1. Model Verification of Short Range High Impact Weather in Central Florida Christopher Hicks Department of Marine and Environmental Systems Florida Institute of Technology Melbourne, Florida 32901 July 18th, 2007

2. Outline • Motivations • Objectives • Methods • Background Info • The NAM-218 model • The weather stations • Results Analysis • Temperature Comparison • Precipitation Comparison • Summary • Questions

3. Motivations • The predictability of current operational models need to be evaluated. • To figure out the difference of inland and coastal forecasts in the model.

4. Why Forecast Models Are Used? • Models are able to provide guidance for weather forecasters. • There’s also less chance of error in the calculations of forecast models. • With supercomputers, running forecast models can take a very short time.

5. Objectives • The North American Mesoscale (NAM-218) model’s ability to predict high impact weather in Central Florida. • Compare model data to observed weather data around Central Florida. • Discover how well the NAM-218 model is able to predict temperature and precipitation. • Examine whether the model is better at predicting weather events along coastal regions or inland regions of Florida.

6. Methods • Collected archive data from NOAA’s National Operational Model Archive & Distribution Systems (NOMADS) site. • The forecast model that was used is the 12 UTC (8:00 AM EDT) run on June 18, 2007 which goes out to 8:00 PM EDT on June 21, 2007. • Total 84-hour forecast with 3-hour interval was used to compare to the observed data that was collected.

7. The North American Mesoscale Model (NAM-218) • The NAM-218 is a forecast model that is widely used here in the United States. • Uses a grid forecasting model with a resolution of 12 km (7.5 miles) which makes it one the highest resolution models used in the United States. • Run by the National Centers for Environmental Prediction. • Makes an 84 hour forecast 4 times a day (00, 06, 12, 18 UTC).

8. Weather Stations Used in Project • Weather stations set up by Florida Tech: • Satellite High School (Satellite Beach, FL) • Harmony High School (Harmony, FL) • Deseret Ranch (Rural Eastern Osceola County) • Fay Park (Port St. John, FL) • Permanent weather stations: • Vero Beach, FL (KVRB) • Orlando, FL (KMCO) Deseret Ranch Weather Station (Picture courtesy of Kate Howard)

9. Weather Stations Map

10. Temperature at Satellite High • Satellite High is less than a mile from shoreline. • The NAM forecast is slightly cooler than observed by about 2 to 3 degrees for the first 48 hours.

11. Temperature at Vero Beach • Vero Beach is a little farther inland than Satellite High but still close to the shoreline. • Difference between forecast and observed is about 2 degrees for the daily high and about 7 degrees for the overnight low in the first 24 hours.

12. Temperature at Harmony High • Temperature forecast for Harmony High improves in the early part of the forecast window compared to both Satellite High and Vero Beach. • Forecasted diurnal high for the 19th is off by only 1 degree. • Accuracy of model still degrades the farther into the future it goes.

13. Temperature at Orlando • The model’s forecast for Orlando becomes even more better than Harmony High School. • Forecast is only off by a degree or less in the first 48 hours. • In this case, the data supports the idea that model forecasts for temperature improves as farther inland you go.

14. Precipitation at Satellite High • Precipitation that occurs on the 20th is underestimated by .6 inches. • The model predicted the rain event occurring approximately 6 hours earlier than the observed.

15. Precipitation at Vero Beach • Precipitation for the 20th only off by about a tenth of an inch. • However the forecast model predicted later than what was observed, instead of earlier.

16. Precipitation at Harmony High • Forecast is very close to two of the three forecast day that have rain. • After 48 hours, timing of the rain events degrades.

17. Precipitation for Orlando 0.02 inches observed • Forecast for Orlando was off by over 2.5 inches for the 20th of June. • Observed precipitation levels for Orlando significantly lower than other three weather stations. • Overall, it’s possible that the model misinterpreted where the thunderstorm convection would go and how fast it moved.

18. Summary • In this case, the model is able to predict temperature for inland area much better than coastlines. • Precipitation is still misinterpreted for all regions no matter how close to the coast the weather station is. • Precipitation forecasts can be improved once thunderstorm development can be well simulated for the region. • According to this case, the NAM-218 is good for short range (0-48 hours) forecasts in the Central Florida region.

19. References • NOAA National Operational Model Archive & Distribution System (2007) http://nomads.ncdc.noaa.gov/data/meso-eta-hi/200706/20070618/ • Wikipedia (2007) North American Mesoscale Model. http://en.wikipedia.org/wiki/North_American_Mesoscale_Model • Weather Underground (2007) History. http://www.wunderground.com/history/airport/KVRB/2007/6/18/DailyHistory.html • Google (2007) Google Earth. http://earth.google.com • University of Utah Department of Meteorolgoy (2007) MesoWest Data http://www.met.utah.edu/mesowest/

20. Questions?