Tropical Storm Danny (2021)

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Tropical Storm Danny
Tropical storm (SSHWS/NWS)
Danny 2021-06-28 1840Z.jpg
Tropical Storm Danny at peak intensity on June 28
FormedJune 27, 2021
DissipatedJune 29, 2021
Highest winds1-minute sustained: 45 mph (75 km/h)
Lowest pressure1009 mbar (hPa); 29.8 inHg
FatalitiesNone reported
Damage$5,000 (2021 USD)
Areas affectedSoutheastern United States (mainly South Carolina and Georgia)
Part of the 2021 Atlantic hurricane season

Tropical Storm Danny was a weak and short-lived tropical cyclone that brought minor damage to the U.S states of South Carolina and Georgia. The fourth named storm of the 2021 Atlantic hurricane season, the system formed from an area of low-pressure that developed from an upper-level trough over the central Atlantic Ocean on June 22. Moving briskly west-northwestward, the disturbance gradually developed as convection, or showers and thunderstorms, increased over it. Although it was moving over the Gulf Stream, the organization of the disturbance was hindered by strong upper-level wind shear. By 18:00 UTC of June 27, as satellite images showed a well-defined center and thunderstorms, the system was upgraded to a tropical depression by the National Hurricane Center (NHC). At 06:00 UTC on the next day, the system further strengthened to Tropical Storm Danny, east-southeast of Charleston, South Carolina. Danny continued its track towards South Carolina while slowly strengthening, subsequently reaching its peak intensity at that day of 45 mph (75 km/h) and a minimum central pressure of 1009 mb (29.80 inHg) at 18:00 UTC. Danny made landfall in Pritchards Island, north of Hilton Head, in a slightly-weakened state at 23:20 UTC on the same day, with winds of 40 mph (65 km/h) and a minindicating that Danny weakened prior to moving inland. The system then weakened to a tropical depression over east-central Georgia, before dissipating shortly afterward.

Danny was the first system to make landfall on the U.S. state of South Carolina in the month of June since Hurricane One in 1867.[1] Large amounts of rainfall were recorded on some parts of Georgia and South Carolina, causing minor flooding. Effects were also limited to some fallen trees and lightning strikes. Ten rescues were required on two different beaches on North Carolina due to rip currents. No deaths were reported due to the Danny, while the damages from it in the Southeastern United States totaled $5,000 (2021 USD).

Meteorological history[]

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
▲ Extratropical cyclone / Remnant low / Tropical disturbance / Monsoon depression

On June 22, an upper-level trough separated from the jet stream and evolved into an upper-level low-pressure system. Two days later, the low turned westward under the influence of a strong ridge to its north. Disorganized convection, or showers and thunderstorms, increased as the system moved over warmer waters. Near this time, a surface trough in relation to the upper-level low became better defined.[2] Over the next few days, the trough moved quickly west-northwestward, and on June 26, the National Hurricane Center (NHC) began to monitor the disturbance for development, as it passed several hundred miles south of Bermuda.[3][4][5] On June 27, ship observations, buoy and satellite imagery revealed that a small area of low pressure had developed about 500 miles (800 km) east-southeast of the Georgia-South Carolina border.[2][6] Surface pressure decreased,[6] and over the next 12 hours, the system continued to organize. At 18:00 UTC on June 27, the disturbance consolidated into a tropical depression,[2] but operationally, the NHC did not upgrade the system to a tropical depression until 15:00 UTC on June 28, while it was located offshore South Carolina.[7] A short time after formation, convection over the system decreased, and low-level circulation center (LLCC) became partially exposed.[2] Convection remained displaced to the northwest of the center due to strong upper-level wind shear.[8] Nevertheless, an Advanced Scatterometer pass discovered peak winds of 40 mph (65 km/h) – tropical storm-force – early on June 28. The NHC estimated that the depression strengthened into a tropical storm at 06:00 UTC that day, receiving the name Danny.[2]

On the morning of June 28, the cloud structure of the cyclone continued to consolidate, sporting deep convection with cloud top temperatures of −76 °F (−60 °C) on its western periphery.[9] Later, in the afternoon, a mass of deep convection quickly expanded over Danny's center. A U.S. Air Force Hurricane Hunter reconnaissance aircraft found gale-force surface winds of 45 mph (75 km/h), and NEXRAD radar in Charleston also found data supporting this value.[2][10] Thus, it is estimated that Danny reached its peak intensity with maximum sustained winds of 45 mph (70 km/h) and a minimum barometric pressure of 1009 mb (29.80 inHg) at 18:00 UTC on July 28.[2] Steadily maintaining its motion, Danny made landfall on Pritchards Island, South Carolina, north of Hilton Head as a minimal tropical storm at 23:20 UTC, with winds of 40 mph (65 km/h), indicating that the storm weakened slightly before moving inland.[2][11] Upon entering the east-central portion of Georgia, the system weakened to a tropical depression as evidenced by Doppler weather radar velocity data and surface observations.[11][2] The weakening tropical cyclone dissipated by 06:00 UTC on July 29.[2]

Preparations and impact[]

Map of rainfall accumulations from Tropical Storm Claudette across the United States
Map of rainfall accumulations from Tropical Storm Danny across the United States

Danny's tropical cyclogenesis was poorly forecast, due to the disorganized nature of the precursor disturbance and low model support. This resulted in the onset of tropical cyclone watches and warnings occurring only 12 hours before landfall.[2] A Tropical Storm Warning was issued from Edisto Beach to Santee River in South Carolina at 15:00 UTC on June 28.[12] The warnings on the state from Danny were canceled at 03:00 UTC on June 29 as the system weakened to a tropical depression, inland Georgia.[13][11] The Storm Prediction Center, in anticipation of Danny, also published a marginal risk of severe weather on the state on June 29.[14] As the system moved inland, Lake Wind Advisories were also issued on portions of the Midlands on the same day.[15] Despite Danny being predicted not to bring any major impacts to the Southeastern United States, portions of Georgia, South Carolina, and northern Alabama were expected to see inches of rain from the system. Flash flooding was also a potential on the mainland.[16][17] Double red flags were placed on Myrtle Beach, South Carolina to warn people that swimming in the area is prohibited.[18]

The system was the first storm to make landfall in South Carolina in the month of June since an unnamed Category 1 hurricane in 1867.[1] Ten rescues were required on Carolina and Wrightsville beaches on North Carolina due to rip currents on June 28.[16] On the same day, a weather station at Folly Beach recorded a wind gust of 41 mph (66 kph) as Danny moved inland.[19] Palmetto Electric and Dominion Energy both reported over 1,251 power outages in total due to the storm in In Beaufort County, South Carolina.[20] Lightning strikes were also seen in the state, along with minor flooding and heavy rainfall.[21] A tree was downed in SC 170 and some damage occurred in Savannah, Georgia.[21] Minor flooding was also reported in portions of Jasper and Chatham counties.[22] Purrysburg in the state got the highest rain amount from Danny, amounting to 5.21 inches (132 mm) while Monteith in the lowest, with 3.10 inches (79 mm).[23]

See also[]

References[]

  1. ^ a b Philip Klotzbach [@philklotzbach] (June 28, 2021). "Tropical Storm #Danny has made landfall in South Carolina - the first June named storm to make landfall in South Carolina since #Hurricane One of 1867" (Tweet). Colorado. Archived from the original on June 30, 2021. Retrieved June 29, 2021 – via Twitter.
  2. ^ a b c d e f g h i j k Latto, Andrew (October 14, 2021). Tropical Cyclone Report: Tropical Storm Danny (AL042021) (PDF) (Report). National Hurricane Center. Retrieved October 14, 2021.
  3. ^ Tropical Weather Discussion: Atlantic [1205 UTC Thu Jun 24 2021]. nhc.noaa.gov (Report). Miami, Florida: National Hurricane Center. June 24, 2021. Retrieved June 28, 2021.
  4. ^ Tropical Weather Discussion: Atlantic [1205 UTC Fri Jun 25 2021]. nhc.noaa.gov (Report). Miami, Florida: National Hurricane Center. June 25, 2021. Retrieved June 28, 2021.
  5. ^ Papin, Philippe; Stewart, Stacy (June 26, 2021). Five-Day Graphical Tropical Weather Outlook. www.nhc.noaa.gov (Report). Miami, Florida: National Hurricane Center. Retrieved June 28, 2021.
  6. ^ a b Stewart, Stacy; Latto, Andy (June 27, 2021). 5-Day Graphical Tropical Weather Outlook. www.nhc.noaa.gov (Report). Miami, Florida: National Hurricane Center. Retrieved June 28, 2021.
  7. ^ Stewart, Stacy (June 28, 2021). Tropical Depression Four Discussion Number 1. www.nhc.noaa.gov (Report). Miami, Florida: National Hurricane Center. Retrieved June 29, 2021.
  8. ^ Latto, Andrew; Pasch, Richard (June 28, 2021). Two-Day Graphical Tropical Weather Outlook (Report). Miami, Florida: National Hurricane Center. Retrieved June 28, 2021.
  9. ^ Stewart, Stacy (June 28, 2021). Tropical Depression Four Discussion Number 1 (Report). National Hurricane Center. Retrieved October 14, 2021.
  10. ^ Stewart, Stacy (June 28, 2021). Tropical Storm Danny Discussion Number 2 (Report). Miami, Florida: National Hurricane Center. Retrieved June 29, 2021.
  11. ^ a b c Cangialosi, John (June 28, 2021). Tropical Depression Danny Discussion Number 3. www.nhc.noaa.gov (Report). Miami, Florida: National Hurricane Center. Retrieved June 29, 2021.
  12. ^ Stewart, Stacy (June 28, 2021). Tropical Depression Four Forecast/Advisory Number 1. www.nhc.noaa.gov (Report). Miami, Florida: National Hurricane Center. Retrieved June 29, 2021.
  13. ^ "Danny weakens to a tropical depression, heavy rains continue". News Observers. June 29, 2021. Archived from the original on June 30, 2021. Retrieved June 30, 2021.
  14. ^ Gard, Hannah; Brink, Haley (June 29, 2021). "Tropical Storm Danny forms and quickly makes landfall in South Carolina". CNN. Archived from the original on June 30, 2021. Retrieved June 29, 2021.
  15. ^ Saric, Ivana (June 29, 2021). "Tropical Storm Danny forms off coast of South Carolina". Yahoo News. Archived from the original on June 30, 2021. Retrieved June 30, 2021. A Lake Wind Advisory has been issued for much of the state.
  16. ^ a b "Tropical Storm Danny Made Landfall in South Carolina Just Hours After Forming". The Weather Channel. June 29, 2021. Archived from the original on June 29, 2021. Retrieved June 29, 2021.
  17. ^ McCloud, Cheryl; Rice, Doyle (June 28, 2021). "Tropical Storm Danny makes landfall north of Georgia, South Carolina border; expected to dissipate late Tuesday". USA Today. Archived from the original on June 30, 2021. Retrieved June 29, 2021.
  18. ^ Brooking, Ian (June 28, 2021). "Myrtle Beach area to see impacts of Tropical Storm Danny as it approaches the Lowcountry". MyHorryNews. Archived from the original on June 30, 2021. Retrieved June 30, 2021.
  19. ^ "Danny weakens to a tropical depression, heavy rains continue". Associated Press. June 29, 2021. Archived from the original on June 30, 2021. Retrieved June 29, 2021.
  20. ^ Sanches, Sofia; Wilson, Lisa; Ferguson, Lana (June 29, 2021). "Tropical Storm Danny makes landfall just north of Hilton Head. Here's Tuesday's outlook". The State. Archived from the original on June 30, 2021. Retrieved June 29, 2021.
  21. ^ a b Curley, Molly (June 29, 2021). "Tropical Storm Danny brings lightning, flooding locally". WSAV-TV. Archived from the original on June 30, 2021. Retrieved June 29, 2021.
  22. ^ "Tropical Storm Danny is gone. But another potential storm is on the horizon". WJCL. June 29, 2021. Archived from the original on June 30, 2021. Retrieved June 29, 2021.
  23. ^ Duff, Renee (June 29, 2021). "Danny makes landfall in the southeastern US". Accuweather. Archived from the original on June 30, 2021. Retrieved June 29, 2021.

External links[]

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