A cold trough of low pressure brought heavy rain to the Cataract/Havasu Creek drainage. The creek rose around 3 feet through the Village of Supai.
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The episode as NWS FGZ wrote it up.
A cold trough of low pressure brought heavy rain to the Cataract/Havasu Creek drainage. The creek rose around 3 feet through the Village of Supai.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Flagstaff, AZ wrote its last area forecast discussion before the first event at Oct 6, 3:08 PM MST, 1 hour 22 minutes earlier.
Area Forecast Discussion National Weather Service Flagstaff AZ 308 PM MST Sat Oct 6 2018 .SYNOPSIS...A significant storm system will bring colder and stormy conditions to the area this weekend. Expect rain showers and thunderstorms to spread across much of northern Arizona tonight through Sunday. A few strong or severe storms are possible and could produce locally heavy rainfall. Cool and unsettled conditions will persist through Tuesday. Fair weather returns on Wednesday. && .DISCUSSION...A deepening trough of low pressure over the Great Basin this afternoon has pushed a cold front into far northwestern Arizona (Mohave County). The trough will continue to deepen while pushing the potent cold front southeast through Arizona tonight into Sunday morning. Plenty of dynamic lift will lead to a band of moderate to locally heavy rain showers and thunderstorms moving west to east across the area. Marginal instability will combine with sufficient deep layer shear of 40-60 kt tonight to produce a few strong or severe thunderstorms capable of hail and strong winds. Enhanced low level southerly flow will draw additional moisture northward ahead of the cold front ensuring efficient rainfall production. The best combination of moisture and instability will come together over southern Coconino, eastern Yavapai, and Gila Counties which are forecast to receive between 1-2 inches of rain, with locally higher amounts possible from stronger convection. Due to saturated soils in this area from widespread rain earlier this week, watersheds will see a faster than normal response to any heavy rain and we have issued a Flash Flood Watch for tonight through Sunday afternoon. By daybreak Sunday, the frontal boundary will be moving across eastern Arizona while the cold post-frontal air mass settles into northern Arizona. Showers will become more scattered behind the main frontal passage. Much colder temperatures are in store Sunday with 40s in the mountains and 50s - low 60s in the valleys. The first accumulating snow of the season will fall over the highest mountains above 8,000 - 9,000 feet, with several inches possible above 10,000 feet. Snow levels will mostly remain at or above 8,000 feet through the event. The trough will remain over the region through Monday with cold and unsettled weather persisting. Drier and briefly warmer weather will ensue midweek before another cold trough moves into the region. There is still a possibility of this next trough interacting with the remnants of Hurricane Sergio. Latest forecasts are trending this moisture further south, but stay tuned through the coming days for updates. && .AVIATION...For the 00Z package...MVFR/IFR conditions will continue to move E/SE with an approaching cold front bringing cloud cover and SHRA/-TSRA. SW sfc winds at 10-15 kts, gusts up to 25-30 kts, remain through Saturday evening. More widespread -RA/-TSRA will begin this evening and through the overnight. ISLT -SHRA/-TSRA return on Sunday. Aviation discussion not updated for TAF amendments. && .Fire Weather...Gusty southwest winds will remain through Saturday evening ahead of an approaching cold front. This front is producing showers and thunderstorms across northern Arizona that will last through Sunday night. Temperatures will drop 10-15 degrees Sunday. Mountain snow accumulation is expected over the highest peaks. Cold and unsettled weather will continue Monday. .Tuesday through Thursday...Chance for showers begins to decrease Tuesday with possible gusty winds. Drier weather and warmer temperatures return Wednesday. && .FGZ WATCHES/WARNINGS/ADVISORIES...Flash Flood Watch from 11 PM MST this evening through Sunday afternoon FOR AZZ016-018. Flash Flood Watch from 8 PM MST this evening through Sunday afternoon FOR AZZ008-015-037-038. && PUBLIC...MCT AVIATION...NL FIRE WEATHER...NL For Northern Arizona weather information visit weather.gov/flagstaff
The Cedar City radar (KICX), 144 km away, was scanning. The volume nearest the first event began at 23:28 UTC.
1 flash flood. Local standard time, as filed.
The police in the Village of Supai reported a 3 foot rise in Havasu Creek at 430 PM MST. The river gauge on Havasu Creek near the Colorado River (at least 10 miles downstream) showed a 2 foot rise at 545 PM MST.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Arizona in 2018Every state in 2018This day in weather historyWarnings in Arizona, October 2018
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-30. Each event’s entry at NCEI: 789971.