Monday, 20 June 2005: 10:00 AM
North & Center Ballroom (Hilton DeSoto)
The Air Force's 45th Weather Squadron (45 WS) provides comprehensive meteorological services to operations at the Cape Canaveral Air Force Station (CCAFS) and Kennedy Space Center (KSC). Various low temperature weather warnings, watches, and advisories are the most frequently issued products during the winter at CCAFS/KSC. Actions must be taken to prevent damage due to cold air on exposed refrigerated surfaces when the temperature falls below established thresholds beginning as high as 15.6°C (60°F). The 45 WS issues four low temperature advisories: 1) 15.6°C (60°F) or less forecast to occur during a three day period, 2) 7.2°C (45°F) or less for 4 hours with a minimum notification time of 4 hours, 3) 4.4°C (40°F) or less with a minimum notification time of 4 hours, and 4) 0.0°C (32°F) or less for 4 hours with a minimum 16 hour notification time. The 45 WS has a locally developed temperature flowchart for forecasting temperatures below 15.6°C (60°F). This flowchart uses a first guess minimum temperature based on the 1000-500 HPa (1000-500 Mb) thickness with a series of correction factors for cloud cover, wind speed, wind direction, and the presence of a radiation inversion. This forecasting flowchart was based on subjective professional judgment based on many years of local experience.
The upgrade to this technique is a new first guess based on climatological analysis of local weather balloon and temperature observations, new and refined correction factors, and a Graphical Users Interface (GUI). The new first look uses the 1000-850 HPa (1000-850 Mb) thickness, which is more representative of the surface and boundary layer. In addition, it also now uses a climatologically based linear regression equation to predict the minimum temperature based on 27 years of local radiosonde balloon soundings and temperature observations. This regression equation explains 76% of the observed variance and provides an up to 5.6C (10°F) improvement over the previous first guess. The logic for the cloud cover and wind speed correction factors was enhanced. The previous correction factors for wind direction and radiation inversion were continued. New correction factors were added for low-level humidity from the local weather balloon, mid-level humidity from weather satellites, and local surface dewpoint. All the correction factors are being optimized based on past climatological observations. The entire process is now automated using a GUI on the 45 WS internal operational website. This eases the process for the forecasters, reduces potential errors, and increases the use of the tool. Plans for further improvements to the minimum temperature tool are being considered.
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