2018 Hawaii floods: Difference between revisions
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{{Infobox flood |
{{Infobox flood |
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|name=2018 Hawaii floods |
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|areas affected=[[Kauai]], [[Oahu]] ([[Hawaii]]) |
|areas affected=[[Kauai]], [[Oahu]] ([[Hawaii]]) |
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On April 14 into the following day, a [[flash flood]] struck the Hawaiian island of [[Kauaʻi]], caused by a period of intense rainfall. |
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| ⚫ | On |
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==Meteorological history== |
==Meteorological history== |
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On April 11, 2018, an [[cold-core low|upper-level low]] was located west of the Hawaiian island of Kauaʻi. The low weakened and opened into a [[trough (meteorology)|trough]], which moved over the Hawaiian islands on April 13, producing heavy rainfall. That day, A [[mesoscale convective system]] (MCS) developed northwest of [[Molokai]] and intensified while moving westward through the [[trade winds]]. The MCS moved over eastern [[Oahu]], dissipating after moving ashore. Another upper-level low developed on April 14, fueling further rainfall through April 16. The first of a series of thunderstorms moved over northern [[Kauai]] around midnight (local time{{#tag:ref|All times in this article are in local [[Hawaii–Aleutian Time Zone|Hawaiian Standard Time]].|group="nb"}}) on April 14. After a five hour break in rainfall, another set of thunderstorms hit northern |
On April 11, 2018, an [[cold-core low|upper-level low]] was located west of the Hawaiian island of Kauaʻi. The low weakened and opened into a [[trough (meteorology)|trough]], which moved over the Hawaiian islands on April 13, producing heavy rainfall. That day, A [[mesoscale convective system]] (MCS) developed northwest of [[Molokai]] and intensified while moving westward through the [[trade winds]]. The MCS moved over eastern [[Oahu]], dissipating after moving ashore. Another upper-level low developed on April 14, fueling further rainfall through April 16. The first of a series of thunderstorms moved over northern [[Kauai|Kauaʻi]] around midnight (local time{{#tag:ref|All times in this article are in local [[Hawaii–Aleutian Time Zone|Hawaiian Standard Time]].|group="nb"}}) on April 14. After a five hour break in rainfall, another set of thunderstorms hit northern Kauaʻi around midnight on April 15 and lasted for about eight hours. The third set of thunderstorms began around 10:00 AM on April 15 and continued until around 7:00 PM.<ref name="hon">{{cite report|title=Kauai and Oahu Flash Flooding - April 13 - 15, 2018|publisher=Honolulu, Hawaii National Weather Service|year=2018|url=http://www.prh.noaa.gov/hnl/pages/events/KauaiOahuApril2018Floods/|accessdate=January 12, 2019}}</ref> |
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==Impact and aftermath== |
==Impact and aftermath== |
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The heavy rainfall caused flooding that affected 532 houses. Public damage totaled over $20 million.<ref name="hon"/> |
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After the floods, [[Governor of Hawaiʻi|Hawaiian Governor]] [[David Ige]] declared a State of Emergency. On April 18, the Hawaiian legislature approved $125 million in disaster funding, including $100 million for Kauaʻi.<ref name="twc"/> |
After the floods, [[Governor of Hawaiʻi|Hawaiian Governor]] [[David Ige]] declared a State of Emergency. On April 18, the Hawaiian legislature approved $125 million in disaster funding, including $100 million for Kauaʻi.<ref name="twc"/> |
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At [[Waimanalo]] Stream north of Niu Valley, the rains caused the waters to rise {{convert|3|ft|m|abbr=on}} in 30 minutes, and {{convert|5|ft|m|abbr=on}} in an hour. During the rain event, Wailupe Gulch reported an {{convert|8|ft|m|abbr=on}} rise in floodwaters. The flooding caused significant [[surface runoff|runoff]], leaving a layer of debris on roads. Flooding entered several houses and cars on the island.<ref name="hon"/> |
At [[Waimanalo]] Stream north of Niu Valley, the rains caused the waters to rise {{convert|3|ft|m|abbr=on}} in 30 minutes, and {{convert|5|ft|m|abbr=on}} in an hour. During the rain event, Wailupe Gulch reported an {{convert|8|ft|m|abbr=on}} rise in floodwaters. The flooding caused significant [[surface runoff|runoff]], leaving a layer of debris on roads. Flooding entered several houses and cars on the island.<ref name="hon"/> |
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===Kauaʻi=== |
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| ⚫ | On Kauaʻi, the rainfall event occurred at low elevations near the northern coast. This was unusual, as previous rain events on the island usually occurred over higher elevations. The heaviest rainfall occurred early on April 15.<ref name="hon"/> A [[pluviometer|rain gauge]] owned by the [[Waipa Foundation|Waipā Foundation]], just west of [[Hanalei, Hawaii|Hanalei]] on Kauaʻi's northern coast, recorded {{convert|49.69|in|mm|abbr=on}} of rainfall in the 24 hours ending at 12:45 PM. Pending verification by the National Climatic Extremes Committee, the rainfall total broke the 24 hour rainfall set during [[Tropical Storm Claudette (1979)|Tropical Storm Claudette]] on July 26, 1979 in [[Alvin, Texas]]. The total would also break the Hawaiʻi record of {{convert|38|in|mm|abbr=on}} set on January 25, 1956 at [[Kīlauea]], also on Kauaʻi.<Ref name="hon"/><ref>{{cite web|author=Kevin Kodama|url=http://w2.weather.gov/climate/index.php?wfo=hnl|accessdate=April 25, 2018|publisher=Honolulu, Hawaii National Weather Service|date=April 25, 2018|title=Possible New National Record 24-Hour Rainfall from }}</ref><ref>{{cite web|author=David M. Roth|accessdate=April 25, 2018|date=November 29, 2017|title=Tropical Storm Claudette - July 16-31, 1979|url=http://www.wpc.ncep.noaa.gov/tropical/rain/claudette1979.html|publisher=Weather Prediction Center}}</ref> The Waipā rain gauge also recorded {{convert|1.77|in|abbr=on}} over 15 minutes, {{convert|5.51|in|mm|abbr=on}} over an hour, {{convert|19.52|in|mm|abbr=on}} over 6 hours, {{convert|33.33|in|mm|abbr=on}} over 12 hours, and {{convert|53.57|in|mm|abbr=on}} over 48 hours. Elsewhere on northern Kauaʻi, a rain gauge in [[Wainiha, Hawaii|Wainiha]] recorded {{convert|32.35|in|mm|abbr=on}}, and a gauge in Hanalei recorded {{convert|28.41|in|mm|abbr=on}} before it failed. Minimal rainfall occurred on the southern and western coasts of Kauaʻi.<ref name="hon"/> |
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| ⚫ | The sudden rainfall caused flooding and [[landslide |
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| ⚫ | The sudden rainfall caused flooding and [[landslide]]s, which washed out several roads and homes. Landslides and flooding closed a portion of [[Hawaii Route 56|Kuhio Highway]], which was under {{convert|5|to|8|ft|m|abbr=on}} of waters.<ref name="hon"/> The worst erosion occurred in isolated areas. At least four vacant houses were washed away, and dozens of homes had water intrusion. There were no injuries during the event. Local and national emergency crews rescued 273 people from their homes by helicopter, boat, and bus. An [[American Red Cross|Red Cross]] shelter in Kilauea housed 13 people after the event.<ref>{{cite news|date=April 17, 2018|title=Over 200 Hawaiʻi residents airlifted from Kauaʻi flooding following 30 inches of rain|newspaper=USAToday|accessdate=April 25, 2018|url=https://www.usatoday.com/story/news/nation/2018/04/17/over-200-hawaii-residents-airlifted-kauai-flooding-following-30-inches-rain/526006002/}}</ref><ref name="twc">{{cite news|publisher=Weather.com|accessdate=April 25, 2018|title=Kauai Flooding Eases But Damage Is Worse Than Expected, Aerial Survey Shows|date=April 19, 2018|url=https://weather.com/news/news/2018-04-15-hawaii-heavy-rain-flood-mudslides-impacts}}</ref> |
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==See also== |
==See also== |
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Revision as of 17:48, 12 January 2019
| Date | April 14–15, 2018 |
|---|---|
| Location | Kauai, Oahu (Hawaii) |
| Deaths | None reported |
| Property damage | $20 million (2018 USD)[nb 1] |
On April 14 into the following day, a flash flood struck the Hawaiian island of Kauaʻi, caused by a period of intense rainfall.
Meteorological history
On April 11, 2018, an upper-level low was located west of the Hawaiian island of Kauaʻi. The low weakened and opened into a trough, which moved over the Hawaiian islands on April 13, producing heavy rainfall. That day, A mesoscale convective system (MCS) developed northwest of Molokai and intensified while moving westward through the trade winds. The MCS moved over eastern Oahu, dissipating after moving ashore. Another upper-level low developed on April 14, fueling further rainfall through April 16. The first of a series of thunderstorms moved over northern Kauaʻi around midnight (local time[nb 2]) on April 14. After a five hour break in rainfall, another set of thunderstorms hit northern Kauaʻi around midnight on April 15 and lasted for about eight hours. The third set of thunderstorms began around 10:00 AM on April 15 and continued until around 7:00 PM.[1]
Impact and aftermath
The heavy rainfall caused flooding that affected 532 houses. Public damage totaled over $20 million.[1]
After the floods, Hawaiian Governor David Ige declared a State of Emergency. On April 18, the Hawaiian legislature approved $125 million in disaster funding, including $100 million for Kauaʻi.[2]
Oahu
Across eastern Oahu, the mesoscale convective system produced rainfall rates of about 4 in (100 mm) per hour. Over a 15 minute period, a rain gauge in Niu Valley recorded 1.42 in (36 mm) of precipitation, which has a 4–10% annual return period. The same station recorded 5.52 in (140 mm) of rainfall over a two hour period, which has a 0.5–1% annual return period. The rainfall on Oahu was largely limited to the eastern one-third of the island. A station at Daniel K. Inouye International Airport recorded 0.01 in (0.25 mm) of rainfall, just 14 mi (23 km) west of Niu Valley, which recorded 5.55 in (141 mm) during the same 24 hour period.[1]
At Waimanalo Stream north of Niu Valley, the rains caused the waters to rise 3 ft (0.91 m) in 30 minutes, and 5 ft (1.5 m) in an hour. During the rain event, Wailupe Gulch reported an 8 ft (2.4 m) rise in floodwaters. The flooding caused significant runoff, leaving a layer of debris on roads. Flooding entered several houses and cars on the island.[1]
Kauaʻi
On Kauaʻi, the rainfall event occurred at low elevations near the northern coast. This was unusual, as previous rain events on the island usually occurred over higher elevations. The heaviest rainfall occurred early on April 15.[1] A rain gauge owned by the Waipā Foundation, just west of Hanalei on Kauaʻi's northern coast, recorded 49.69 in (1,262 mm) of rainfall in the 24 hours ending at 12:45 PM. Pending verification by the National Climatic Extremes Committee, the rainfall total broke the 24 hour rainfall set during Tropical Storm Claudette on July 26, 1979 in Alvin, Texas. The total would also break the Hawaiʻi record of 38 in (970 mm) set on January 25, 1956 at Kīlauea, also on Kauaʻi.[1][3][4] The Waipā rain gauge also recorded 1.77 in (45 mm) over 15 minutes, 5.51 in (140 mm) over an hour, 19.52 in (496 mm) over 6 hours, 33.33 in (847 mm) over 12 hours, and 53.57 in (1,361 mm) over 48 hours. Elsewhere on northern Kauaʻi, a rain gauge in Wainiha recorded 32.35 in (822 mm), and a gauge in Hanalei recorded 28.41 in (722 mm) before it failed. Minimal rainfall occurred on the southern and western coasts of Kauaʻi.[1]
The sudden rainfall caused flooding and landslides, which washed out several roads and homes. Landslides and flooding closed a portion of Kuhio Highway, which was under 5 to 8 ft (1.5 to 2.4 m) of waters.[1] The worst erosion occurred in isolated areas. At least four vacant houses were washed away, and dozens of homes had water intrusion. There were no injuries during the event. Local and national emergency crews rescued 273 people from their homes by helicopter, boat, and bus. An Red Cross shelter in Kilauea housed 13 people after the event.[5][2]
See also
- List of wettest tropical cyclones in the United States
- Hurricane Lane (2018) - a hurricane that brought heavy rainfall to Hawaii in August 2018
Notes
- ^ All damage totals are in 2018 United States dollars.
- ^ All times in this article are in local Hawaiian Standard Time.
References
- ^ a b c d e f g h Kauai and Oahu Flash Flooding - April 13 - 15, 2018 (Report). Honolulu, Hawaii National Weather Service. 2018. Retrieved January 12, 2019.
- ^ a b "Kauai Flooding Eases But Damage Is Worse Than Expected, Aerial Survey Shows". Weather.com. April 19, 2018. Retrieved April 25, 2018.
- ^ Kevin Kodama (April 25, 2018). "Possible New National Record 24-Hour Rainfall from". Honolulu, Hawaii National Weather Service. Retrieved April 25, 2018.
- ^ David M. Roth (November 29, 2017). "Tropical Storm Claudette - July 16-31, 1979". Weather Prediction Center. Retrieved April 25, 2018.
- ^ "Over 200 Hawaiʻi residents airlifted from Kauaʻi flooding following 30 inches of rain". USAToday. April 17, 2018. Retrieved April 25, 2018.