December 12th, 2012
SCORING STORMSOptimize Mobility, Zero Crashes, Injuries and Fatalities, by Catherine Higgins.
UDOT is developing a way to rate storm severity in order to make better use of resources.
Managing resources during winter months in a state that experiences extreme to mild weather conditions can be challenging. Researchers working with UDOT are investigating a method to define the severity of storms and seasons by using a winter severity index to assign numerical value that represents storm characteristics like intensity and duration. Rating storms will help the UDOT Maintenance Division evaluate the allocation of resources like staffing, de-icing chemicals and equipment.
A number of Midwestern states and provinces in Canada have developed weather severity indexes. While examining how those indexes were developed is useful, those models consider region-specific terrain and weather patterns. For example, some states have indexes that take freezing rain into account; freezing rain is common in other parts of the country but rare in Utah.
Terrain plays a significant role in Utah’s climate, according to Jeff Williams, UDOT Weather Programs Manager. The mountain range that extends from Logan to St. George is a “spine” that divides Utah and acts as a climate barrier. Precipitation patterns differ widely from the east to the west side of the mountain range.
During winter, storms move in from the west. “When storms arrive from the west and meet the mountains, rising air leads to increased precipitation,” says Williams. Those storms cover the mountains with snow. Sinking air dries the area east of the mountains making winter the most arid time of year.
During summer, Monsoons that originate from the Gulf of Mexico bring warm moist air to Utah. Storms and sometimes floods occur east of the mountains while the mountains usually stay dry.
A Utah-specific weather severity index will help normalize the difference between locations and weather events. By comparing resource use from location to location, operations and maintenance managers will be able to improve the efficiency of snow fighting efforts.