Dreary weather pattern preparing to change

I feel sorry for anyone who's tried to take vacation days since last weekend -- assuming those vacation plans involved anything outdoors.

Charlotte-area weather has been rather unpleasant. It's been wet in many places, the humidity has been high, and sunshine has been scarce. Temperatures have been cool, but I realize some people are pleased with that development.

That cool high pressure system that we talked about 10 days ago set up shop over the Northeast, and that provided the area with the below-average temperatures last weekend. Then an upper-level low pressure system moved into the Florida Panhandle area and became stationary for a few days.

The Charlotte region was on the boundary between the influence of high pressure to the north and low pressure over the Gulf coast. Along that boundary, showers and thunderstorms developed. The Florida low pumped enough tropical moisture into the area that heavy rain fell. At my home in Matthews, we've recorded as much rain in the past week that we normally get for all of June and July.

Now all that is ready to change, for a few days, at least.

By Tuesday night, the Florida low will backtrack to the west, and the prevailing east-southeast flow in the Carolinas will switch around to the southwest and west.  That will help dry things out.

The results should be obvious Wednesday, with more of a typical summer pattern -- highs in the upper 80s, humid conditions, and afternoon thunderstorms. But "typical" won't last long.

Another cold front is forecast to barrel into the area Thursday, and drier conditions will follow Friday and Saturday.

One key player in the weather pattern has been a large area of stifling hot high pressure over the Southwest. That strong high has been nearly stationary, and it has helped set up a blocking pattern over the United States.

Much of the Great Lakes has been rather cool this month. Energy use in parts of Indiana, Michigan and Illinois is 25 to 30 percent below seasonal averages.

While Charlotte has seen some cool weather in recent days, we're only about 1 degree below average for the month. The number of cooling days -- a measurement of how the weather affects air conditioning use -- is down about 5 percent for the month in Charlotte.

It looks as if the cold front that moves through Charlotte later Thursday will dissipate after reaching the coast. Then warm and humid conditions with afternoon thunderstorms will return for next week.

Paul Pastelok, a long-range forecaster for Accu-Weather, thinks August could mark a return to more typical summer weather. He said a Bermuda high pressure system likely will establish itself off the Atlantic coast and dominate Eastern U.S. weather.  That Bermuda high, a fixture of summer weather in the Southeast, has been missing in recent days.