An empirical model for forecasting solar wind speed related geomagnetic events is presented here .
The model is based on the estimated location and size of solar coronal holes .
This method differs from models that are based on photospheric magnetograms ( e.g. , Wang-Sheeley model ) to estimate the open field line configuration .
Rather than requiring the use of a full magnetic synoptic map , the method presented here can be used to forecast solar wind velocities and magnetic polarity from a single coronal hole image , along with a single magnetic full-disk image .
The coronal hole parameters used in this study are estimated with Kitt Peak Vacuum Telescope He I 1083 nm spectrograms and photospheric magnetograms .
Solar wind and coronal hole data for the period between May 1992 and September 2003 are investigated .
The new model is found to be accurate to within 10 \% of observed solar wind measurements for its best one-month periods , and it has a linear correlation coefficient of \sim 0.38 for the full 11 years studied .
Using a single estimated coronal hole map , the model can forecast the Earth directed solar wind velocity up to 8.5 days in advance .
In addition , this method can be used with any source of coronal hole area and location data .