Hurricane Douglas (2020)

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Hurricane Douglas
Douglas at peak intensity in the open Pacific on July 23
Meteorological history
FormedJuly 20, 2020
Remnant lowJuly 29, 2020
DissipatedJuly 30, 2020
Category 4 major hurricane
1-minute sustained (SSHWS/NWS)
Highest winds130 mph (215 km/h)
Lowest pressure954 mbar (hPa); 28.17 inHg
Overall effects
FatalitiesNone
DamageMinimal
Areas affectedHawaii
Part of the 2020 Pacific hurricane season

Hurricane Douglas was a strong tropical cyclone that became the closest passing Pacific hurricane to the island of Oahu on record, surpassing the previous record held by Hurricane Dot in 1959. The eighth tropical cyclone, fifth named storm,[a] first hurricane, and first major hurricane of the slightly below-average 2020 Pacific hurricane season, Douglas originated from a tropical wave which entered the basin in mid-July. Located in favorable conditions, the wave began to organize on July 19. It became a tropical depression on July 20 and a tropical storm the following day. After leveling off as a strong tropical storm due to dry air, Douglas began rapid intensification on July 23, becoming the season's first major hurricane the following day and peaking as a Category 4 hurricane. After moving into the Central Pacific basin, Douglas slowly weakened as it approached Hawaii. The storm later passed north of the main islands as a Category 1 hurricane, passing dangerously close to Oahu and Kauai, causing minimal damage, and resulting in no deaths or injuries. Douglas weakened to tropical storm status on July 28, as it moved away from Hawaii, before degenerating into a remnant low on July 29 and dissipating on the next day.

Meteorological history[edit]

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

Douglas originated from a tropical wave located over the central portion of the East Pacific basin on July 19.[1] This tropical wave was located further east and in a slightly more conducive environment than another tropical wave to its east, later to become Tropical Depression Seven-E.[1] With large convective bursts repetitively occurring near the circulation, the wave became more organized into the day and chances of development were gradually raised.[2] This organization was followed by a scatterometer pass which indicated the system had a well-defined, closed low level circulation, indicating the system had very quickly developed.[3] Thus, the first advisory was issued on the system as Tropical Depression Eight-E at 15:00 UTC on July 20.[3] This quick evolution of the storm continued, and a small but defined central dense overcast became evident on satellite imagery.[4] This, bundled with increasing satellite estimates, allowed the National Hurricane Center (NHC) to upgrade the depression to Tropical Storm Douglas at 03:00 UTC, July 21.[4]

A small cyclone, Douglas continued to take advantage of its favorable environment and continuously intensified.[5] Well-defined banding developed on the storm's western side, while thunderstorms near the center gathered into a comma head shape.[6] At the time, Douglas' southwest movement was largely influenced by strong mid-level ridging to its north.[6] However, Douglas' small size and this movement allowed a moderate intake of dry air to be entrained into the circulation.[7] Intensification took a halt for much of July 22, as a result, and Douglas' thunderstorms began to slowly decay.[8] After successfully mixing out mid-level dry air from the core of the system, Douglas swiftly recuperated.[9] Convection re-developed, and a ragged eye became briefly evident on satellite imagery, indicating Douglas had strengthened to low-end Category 1 hurricane intensity.[9] This marked the fourth-latest date on record that the first hurricane formed in a season, tying the record of 2004's Hurricane Celia.[9] It soon became apparent Douglas was entering a phase of rapid intensification, as a ring of intense thunderstorms formed around a warming eye.[10] Douglas jumped to Category 3 major hurricane status, as rapid intensification continued, and the storm became larger in size.[11] Intensification slightly leveled off as the day went on, but the formerly-ragged eye became very warm and symmetrical, indicating the storm had entered a more stable state.[12] Despite this, a regrowth of the eyewall began, and Douglas reached its peak intensity as a Category 4 hurricane at 21:00 UTC on July 23, with maximum 1-minute sustained winds of 130 mph (210 km/h) and a minimum central pressure of 954 millibars (28.2 inHg).[13][14]

On July 24, visible imagery revealed Douglas' eye had become increasingly cloud-filled, while the storm's overall satellite appearance degraded.[15] Douglas entered the Central Pacific Hurricane Center's area of responsibility by 21:00 UTC on July 24.[16] As Douglas drifted over cooler sea surface temperatures, more weakening ensued as the system continued northwest.[17] Douglas eventually fell below Category 3 major hurricane status late on July 24, and weakened to a Category 1 hurricane about 12 hours later.[18][19] At this time, Douglas was located roughly 325 miles (523 km) east of Hilo, Hawaii.[20] Douglas continued a slow movement towards the Hawaiian islands, while retaining its intensity,[21] before weakening further as it passed north of Big Island.[22][23] Nonetheless, the storm remained in rather healthy condition, despite being situated over cold sea surface temperatures and experiencing wind shear near Hawaii.[22] Douglas passed north of Maui at 01:00 UTC on July 27, Oahu at 07:00 UTC, and Kauai at 22:00 UTC.[24][25][26] Douglas' close pass just 30 mi (48 km) north of Oahu broke the previous record set by Hurricane Dot for closest passing tropical cyclone to the island, whereas Dot passed about 60 mi (97 km) southwest of Oahu.[27] After moving away from Kauai, Douglas briefly re-intensified as confirmed from reconnaissance.[28] However, strengthening was very short-lived as wind shear quickly displaced deep convection from the storm's circulation.[29] Douglas weakened into a tropical storm shortly afterward,[30] and eventually became a remnant low by 12:00 UTC on July 29.[31][13] Douglas' post-tropical low entered the Western Pacific basin later on July 30,[32] before opening up into a trough at 06:00 UTC that day.[13]

Preparations and impact[edit]

Hurricane Douglas passing just north of the Hawaiian Islands on July 26

In preparation for the arrival of Douglas in Hawaii, Hurricane Watches were issued for Big Island and Maui on July 24.[33] By July 25, hurricane warnings were issued for Oahu and Kauai, while tropical storm warnings were issued for the Big Island and Maui, as Douglas' track forecast became more definitive.[34] Emergency sirens were blared across Oahu and Maui on July 26 as Douglas approached closer to the islands.[35] United States President Donald Trump issued an emergency declaration for the entire state of Hawaii, in preparation of the hurricane.[35] On Oahu, 13 emergency shelters were opened across the island for those in need.[36] On July 25, the Hawai'i Volcanoes National Park closed due to the hurricane.[37]

Despite Douglas' close pass to the Hawaiian Islands, much of the islands were spared from the worst of the hurricane as only the weak southern eyewall of Douglas brushed the islands.[38] Overall damage was relatively minor; however, storm surge and rainfall caused moderate flooding in Kauai and Oahu.[38] Winds never exceeded hurricane-force, although a 69 mph (111 km/h) wind gust occurred on Maui.[39] Rainfall totals also reached up to 6 inches in Maui and Oahu.[39] On July 26, Maui Mayor Mike Victorino stated: "You can pretty much see clear skies. We're so very thankful. I'm thankful that it passed us with very little damage and very little incidents."[40]

See also[edit]

Notes[edit]

  1. ^ This includes an unnamed tropical storm in July 2020.

References[edit]

  1. ^ a b Robbie Berg (July 19, 2020). "Five-Day Graphical Tropical Weather". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  2. ^ Richard Pasch (July 20, 2020). "Two-Day Graphical Tropical Weather Outlook". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  3. ^ a b Jack Beven (July 20, 2020). "Tropical Depression Eight-E Discussion Number 1". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  4. ^ a b John Cangialosi (July 21, 2020). "Tropical Storm Douglas Discussion Number 3". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  5. ^ Stacy R. Stewart (July 21, 2020). "Tropical Storm Douglas Discussion Number 4". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  6. ^ a b Robbie Berg (July 21, 2020). "Tropical Storm Douglas Discussion Number 5". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  7. ^ Robbie Berg (July 22, 2020). "Tropical Storm Douglas Discussion Number 6". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  8. ^ Dave Roberts (July 22, 2020). "Tropical Storm Douglas Discussion Number 7". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  9. ^ a b c Robbie Berg (July 22, 2020). "Hurricane Douglas Discussion Number 9". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  10. ^ Michael Brennan (July 23, 2020). "Hurricane Douglas Discussion Number 11". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  11. ^ Andrew Latto (July 23, 2020). "Hurricane Douglas Discussion Number 12". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  12. ^ Eric S. Blake (July 23, 2020). "Hurricane Douglas Discussion Number 13". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  13. ^ a b c Roberts, David; Pasch, Richard (May 25, 2021). Tropical Cyclone Report: Hurricane Leslie (PDF) (Report). Miami, Florida: National Hurricane Center. Retrieved May 31, 2021.
  14. ^ Daniel Brown (July 24, 2020). "Hurricane Douglas Discussion Number 15". nhc.noaa.gov. Miami, Florida: National Hurricane Center. Retrieved July 29, 2020.
  15. ^ Jon Jelsema (July 24, 2020). "Hurricane Douglas Discussion Number 17". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 29, 2020.
  16. ^ Jon Jelsema (July 24, 2020). "Hurricane Douglas Advisory Number 17". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved August 1, 2020.
  17. ^ Thomas R. Birchard (July 24, 2020). "Hurricane Douglas Discussion Number 18". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved August 1, 2020.
  18. ^ Jon Jelsema (July 25, 2020). "Hurricane Douglas Discussion Number 20". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  19. ^ Derek Wroe (July 25, 2020). "Hurricane Douglas Discussion Number 22". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  20. ^ Derek Wroe (July 25, 2020). "Hurricane Douglas Advisory Number 22". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  21. ^ Tomas R. Birchard (July 26, 2020). "Hurricane Douglas Discussion Number 24". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  22. ^ a b Derek Wroe (July 26, 2020). "Hurricane Douglas Discussion Number 26". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  23. ^ Derek Wroe (July 26, 2020). "Hurricane Douglas Advisory Number 25A". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  24. ^ Maureen Ballard (July 27, 2020). "Hurricane Douglas Tropical Cyclone Update". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  25. ^ Sam Houston; Thomas R. Birchard (July 27, 2020). "Hurricane Douglas Tropical Cyclone Update". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  26. ^ Sam Houston; Thomas R. Birchard (July 27, 2020). "Hurricane Douglas Tropical Cyclone Update". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  27. ^ "Public Information Statement". nwschat.weather.gov. National Weather Service. July 17, 2020. Retrieved July 31, 2020.
  28. ^ Thomas R. Birchard (July 27, 2020). "Hurricane Douglas Discussion Number 29". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  29. ^ Jeff Powell (July 27, 2020). "Hurricane Douglas Discussion Number 30". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  30. ^ Jeff Powell (July 28, 2020). "Tropical Storm Douglas Discussion Number 31". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  31. ^ Thomas R. Birchard (July 29, 2020). "Post-Tropical Cyclone Douglas Discussion Number 37". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved July 31, 2020.
  32. ^ "NASA finds Post-Tropical Low Douglas crossing a line". phys.org. July 30, 2020. Retrieved August 1, 2020.
  33. ^ Ige, David (July 23, 2020). "Anticipation of Hurricane Douglas". governor.hawaii.gov. Hawaii State Government. Retrieved July 29, 2020.
  34. ^ Thomas R. Birchard (July 26, 2020). "Hurricane Douglas Advisory Number 24". nhc.noaa.gov. Honolulu, Hawaii: Central Pacific Hurricane Center. Retrieved August 1, 2020.
  35. ^ a b Audrey McAvoy (July 27, 2020). "Hurricane Douglas swirls 'uncomfortably close' to Hawaii". abcnews.go.com. ABC News. Retrieved August 1, 2020.
  36. ^ Ron Brackett (July 26, 2020). "Hawaii Opens Shelters as Hurricane Douglas Approaches the Islands". weather.com. The Weather Company. Retrieved August 1, 2020.
  37. ^ Hawaiʻi Volcanoes National Park Closes in Preparation for Hurricane Douglas, NPS.com, July 25, 2020
  38. ^ a b Ron Brackett (July 27, 2020). "Hurricane Douglas Blows by Hawaii, Leaving Little Damage Behind". weather.com. The Weather Company. Retrieved August 1, 2020.
  39. ^ a b "Hawaiʻi Island Recorded Highest Wind From Hurricane Douglas". bigislandvideonews.com. Big Island Video News. July 28, 2020. Retrieved August 1, 2020.
  40. ^ "'Very thankful': Maui mayor reports no major damage from Douglas". Hawaii News Now. July 27, 2020. Retrieved August 1, 2020.

External links[edit]

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