Building a Weather-Ready Nation

National Weather Service

Warnings for Flash Floods and Debris Flows

Alex Tardy - Meteorologist

Weather.Gov

Building a Weather-Ready Nation

Warning Notification

Flash Flood Watch – potential for heavy rain exceeding thresholds today or tonight

Flash Flood Warning – heavy rain is occurring or imminent and flooding is expected along with possible debris flow for “defined area”

Threshold for rainfall (rate per hour) would be met and burn scar would be mentioned in Flash Flood Warning if affected

W th /S Di

FEMA alert app

Building a Weather-Ready Nation

Wireless emergency alertsTV and radio EAS alerts

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Wireless Emergency Alert in polygonNWS Warning polygon

Building a Weather-Ready Nation

Monitoring weatherfrom the Emergency Operations

Center and NWS

NWS San Diego

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Rain showers on Weather RadarShowers came in late Wednesday evening

October 3 (Orange County)

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Rainfall from Showers

Building a Weather-Ready Nation

https://www.wrh.noaa.gov/sgx/kml/holyfire.php

Building a Weather-Ready Nation

Flash Floods and Debris FlowsNational Weather Service

Building a Weather-Ready Nation

Burn assessmentCranston Fire Scar

USGS and USFS report

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Monsoon thunderstormRainfall can be localized

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Radar estimated (no gauges)Rainfall Distribution

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Basin level for each drainageFlash Flood monitoring

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Force and depth of flash flood debris flow

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Atmospheric River

Jet Stream

highest moisture in yellow and red

BIG storms

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Rainfall is widespread but localized heavyWinter Storm

This type of “embedded rainfall” can cause high rain rates and debris flows

Building a Weather-Ready Nation

Partnering with CaltransTADD program

http://www.nws.noaa.gov/os/water/tadd/

Weather.Gov