Past IEM Features tagged: mos

List all tags


MOS Forecasting

11 Oct 2016 05:34 AM
The featured chart displays the combination of MOS forecasts of morning low temperature and afternoon high temperature for Des Moines this month. Model Output Statistics (MOS) forecasts take raw weather forecast model output and using past forecasts with actual observations, attempt to provide a more accurate forecast. These forecasts are made four times per day, so the bars represent the range of values forecasted as the forecast is updated with time. It is interesting to note the cold weather forecasted for tomorrow, with the highs only in the mid 50s!

Voting:
Good: 10
Bad: 0
Abstain: 1

Tags:   mos  

December Forecasts

08 Dec 2014 05:41 AM
The featured chart displays the combination of Model Output Statistics (MOS) forecasts and observations for Des Moines this month. MOS forecasts take raw forecast model output and apply statistical models to it based on time series data from observation sites. The hope is to account for biases in the model by fitting the model output to the local observation data. These MOS forecasts come out multiple times per day with each forecast producing data for the next few days into the future. Combining these forecasts in time create ranges of forecasted values that are expressed by bars in this chart. The actual observations from the site are the dots. You can now generate these charts on demand on the IEM website!

Voting:
Good: 8
Bad: 9
Abstain: 6

Tags:   mos  

MOS Forecasts

25 Apr 2014 05:35 AM
Model Output Statistics (MOS) are point forecasts produced from combining raw numerical model output and statistics on past model performance. Over time as subsequent MOS forecasts are produced, these forecasts create a range of predicted values. The featured chart shows the range of the combined MOS forecasts over time and the actual observations from the Des Moines Airport. The MOS forecast range from the NAM model has missed the high temperature for the past two days and seven out of the past nine days. Even with this seemingly inaccuracy, the forecast for April 22 was very precise over time and accurate! Models are not perfect, so there is still plenty of room for humans to add value.

Voting:
Good: 48
Bad: 16
Abstain: 17

Tags:   mos  

Forecast Ranges

03 Dec 2013 05:38 AM
The forecast for the beginning of this week has been difficult to pin down as models have advertised wildly varying temperatures. The featured chart shows the range of forecasted daytime high temperature and overnight low temperature based on NAM Model Output Statistics (MOS) for Des Moines. The MOS output attempts to take raw numerical model output on a grid and tailor it for specific locations where observations are available. The range plotted is produced by looking at the various forecast model runs leading up to a day. The dots represent what actually happened. The forecast for today is shown as large bars, meaning the models have produced a wide range of values over time leading up to today. A more definite forecast is that it will get cold later this week, so enjoy whatever happens today!

Voting:
Good: 29
Bad: 9
Abstain: 7

Tags:   mos  

Missing MOS

16 Sep 2011 06:02 AM
Model Output Statistics (MOS) are produced by taking raw numerical forecast model output and comparing it with observations to produce hopefully bias corrected results. Some of the models were predicting very cold temperatures yesterday and actual reported lows ended up being a bit warmer than predicted. The featured chart looks at the range of predicted morning low and afternoon high temperatures by the NAM MOS data along with the actual observation from the Des Moines Airport sensor. This range is produced by looking at the various MOS output from the model runs for each forecast time.

Voting:
Good: 19
Bad: 9

Tags:   mos  

Computers aren't perfect

16 Dec 2010 05:49 AM
Each day, computerized forecast models attempt to predict the weather and produce a lot of numeric output. One application of this output is to apply statistics to these values and attempt to produce more accurate forecasts (called Model Output Statistics [MOS]). The featured chart presents the range of MOS forecasts of daytime high and overnight low temperature for Des Moines from the GFS model along with the actual observations. In general, you can see that the MOS is by no means perfect, so there is currently room for humans to hopefully improve the process.

Voting:
Good: 29
Bad: 5

Tags:   mos