Monday, Nov. 2 has been declared a First Alert Weather Day for western South Dakota as damaging winds, heavy rain, areas of dense fog and possible snow are expected to make travel difficult. Gusts could top 60 mph in several spots and may reach 65 mph in the strongest bursts.
The warning reaches beyond one town. It covers communities from Rapid City and Spearfish to Belle Fourche, Philip, Kadoka and Hot Springs, with parts of Butte County also included. Near and east of the Black Hills, the wind threat looks strongest, while the same system could produce more than an inch of rain in Rapid City and even higher totals along the northern Black Hills slopes and parts of the western South Dakota plains.
That mix is what makes the setup so messy. Rain could begin as early as midnight, and heavier rainfall may develop along and south of I-90 as Monday gets underway. Recent guidance has shifted the better moisture farther west into western South Dakota, which raises the odds of higher rain totals in places that were not favored earlier in the forecast. Some projections now point to 1 to 1.75 inches in Rapid City, with a chance of totals approaching 2 inches.
Fog adds another layer of risk before daylight. Visibility could fall sharply around 4 a.m. near Wright, Wyoming; Ekalaka, Montana; and Philip, South Dakota, with some model guidance showing one-eighth of a mile near Wright, about half a mile near Philip, and near zero around Ekalaka. That kind of visibility can make even short drives hazardous, especially along Interstate 90 and other roads across western South Dakota and northeastern Wyoming.
Snow remains the least certain part of the forecast, but it is still on the table in the higher elevations. In the Black Hills, the best chance for accumulating snow appears to be around 5,000 feet and higher, including terrain above Deadwood. Where temperatures cool enough, an inch or two is possible, though the outcome will depend on elevation, rainfall intensity and how quickly precipitation changes over to snow. Colder air could also allow rain to mix with or change to snow around Gillette, Wright, Sundance and Sheridan, with slick spots possible in parts of Campbell County.
The larger concern is how the storm will balance wind and water across the region. Forecast winds near 5,000 feet could reach about 70 mph Monday evening, enough to help stronger gusts mix down to the surface and keep the threat focused just east of the Black Hills and across portions of northwestern and west-central South Dakota. Winds should begin easing toward 6 a.m. Tuesday, but not before a long stretch of poor travel conditions that will hinge on where the heaviest rain and any higher-elevation snow end up setting up.
