Tropical Storm Gamma (2020)

Tropical Storm Gamma was a near-hurricane strength tropical storm that brought heavy rains, floods, and landslides to the Yucatán Peninsula in early October 2020. The twenty-fifth depression and twenty-fourth named storm of the extremely active 2020 Atlantic hurricane season, Gamma developed from a vigorous tropical wave that had been monitored as it was entering the Eastern Caribbean on September 29. The wave moved westward and slowed down as it moved into the Western Caribbean, where it began to interact with a dissipating cold front. A low formed within the disturbance on October 1 and the next day, it organized into a tropical depression. It further organized into Tropical Storm Gamma early the next day. It continued to intensify and made landfall just below hurricane strength near Tulum, Mexico, on October 3. It weakened over land before reemerging in the Gulf of Mexico. Gamma then briefly restrengthened some before being blasted by high amounts of wind shear, causing it to weaken again. It degenerated into a remnant low on October 6, before dissipating on the next day.

Tropical Storm Gamma
Tropical storm (SSHWS/NWS)
Gamma 2020-10-03 1810Z.jpg
Tropical Storm Gamma making landfall in the Yucatan Peninsula at peak intensity on October 3
FormedOctober 2, 2020
DissipatedOctober 7, 2020
(Remnant low after October 6)
Highest winds1-minute sustained: 70 mph (110 km/h)
Lowest pressure980 mbar (hPa); 28.94 inHg
Fatalities7 total
Damage$100 million (2020 USD)
Areas affectedHonduras, Yucatán Peninsula, Cayman Islands, Cuba, Florida
Part of the 2020 Atlantic hurricane season

Numerous tropical cyclone watches and warnings were issued for parts of Mexico in the Yucatán Peninsula following the formation of Gamma and thousands of people were evacuated. Gamma produced strong winds, heavy rainfall, flash flooding, landslides, and mudslides to the region. At least seven fatalities have been confirmed so far. The areas affected by Gamma were affected by stronger Hurricane Delta four days after the former made landfall.

Meteorological historyEdit

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

On September 29, the National Hurricane Center began to monitor a tropical wave over the Lesser Antilles for potential development as it moved into the Western Caribbean.[1] It drifted slowly westward and remained very broad and disorganized for a couple of days.[2] As it neared the coast of Honduras on October 1, the wave spawned a broad low pressure area and began to quickly organize over the unusually warm waters of the Western Caribbean.[3] By 15:00 UTC on October 2, the low had become sufficiently organized to be designated as Tropical Depression Twenty-Five.[4] The system continued to organize, and strengthened into Tropical Storm Gamma at 00:00 UTC on October 3,[5] becoming the earliest 24th tropical or subtropical Atlantic storm on record, surpassing the old mark of October 27, set by Hurricane Beta in 2005.[6] Gamma began to quickly intensify afterward, reaching just below hurricane strength as an eye began to form at 15:00 UTC on October 3.[7] At 16:45 UTC that same day, Gamma made landfall near Tulum, Quintana Roo, Mexico, at peak intensity with winds of 70 mph (110 km/h) and a minimum central pressure of 980 mb (28.94 inHg), which was unusually low for a tropical storm. However, the NHC noted that Gamma was very near hurricane strength at the time of landfall.[8]

After making landfall, Gamma weakened before emerging into the Gulf of Mexico with winds of 50 mph (80 km/h) winds and a central pressure of 995 mb (29.4 inHg) on October 4.[9] Its forward motion then slowed as a ridge developed to the north. Gamma then subsequently restrengthened to 60 mph (97 km/h) around mid-day, although this proved to be brief, as its central pressure increased and winds decreased in speed.[10] As Gamma stalled a rapid increase in wind shear decoupled central convection by that evening, causing it to move further east than originally forecast.[11][12] Gamma began to weaken shortly thereafter as it turned southwestward.[13] Though strongly sheared, there was vigorous convection located 60 miles north of Gamma's center.[14] By 21:00 UTC on October 5, Gamma's center was completely devoid of any convection and was downgraded to a tropical depression at 21:00 UTC.[15] The storm became post tropical six hours later.[16] It continued to produce disorganized convection, but the convection was forced by a sea breeze boundary.[17] Early on October 7, Gamma's remnants were absorbed into the circulation of Hurricane Delta, as Delta passed through the Yucatán Peninsula and into the Gulf of Mexico.[18]

Preparations and impactsEdit

Tropical Depression Twenty-Five shortly after formation over the Gulf of Honduras on October 2


Tropical storm watches and warnings were issued for the northeastern part of the Yucatán Peninsula when advisories were first initiated on October 2. When Gamma intensified more than originally predicted, hurricane warnings were issued for a small portion of the Mexican coast in preparation for Gamma to become a hurricane at landfall.[19] In Quintana Roo, 40 people in Tulum evacuated to shelters. Numerous flights were affected at the Cancun International Airport and in Cozumel.[20] In Tabasco, roughly 3,400 people evacuated to shelters.[21]

A weather station at Xel-Ha Park just north of the landfall point at Tulum, reported a sustained wind of 55 mph (89 km/h) and a gust to 68 mph (109 km/h) around the time of landfall.[8] At least 6 people died and thousands were evacuated in southeastern Mexico after Tropical Storm Gamma lashed the Yucatan Peninsula. Four of the deaths, which included two children, occurred in Chiapas after a landslide buried a home. Two other deaths occurred in Tabasco after a person was swept away by flood waters and another drowned.[22] Another cause for a death was not specified, bringing the total number of deaths to seven. In addition, a total number of 5,000 people in Tabasco were displaced due to the storm.[23]


Moisture associated with Gamma moved over the US state of Florida where 7 in (180 mm) of rain had fell in the days previous to Gamma. Moderate to heavy rainfall affected the Cayman Islands causing some flooding in some low-lying areas. Heavy rainfall also affected western Cuba where isolated spots received 6 in (150 mm) of total rainfall.[24]

See alsoEdit


  1. ^ Stacy Stewart (30 September 2020). "Two-Day Graphical Tropical Weather Outlook". Miami, Florida: National Hurricane Center. Retrieved 2 October 2020.
  2. ^ Richard Pasch (30 September 2020). "Two-Day Graphical Tropical Weather Outlook". Miami, Florida: National Hurricane Center. Retrieved 2 October 2020.
  3. ^ Robbie Berg (1 October 2020). "Two-Day Graphical Tropical Weather Outlook". Miami, Florida: National Hurricane Center. Retrieved 2 October 2020.
  4. ^ Robbie Berg (2 October 2020). "Tropical Depression Twenty-Five Discussion Number 1". Miami, Florida: National Hurricane Center. Retrieved 2 October 2020.
  5. ^ "Tropical Storm GAMMA". Retrieved 3 October 2020.
  6. ^ Discher, Emma (2 October 2020). "Tropical Storm Gamma develops over Caribbean Sea; here's the latest forecast". New Orleans, Louisiana. Retrieved 2 October 2020.
  7. ^ "Tropical Storm GAMMA". Retrieved 3 October 2020.
  8. ^ a b "Tropical Storm GAMMA". Retrieved 5 October 2020.
  9. ^ "Tropical Storm GAMMA". Retrieved 5 October 2020.
  10. ^ "Tropical Storm GAMMA". Retrieved 5 October 2020.
  11. ^ "Tropical Storm GAMMA". Retrieved 5 October 2020.
  12. ^ "Tropical Storm GAMMA". Retrieved 5 October 2020.
  13. ^ "Tropical Storm GAMMA". Retrieved 5 October 2020.
  14. ^ "Tropical Storm GAMMA". Retrieved 28 January 2021.
  15. ^ "Tropical Depression GAMMA". Retrieved 5 October 2020.
  16. ^ "Post-Tropical Cyclone GAMMA". Retrieved 6 October 2020.
  17. ^ "Post-Tropical Cyclone GAMMA". Retrieved 21 January 2021.
  18. ^ Jeff Masters (7 October 2020). "Hurricane Delta takes aim at U.S. Gulf Coast". Yale Climate Connections. Retrieved 2 January 2021.
  19. ^ "Tropical Storm GAMMA Advisory Archive". Retrieved 3 October 2020.
  20. ^ "Tropical Storm Gamma leaves Cancun, Riviera Maya behind with only minor damage". Riviera Maya News. 5 October 2020. Retrieved 2 January 2021.
  21. ^ Associated Press (5 October 2020). "Tropical Storm Gamma leaves 6 dead in southern Mexico". Fox News. Retrieved 2 January 2021.
  22. ^ Staff (4 October 2020). "Tropical storm Gamma leaves 6 dead as thousands evacuate in southeastern Mexico". Q107. Retrieved 4 October 2020.
  23. ^ "Desalojos masivos de hoteles y alerta roja en México ante la proximidad del huracán Delta, ahora de categoría 3". Univision. 6 October 2020. Retrieved 12 October 2020.
  24. ^ Travis Fedschun (4 October 2020). "Tropical Storm Gamma meanders off Mexico, bringing flooding and storm surge". Fox News. Retrieved 4 October 2020.

External linksEdit