# Presentation: 503937

## Flash FloodMonitoring and Prediction(FFMP)  

**John Ferree**
**Warning Decision Training Branch**
**Norman, OK**

- Severe Weather/Flash Flood WDM
- July 9-12, 2002

##  Quote

## Overview

**FFMP – How?, What?, When?, and Why?**
**FFMP 2.0 Products**
**FFMP 2.0 Limitations and Operational Use**

**Notes:**
1. A review of the findings of recent work teams looking at warning improvement,and some specifics on the near future of warning science and technology. 
2. Some potential uses of the Weather Event Simulator. 
3. What can WDTB do to make your life simpler?
4. Can we learning anything with one single headed simulator, on single headed facilitator, and 32 SOOs?   

## Flash Flood Lead Times

**GPRA Information**
- _[http://205.156.54.206/](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[ost](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[/](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[nws](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[_](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[sci](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[_needs_final_02_20_02.](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[pdf](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)_

**Notes:**
These are the new goals as recently amended by the NWS Corporate Board. Note the goals are meant to be challenging yet achievable. Note that in Tornado Lead Time we are being asked to substantially outperform what we have done in recent years! 

## Flash Flood Accuracy (POD)

**GPRA Information**
- _[http://205.156.54.206/](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[ost](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[/](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[nws](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[_](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[sci](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[_needs_final_02_20_02.](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)__[pdf](http://205.156.54.206/ost/nws_sci_needs_final_02_20_02.pdf)_

**Notes:**
We are also going to shoot for a lower FAR than the current trend, but at least this is reasonable as compared to the 0.40 goal published in VISION 2005.

## PBZ Flash Flood Verification

**Flash Flood Monitoring and Prediction (FFMP) algorithm is based on the Areal Mean Basin Estimated Rainfall (AMBER)**
***Bob Davis***
**Pittsburgh, PA WFO**
***Paul Jendrowski***
**Blackburg, VA WFO**

**AMBER operational since May 1996**

##  FFMP Overview

**Continuous monitoring of ****rainfall rate**** and its ****comparison**** ****to flash flood guidance**** (FFG) for high resolution stream basins.**
**Automated alerts**** when a dangerous flood situation may be developing on a given stream or catchment. **

**Flash Flood Monitoring and Prediction In AWIPS Build 5 and Beyond**
**	****- Smith et al 2000, ***Preprints 15**th** **	**Conference on Hydrology, AMS*

## FFMP Benefits

**Longer lead times**
**Fewer missed events**
**Increased forecaster situational awareness**
**Reduced forecaster fatigue**
**Focus for applied research**

**Flash Flood Monitoring and Prediction In AWIPS Build 5 and Beyond**
**	****- Smith et al 2000, ***Preprints 15**th** **	**Conference on Hydrology, AMS*

## FFMP 2.0 Basics

**AWIPS build 5.1.2 - using WSR-88D Digital Hybrid Scan Reflectivity (DHR) **
**All basins (>2 mi****2****) in county warning area are pre-defined**
**Basin rainfall rate (in/hr) is computed from the DHR on a basin level every volume scan **
**Accumulations (of various time scales) are compared to Flash Flood Guidance (FFG) on a county and basin scale**

## FFMP Outputs

**Graphic displays of:**
***Basin rainfall accumulation***
***Ratio of basin accumulations to FFG ***
***Accumulations – FFG (Difference) ***
***For time periods of from 30 minutes to 6 hours***
**Line graph of basin rainfall, basin rainfall rate, and FFG for the same time periods.**

## County Level Display of Basin Average Precipitation

**Displays the data value for the basin in the county that has the**** highest**** precipitation accumulation **

## Basin Average Precipitation

**Display of Basin level precipitation will only display those basins within the county selected.**

## Ratio County Precip. / FFG

**Ratio County Precip. / FFG**

**County level ratio values are calculated using the maximum ****basin**** precipitation in the county, divided by the ****county average**** FFG. **

## Ratio Basin Precip. / FFG

**Ratio Basin Precip. / FFG**

**Basin level ratio of precipitation accumulations divided by basin level FFG. **

## County Precip – FFG (Diff)

**County Precip – FFG (Diff)**

**County level difference values are calculated using the maximum basin precipitation in the county minus the ****county average**** FFG. **

## Basin Precip. - FFG (Diff)

**Basin Precip. - FFG (Diff)**

**Basin level 1 hour precipitation minus FFG**
**Note table duration is set at 1 hour, but graphic states 1.5 hour.****What happened here?**

## What’s Better?

**Ratio**

**Difference**

## FFMP Flash Flood Analysis

**Basin Trend Graph takes some getting used to.**** Where the ****accumulation (colored area) exceeds the FFG (purple line****) there is a threat of flash flooding. **

**Flash Flood Guidance**

- Rate

## Flash Flood Threat Index (FFTI)

**The color of the FFTI will represent the value of the chosen attribute over a chosen time period**
***Basin Accumulation***
***Ratio of accumulation to FFG***
***Difference between accumulation and FFG***
***Time Frame from 30 minutes to six hours***

## Flash Flood Threat Index (FFTI)

**White - ****Little or no activity**
**Green - ****Precipitation**
**Yellow - ****Moderate precipitation **
**Red - ****Heavy precipitation**** **
**Grey - ****Not functioning properly**

**FFTI Change GUI – left click on “FF” button**

## FFMP Limitations

**Delineated basins require customization**
**Mapping of basin to DHR critical to output**
**Requires knowledge of basins and stream flow from basin to basin**
**Radar limitations are masked**
**Flash Flood Guidance development processes inconsistent from RFC to RFC **

## FFMP 2.0 Basin Delineation

**National Basin Delineation Project**
***NSSL ***
**ArcInfo used to define the watershed boundaries**
**USGS 1 arc second (30 m) DEM data supplied by EROS Data Center**
**Continental U.S. completed June 2002.**

**www.nssl.noaa.gov/teams/western/basins**

## FFMP 2.0 Basin Delineation

**Basin Customization**
***COMET***
***3-day course ***
***Skills to identify, create, alter, and re-define high resolution basins delineated by NSSL***
***GIS skills and tools***

**http://www.comet.ucar.edu/class/basin_customization/index.htm**

## 229.5 km

**229.5 km**
**Range ring**

**NSSL Basins 18,488**
**Aggregated 12,784 **

**Aggregate:**
**Clip all basins beyond 230 km**
**Eliminate all segments < 2 mi****2**

## FFMP Basins

**FFMP Basins**
**5,608**

**NSSL CD**

**FFMP**

## FFMP Limitations

**Delineated basins require customization**
**Mapping of basin to DHR critical to output**
**Requires knowledge of basins and stream flow from basin to basin**
**Radar limitations are masked**
**Flash Flood Guidance development processes inconsistent from RFC to RFC **

## DHR to Rainfall Rate

**Digital Hybrid Reflectivity (DHR)**
***1 km (.54nm) x 1 degree***
***256 data levels***
***124 nm range ***
***Nearest  0.5 dBZ***
**FFMP processor****converts to rainfall rate**

## Conversion Rainfall Rate to Basin Rainfall Rate

- .41

- .38

- .39

- .37

- .29

- .14

- .20

- .30

- .16

- .24

- Grid size 1o x 1km

**Conversion Rainfall Rate to Basin Rainfall Rate**

**Watershed  Boundary**

## Conversion Rainfall Rate to Basin Rainfall Rate

- .29

- .29

- .29

- .29

- .29

- .29

- .29

- .29

- .29

- Grid size 1o x 1km

**Conversion Rainfall Rate to Basin Rainfall Rate**

**Watershed  Boundary**

- .29

## Conversion Rainfall Rate to Basin Rainfall Rate

- .41

- .38

- .39

- .37

- .29

- .14

- .20

- .30

- .16

- .24

**Conversion Rainfall Rate to Basin Rainfall Rate**

- If watershed is divided into segments

## Conversion Rainfall Rate to Basin Rainfall Rate

- .37

- .37

- .37

- .25

- .25

- .25

- .25

- .37

- .20

- .20

**Conversion Rainfall Rate to Basin Rainfall Rate**

**Large Variation in Rainfall Rate in Short Distance**

## FFMP Limitations

**Delineated basins require customization**
**Mapping of basin to DHR critical to output**
**Requires knowledge of basins and stream flow from basin to basin**
**Radar limitations are masked**
**Flash Flood Guidance development processes inconsistent from RFC to RFC **

## Basin to Basin Flow

**Basin to Basin Flow**

**     ****Flash Flood forecasting requires more than accurate forecasts of excessive accumulation.**

**Know your basins!    **

## FFMP Limitations

**Delineated basins require customization**
**Mapping of basin to DHR critical to output**
**Requires knowledge of basins and stream flow from basin to basin**
**Radar limitations are masked**
**Flash Flood Guidance development processes inconsistent from RFC to RFC **

## Basin Average Rainfall

**Basin may include**
***Several 1 km (.54nm) x 1 degree bins***
***One 1 km (.54nm) x 1 degree bin***
**Height of reflectivity used for calculation may be**
***Hundreds of feet ***
***Over 10,000 feet***

**DHR Grid Area vs. Radar Range**

## Radar Precipitation Estimates

**Recall limitations of radar precipitation estimates**
***Brightband contamination***
***Hail contamination***
***Inaccurate Z/R relationship***

**More difficult to identify bright band on FFMP than on precipitation products**

## FFMP Limitations

**Delineated basins require customization**
**Mapping of basin to DHR critical to output**
**Requires knowledge of basins and stream flow from basin to basin**
**Radar limitations are masked**
**Flash Flood Guidance development processes inconsistent from RFC to RFC **

## Flash Flood Guidance (FFG)

**RFC provided guidance on the basin rainfall accumulations over a specific time period (1, 3 hours) needed to initiate flooding on streams.**
**Assumes no rainfall since data cutoff.**

## Summary

**Flash Flood forecasting requires more than accurate forecasts of excessive accumulation.**
***Know your basins!***
**Radar estimates of rainfall accumulations may be inaccurate.**
***Keep radar limitations in mind! ***
**Flash Flood Guidance does not take into account rainfall and associated soil saturation since data cutoff time.**

## Questions or Comments? 

**John.T.Ferree@noaa.gov**
**www.wdtb.noaa.gov**
**405-366-6560 ext 4266**