Monday, June 30, 2014

A dry and pleasant July 4 ... is that possible?

The Carolinas coast is getting most of the attention from meteorologists this week, as they watch the possible development of a tropical low pressure system east of Florida.

But back here in the Piedmont and foothills, conditions are shaping up for what might be an unusually nice Independence Day holiday. If everything develops the way the computer models indicate, our July 4th could be dry and pleasant.

High temperatures in Charlotte might climb only into the upper 80s, humidity levels might be tolerable, and skies might be clear.

Scott Krentz, of the National Weather Service's office in Greer, S.C., said Monday morning that the computer-generated forecasts seem to be pointing toward one prediction -- that a fairly vigorous cold front will push across the Charlotte region late Thursday and be followed on the Fourth of July by a high pressure system.

Under that solution, Thursday would be a stormy day, especially in the afternoon and nighttime hours.

For several days, the Carolinas have been under the influence of an unsettled pattern, as an easterly flow off the Atlantic brought a lot of moisture into the area. Some locations in the North Carolina mountains got 6 to 8 inches of rain over the weekend. A vigorous thunderstorm Friday night dumped about 3 inches in parts of southeastern Mecklenburg County.

Additional showers and storms developed Saturday and Sunday, and more of the same is forecast for the first few days this week -- although storm activity will be scattered, forecasters say.

The chances of thunderstorms probably will increase into the "likely" category Thursday, as the cold front approaches. Anyone planning outdoor activities Thursday night -- and there are plenty of concerts, festivals and fireworks displays scheduled -- would have to keep an eye on the forecast. The storms could continued into the overnight hours.

Then the cold front is predicted to push all the way to the coast Friday. Under that scenario, the cold front would serve as a pipeline for the tropical weather system expected to move up the East Coast. If you're planning to spend the Fourth of July at the coast, that's a problem.

But for those remaining in the Piedmont, foothills or mountains, the holiday could be really nice.

Independence Day typically in the Charlotte area is hot and humid, with a scattering of late-afternoon and evening thunderstorms. Highs in the low 90s are common.

But we could be looking at a holiday with highs from 85 to 88 degrees and no worries about whether a thunderstorm will interrupt the holiday fireworks displays and other evening events.

Sunday, June 29, 2014

Season's first Atlantic tropical system forming

That broad area of low pressure that had been off the South Carolina coast earlier this weekend and was partially responsible for all the clouds, heavy showers and high humidity this weekend in the Charlotte area might be destined to become 2014's first Atlantic tropical system.

By mid afternoon Sunday, the low pressure system had drifted southward and was about 230 miles east of St. Augustine, Fla.

The National Hurricane Center said an area of relatively dry air in mid levels of the atmosphere over North Carolina is expected to be dragged into the low pressure area later Sunday, but by Tuesday or Wednesday, that dry air will be gone, and the low is given an 80 percent chance of becoming an organized tropical depression.

Steering currents off the Southeast Coast are extremely weak, and that makes any long-range forecasts very difficult.

But there doesn't seem to be any indication that the tropical system will have any impact on the Carolinas, at least for the next few days.

Some of the computer models show the low pressure system drifting south and then southwest, making landfall in three or four days along the eastern Florida coast.  But a few other models show the system remaining over open water and then being dragged northeast later in the week when steering currents increase.

In that case, there could be some rainy and windy periods around the Fourth of July holiday on the Carolinas coastline. But that's a highly uncertain forecast, and if you have plans for an Independence Day trip to the beach, there's no need to worry.  Nothing will happen for several days, at the earliest.

Friday, June 20, 2014

Too much rain? Not where I live

Summer thunderstorms can be capricious, dumping big amounts of rainfall in some places and leaving nearby areas dry. That's especially true in the Southeast, where summer is loaded with what meteorologists call "pulse" storms that strengthen and weaken quickly.

Those hit-and-miss storms have been a staple product of the Charlotte area's weather this week.

It seems as if there have been daily thunderstorms in parts of the foothills, and areas to the east of Charlotte have received more than 3 inches of rain this week. But in much of Mecklenburg County, little or no rain has fallen.

Thunderstorms repeatedly have formed in the foothills and moved very slowly into the Piedmont, drying out as they reach Mecklenburg County.  At my house, no rain has fallen this week (through Friday afternoon).

Now the pattern is getting ready to change. A weak cold front is expected to slip southward across the Carolinas on Saturday, and that will serve two purposes.  It will drop temperatures a few degrees late this weekend and early next week. And it will decrease thunderstorm chances, especially Sunday and Monday.

Computer models indicate thunderstorm activity will be a bit lower on Friday afternoon and evening than the past two days, but storms are predicted to be more numerous Saturday as the front pushes southward.

But if you need rain and don't get hit by a storm Saturday, it'll be time to get the sprinkler out.

Temperatures, which have climbed into the low and mid 90s on a daily basis this week, will fall back a bit. Charlotte has been in the 90s for five straight days, and it could climb into the low 90s again Saturday, before the cold front arrives. But highs are predicted to hold in the upper 80s from Sunday into Tuesday of next week.

Thursday, June 19, 2014

Slight change in weather pattern is coming

The late-afternoon thunderstorms that have developed on a daily basis this week are a good-news/bad-news kind of thing.

Just about everyone appreciates that the storms drop temperatures to more tolerable levels and produce rainfall, to compensate for the very high levels of drying that take place at this time of year.

But nobody is a big fans of the damage these storms sometimes produce. That has been the case each day so far this week, and the power of summer thunderstorms was on display Wednesday afternoon in Lincoln County. Strong winds blew trees onto houses, and there also was damage in York, Iredell, Alexander and Catawba counties.

We can expect more of the same over the next few days, forecasters say. The only difference is a slight decrease in temperatures.

Charlotte had a high of 93 degrees Wednesday, and the temperature was climbing toward the mid 90s again Thursday at the time of this writing (mid-afternoon). Forecasters say that by Thursday or Friday, high pressure responsible for this mid-June heat wave will slide off the Gulf Coast, and its grip over the Carolinas will lessen.

If you've been watching to the north over the past few days, you've seen several clusters of thunderstorms sweep from west to east across the Midwest and Great Lakes. As high pressure weakens over the Carolinas, those clusters of storms will take a more southerly track and will affect the Charlotte region by Friday or Saturday.

What does all that mean?

It means highs probably will be closer to 90 than 95 this weekend and early next week, and it means the scattering of afternoon and evening thunderstorms will increase. Some of those thunderstorm clusters moving out of the Midwest could arrive in the overnight hours, so we could get an overnight storm or two.

If you've lived in the Carolinas for any length of time, you know that this is typical summer weather. It's how we get our rainfall at this time of year.

Wednesday, June 18, 2014

Summer's off to a hot start

Summer doesn't officially begin until this weekend, but meteorological summer started June 1, and it's off to a hot start in the Carolinas.

Wednesday marks the third straight day of 90-degree-plus weather, and it appears as if we're in for at least three to five more days of 90 degrees or hotter before there's a change in the pattern.

By mid-afternoon Wednesday, temperatures were in the low to mid 90s across the Piedmont and Sandhills of the Carolinas. An automated thermometer in Camden, S.C., about 80 miles south of Charlotte was showing 99 degrees at 2:30 p.m.

Technically, a heat wave is a string of three or more days with 90 degrees and above, so this is officially a heat wave.

The National Weather Service forecast a high of 94 Wednesday in Charlotte. That would be the hottest temperature in the city in two years, since a reading of 94 degrees at the end of the Democratic National Convention in Charlotte -- on Sept. 1, 2012.

The hottest temperature in Charlotte last year was 93 degrees. That's a testimony to the frequent and heavy rain we got in the summer of 2013.  The rain and clouds kept the heat under wraps.

Wednesday, June 4, 2014

Thursday storm threat is wait-and-see for forecasters

Meteorologists in the Carolinas have a very tricky call to make, regarding the possibility of a severe weather outbreak Thursday.

There actually could be a pair of threats, with the first developing in the early-morning hours and the second on Thursday afternoon.

A clusters of strong thunderstorms was moving across the Midwest on Wednesday morning. That mesoscale convective system (MCS), a fancy word for a batch of storms, is forecast to continue moving eastward during the day, crossing Illinois, Indiana and Ohio. Then the MCS is expect to curve southeast, and that's where it starts getting tricky.

Some of the computer models predict the storms will move across Kentucky, West Virginia and Virginia overnight. Other models predict the storms will curve far enough southeast to affect the Carolinas in the early-morning hours Thursday. That MCS could bring damaging wind gusts, so the track of the storms is important.

The path of the storms also could have a big impact on what happens Thursday afternoon, when a weak cold front is predicted to move into the Carolinas.

The atmosphere in areas affected by early-morning storms will become relatively stable afterwards. That would discourage the development of afternoon thunderstorms.

So if the overnight batch of storms curve far enough southeast to affect the Charlotte area, there are questions about whether the atmosphere really will become unstable enough for another round of stormy weather in the afternoon.  If the MCS stays farther north and crosses Virginia tonight, then the Charlotte area's atmosphere will be plenty unstable in the afternoon.

Justin Lane, from the Weather Service's office in Greer, S.C., said it probably won't be until 3 or 4 a.m. Thursday before forecasters have a good idea on what will happen in the afternoon across the Charlotte region.