The warmth of the past several days was associated with a ridge of high pressure aloft over the northern plains. That bubble in the jetstream has now flattened out and will gradually turn into a trough of low pressure in the next few days. What this means is a threat of rain showers just about every day this week, with today and Thursday night into Friday being the most widespread periods for rain. Also, the clouds associated with the rain in combination with that shift in the upper-level wind means that much cooler air is expected the rest of this week. In fact, high temperatures in the 50s is anticipated on Thursday into Friday. Cool is back.