Model Verification of Short Range High Impact Weather in Central Florida Christopher Hicks

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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


  • Motivations

  • Objectives

  • Methods

  • Background Info

    • The NAM-218 model
    • The weather stations
  • Results Analysis

  • Summary

  • Questions


  • The predictability of current operational models need to be evaluated.

  • To figure out the difference of inland and coastal forecasts in the model.

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.


  • 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.


  • 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.

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).

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)

Weather Stations Map

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.

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.

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.

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.

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.

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.

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.

Precipitation for Orlando

  • 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.


  • 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.


  • NOAA National Operational Model Archive & Distribution System (2007)

  • Wikipedia (2007) North American Mesoscale Model.

  • Weather Underground (2007) History.

  • Google (2007) Google Earth.

  • University of Utah Department of Meteorolgoy (2007) MesoWest Data


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