Thursday, August 21, 2014

Heat wave won't last long for us

Strong high pressure is building over the lower Mississippi Valley, and it's pumping the hottest air of the summer into the Carolinas on Thursday and Friday, but the Charlotte region won't have to endure the heat as long as our neighbors to the west.

Slightly cooler weather is likely Saturday, and a pronounced cooldown will arrive Sunday and last through the middle of next week.

That's because another high pressure system is forecast to build this weekend in the New England area. If that sounds familiar, it's because New England highs have been the dominant pattern in the eastern United States since mid-July.

The New England high will push its influence down the East Coast, driving a "back-door" cold front southward across the Carolinas on Saturday night. Behind that front, we'll be in a cooler air mass that also will be stable enough to prevent thunderstorm activity.

That cold front won't push much farther west than the eastern part of Georgia, so much of the South -- except the Carolinas and Virginia -- will continue to deal with temperatures in the mid and upper 90s into early next week.

For us, it'll be low to mid 80s for highs from Sunday through next Wednesday.

Before that, it will be hot. Temperatures climbed into the mid 90s Thursday afternoon across the area, and National Weather Service meteorologist Harry Gerapetritis said we could add a degree or two Friday. "Southern Piedmont heat index values could surpass 100 degrees Friday afternoon," Gerapetritis said, referring to the combined impact of temperature and humidity.

By Saturday, that New England high will be pushing its influence into Virginia. That, in turn, will push the track of thunderstorms from Kentucky-West Virginia-Virginia-Maryland farther south, into the Carolinas. We could see another 90-degree day Saturday, but there'll be more clouds and higher thunderstorm chances than Thursday and Friday.

The cooler weather will be apparent Sunday, with more clouds than sun and highs around 82 degrees in Charlotte.

Those cooler conditions will arrive just in time for the first day of school for most of North Carolina's public school students.

And in the tropics ... The National Hurricane Center is following an area of disturbed weather east of the Lesser Antilles. That area could become a tropical depression by Friday, and it's forecast to curve northwest.  That track will take the system near Hispaniola and Puerto Rico, and that means the mountains of those two islands could suppress the storm's development.

Once it clears those islands, it's expected to strengthen again over the Bahamas by late in the weekend or early next week.

I've seen talk about a possible impact on the U.S. Gulf or Southeast coasts, but that's extremely premature. The system could disintegrate over the Dominican Republic and Haiti, or it could recurve away from the U.S. coast.  It's far too early to worry about anything threatening the U.S. mainland.

Otherwise, it's quiet in the tropics as we move into what is typically the busiest time of the year for hurricanes. But that's what forecasters expected this year -- a quieter season.