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Summary
 

Two flood waves hit the Supai area late on July 11th. The first (and most damaging) occurred around 7-7:30pm (the other was later that night). Serious flooding occurred in the Supai campground, with reports of a 7’ rise in Havasu Creek. The media reports of a ‘7 foot wall of water’ hitting the area is consistent with gauge data, with a 4’ rise at the Supai Gauge (850 CFS), and an 8’ rise downstream at the Colorado River (3760 CFS). The last Supai flood event of a similar magnitude occurred during the afternoon/evening of 26 August 2013. It is estimated that Havasu Canyon will be closed from 7-10 days due to the damage.

 
Timeline
Radar Loop July 11th From 4:13pm To 7:16pm

Radar Loop July 11th From 4:13pm To 7:16pm

Storm Total Precipitation July 11th From 4:13pm To 7:16pm

Storm Total Precipitation July 11th From 4:13pm To 7:16pm

Radar Estimated Rainfall from 5pm - 8pm July 11th

Radar Estimated Rainfall from 5pm - 8pm July 11th

Radar Estimated Rainfall from 12pm - 3am July 12th

Radar Estimated Rainfall from 12pm - 3am July 12th

Flood Event #1: July 11

  • 5:30 PM: Heavy Rainfall. Radar est 1 - 1.5" rain fell in the Supai area between 5:30 pm and 6:30 pm MST.
    Storms moving from SE to NW. KICX estimates 1-1.5” of rain fell a few miles upstream of the USGS gauge in about an hour, from 5:30 pm to 6:30 pm. In addition, about 1-1.5” of rain fell over and just downstream of Supai Village in about 40 minutes, between 5:50 pm and 6:30 pm).

  • 6:37 PM: Supai dispatch was called and notified that a Flood Advisory was issued for the Havasu Creek and Supai at 6:37 pm. The potential impacts related to the Advisory were briefed at that time.

  • 7:00-7:30 PM: It is estimated that the flooding began in the campground area between 7:00 and 7:30 pm.

  • 7:30 PM: Flood crest (4’ rise, 800 CFS) hits the Supai Gauge at 7:30 pm.

  • ** Important to note that most of the rain impacting the camping area fell downstream of the Supai gauge...the 4’ rise and 850 CFS at the gauge the does not accurately represent the impacts at the camping area. Downstream gauge at the Colorado River recorded 8’ rise with 3760 CFS **

  • 7:45 PM: Flood crest (8’, 3760 CFS) hits the Havasu Creek Gauge at Mouth (downstream near the Colorado River)

  • 10:00 PM: Flood recedes from Supai gauge (below 100 CFS).

  • 10:30 PM: First call from Supai (Peach Springs dispatch) of flood impacts.

  • 1:00 AM: Flood recedes from the Havasu Creek gauge at Mouth (below 250 CFS)

Flood Event #2: July 12

  • 12:00 AM: At 12:00 am MST, additional storms developed over and just south of Supai - with an additional 1" of rain falling upstream of the campground between approximately 12:00 and 1:00 am.

  • 1:22 AM: Supai dispatch was called and notified that a new Flash Flood Warning was issued at 1:22 am.

  • 2:00 AM: Gauge at Supai rose above flood stage again at 2:00 am (4.5' rise, 1700 CFS).

  • 3:30 AM: Called Supai to check on status of flooding. They reported no additional issues, likely a result of everyone being out of the campground area due to earlier flooding.

  • 4:15 AM: Flood crest (6.5’, 1990 CFS) hits the Havasu Creek at Mouth gauge (downstream near Colorado River).

  • 7:45 AM: Flood recedes from Havasu Creek at Mouth gauge (below 250 CFS)


Impacts
  • Campers were displaced, tents and belongings swept away, with 15 campers stranded on high ground.
  • A total of 172 visitors were evacuated from the campground to the Community Center and Elementary School.
  • No serious injuries reported.
  • No damage was reported in the Village of Supai.
Hydrographs

 

Two flood waves hit the Havasu Creek gauge at Supai

Two flood waves hit the Havasu Creek gauge at Supai

Flood waves were recorded at the gauge on Havasu Creek near the mouth

Flood waves were recorded at the gauge on Havasu Creek near the mouth

Cataract Creek at Heather Wash recorded a roughly 3 foot rise

Cataract Creek at Heather Wash recorded a roughly 3 foot rise

A significant rise of around 7 feet was recorded at the Cataract Creek gauge below Topocoba

A significant rise of around 7 feet was recorded at the Cataract Creek gauge below Topocoba

 

Meteorology

 

By mid-day on July 11, 2018, surface and mid-level south to southeast winds associated with the desert Southwest monsoon created conditions favorable for the formation of scattered thunderstorms over the Cataract Creek drainage basin. These thunderstorms contained enough monsoonal moisture to cause rainfall of up to 1 – 1.5” over Cataract Creek and washes that drain into the creek. Eventually, the flood waters traveled far enough downstream to result in the flash flooding of Supai Creek (represented by the hydrographs above).

 

Points of Contact

For more information on impacts and general inquiries about this event, please reference the contacts below:

  • National Weather Service: Brian Klimowski, Meteorologist-in-Charge at (928) 556-9161 ext. 222 or brian.klimowski@noaa.gov
    Tony Merriman, Warning Coordination Meteorologist at (928) 556-9161 ext. 223 or tony.merriman@noaa.gov

  • Local and Tribal Information: Havasupai Tribal Offices at (928) 448-2731 or info@havasupai-nsn.gov

  • Coconino County Emergency Management at (928) 679-8310