A Synoptic Evolution Comparison of the Smallest and Largest MCSs in Subtropical South America between Spring and Summer

Piersante, Jeremiah O.; Rasmussen, Kristen L.; Schumacher, Russ S.; Rowe, Angela K.; McMurdie, Lynn A.

doi:10.1175/mwr-d-20-0208.1

Cited by 7 publications

(13 citation statements)

References 63 publications

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“…Overall, for OND the intensity of the anomalous low-level northerly component of the wind and the extension of the area affected by this anomaly and, consequently the anomalies of the equivalent potential temperature, are larger compared to JFM. Moreover, the region with the largest upper-level wind divergence covers a broader area for OND compared with JFM and the location of this region for JFM is confined to the western part of SESA, in agreement with recent findings by Piersante et al (2021).…”

Section: Synoptic Drivers Of the Extreme Events During Ond And Jfmsupporting

confidence: 91%

“…Moreover, the region with the largest upper‐level wind divergence covers a broader area for OND compared with JFM and the location of this region for JFM is confined to the western part of SESA, in agreement with recent findings by Piersante et al . (2021).…”

Section: Resultsmentioning

confidence: 99%

“…Likewise, the authors emphasize that the trough at the middle levels of the troposphere is more evident in the case of MCSs. Recently, Piersante et al (2021) evaluated the environmental conditions associated with weak and strong wide convective cores occurring during spring and summer seasons in SESA and found that the spring MCSs may be more vigorous due to the larger anomalous northerly flow.…”

Section: Introductionmentioning

confidence: 99%

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Synoptic patterns associated with extreme precipitation events over southeastern South America during spring and summer seasons

Martinez

Solman

2022

Intl Journal of Climatology

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This study focuses on characterizing the diversity of synoptic forcing precursors of extreme precipitation events in southeastern South America (SESA) during the warm season, as well as identifying the differences in the synoptic environment during spring (October-November-December) and summer (January-February-March). The characterization of extreme events was carried out using daily precipitation data from the CPC gridded dataset for the period 1979-2017. Extreme events were defined when the daily precipitation exceeds the 95th percentile of the daily rainy days and covers a minimum area of 100 km 2 . During the spring months extremes are more intense and are preferably located over the central and eastern part of SESA, while during the summer they occur towards the west and south of SESA. The associated synoptic conditions were identified after applying a principal component analysis to the 850 hPa geopotential height for extreme precipitation days using the ERA-Interim reanalysis. Two distinctive patterns for each season were identified. The anomalous intense wind with a northerly component and a negative geopotential height anomaly over northwestern Argentina emerged as the most common features associated with the occurrence of extreme events. Differences between the two patterns emerge in terms of the southward penetration of the northerly wind and the anomalous circulation off the east coast of South America. A high-level jet was detected in both patterns, although a weaker core and located in a position further south is found for the second pattern compared with the first one. Differences in the synoptic forcing features between spring and summer, such as a more intense low-level northerly wind, a deeper northwestern low, a more intense upper-level jet stream and a more extended area of maximum upper-level wind divergence during spring compared with summer, may explain the differences found in the extreme precipitation in SESA for the two seasons.

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Section: Synoptic Drivers Of the Extreme Events During Ond And Jfmsupporting

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Synoptic patterns associated with extreme precipitation events over southeastern South America during spring and summer seasons

Martinez

Solman

2022

Intl Journal of Climatology

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“…The south-central part of R3-which includes northern Argentina, northwestern Paraguay, and southern Bolivia, comprising portions of LPB-has its spring and summer rainfall variability strongly related to MCSs [162]. Furthermore, central R3 is a hotspot for MCSs, where they contribute to more than 40% of the rainfall in the warm season, besides being associated with severe events [14,162,163]. Indeed, the region is known for some of the most intense storms ever recorded [164].…”

Section: Cluster 3-region R3 (R3)mentioning

confidence: 99%

“…MCSs acting in R4 have peculiarities concerning those found in other subtropical regions of SA. MCSs in R4 last longer (+3 h) and are 50,000 km 2 larger [175], besides having as sources of moisture for their genesis both the vapor transported by SALLJ and that advected by the SASA northern flow [159][160][161][162][163][175][176][177][178]. During the winter, MCSs can form with the passage of frontal systems in the region, as the propagation and intensification of convection occur along cold fronts, contributing to MCSs development [176].…”

Section: Cluster 4-region 4 (R4)mentioning

confidence: 99%

A New Look into the South America Precipitation Regimes: Observation and Forecast

Ferreira

Reboita

2022

Atmosphere

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South America is a vast continent characterized by diverse atmospheric phenomena and climate regimes. In this context, seasonal climate predictions are helpful for decision-making in several relevant socioeconomic segments in this territory, such as agriculture and energy generation. Thus, the present work evaluates the performance of ECMWF-SEAS5 in simulating the South American precipitation regimes by applying a non-hierarchical clustering technique. In addition, the study describes the main atmospheric systems that cause precipitation in each cluster and updates a previous work performed in South America in 2010. As a result, ECMWF-SEAS5 simulates (with good correspondence) the eight climate regimes identified in the analysis of precipitation from the Climate Prediction Center (CPC). Moreover, ECMWF-SEAS5 has a satisfactory ability in representing the rainfall regime in low and medium climate predictability regions, such as central and southern South America. ECMWF-SEAS5 has good performance in the climate characterization of South America and it gives us confidence in using its seasonal climate predictions throughout the continent.

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Convective-Storm Environments in Subtropical South America from High-Frequency Soundings during RELAMPAGO-CACTI

Schumacher

Hence

Nesbitt

et al. 2021

Monthly Weather Review

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During the RELAMPAGO-CACTI field experiments in 2018-19, an unprecedented number of balloon-borne soundings were collected in Argentina. Radiosondes were launched from both fixed and mobile platforms, yielding 2712 soundings during the period 15 October 2018-30 April 2019. Approximately 20% of these soundings were collected by highly mobile platforms, strategically positioned for each intensive observing period, and launching approximately once per hour. The combination of fixed and mobile soundings capture both the overall conditions characterizing the RELAMPAGO-CACTI campaign, as well as the detailed evolution of environments supporting the initiation and upscale growth of deep convective storms, including some that produced hazardous hail and heavy rainfall. Episodes of frequent convection were characterized by sufficient quantities of moisture and instability for deep convection, along with deep-layer vertical wind shear supportive of organized or rotating storms. Eleven soundings showed most-unstable convective available potential energy (MUCAPE) exceeding 6000 J kg−1, comparable to the extreme instability observed in other parts of the world with intense deep convection. Parameters used to diagnose severe-storm potential showed that conditions were often favorable for supercells and severe hail, but not for tornadoes, primarily owing to insufficient low-level wind shear. High-frequency soundings also revealed the structure and evolution of the boundary layer leading up to convection initiation, convectively generated cold pools, the South American Low-Level Jet (SALLJ), and elevated nocturnal convection. This sounding dataset will enable improved understanding and prediction of convective storms and their surroundings in subtropical South America, as well as comparisons with other heavily studied regions such as the central United States that have not previously been possible.

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A Synoptic Evolution Comparison of the Smallest and Largest MCSs in Subtropical South America between Spring and Summer

Cited by 7 publications

References 63 publications

Synoptic patterns associated with extreme precipitation events over southeastern South America during spring and summer seasons

Synoptic patterns associated with extreme precipitation events over southeastern South America during spring and summer seasons

A New Look into the South America Precipitation Regimes: Observation and Forecast

Convective-Storm Environments in Subtropical South America from High-Frequency Soundings during RELAMPAGO-CACTI

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