May 22 - July 31
A Case Study of Mesoscale Convective System Reorganization off of the West Coast of Africa
Sonny Kremin, Shun-Nan Wu, and Naoko Sakaeda
What is already known:
- Mesoscale Convective Systems (MCSs) are a major source of precipitation in the tropics
- MCSs can develop and act as a seed for Tropical Cyclones in the East Tropical Atlantic
- MCSs transitioning off of the West African coast tend to persist or decrease in precipitation intensity
What this study adds:
- The study analyzes the pre- & post-storm environment of a land-to-ocean transitioning MCS that initially weakened but later re-intensified offshore
- Transportation of enhanced low-level moisture into the MCS by monsoon flow is a key element in supporting MCS reorganization by aiding in the production of precipitation
- An increase in the extent and magnitude of the AEJ likely enhanced the rear inflow jet of the MCS causing the systems reorganization
- CAPE was found to be less influential on the redevelopment of offshore MCSs
Abstract:
Previous studies on the land-to-ocean transitions of Mesoscale Convective Systems (MCSs) concluded that MCSs tend to weaken or dissipate post-transition. On the 14th September 2022 a MCS transitioning off of the West African coast initially weakened and then later rapidly re-intensified over the Tropical North Atlantic. Precipitation data from the Integrated Multi-satellite Retrievals for GPM (IMERG) and Tracked IMERG Mesoscale Precipitation System (TIMPS) is used to track the position and strength of the system as it transitioned offshore. Dropsonde data from research flight five of the Convective Processes EXperiment–Cabo Verde (CPEX-CV) campaign is analyzed to determine what environmental factors caused this redevelopment over the Atlantic. Boundary layer moisture, 700 hPa winds, and other environmental factors are analyzed and reveal that rapid strengthening of the African Easterly Jet and enhanced moisture ahead of the system are likely factors that caused the system’s re-development.