Tropical Storm Hernan (2020)

Tropical Storm Hernan was a small tropical cyclone that brought heavy rainfall and mudslides to southwest Mexico and made landfall in Baja California Sur as a tropical depression in late August 2020. The thirteenth tropical cyclone and eighth named storm of the below-average 2020 Pacific hurricane season, Hernan developed from a low-pressure area southwest of Mexico on August 26 as Tropical Depression Thirteen-E.[1] The depression strengthened into Tropical Storm Hernan twelve hours after formation.[2] Located within a high wind shear environment, Hernan barely strengthened and achieved peak intensity at 3:00 UTC on August 27 with 45 mph winds and a minimum barometric pressure of 1001 millibars.[3] Passing just offshore Mexico, Hernan turned west and weakened to a tropical depression, and made landfall on the Baja California Peninsula on August 28, dissipating shortly thereafter.[4] Although Hernan was located in very close proximity to Southwestern Mexico, its small size prevented the issuance of tropical storm watches or warnings in nearby coastal areas.

Tropical Storm Hernan
Tropical Storm (SSHWS/NWS)
Tropical Storm Hernan strengthening just offshore Mexico.
FormedAugust 26, 2020
DissipatedAugust 28, 2020
Highest winds1-minute sustained: 45 mph (75 km/h)
Lowest pressure1001 mbar (hPa); 29.56 inHg
Fatalities1
DamageUnknown
Areas affectedWestern Mexico, Baja California Peninsula
Part of the 2020 Pacific hurricane season

Despite Hernan's short existence, it dropped between 5-9 inches of rainfall across six states of western Mexico.[5] Multiple highways had to be shut down due to dangerous conditions, including mudslides and rivers overflowing their banks.[6] Several schools suffered damage in the state of Colima, and in the city of Manzanillo, there were homes and streets damaged and covered in mud.[7] Over 600 homes and nine schools were estimated to have experienced damage from the storm in Jalisco. Jalisco officials reported a fatality when a man fell off his roof checking damages from Hernan.[8]

Meteorological history
Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale

The NHC first noted the potential for an area of low pressure to form off the coast of Mexico on August 17, in the proximity of Hurricane Genevieve.[9] After Genevieve moved away from the area and dissipated, its formation chances were gradually increased by the NHC, and on August 20, a broad area of low pressure developed.[10] The system was slow to organize, progressively acquiring more shower and thunderstorm activity; finally, at 9:00 UTC on August 26, the system had enough well defined deep convection just west of the center to be designated as a tropical depression, the season's thirteenth.[11] The NHC noted the system was facing strong easterly wind shear, was located on the eastern side of a broad monsoon gyre, and was slightly elongated from northeast to southwest. Nevertheless, despite the system's poor satellite presentation, tropical storm-force winds were detected to its southwest, and the system strengthened into a tropical storm, receiving the name Hernan.[12] A strong burst of convection developed southwest of Hernan's center, and it intensified slightly, reaching its peak intensity with 45 mph winds and a minimum barometric pressure of 1,001 millibars. Hernan remained strongly sheared as it moved northeast and then northward, with most of its convection confined to the south and west of its center, causing it to weaken back to a minimal storm.[13] Hernan unexpectedly reformed to the northeast with a small, well-defined center.[14] Despite this, on August 28, Hernan moved over the Gulf of California and turned west, with most of its convection dissipating, and the system was downgraded to a tropical depression.[15] Hernan moved across the coast line of Baja California Sur, degenerated into a broad low pressure area later that day, and dissipated shortly thereafter.[16]

Impact

No prior warnings were issued associated with Hernan due to its small size throughout its existence. However, it still had sizable impacts in multiple western Mexican states. A total of 97,000 people lost electricity in the country due to Hernan.[17] 250 state and federal workers were dispatched to areas affected by Hernan while different agencies traveled by helicopter to bring food and supplies.[18] The name Hernan was respelled as the more common Hernán in most Mexican news reports.[19]

Jalisco

Heavy rains from Hernan left 30 communities in the state of Jalisco without power. 630 houses and nine schools experienced damage throughout the state due to the tropical storm. The hard-hit municipality of Cihuatlan saw 250 homes affected, while the southeastern municipality La Huerta experienced 228 affected homes. A man died in La Huerta when he fell from his roof checking damages from Hernan, and a woman in Cabo Corrientes suffered burns on her arms and legs due to an oven fire, presumably from a short circuit during the storm.[20] 400 people were evacuated prior to Hernan's passing, while 18 people stuck on their roofs were rescued as well. Rescues were required for people trapped in houses where rainfall reached up to two meters. Landslides and mudslisdes covered parts of Mexican federal highways 80 and 200 and were cleared by agency workers.[21]

Colima

The worst-hit municipality from Tropical Storm Hernan was considered to be the port city of Manzanillo in Colima. Many homes, businesses, and streets were covered in mud.[22] Manzanillo's president of the Planning and Tourism Commission, Luis Rogelio Salinas Sánchez, stated large numbers of urban, suburban, and rural areas around Manzanillo "suffered serious damage". According to Sánchez, torrential rain, rip currents, sand, and debris were stirred up throughout Manzanillo from Thursday, August 27 into Friday the 28th. He gravely said that the losses in Manzanillo "are unquantifiable", and the Civil Protection authorities were carrying out damage assessments "to demand an emergency declaration due to natural disasters".[23] In addition, damage was reported to Colima's coastal areas and roadways. 30 people were also evacuated in high-risk areas of Manzanillo. Waves of up to 4 meters (13 feet) in height were reported off the coasts of Manzanillo, Tecomán, and Armería.[24]

Elsewhere

In the state of Michoacán, where disruptions were reported as well, up to 600,000 sea turtle eggs in Ixtapilla Marine Turtle Sanctuary were swept away or destroyed by Hernan, including those of the endangered Olive Ridley turtle, making for a large environmental loss.[25] The state of Sinaloa reported "intense punctual rains",[26] and flooding, hail, minor mudslides, and debris were reported in the south of the state, in addition to that reported in other western Mexican states.

Although Hernan weakened to a tropical depression prior to landfall in Baja California Sur, the National Meteorological Service (SMN) warned residents to take "extreme precautions", as torrential rainfall, gusty winds, and large waves pounded the state, as well as those of Nayarit and Sinaloa.[27]

See also

References
  1. Stacy Stewart (August 26, 2020). "Tropical Depression Thirteen-E Public Advisory Number 1". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved August 26, 2020.
  2. Andrew Latto (August 26, 2020). "Tropical Storm Hernan Discussion Number 3". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved December 12, 2020.
  3. Stacy Stewart (August 27, 2020). "Tropical Storm Hernan Discussion Number 5". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved August 27, 2020.
  4. Beven, John (August 28, 2020). "Post-Tropical Cyclone Hernan Discussion Number 11". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved August 28, 2020.
  5. Lolas, Jose (August 29, 2020). "Tormenta tropical Hernán deja lluvias en seis estados mexicanos". La Primera (in Spanish). Retrieved October 12, 2020.
  6. "Evacuations in Colima and Jalisco in wake of Tropical Storm Hernán". Mexico News Daily. Retrieved August 29, 2020.
  7. Norma Osiris Moreno (August 28, 2020). "Manzanillo después de la Tormenta Tropical 'Hernán'". Retrieved September 4, 2020.
  8. "Rains, flooding from tropical storm isolates 30 communities in Jalisco". Mexico News Daily. Retrieved December 12, 2020.
  9. Andrew Latto (August 17, 2020). "Five-Day Graphical Tropical Weather Outlook". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved August 26, 2020.
  10. Dave Roberts (August 20, 2020). "Five-Day Graphical Tropical Weather Outlook". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved August 26, 2020.
  11. Stacy Stewart (August 27, 2020). "Tropical Depression Thirteen-E Discussion Number 1". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved December 12, 2020.
  12. Andrew Latto (August 26, 2020). "Tropical Storm Hernan Discussion Number 3". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved December 12, 2020.
  13. Andrew Latto (August 27, 2020). "Tropical Storm Hernan Discussion Number 7". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved December 12, 2020.
  14. David Zelinsky (August 28, 2020). "Tropical Storm Hernan Discussion Number 9". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved December 12, 2020.
  15. John L. Beven (August 28, 2020). "Tropical Depression Hernan Discussion Number 10". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved December 12, 2020.
  16. John L. Beven (August 28, 2020). "Post-Tropical Cyclone Hernan Discussion Number 11". www.nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved December 12, 2020.
  17. "Tormenta Tropical "Hernán" dejó sin luz a 97 mil usuarios de CFE". News Report MX. Retrieved August 29, 2020.
  18. "Rains, flooding from tropical storm isolates 30 communities in Jalisco". Mexico News Daily. Retrieved December 12, 2020.
  19. "Evacuan a 400 personas por tormenta tropical "Hernán" en Jalisco". El Universal (in Spanish). 2020-08-28. Retrieved 2020-08-28.
  20. "Rains, flooding from tropical storm isolates 30 communities in Jalisco". Mexico News Daily. Retrieved December 12, 2020.
  21. "Evacuan a 400 personas por tormenta tropical "Hernán" en Jalisco". El Universal (in Spanish). 2020-08-28. Retrieved 2020-08-28.
  22. Norma Osiris Moreno (August 28, 2020). "Manzanillo después de la Tormenta Tropical 'Hernán'". Retrieved September 4, 2020.
  23. "Demandan declarar a Manzanillo en estado de emergencia/". Colimanoticias (in Spanish). 2020-08-31. Retrieved 2020-12-12.
  24. "The tropical storm Hernán leaves damage and lands in Baja California Sur". NewsBeezer. August 28, 2020. Retrieved September 4, 2020.
  25. "Rains, flooding from tropical storm isolates 30 communities in Jalisco". Mexico News Daily. Retrieved December 12, 2020.
  26. Lolas, Jose (August 29, 2020). "Tormenta tropical Hernán deja lluvias en seis estados mexicanos". La Primera (in Spanish). Retrieved October 12, 2020.
  27. "Hernan decrece a depresión en el Pacífico pero golpeará a Baja California Sur". Hola News. August 28, 2020. Retrieved September 4, 2020.

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