Monday could be a wild, wacky weather day

Rainy days and Mondays are not a big hit with most people, especially when they're one and the same.

But Monday could be a very interesting day for weather geeks, especially if you live in the southern portion of the Charlotte region.

A big storm system that covers hundreds of miles and much of the South will affect the Carolinas on Monday, bringing plenty of rain and a chance of severe weather in some places.

If you live to the northwest of Interstate 85, chances are Monday will be a chilly, wet day -- and not a whole lot more. Places like Hickory and Statesville probably will stay in the lower 50s for much of the day, with a steady, soaking rain falling.

To the southeast of I-85 ... that's another story.

First, for the basics.  The center of low pressure will move northeastward Monday, crossing Tennessee and into Kentucky. A cold front that pushed south of Charlotte on Friday evening is moving back to the north as a warm front. Forecasters say any severe weather that develops Monday will be in the warmer, more unstable air.

The question is how far north that front will get. Cool high pressure to our north and falling rain have created a cold air wedge over the Carolinas, and severe weather won't develop in that cool pocket. But the northward-moving warm front on Monday will trim back the cold air pocket. Computer-generated forecasts show the warm front pushing as far north as I-85.

Typically in these situations, the cold air wedge is very difficult to dislodge. If Charlotte, Monroe, Rock Hill and Lancaster get into the warmer air, it probably won't happen until mid or late afternoon.

So here are some things to look for Monday:

1. A lot of rain across the entire area. The National Weather Service is predicting about 1.6 inches in Charlotte, Concord, Monroe, Rock Hill and Salisbury. The forecast is closer to 1.8 or 1.9 inches in Gastonia, Lincolnton, Hickory, Statesville and Shelby. Heavier amounts are possible, however.

2. Most of South Carolina will get into the warm, unstable air.

3. As the warm front moves into North Carolina, it will push inland toward the foothills. Areas east of U.S. 1 are likely to get into the warm, unstable air. How much of the area between U.S. 1 and I-85 gets into the warmer air? That's the question mark.

4. Winds in the atmosphere -- south of the warm front, at least -- will be set up to create rotating thunderstorms.

5. There will be remarkable contrasts in temperatures Monday. Don't be surprised to see some afternoon temperatures in the foothills in the upper 40s, while it's 75 degrees in Columbia or Florence, S.C.  And especially in the early afternoon, don't be surprised to see readings around 70 degrees near Wadesboro or Pageland, S.C., while it's 15 to 20 degrees colder in Gastonia or Lincolnton.

6. If fog develops, it could be a sign that you're near the warm front. Warmer air will pile into the area from upper levels of the atmosphere, squashing the cooler air toward the surface. That's when fog develops. If it's foggy in your area, and the ceiling suddenly lifts (and the temperature climbs), it's an almost certain sign that you're south of the warm front.