Diurnal Variations in Precipitation and Thunderstorm Frequency over the Conterminous United States

• DOI: 10.1175/1520-0493(1975)103<0406:dvipat>2.0.co;2
• Publication Date: 2002-07-27T12:23:59Z
• Authors: J. M. Wallace
• Keywords: Diurnal cycle; Sunrise; Diurnal temperature variation

Hourly data on the frequencies of all types precipitation events, heavy trace events and thunderstorms for more than 100 stations in United States were processed to generate statistics amplitude phase diurnal semidiurnal cycles at each station. Results are displayed seasonal maps a vectorial format that emphasizes large scale geographical consistency variations. During summer four parameters listed above displays distinctive pattern Thunderstorm frequency tends be most strongly modulated by cycle; least modulated. Over central maximum severe convective storms occurs during early evening; exhibit their around midnight, while falls later night. These differences offer some insight into relative importance thermodynamical dynamical processes controlling intensity activity. winter biased toward nighttime over much midwest Atlantic seaboard. Trace exhibits small but geographically consistent oscillation with peak near or slightly after sunrise. It is suggested this morning associated from low stratus decks. The cycle generally smaller diurnal. Effects S2 pressure wave clearly evident tropics, middle latitudes they often obscured regional local influences.