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A Case Study of the Tornadic Supercell in the Province of Pampanga, Philippines (27 May 2024)

Generich H. Capuli, Michael Angelo O. Noveno, Marco Polo A. Ibañez

TL;DR

The paper addresses the under-studied occurrence of tornadic events in tropical Philippines by documenting a rare tornadic supercell near Candating, Arayat on 27 May 2024. It employs an integrated approach using ERA5 reanalysis, proximity soundings, HIMAWARI-9 and Landsat-9 observations, and DOST-PAGASA radar/lightning data to diagnose the synoptic, mesoscale, and storm-scale processes behind tornadogenesis. The study finds a ~2 km damage path with EF2-level damage, supported by overshooting tops, a low-level mesocyclone, and a radar-observed velocity couplet, within a moist, strongly sheared tropical environment modulated by the Southwest Monsoon and Mt. Arayat terrain. These results highlight similarities with North American tornadic regimes while underscoring the need for tropical climatologies, region-specific damage scales (IF), and upgraded observational infrastructure to improve predictive capabilities in the Philippines.

Abstract

This study provides an integrated damage assessment, visual evaluation, environmental context, and remote sensing analysis of the tornado event that struck the suburb of Candating in Arayat, Pampanga on 27 May 2024. Satellite imagery and ground-level damage photographs reveal a $\sim$2 km path, with damage reaching EF2 intensity at one point along the track, based on the Enhanced Fujita (EF) scale. Videos of the tornado and its parent storm reveal a well-defined wall cloud and low-level mesocyclone. Subsequent radar analysis supports these and other features of a tornadic supercell. Synoptic-scale ascent in the mid- and upper-troposphere was subtle, influenced by the approach of Tropical Cyclone Ewiniar. However, a modest meridional flow aloft provided sufficient deep-layer shear to support supercell development. The southwest monsoon acted as a low-level jet, promoting warm, moist advection into western Luzon. The supercell developed around midday and was characterized by large-undiluted instability, attributed to steep low-level lapse rates. Although low-level shear and the associated near-surface horizontal vorticity were weak, the latter is highly streamwise, allowing for efficient ingestion, tilting, and stretching into vertical vorticity, which aided in tornadogenesis. Both satellite and radar data suggest that storm interactions, such as a nudging mechanism and terrain effects from nearby Mt. Arayat may have contributed to the initiation and intensification of the supercell through lee-side convergence and vorticity enhancement. The complex tropical environment of the Candating, Arayat tornado exhibits several similarities to well-documented tornadic events in North America. These findings highlight the need for further research into the atmospheric conditions conducive to tornadic activity in the Philippines.

A Case Study of the Tornadic Supercell in the Province of Pampanga, Philippines (27 May 2024)

TL;DR

The paper addresses the under-studied occurrence of tornadic events in tropical Philippines by documenting a rare tornadic supercell near Candating, Arayat on 27 May 2024. It employs an integrated approach using ERA5 reanalysis, proximity soundings, HIMAWARI-9 and Landsat-9 observations, and DOST-PAGASA radar/lightning data to diagnose the synoptic, mesoscale, and storm-scale processes behind tornadogenesis. The study finds a ~2 km damage path with EF2-level damage, supported by overshooting tops, a low-level mesocyclone, and a radar-observed velocity couplet, within a moist, strongly sheared tropical environment modulated by the Southwest Monsoon and Mt. Arayat terrain. These results highlight similarities with North American tornadic regimes while underscoring the need for tropical climatologies, region-specific damage scales (IF), and upgraded observational infrastructure to improve predictive capabilities in the Philippines.

Abstract

This study provides an integrated damage assessment, visual evaluation, environmental context, and remote sensing analysis of the tornado event that struck the suburb of Candating in Arayat, Pampanga on 27 May 2024. Satellite imagery and ground-level damage photographs reveal a 2 km path, with damage reaching EF2 intensity at one point along the track, based on the Enhanced Fujita (EF) scale. Videos of the tornado and its parent storm reveal a well-defined wall cloud and low-level mesocyclone. Subsequent radar analysis supports these and other features of a tornadic supercell. Synoptic-scale ascent in the mid- and upper-troposphere was subtle, influenced by the approach of Tropical Cyclone Ewiniar. However, a modest meridional flow aloft provided sufficient deep-layer shear to support supercell development. The southwest monsoon acted as a low-level jet, promoting warm, moist advection into western Luzon. The supercell developed around midday and was characterized by large-undiluted instability, attributed to steep low-level lapse rates. Although low-level shear and the associated near-surface horizontal vorticity were weak, the latter is highly streamwise, allowing for efficient ingestion, tilting, and stretching into vertical vorticity, which aided in tornadogenesis. Both satellite and radar data suggest that storm interactions, such as a nudging mechanism and terrain effects from nearby Mt. Arayat may have contributed to the initiation and intensification of the supercell through lee-side convergence and vorticity enhancement. The complex tropical environment of the Candating, Arayat tornado exhibits several similarities to well-documented tornadic events in North America. These findings highlight the need for further research into the atmospheric conditions conducive to tornadic activity in the Philippines.
Paper Structure (18 sections, 9 equations, 21 figures, 5 tables)

This paper contains 18 sections, 9 equations, 21 figures, 5 tables.

Table of Contents

  1. INTRODUCTION
  2. METHODS
  3. Environmental Reanalysis Dataset
  4. Vertical Profile: Skew-T Hodograph
  5. Spaceborne Data
  6. HIMAWARI-9 Satellite Data
  7. Landsat-9 OLI
  8. Observational Data from DOST-PAGASA
  9. Radar Data
  10. Lightning Data
  11. RESULTS
  12. Tornado damage path and visual observations
  13. Synoptic Environment
  14. Mesoscale Environment
  15. Storm Development and Life Cycle
  16. ...and 3 more sections

Figures (21)

  • Figure 1: Elevation map of Metro Manila (NCR) and surrounding provinces. S-SUB radar is shown as a small red circle, with 120 km radar extent coverage depicted as a red circle (solid line). The red triangle enclosed by a box is the location of the tornadic event
  • Figure 2: Landsat-9 OLI Damage Extent of the Arayat, Candating Tornado. (a) Before the event at 01 May 2024, (b) After the event at 02 June 2024, and (c) Difference between the NDVI before and after. Highlighted is the potential damage track of the tornado
  • Figure 3: Photographs of the 27 May 2024 Tornado that impacted Brgy. Candating in Arayat, Pampanga. Courtesy of (a-c) Joel Ulanday Soliman, (d) Aries Cruz, (e) Mark Guinto Estopin, and (f) Renz Reyes
  • Figure 4: HIMAWARI-9 AHI scans at (1) 00 UTC/08 LST and (2) 05 UTC/13 LST; (a) Band 03 0.64 μm with 0-6 km Shear Vectors (kt) and Mean Sea-Level Pressure (blue solid; hPa), and (b) Daytime Convective RGB with 0-6 km Shear Magnitudes $>$ 20 kts (dashed lines). The area of interest is demarcated in yellow box
  • Figure 5: Synoptic environment of the Philippine archipelago before (1; 04 UTC/12 LST), during (2; 05 UTC/13 LST), and after (3; 06 UTC/14 LST) the event. (a) 500-hPa Geopotential Heights (blue solid; dam) and winds (kt). Contours are wind speeds $>$ 10 kts. (b) 700-hPa Geopotential Heights (blue solid; dam), Precipitable Water Vapor $>$ 50 kg m$^{-2}$ (contour), and winds (kt). (c) 850-hPa Geopotential Heights (blue solid; dam), Dewpoints $>$ 15 $^{\circ}$C (contour), Temperature (red dashed; $^{\circ}$C), and winds (kt)
  • ...and 16 more figures