AAVSO: American Association of Variable Star Observers

Clear-sky Forecasting for Variable Star Observers (Abstract)

Volume 45 number 1 (2017)

Frank Dempsey
RR #1, 3285 Sideline 20, Locust Hill, ON L0H 1J0, Canada; cosmicfrank99@gmail.com

Abstract

(Abstract only) Many amateur astronomers seem to rely on computer model-generated weather forecasts for clear sky predictions and get frustrated by imperfect forecasts. It is worthwhile to consider the shortcomings of computer model forecasts and look at some resources to help the variable star observer plan for clear skies, whether for visual observers wanting to get an observation of a particular target star in long-term light curve programs, multi-hour observations of short-period pulsating variables or eclipsing binaries, or photometry. I discuss difficult-to-forecast factors including low clouds caused by local terrain and topographic effects, persistent low-level stratocumulus during the cold season, fog, post-cold front dry intrusions, pre-warm front waves of clouds, gradual sinking and clearing of cloud layers, jetstream-level cirrus, debris clouds persisting from upwind thunderstorms and distant thunderstorm complexes, large-scale blocking patterns, and other situations to hopefully help the variable star observer to make optimum use of limited time under clear skies.