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  Scatterplot
  Error Distribution
  Sample Size
    By Year
    By Leadtime
  Mean Absolute Error
    By Year
    By Leadtime
  Mean Error
    By Year
    By Leadtime
  RMSE Skill Score
    By Year
    By Leadtime
  Pearson's Correlation
    By Year
    By Leadtime
  Probability of Detection
    By Year
    By Leadtime
  Hydrologic False Alarm Rate
    By Year
    By Leadtime
 
  RFC Milestones

River Forecast Verification - LUSN1

Lincoln%2C+NE - Salt+Creek

LUSN1 is a Flood Only Forecast Point

Scatterplot of Data




Scatterplot

The scatterplot view gives a general overview of the forecast and observed data. Under forecasting is indicated blow the diagonal while over forecasting is above the diagonal. Ideally, the closer the values to the diagonal, the better the forecasts.



Scatterplots Day 1 thru Day 5: These scatterplots are using the 12z data pairs only.

Day 1

Day 2

Day 3


Day 4

Day 5



Forecast Error Distribution




Forecast Error Distribution

The information in this section provides the user with an idea of the quality of a forecast based on the forecast error and bias of past forecasts. Three pieces of information are proved 1) forecast quality pie chart, 2) a summary of forecast error data, and 3) a forecast error distribution bar chart. The pie chart gives a qualitative general overview of the forecast quality. The summary table provides information on forecast skill, based on the size of the errors and how often forecast falls with in a range. The forecast error distribution bar chart shows the under- and over-forecasting basis. Ideally, one would want the forecast errors to always fall within the +/- 0.5 range.




Sample Size




Sample Size

The sample size displays the number of forecast-observed pairs used in the verification calculations.




Mean Absolute Error



Mean Absolute Error

Mean Absolute Error is the average error between the absolute value of the forecast and observed value for each pair. The closer the value is to zero, the better the forecast.



Mean Error



Mean Error

Mean Error is the average error between the forecast and observed value for each pair. The closer the value is to zero, the better the forecast.



RMSE Skill Score



Root Mean Squared Error Skill Score

The RMSE skill score is computed as a comparison to a persistance forecast. A persistence forecast is a forecast that takes the most recent observed value and extends to forecast out at that value. A value of 1 implies perfect skill, while a value of 0 implies no additional skill over a persistence forecast. Any value greater than zero shows an improvement over persistence. Any value less than zero shows that the forecast is worse than persistence.



Pearson's Correlation



Pearson's Correlation

Pearson's Correlation is the covariance of the forecasts and observations divided by the product of their individual standard deviations. A value of one is ideal.



Probability of Detection



Probability of Detection

The probability of detection displays the probability that given an observed value in a category (greater than flood stage in this case), that the forecast value also falls in that category. A value of 1 depicts that 100% of the time the forecast and observed values will fall in the same category and is the most desired.



Hydrologic False Alarm Rate



Hydrologic
False Alarm Rate

The hydrologic false alarm rate displays the probability that, given a forecast value within a category (greater than flood stage in this case), that the observed value is below that category. A value of 0 is ideal and depicts that a forecast is never issued above flood stage that the observed is not above flood stage.




Noteable River Forecast Center Milestones

QPF Usage

1983 - July 1996No QPF included in the Model.
July 1996 - July 200124 hour QPF included in the Model.
July 2001 - May 2009April 1 - September 30 : 12 hour QPF included in the Model.
October 1 - March 31 : 24 hour QPF included in the Model.
June 2009 - March 201524 hour QPF included in the Model.
April 2015 - PresentApril 1 - September 30 : 24 hour QPF included in the Model
October 1 - March 31 : 48 hour QPF included in the Model

River Model Used

Mid 1960s - October 1994RIVALL (API/AI - Event Oriented Model)
November 1994 - January 1997NWSRFS (API/AI - Event Oriented Model)
February 1997 - November 2011NWSRFS (SAC-SMA - Conceptual Model)
December 2011 - PresentCHPS/FEWS (SAC-SMA - Conceptual Model)

River Model Timesteps

1982 - 1997Model locations calculated on a 6, 12, or 24 hour time step.
January 1998 - May 2010All model segments switched to calculate on a 6 hour time step.
May 2010 - PresentSeveral Lower Missouri Tributary locations switched to a 1 hour time step.
All other locations remain on a 6 hour time step.

River Forecast Issuance

1982 - 19971 Value per day forecast (24 hour time step); 3 day forecast.
January 1998 - May 20104 Forecast Values per day (6 hour time step) 5 Day forecast.
May 2010 - Present6 hour segments - 4 Forecast Values per day; 5 day forecast.
1 hour Segments - 24 Forecast Values per day; 3 day forecast.