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Hurricane Alma (1970)

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This article is about the Atlantic hurricane in 1970. For other storms of the same name, see List of storms named Alma.
Hurricane Alma
Alma on May 20
Meteorological history
FormedMay 18, 1970
DissipatedMay 27, 1970
Category 1 hurricane
1-minute sustained (SSHWS/NWS)
Highest winds75 mph (120 km/h)
Lowest pressure993 mbar (hPa); 29.32 inHg
Overall effects
Fatalities8 total
Areas affectedCayman Islands, Jamaica, Cuba, Southeast United States
IBTrACSEdit this at Wikidata
Part of the 1970 Atlantic hurricane season

Hurricane Alma was one of only four Atlantic tropical cyclones to reach hurricane status in the month of May. It developed on May 18, 1970 north of Panama, and rapidly intensified on May 20 to peak winds of 75 mph (120 km/h), near Jamaica and the Cayman Islands. It stalled south of Cuba and deteriorated due to wind shear, and by May 22 it weakened to tropical depression status. After progressing northwestward and crossing western Cuba, Alma reorganized in the Gulf of Mexico, although continued shear prevented strengthening. It moved across Florida on May 25, and on May 27 it dissipated off the coast of Virginia.

The storm first brought gusty winds and heavy rainfall to Jamaica and the Cayman Islands. While it was weakening, Alma produced flooding in central and eastern Cuba, causing seven deaths and forcing 3,000 people to evacuate. Moderate precipitation spread across Florida, while thunderstorms from the storm caused light damage, killing one. Moisture from the storm spread up the Atlantic coast.

Meteorological history

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Map plotting the storm's track and intensity, according to the Saffir–Simpson scale
Map key
Saffir–Simpson scale
  Tropical depression (≤38 mph, ≤62 km/h)
  Tropical storm (39–73 mph, 63–118 km/h)
  Category 1 (74–95 mph, 119–153 km/h)
  Category 2 (96–110 mph, 154–177 km/h)
  Category 3 (111–129 mph, 178–208 km/h)
  Category 4 (130–156 mph, 209–251 km/h)
  Category 5 (≥157 mph, ≥252 km/h)
  Unknown
Storm type
triangle Extratropical cyclone, remnant low, tropical disturbance, or monsoon depression

Late on May 17, the US National Hurricane Center, reported that a tropical depression had formed about 470 miles (760 km) to the southeast of Kingston, Jamaica. Over the next couple of days, the depression became better organized as it moved towards the northwest; on May 19 it entered an area of favorable environmental conditions, which enabled the depression to rapidly intensify. On May 20 it strengthened into a tropical storm, at which point it was given the name Alma. That day, it rapidly strengthened under favorable developmental conditions, which included low wind shear, strong upper-level outflow, and apparent eastward inflow. Later on May 20, a Navy reconnaissance plane recorded winds of 80 mph (130 km/h), which proved to be the peak intensity of Alma.[1] It became one of only four Atlantic hurricanes on record in the month of May. In January 2022, as part of the ongoing HURDAT Atlantic hurricane reanalysis project, the peak intensity of Alma was downgraded slightly to 75 mph (120 km/h).[2]

Subsequent to its peak intensity, increasing westerly shear disrupted the storm's circulation and thermal pattern, which caused rapid weakening to tropical storm strength and later tropical depression status.[1] By May 22, the low pressure area became poorly defined after stalling south of Cuba; with only a few squalls and showers, advisories were discontinued on Alma.[3] The remnants of Alma continued westward near the Cayman Islands, and later turned to the north, passing over western Cuba.[4]

On May 24, the low pressure area reorganized as spiral rainbands became more evident on radar, and Alma was re-classified as a tropical depression.[5] As the depression approached the Florida coast, radar imagery indicated the system remained well-organized, with a spiral band structure around an eye feature; however, wind shear limited convection and strength, and Alma moved ashore as a depression near Cedar Key on May 25. It turned northeastward and moved across the southeastern United States, becoming extratropical in North Carolina on May 27. After moving off the coast of Virginia, the remnants of Alma were absorbed by an approaching cold front.[4]

Impact

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Rainfall map

After Alma weakened from hurricane status, it passed near the Cayman Islands on May 21, where winds of up to 65 mph (105 km/h) were recorded.[6] Gale-force winds and heavy rainfall also occurred in Jamaica.[7] Heavy rains ahead of the storm caused flash flooding in central and eastern Cuba.[4] Seven people died as a result, and several homes were destroyed. The flooding forced the evacuation of 3,000 people in Oriente Province. Inclement weather closed 16 sugar mills, which stalled harvesting that was already behind schedule in the country.[8]

In Florida, the remnants of Alma brought rainfall across most of the state, with some isolated areas experiencing 5 inches (12.70 cm) or more. The highest rainfall from the storm was near Miami, Florida, with 6.66 inches (16.92 cm) of rain.[9] The rainfall was beneficial in alleviating drought conditions,[4] although thunderstorms caused hazardous driving conditions in the Florida Keys and elsewhere in the state.[10] Small craft warnings were posted along the coast.[11] One girl died from lightning in Miami,[12] and a thunderstorm near Fort Myers damaged some roofs and outbuildings.[13] In Saint Petersburg, flooding disrupted phonelines in about 400 households.[14] Merritt Island experienced 45 mph (72 km/h) wind gusts.[15] In Georgia, South Carolina, North Carolina, Virginia, and Maryland, Alma dropped moderate rainfall, with some isolated areas receiving up to 3 inches (7.62 cm).[9] Near Columbia, South Carolina, the remnants of Alma spawned a tornado which destroyed a roof.[14]

See also

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References

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  1. ^ a b National Hurricane Center (1970). "Hurricane Alma Preliminary Report (Page 1)". Retrieved 2009-10-26.
  2. ^ "Atlantic hurricane best track (HURDAT version 2)" (Database). United States National Hurricane Center. April 5, 2023. Retrieved October 28, 2024. Public Domain This article incorporates text from this source, which is in the public domain.
  3. ^ RHS/GBC (1970-05-22). "Tropical Depression Alma advisory". National Hurricane Center. Retrieved 2009-12-26.
  4. ^ a b c d National Hurricane Center (1970). "Hurricane Alma Preliminary Report (Page 2)". Retrieved 2009-10-26.
  5. ^ Sugg (1970-05-24). "Tropical Depression Alma bulletin". National Hurricane Center. Retrieved 2009-12-26.
  6. ^ National Hurricane Center (1970). "Observations from the Cayman Islands". Retrieved 2009-12-26.
  7. ^ National Hurricane Center (1970). "Hurricane Alma Marie Advisory". Retrieved 2009-12-26.
  8. ^ "Seven Cubans Drown in Floods of Alma". The Miami News. 1970-05-25. p. 6-A. Retrieved 2021-09-28.
  9. ^ a b National Hurricane Center (1970). "Hurricane Alma — Rainfall". Retrieved 2009-10-26.
  10. ^ National Hurricane Center (1970). "Thunderstorms in the Florida Keys". Retrieved 2009-12-26.
  11. ^ National Weather Service (1970). "Fort Myers Weather Statement". Retrieved 2009-12-26.
  12. ^ National Hurricane Center (1970). "Deaths from Hurricane Alma". Retrieved 2009-12-26.
  13. ^ National Hurricane Center (1970). "Wind Damage Reports from Alma". Retrieved 2009-12-26.
  14. ^ a b Saint Petersburg Times (1970). "Alma Brings an End to the Drought". Retrieved 2010-02-17.
  15. ^ National Hurricane Center (1970). "Merritt Island Wind Reports". Retrieved 2009-12-26.

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