To Forecast or Not: LIFR (Limited Instrument Flight Rules) or IFR (Instrument Flight Rules). Forecasting Fog/Stratus 20-21 October 2005

摘要

All forecasters can forecast low clouds, especially when environmental and computer models are suggesting such conditions. However, what is more difficult is forecasting whether the conditions will be LIFR (limited instrument flight rules) or IFR (instrument flight rules). Table one breaks down the definitions of flight condition categories. Local office verification of aviation forecasts has shown over the last several years that LIFR flight conditions are forecast well during the first six hours of the aviation aerodrome terminal forecasts, or TAFs. However, the ability of forecasters to accurately forecast IFR has proven more elusive. This need to improve the IFR forecasts has been further motivated by GPRA goals recommended by the National Weather Service headquarters. In short, forecasters need to better forecast when conditions will be predominantly IFR or LIFR.