A STUDY OF THE DISTRIBUTION OF WEATHER ACCOMPANYING COLORADO CYCLOGENESIS¹

Abstract

The distribution of weather with 21 cyclones which formed in the lee of the Colorado Rockies during the winter and spring of 1959 through 1963 is studied. The relation of the probability and form of precipitation and severe weather to circulation patterns (and their derivatives) at the surface and 500 mb. is shown from 12 hr. before cyclogenesis to 48 hr. after cyclogenesis. It is concluded that the weather models derived by this procedure are a useful starting point for weather forecasting, given predictions of 500-mb. flow and vorticity, vertical velocity, and surface pressure pattern. 360~~ MONTHLY WEATHER REVIEW Vol. 93, No. 6

Statistical Differences of Quasigeostrophic Variables, Stability, and Moisture Profiles in North American Storm Tracks

“…The aforementioned reasons for the motion of the CVA maximum for the AB cyclones apply for the CO cyclones as well. In a paper by Fawcett and Saylor (1965), low-level relative vorticity maxima appeared well east of the surface cyclone, implying a westward tilt with the height of the cyclone, consistent with the results herein. CVA within the EC cyclone ( Fig.…”

On cyclogenesis in the lee of the Canadian Rocky Mountains

“…Bolin [3] and Reiter [23] show that the large mountain ranges of the Himalayas and the Rockies induce each a quasi-stationary long-wave trough --one at about 1300 E and another at 80~ If a broad belt of westerlies flows over a meridionatly extensive range of mountains, a long north to south trough can be found in the lee of the massif, frequently containing two cyclones. Fawcett and Saylor [7] studied the changes of weather patterns accompanying Colorado cyclones. By contrast, maritime cyclogenesis may begin under a straight upper current without appreciable vorticity advection in a strongly baroclinic region.…”

“…However, the doubling time may be also deduced from computations of the vorticity of sea-level cyclones, as was done by Hage [9], and Fawcett and Saylor [7]. The "doubling time was obtained from plots of intensity (V2p) versus time.…”

An Investigation of the Influence of Cyclonic Airstreams on Midwestern Snowfall

“…These studies were later expanded by Reitan (1974), Zishka and Smith (1980), and Whittaker and Horn (1981), who critically examined the cyclogenesis regions suggested by the earlier studies and investigated elements of cyclone trajectory and trends in cyclone frequency through time. Fawcett and Saylor (1965) and Goree and Younkin (1966) introduced synoptic climatological evidence for the significance of Colorado cyclones in severe weather and snowfall events by relating the position of the short wave in the middle troposphere to regions within the developing storm where snowfall or severe weather was likely. A study by Harman et al (1980) emphasized the importance of Colorado cyclones in the Great Lakes cold season climate, stating that southwestern systems were the most intense storms crossing the Lakes in all cold season months, particularly November.…”

“…A tmospheric scientists, particularly geographers, have long recognized the association of cyclone climatology to regional precipitation distribution (Fawcett and Saylor 1965;Goree and Younkin 1966;Jorgensen et al 1967;Whittaker and Horn 1981;Raphael and Mills 1996). However, most studies investigating these relationships are focused on cyclone trajectory and frequency characteristics and fail to address the role of cyclone airflow features in the generation of rain and snowfall.…”