Temperature forecast opportunities across the NWS Southern Region

As the skill of the guidance from numerical weather prediction models continues to improve, the role of National Weather Service forecaster is evolving from primarily producing forecasts to interpreting the forecasts for its core partners. Nevertheless, there remains a fraction of days for which the forecaster can add substantial value to the numerical guidance. The purpose of this study was to identify the number of Forecast Opportunities, days for which the maximum and/or minimum temperature guidance is in error by ten or more Fahrenheit degrees. We compared the forecast daily maximum and minimum temperatures from the extended Global Forecast System-based Model Output Statistics for 32 sites in the National Weather Service Southern Region to the observed temperatures for the period January 2007-May 2009. Forecast Opportunities typically occurred as frequently as 15-20% of the time during the cold half of the year, but were much less frequent, or even absent, during the summer. To put those values in context, a frequency of 15% suggests one day out of a seven day forecast would be a Forecast Opportunity. Forecast Opportunities occurred most often for Days Three through Six, indicating forecasters should not focus their efforts on the short-term only. For most sites, the number of Forecast Opportunities increased from 2007-2009; research to date has not provided a clear explanation for that increase.