WESTERN S.D. AND NORTHEASTERN WYO. – A chilly autumn pattern continues to hold across the forecast area Tuesday morning. Light overnight rainfall has pulled some low-level moisture out of the air keeping fog from forming, but localized pockets of low-lying stratus and patchy fog continue to drift across portions of the Black Hills and plains.
Low cloud decks and patchy fog will linger intermittently throughout the day. Highs will run a few degrees cooler than Monday with Rapid City is forecasted to reach near 53° under fairly cloudy skies. Spotty, light rain showers will remain possible through the early afternoon before moisture tapers off later today. However, overnight rainfall barely registered a few hundredths of an inch on most gauges, leaving Rapid City’s year-to-date precipitation deficit above 4 ½ inches.
As skies gradually thin tonight, radiational cooling will allow pre-existing moisture to redevelop into fog. Temperatures are forecast to fall into the upper 30s for most of the plains, with Rapid City projecting an overnight low around 37°.
Patchy frost may develop early Wednesday morning in low-lying rural valleys and areas where cloud cover breaks apart. Gardeners with sensitive outdoor plants or cold-sensitive vegetation should take steps to protect them before heading to bed. Moving potted plants into an unheated garage or sheltered porch is ideal, avoid bringing cold-hardened plants directly into heated indoor spaces, as rapid thermal shock can damage them.
Few showers linger into Wednesday under partly to mostly cloudy skies, though temperatures remain seasonably cool with a high near 56° in Rapid City. Better chances for measurable rainfall will remain south towards the Nebraska state line with more chances of rainfall Wednesday night…