WINTER SEASON

Winter Season forecasts for Michigan and/or the North Central US

Winter Season forecasts for Michigan and/or the North Central US

1st forecast Summary

The North Central United States has indeterminate chances of above-normal, near-normal, or below normal temperatures during the month of December; i.e. a 33% probability of any of the three categories occurring during the month. The reason for this large area of equal chances is because of some uncertainty in the southward extent of the colder than average conditions that are expected to develop across portions of southern Canada and the northwestern United States in association with La Nina conditions. Although a La Nina composite suggests a cold signal extends southward across the North Central United States, the statistical/dynamical tools that the CPC uses show an inconsistent signal. (Gershunov, 2010)

Most of the North Central United States has indeterminate chances of above-normal, near-normal and below-normal precipitation during December; or stated another way, a 33% chance of above-normal precipitation, a 33% chance of near-normal precipitation, and a 33% chance of below-normal precipitation relative to climatology. This forecast is due to lack of a consistent precipitation signal from statistical/dynamical tools the CPC utilizes. The exception will be over western North Dakota, where there will be an enhanced chance of above-normal precipitation; with a greater than 33% probability of above-normal precipitation, a 33% chance of near-normal precipitation, and a 27% to 33% chance of below-normal precipitation.

During the meteorological winter season, enhanced probabilities for below-normal temperatures are forecast for much of the North Central United States. The best chance of below-normal temperatures relative to climatology will occur over North Dakota and northern Minnesota, where there will be a greater than 40% chance of below-normal temperatures for December through February (with a 33% chance of near-normal temperatures, and a 17% to 27% of above-normal temperatures). Northern South Dakota and southern Minnesota will have a 33% to 40% chance of temperatures colder than normal relative to climatology (with a 33% chance of temperatures near normal, and a 27% to 33% chance of temperatures warmer than normal). To the south of this area, there are indeterminate chances of above-normal, near-normal, or below-normal temperatures over southern South Dakota, Nebraska, and Iowa. (Gershunov, 2010)

2nd forecast Summary

The majority of the North Central United States will have enhanced chances of above-normal precipitation for the meteorological winter season of December through February. There will be a 50% probability of above normal precipitation over western North Dakota and northwestern South Dakota (with a 33% chance of near-normal, and a 7% to 17% chance of below-normal precipitation relative to climatology). Through northwestern Minnesota, eastern North Dakota, into portions of northern and western South Dakota there will be a 40% to 50% probability of above-normal precipitation (with a 33% chance of near-normal, and a 17% to 27% chance of below-normal precipitation). To the south and east, there will be a 33% to 40% probability of above-normal precipitation over the remainder of Minnesota, eastern South Dakota, and northwestern Nebraska through the period (with a 33% chance ...