Severe weather events in Southern Brazil and their similarity with events in the United States Bruno Ribeiro, Lance Bosart National Institute for Space Research - INPE, Brazil SUNY - University at Albany, NY 16th NROW - November 2015

Purpose:

Compare severe weather events in Southern Brazil to that in the U.S. and show some forecast issues.

Purpose: Compare severe weather events in Southern Brazil to that in the U.S. and show some forecast issues. Motivation: - Little research on severe weather in South America;

Purpose: Compare severe weather events in Southern Brazil to that in the U.S. and show some forecast issues. Motivation: - Little research on severe weather in South America; - Most conceptual models of severe weather for the U.S. are applicable in Southern Brazil;

Purpose: Compare severe weather events in Southern Brazil to that in the U.S. and show some forecast issues. Motivation: - Little research on severe weather in South America; - Most conceptual models of severe weather for the U.S. are applicable in Southern Brazil; - Look for when these models may NOT be applicable in Southern Brazil.

Introduction 1) Similarities between North and South America;

Introduction 1) Similarities between North and South America; 2) Two cases: - A Squall Line in Sao Paulo state on 08 September 2015;

Introduction 1) Similarities between North and South America; 2) Two cases: - A Squall Line in Sao Paulo state on 08 September 2015; - A EF2-EF3 tornado case in Santa Catarina State on 20 April 2015.

South America Topography

’Classic’ severe weather environment

Elevated Mixed Layers and Supercells

Bow-echoes

Squall Line Case

Affected most of the Sao Paulo state, including Sao Paulo metropolitan region:

Squall Line Case Affected most of the Sao Paulo state, including Sao Paulo metropolitan region: - Hundreds of downed trees and flooded streets;

Squall Line Case Affected most of the Sao Paulo state, including Sao Paulo metropolitan region: - Hundreds of downed trees and flooded streets; - Several 5 cm ( 2”) hail reports;

Squall Line Case Affected most of the Sao Paulo state, including Sao Paulo metropolitan region: - Hundreds of downed trees and flooded streets; - Several 5 cm ( 2”) hail reports; - Wind gusts peaked 120 km/h (65 kt) in the entrance of Paraiba Valley.

Squall Line Case - Synoptic Environment

Weak quasi-geostrophic forcing

Squall Line Case - Synoptic Environment

Divergent upper-level flow at jet-streak equatorial entrance

Squall Line Case - Synoptic Environment

Low-level cyclonic vorticity associated with the front

Squall Line Case - soundings

Squall Line Case - satellite imagery

Squall Line Case - radar imagery

Tornado Case

Estimated EF2-EF3 tornado affected the city of Xanxere on 20 April 2015:

Tornado Case Estimated EF2-EF3 tornado affected the city of Xanxere on 20 April 2015: - 2 people dead and hundreds injured;

Tornado Case Estimated EF2-EF3 tornado affected the city of Xanxere on 20 April 2015: - 2 people dead and hundreds injured; - Severe damage to about 50% of the city.

Tornado Case

Tornado Case - Synoptic Environment

Weak quasi-geostrophic forcing:

Tornado Case - Synoptic Environment

Tornado Case - Forecast issues

Conclusions

Large-scale severe weather environments are similar:

Conclusions Large-scale severe weather environments are similar: 1- Strong low-level jet bringing warm and moist air from the tropics;

Conclusions Large-scale severe weather environments are similar: 1- Strong low-level jet bringing warm and moist air from the tropics; 2- Severe weather along a low-level baroclinic region.

Conclusions Large-scale severe weather environments are similar: 1- Strong low-level jet bringing warm and moist air from the tropics; 2- Severe weather along a low-level baroclinic region. 3- Upper-level forcing by the Subtropical/Polar Jet.

Conclusions Large-scale severe weather environments are similar: 1- Strong low-level jet bringing warm and moist air from the tropics; 2- Severe weather along a low-level baroclinic region. 3- Upper-level forcing by the Subtropical/Polar Jet. 4- South America also have ‘cold season’ and ‘warm season’ patterns;

Conclusions - Issues and future research

- Role of drylines (?) and local topography in triggering severe convection;

Conclusions - Issues and future research - Role of drylines (?) and local topography in triggering severe convection; - Elevated mixed layers

Conclusions - Issues and future research - Role of drylines (?) and local topography in triggering severe convection; - Elevated mixed layers Observational framework must be improved:

Conclusions - Issues and future research - Role of drylines (?) and local topography in triggering severe convection; - Elevated mixed layers Observational framework must be improved: - Radars, soundings and surface observations;

Conclusions - Issues and future research - Role of drylines (?) and local topography in triggering severe convection; - Elevated mixed layers Observational framework must be improved: - Radars, soundings and surface observations; - Severe weather reports network.

Thank you