Flood
Categories |
Minor
- Some public inconvenience, but minimal or no property damage
likely. |
![](images/transparent.gif) |
Moderate
- Closure of secondary roads. Transfer to higher elevation may
be necessary to save property. Some evacuations may be required. |
![](images/transparent.gif) |
Major
- Extensive inundation and property damage. Usually characterized
by the evacuation of people and livestock and the closure of
primary and secondary roads |
![](images/transparent.gif) |
Record
- The highest observed River stage or discharge at a given site
during the period of record keeping. |
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Categorical
Flood Forecast Verification System - Cumulative River Forecast Center
Verification Statistics
1st Quarter (Oct 2008 - Dec 2008) FY2009 |
![](images/transparent.gif) |
![Average Lead Times](images/fy09_qtr1/sr/leadtimes_tn.gif) |
Average
Lead Time
A categorical lead time is the number of hours from
the time of forecast issuance to the time of the forecast hit. A lead
time is only computed when, (1) the ordinate�s forecast and observation
are in the same category, and (2) the previous ordinate�s observation
was lower than the current category. This restricts lead time calculations
to instances where the stage is rising, and crossing categories. |
|
Average
Categorical Errors
This is the amount the forecast would have to be changed
to reach the observed category. Categorical error is only computed
when you have a miss. |
![Average Categorical Errors](images/fy09_qtr1/sr/aveerror_tn.gif) |
|
![Average Lead Times](images/fy09_qtr1/sr/events_tn.gif) |
Number
Of Events
The number of events during the quarter for each flood
category. |
False
Alarm Ratio (FAR)
The number of missed categorical flood forecasts divided
by the total number of categorical flood forecasts issued.
FAR = (False Alarms / (False Alarms + Hits) ) {0.00 is best} |
Day
1 |
Day
2 |
Day
3 |
![False Alarm Ratio Day 1](images/fy09_qtr1/sr/farday1_tn.gif) |
![False Alarm Ratio Day 2](images/fy09_qtr1/sr/farday2_tn.gif) |
![False Alarm Ratio Day 3](images/fy09_qtr1/sr/farday3_tn.gif) |
Probability
of Detection (POD)
The number of categorical flood forecast hits divided
by the total number of categorical flood forecasts observed.
POD = (Hits / (Hits + Misses + No Forecast Misses) ) {1.00 is best}
|
Day
1 |
Day
2 |
Day
3 |
![False Alarm Ratio Day 1](images/fy09_qtr1/sr/podday1_tn.gif) |
![False Alarm Ratio Day 2](images/fy09_qtr1/sr/podday2_tn.gif) |
![False Alarm Ratio Day 3](images/fy09_qtr1/sr/podday3_tn.gif) |
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