Development of a probability equation for winter-type precipitation patterns in Great Falls, Montana

Four parameters known to be reliable predictors of winter-type precipitation patterns (Oct-Mar) at Great Falls, Montana, are analyzed independently and then integrated into a probability of measurable precipitation equation. Five hundred fifty-one (551) cases are studied involving surface and upper-air data. The occurrence of precipitation at Great Falls, Montana, is strongly dependent upon the development of upslope conditions along the east slopes of the Rocky Mountains in Montana. Successive graphical regression analysis is first used to show the strength of the four parameters collectively. A probability equation is then developed by a linear regression program. The derived equation is compared with the Model Output Statistics and is shown to have practical value as a forecast tool. Kenneth B. Mielke. Includes bibliographical references (page 7). 1978 NWS (National Weather Service) WR (Western Region) Library Public Domain 1931