Northeast Montana received record snowfall with extremely high water content during the winter of 2003-04. Glasgow, Montana measured about 175 cm (70 in), more than double the seasonal average snowfall (89 cm; 35 in); surpassing the previous record of 154 cm (60.9 in) during the winter of 1951-52. The spring of 1952 recorded the highest river stage reading on the Milk River at Glasgow (10.03 m; 32.9 ft).

An analysis of previous winters indicated a 95% chance of reaching flood stage in spring when total snowfall equaled or surpassed 114 cm (45 in). Given record snowfall on the ground by the end of January, the staff at NOAA’s National Weather Service Forecast Office in Glasgow, Montana, community leaders, and residents along the Milk River began preparing for potential major flooding.

In mid-February, the Missouri Basin River Forecast Center issued a spring outlook with a potential crest in Glasgow of 9.75 m (32 ft). A number of factors, including extensive snow water equivalent measurements were used in the model simulation resulting in this prediction. In fact, the river crested at just under 8 m (25.6 ft), slightly above flood stage (7.62 m; 25 ft).

This paper will examine all factors leading to the outlook, including parameters such as soil conditions, temperature and precipitation forecasts, snow water equivalent measurements, and upstream conditions. Multiple river model simulations will be presented to illustrate likely factors leading to lower than predicted crests on the Milk River during the spring 2004 melt.