Medium Range Forecast Exercise for Tallahassee, Florida: A Prototype for Forecasting Along the Gulf Coast in Fall

Research Associate, Department of Meteorology, Florida State University
Professor Emeritus, Department of Earth Sciences, Millersville University of PA

Andrew I. Watson

Science and Operations Officer, National Weather Service Forecast Office Tallahassee, FL

Credits:

The development of this tutorial was funded by the COMET Outreach Program as a Partners Project between Professor T. N. Krishnamurti of the Florida State University, and the National Weather Service Forecast Office in Tallahassee, Florida. The tutorial was created through the partnership of Dr. Robert S. Ross and Mr. Andrew I Watson.

Introduction

Goals

Part I. To have the forecaster make a day-5 forecast, valid on 28 October 2003, for Tallahassee, Florida (TLH) based on examination of available forecast guidance at the initial time of 0000 UTC 23 October 2003. Forecast will include maximum and minimum temperature, cloud cover, probability and amount of precipitation.

Part II. To provide the forecaster with the opportunity to revise his/her day-5 forecast based on inspection of model initializations for 28 October 2003, which serve as a verification of the model forecasts from 23 October 2003.

Part III. To have the forecaster compare the objective guidance and his/her own forecast to the observed weather at Tallahassee (TLH) on 28 October 2003 and then write a short essay giving reasons for any discrepancies.

Background

During the transition seasons of fall and spring, numerical weather prediction (NWP) models are likely to exhibit their largest errors, as the atmosphere undergoes significant adjustments to the rapidly changing patterns of heating and cooling. Objective guidance based on these models, such as Model Output Statistics (MOS), can correspondingly show significant errors. A medium range forecast (3-5 day) during October for a city along the Gulf coast, such as Tallahassee, is influenced by the prevailing long wave pattern, the progression of short waves in the westerlies, and by the possible input of moisture from a late season tropical system in the Gulf of Mexico, or even the eastern Pacific. Forecasters must use the available objective guidance in combination with their own understanding of synoptic meteorology and an awareness of climatology in order to make a successful forecast.