NOAAs National Weather Service Flood and Flash Flood

NOAA’s National Weather Service Flood and Flash Flood Warning Program Michelle Schmidt Western Region Hydrology and Climate Services Division

Outline • • • Mission of the NWS Hydrology Program Impacts of floods in the United States Field Structure for the Hydrology Program Watches and Warnings Floods versus Flash Floods Improving the hydrology program

Mission of NWS Hydrologic Services Program • Provide river and flood forecasts and warnings for the protection of lives and property. • Provide basic hydrologic forecast information for the nation’s environmental and economic well being.

Impacts of Natural Disasters United States of America Average Annual Deaths (1990 -99): 502 14 99 Flood 193 55 Heat Flood Hurricane 57 Winter Storm 58 26 Lightning Average Annual Damages (1990 -99): $13. 1 Billion Hail $4. 97 Hurricane $5. 60 Tornado Flood 4. 4 $0 $0. 6 $0. 06 9 Cold $0. 47 $0. 87 $0. 03 Heat

National Weather Service Hydrology Program • • • Flash Flood Program Flood Forecasting Snowmelt Forecasting Water Supply Forecasting Dam Break Support

Hydrology Program Field Office Support Services provided through collaborative efforts of National Centers, River Forecast Centers (RFCs), and Weather Forecast Offices (WFOs) Hydrometeorological Prediction Center (HPC) Camp Springs, MD Storm Prediction Center (SPC) Norman, OK

NWS Products Watches and Warnings • Flood Watch • Inform the public of conditions which may cause flooding - flooding is not certain or imminent • Possible flooding in the next 36 hours • Alert decision makers to pay closer attention and position resources

NWS Products Watches and Warnings • Flash Flood and Flood Warnings • Flooding is imminent • Provide advance notification of flood events which require immediate action to protect lives and property • Allow customers and partners to take immediate mitigation actions such as evacuation to higher ground

Floods versus Flash Floods Different Events Different program Different tools • River Flood • River rises to flood stage over many hours or days (6 hours or more) • Longer lasting events • Hydrologic event • Flash Flood • Quick responding streams and rivers – 6 hours or less after the heavy rain started • Meteorological event

Floods River Flood Program

Spring snowmelt flooding Heavy rain flooding

Flood Warning Mission 1. National Center: Prediction Center Hydrometeorological http: //www. hpc. ncep. noaa. gov/ Quantitative Precipitation Forecasts Temperature Forecasts

Flood Warning Mission 2. River Forecast Centers (RFCs) • • • Calibrate, maintain and run hydrologic model – NWSRFS Produce hydrologic forecasts Provide the forecasts to the Weather Forecast Offices (WFOs)

River Forecast Center Tools

Flood Warning Mission 3. Weather Forecast Offices (WFOs) • Customer outreach • Field work to keep information up to date (flood stage, impacts, etc. . ) • Monitor situation • Issue flood watches and warnings based on forecasts from the River Forecast Centers

Operational Tools at the WFO WHFS – components • Viewing • Editor - Quality control • Database • Product maker

UTC 043 -250400 FLOOD WARNING NATIONAL WEATHER SERVICE SALT LAKE CITY UT 115 PM MDT TUE MAY 24 2005. . . RIVER FLOOD WARNING FOR THE UPPER WEBER RIVER UNTIL FURTHER NOTICE. . THE NATIONAL WEATHER SERVICE IN SALT LAKE CITY HAS ISSUED A RIVER FLOOD WARNING FOR THE UPPER WEBER RIVER FROM THE OUTLET OF SMITH MOREHOUSE RESERVOIR TO ROCKPORT RESERVOIR. THIS WARNING IS IN EFFECT UNTIL FURTHER NOTICE. THE LATEST STAGE FOR THE WEBER RIVER NEAR OAKLEY IS 4. 3 FEET AT 12 PM TUESDAY. MINOR FLOODING IS FORECASTED. . . WITH A MAXIMUM STAGE OF 4. 5 FEET AT 6 AM WEDNESDAY. . . WHICH IS EQUAL TO THE FLOOD STAGE. THE RIVER IS FORECAST TO CONTINUALLY RISE THROUGH SUNDAY. . . MAY 29 TH. FLOODING IS EXPECTED TO IMPACT STRUCTURES ADJACENT TO THE RIVER BELOW SMITH MOREHOUSE RESERVOIR TO ROCKPORT RESERVOIR. THESE WATERS ARE VERY COLD. . . FAST. . . AND DANGEROUS. PLEASE USE CAUTION WHEN RECREATING NEAR THESE WATERS. ALSO. . . PLEASE MONITOR ANY CHILDREN WHO MAY VENTURE TOO CLOSE TO THESE RIVERS AND STREAMS. STAY TUNED TO NOAA WEATHER RADIO. . . YOUR FAVORITE LOCAL MEDIA SOURCE. . . OR ON THE INTERNET AT WEATHER. GOV FOR THE LATEST HYDROLOGIC INFORMATION.

Advanced Hydrologic Prediction Services – AHPS Improving Hydrologic Services • Improving dissemination • • More graphics More standard formats Better use of the Internet User friendly

http: //www. weather. gov/rivers_tab. php

Flash Flood Program

Flash Floods Driven by heavy rain Respond too quickly to be modeled in RFC hydrologic model Meteorologic event

Flash Flood Warning Program 1. National Centers • Storm Prediction Center heavy rain meso-scale discussion • Hydrometeorologic Prediction Center excessive rainfall product and quantitative precipitation product

Flash Flood Warning Program 2. River Forecast Centers (RFCs) - Flash Flood Guidance

Flash Flood Warning Program 3. Weather Forecast Offices (http: //weather. gov/ ) • Pre-event partner/customer outreach and education • Hydrometeorological monitoring and threat assessment • Issuance of Flash Flood Watches and Warnings

Advanced Hydrologic Prediction Services - AHPS Improving Hydrologic Services • Flash Flood Monitoring and Prediction – FFMP • Continuous monitoring of rainfall rates and accumulations compared to flash flood guidance for high resolution basins • Automated alerts when dangerous flash flood situations may be developing • Distributed to the Weather Forecast Offices in 2002

Flash Flood Monitoring and Prediction FFMP Data Integration

Flash Flood Monitoring and Prediction Mapping Radar Bins to a Basin 2130 – 2135 UTC Rainfall (in/hr) . 16 . 30 . 38 . 29 . 14 . 24 . 39 . 41 . 37 . 20 ed h s ter ary a W nd u o B o Grid size 1 x 1 km

Flash Flood Monitoring and Prediction County Precipitation Accumulation • Displays precipitation for the basin in the county that has highest accumulation FFMP 1. 0 Hour Basin Avg Precip

Flash Flood Monitoring and Prediction Basin Precipitation Accumulation • Displays basin precipitation within the selected county FFMP 1. 0 Hour Basin Avg Precip

Summary • National Weather Service mission is to save lives and property • National, regional and local offices work together to carry out this mission • Weather Forecast Offices issue watches and warning to the public • Continuously improving our services

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