Plenty of question marks in this week's forecast

At first, it seemed so easy.

A strong high pressure system would build over the Carolinas, and we'd experience a week of hot weather -- perhaps our hottest week of the summer.

The heat would extend through the week and possibly into the early part of next week, with only a few chances of thunderstorms. The greatest chance of storms would come Monday afternoon and evening.

Scratch that idea.

As it turns out, Monday's thunderstorms affected the mountains during the morning, then split apart and developed in the afternoon over the South Carolina Midlands and up in Virginia. The Charlotte region could escape without a drop of rain.

And as for the rest of the week?

Well, it figures to be warm, but not at the kind of levels -- mid and upper 90s -- that we first expected. Instead, it appears as if the Carolinas might wind up being right along the path of several clusters of showers and thunderstorms being shunted from the Great Lakes southeastward.

High pressure that has dominated the western United States has shifted a bit to the east, and the computer models indicate that the Carolinas will be on the eastern edge of the high. Often, clusters of storms -- known to meteorologists as mesoscale convective system (MCS) -- form on the edge of the high pressure systems and are steered around that edge.  It appears as if the Carolinas could be on that edge.

That means these clusters of storms could move into the Carolinas at times during the week. For meteorologists, that's a headache.  It makes forecasts of more than 36 or 48 hours a bit risky, and that could be the case this week.

And later in the week, there are growing signs that another cold air wedge could push into the Carolinas. Those wedges, formed when cool and moist air is pumped from the Atlantic Ocean into the Piedmont by high pressure systems over the Northeast, have made frequent appearances this summer in our region.

If that happens, forget about the 90s this weekend.  We could be looking at thick overcast and temperatures in the mid and upper 70s.