainment of unusually wet trade winds in the tropical Atlantic enhanced by a vigorous warm tropical South Atlantic (TSA) index has enhanced the Brazilian rainfall caused by the upper trough. Important is understanding the emergence of an increasingly influential mid-latitude oceanic regime where regions of surface (and subsurface) water are unusually warm and can lead to regional climate extremes not necessarily related to ENSO. Fig. 1-3: The South America temperature anomalies and precipitation rate for Dec. 1, 2021 to Feb. 5, 2022 (top) and correlating upper air pattern using the 400 MB level (bottom). Fig. 4: The global SSTA analysis for the past 90 days revealing regional SSTA and their climate influences other than La Nina. Fig. 5-6: The DEC/JAN La Nina temperature and precipitation anomalies for the past 10 episodes.
01/02/2022, 3:11 pm EST

AG Market Research: Expanding drought concerns in U.S. heading toward Q2/2022!

A conservative U.S. drought forecast is most-focused on West-central to Mid-south U.S. drought expansion/strengthening while also strengthening drought from the Carolinas to Florida. The “caveat” (and more extreme scenario) forecast projects a wider drought stretching across the southern half of the U.S. and possibly into the Western U.S. Corn Belt.
12/28/2021, 5:00 am EST

AG Research: The Climate Drivers Leading to Historic Flooding in Brazil

To the north of a blocking high-pressure system stretched west-to-east across southern portions of South America, two cutoff upper-level low-pressure systems have formed. One low is southeast of Brazil and is causing historic rainfall across Brazil. A second upper low is off the West Coast of South America causing the heavy rain pattern to arc westward. The upper-level features are reflected in the regional SSTA pattern. These conditions are likely to last into January causing more excessive rainfall in Brazil.
11/28/2021, 12:58 pm EST

AG Market Weather/Climate Research: “Warm Blobs” Shaping the Southern Hemisphere Early Summer Climate Pattern

Executive summary: In recent years large areas of warm SSTA commonly referred to as “warm blobs” have emerged as prominent influencers on regional climate. The Northeast Pacific “warm blob” emerging in 2013-14 is the most talked about (and researched) climate influencer but others have emerged. “Warm blobs” are effective climate diagnostics correlating to large regions of semi-permanent high-pressure featuring above normal sunlight and anomalous dry/warm climate. Emergence of “warm blobs” certainly is consistent with the accelerating warming atmosphere of the past decade. To compensate for the “warm blob” to semi-permanent high-pressure ridge areas (in the subtropical and middle latitudes) areas of storm-generating trough(s) are also vividly present. Given the high-amplitude upper air pattern associated with the “warm blob” SSTA pattern slow-moving climate regimes capable of producing harsh conditions such as drought or flooding are generated. In this report, we take a look at the southern hemisphere “warm blobs” and the correlating upper air pattern just ahead of meteorological summer in the southern hemisphere. Discussion: The “warm blob” SSTA regions near and east of New Zealand and east of Argentina are semi-permanent and dominant features in the southern hemisphere SSTA regime (Fig. 1). However, relatively new “warm blobs” have recently emerged off Southwest Africa and in the South Indian Ocean. In fact, ahead of summer, the “warm blobs” off Southwest Africa and particularly in the South Indian Ocean are strengthening most quickly (Fig. 2). The correlating “warm blob” SSTA regions to the upper-level semi-permanent high-pressure ridge areas in the southern hemisphere is striking! The strongest high-pressure ridge areas are across/near the South Indian Ocean and New Zealand “warm blobs” (Fig. 3). High-pressure ridging is also intense to the east of Argentina. Fig. 1:  Daily global SSTA analysis for Nov. 27, 2021 identifying the southern hemisphere “warm blobs” just-ahead of meteorological summer 2021-22. Fig. 2:  Southern hemisphere SSTA changes over the past 30 days. Fig. 3:  The November 2021 semi-permanent high-pressure ridge areas across or near “warm blob” SSTA regions (and compensating upper trough locations). Beneath high-pressure areas sunlight is above normal and a feedback mechanism develops as increased sunlight generates stronger warm SSTA which in-turn maintains/strengthens high-pressure ridging. Often less-discussed is the downstream compensating effects. For instance, note that in-between the South Indian Ocean and New Zealand upper-level ridge areas a compensating upper trough is located over Australia and responsible for bringing drenching rains during late spring. Additionally, just north of the high-pressure region to the east of Argentina a semi-permanent upper trough has generated and responsible (in-part) for bringing significant rains to parts of South America during mid-to-late spring. The ECMWF global SSTA forecast for January 2022 indicates that during mid-summer in the southern hemisphere “warm blobs” will strengthen (Fig. 4). Consequently, attendant semi-permanent high-pressure centers are also likely to intensify. ECMWF upper air forecast for January 2022 projects further amplification of the New Zealand high-pressure ridge which extends eastward across the South Pacific subtropics (Fig. 5). Additionally, the South Atlantic “warm blob” intensification is well-correlated to an amplified high-pressure ridge in that position. Of interest is the compensating upper trough(s) which are weaker during summertime but located over east-central South America and Australia. Presence of the weak upper trough patterns increases risk of wet mid-summer climate most likely for east/north Australia and East Brazil certainly defeating any drought scare but adding to the risk of gully-washer mid-summer flooding rainfall risk. Fig. 4:  ECMWF global SSTA forecast valid January 2022 indicates southern hemisphere “warm blobs” persist. Fig. 5:  ECMWF upper air forecast for January 2022 in the southern hemisphere. Conclusion: La Nina is present and developing and forecast to peak in January 2022. However, ahead of meteorological summer in the southern hemisphere presence of large “warm blob” SSTA regions are likely most prominent in shaping the summer time climate pattern. Included are “warm blob” SSTA regions southwest of Africa, in the South Indian Ocean, near and east of New Zealand and also east of Argentina. Each “warm blob” has strengthened during November and according to ECMWF further intensification is forecast by mid-summer. The “warm blobs” are well-correlated to high-pressure ridge areas also forecast to strengthen across and downwind from each “warm blob” region. To compensate for each high-pressure ridge, weak upper trough(s) capable of producing flooding rainfall are forecast (by ECMWF) over Southern Brazil and Australia for mid-summer. The primary concern for Australia and South America during mid-summer 2022 is risk of gully-washer flooding rainfall which should restrict mid-summer drought risk. Summary: Climate Impact Company continues to stress recent emergence of warm SSTA regions outside of the tropics commonly referred to as “warm blobs” and their influence on the regional (and hemispheric) climate patterns which are as important as the influence of ENSO. The character of climate patterns associated with “Warm blobs” is slow-moving and therefore more impactful.