Tuesday, June 28, 2011

90-degree day total climbing quickly

Have you gotten your power bill yet for this month?

If so, you won't be surprised to learn that Charlotte is ahead of last year's pace of 90-degree days. And last year's total was the second-largest in history.

This hasn't been the hottest June in recent years. In fact, our average temperature for the month -- 78.1 degrees at Charlotte/Douglas International Airport -- is well short of last year's June average, 80.3. That was the fifth-hottest June on record in Charlotte.

We're above average this year in June, but if it weren't for a few cool mornings in the middle of the month, I think we'd be close to last year.

Anyway, when the thermometer reaches 90 degrees today, it'll be the 23rd 90-degree day of the year. We had five in May, and today will be the 18th in June. Chances are we'll reach 90 on the remaining two days of June, too.

Last year at this time, Charlotte had 19 days of 90 or hotter. So we're ahead of last year's pace, and Charlotte finished the year with 87 days of 90 or higher. The record is 88, set in the torrid summer of 1954.

Will we be in record territory by the end of the summer?

Let's say we have 25 days of 90 or hotter in July and August. That would leave us around 74 for the year when we reach Sept. 1. So we'd need a hot September (more than a dozen 90-degree days). Last year, Charlotte got 18 days of 90 or hotter in September -- one of the hottest Septembers in recent history.

NOAA's Climate Prediction Center is calling for an equal chance of above-average or below-average temperatures in September for our region, which indicates that meteorologists don't think September will be particularly hot.

So June has been well above-average for temperatures, and we're ahead of last year's pace. But summer has a long ways to go yet.

Friday, June 24, 2011

Some peace and quiet this weekend

(Note at 6:15 p.m. ... I wrote the blog entry below early Friday afternoon, hours before a severe thunderstorm roared across Charlotte. At my house in east Mecklenburg, 2/3 of an inch of rain fell in 25 minutes, and 1-inch hail also came down.

Yet most of the area did not get this storm. And the rest of what is written here still looks correct ... storm activity Saturday and Sunday should be minimal. Widespread storm activity shouldn't return until Sunday evening or night).

There haven't been many weekends since spring when we didn't have thunderstorms threatening on at least one day, but we're looking at a clean slate this weekend.

Well, for the part of the weekend most people are interested in, at least.

Weak high pressure is expected to cover the majority of the Carolinas on Saturday and Sunday, and the atmosphere will have a sufficient cap to inhibit thunderstorms. A "cap," to put it simply, is a layer of warm air at mid or upper levels of the atmosphere. It tends to prevent warm air at the surface from climbing and forming clouds.

No clouds, no thunderstorms.

That appears to be the case this weekend. And since a weak front is crossing the region today, the humidity levels might be a bit lower Saturday and possibly Sunday. So the forecast is for high temperatures around 90 degrees, and any thunderstorm activity will be limited to the mountains.

The pattern figures to change a bit by late Sunday, when another of those weak upper-level disturbances is expected to cross the region. That means showers and thunderstorms could be in the region late Sunday night and early Monday morning.

Next week's forecast appears to be typical summer -- daily highs somewhere in the vicinity of 90, and a chance of afternoon and evening thunderstorms.

Texas update: Earlier this week, I mentioned the severe drought in south central Texas. That night, some heavy thunderstorms hit the Austin and San Antonio areas. The international airport in San Antonio got about 1.5 inches of rain, and 2 inches fell at the Camp Mabry airport in Austin.

It's turned dry again, so maybe I'll need to write about them next week.

Summer in Alaska: Alaska's weather is absolutely amazing. High temperatures Saturday and Sunday in Fairbanks are expected to reach 80 degrees. That's in a city where it falls to 40 degrees below zero in January.

And Barrow, along the Arctic Ocean, is forecast to reach 50 degrees both days under partly sunny skies. The temperature swing in that state can exceed 140 degrees between winter and summer in places.

Tuesday, June 21, 2011

Think this is bad? Try Texas!

You had to feel sorry for the Texas Longhorn baseball team when it lost 3-0 Monday to North Carolina at the College World Series in Omaha, Neb.

It's bad enough, being eliminated from the tournament with a second loss.

But then the Longhorns had to go back to Austin. Normally, that's a treat, because Austin is among the nation's greatest cities. But the weather in south central Texas has been absolutely abysmal since mid-May.

Actually, it's been very, very dry in that area since last year, but hot temperatures have combined with drought conditions to make life a bit uncomfortable in Austin and San Antonio.

The last measurable rain at San Antonio International Airport fell May 12, and it was May 20 since the last rain at Austin's Mabry Airport. That streak could come to an end later Tuesday or Wednesday, as a weak Pacific cold front moves into the area. But a return to dry and hot weather is expected later in the week.

It has not been record-dry conditions for that part of Texas. The National Weather Service says Austin had a 65-day dry streak in summer 1993, and Del Rio, along the border, went 87 days on two occasions. San Antonio's record is 63 days.

But when you add in the heat (especially for June), the conditions really become oppressive.

The reporting station at Austin's Mabry Airport has recorded 16 days of 100 degrees or hotter. The average for the entire summer there is 12. San Antonio and Del Rio also have surpassed their annual averages. And it's only the first day of summer, technically. July and August (and September) await.

All of this, of course, is the result, of upper level atmospheric patterns.

La Nina conditions steered storm systems north of Texas during the winter, adding to drought conditions that already existed. This spring, high pressure has been persistent over Texas. Once again, storm systems have been steered in other directions.

All of this evens out, eventually.

We've had droughts before, and we'll have them again in the Carolinas. But looking at Texas' conditions reminds me of life around here in 1986 and 2007, when temperatures climbed above 100 degrees several times and rainfall was scarce.

It's ugly and depressing. Let's hope Texas gets some rain soon.

Friday, June 17, 2011

The oven has been turned on

If you were in the camp of people who enjoyed the cool down earlier this week, here's some bad news: the other camp -- those who like it hot -- are getting their wish now.

High pressure over the southern Plains is taking control of Carolinas weather and should remain the dominant feature for the next week.

It could bring us face-to-face with 100-degree weather, or at least the upper 90s, sometime in the early or middle part of next week. And high temperatures Saturday and Sunday will be well into the 90s.

This won't be a totally dry situation.

On Saturday and Sunday, a few weak impulses of unsettled weather will move along the boundary of the high pressure system and cross the Carolinas. Meteorologists say that if one of those impulses moves through the region during the heat of the day, we could see the development of thunderstorms.

It won't be a widespread outbreak, though. We're talking about a few scattered storms Saturday and Sunday, and many areas will remain dry.

Humidity levels will climb, too. That will be evident from the nighttime temperatures. Morning lows fell into the upper 50s earlier this week, but we'll have 70-degree lows by later this weekend. That's a sign of the humidity's return.

Drink water, put on the sunscreen (make sure it protects you from UVA and UVB rays), and find a swimming pool or lake. Have a nice weekend.

Tuesday, June 14, 2011

Will volcanoes cool the earth?

More than 60,000 would-be air travelers are grounded today in Chile, Argentina and New Zealand, because of ash from the eruption of the Puyehue-Cardon Caulle volcano chain in Chile.

Meanwhile, a volcano which has been dormant for 150 years erupted this week in the east African nation of Eritrea. The Dubbi volcano is spreading ash over that part of the world.

Last month, Iceland's Grimsvatn volcano erupted. And there was considerable activity earlier this spring at Hawaii's Kilauea volcano.

That raises the question, which is being asked in some meteorological circles, if the volcanic activity could put the brakes on the earth's recent warming trend. Joe Bastardi, formerly of Accu-Weather and now with the new private meteorological firm Weather Bell, is a big believer in this.

He says several factors, including reduced solar activity and increased volcanic activity, will drop global temperatures in the next several years.

As always seems to be the case, there's no consensus. But the impact of volcanic eruptions on global temperatures seems to be related to three factors:

-- The height that the ash is sent into the atmosphere. If it gets into the upper part of the stratosphere, there's a greater chance of it being sent around the globe.

-- The amount of ash spewed by a volcano. This is obvious.

-- Where the eruption takes place. The theory seems to be that eruptions near the equator, in tropical areas, are more prone to impact the rest of the world. That's because winds near the equator tend to spread northward and southward (the Coreolis effect).

Eritrea's volcano is not far from the equator, but the eruptions in Iceland and southern Chile are nowhere near the tropics.

There is a history of volcanoes affecting the world's climate, however.

The eruption of Mount Pinatubo in the Philippines in 1991 cooled global temperatures for two or three years, meteorologists say. Those were among the few years in recent decades when global temperatures didn't rise.

Perhaps the greatest example was in 1815, when Tambora erupted in Indonesia, sending thick clouds of ash around the world for several years. Temperatures in 1816 were far below average, and it was known in the United States as the "Year Without A Summer."

In fact, snow fell on June 6, 1816, in Albany, N.Y. Drought was widespread throughout the United States and Europe, and the winter of 1817 was among the coldest in U.S. history.

The current eruptions pale in comparison to Tambora, but keep in mind that some meteorologists believe 2011's volcanic activity could put a damper on global warming.

Monday, June 13, 2011

Why the big-city tornadoes?

I saw an article last week on Accu-Weather's website about 2011 being the year of urban tornadoes.

Alex Sosnowski, who wrote the article, attributed the large number of tornadoes in populated areas this year to chance, an eastward shift in the springtime jet stream, and the growth of populated areas.

The first of those reasons is obvious -- bad luck.

The jet stream that carried storm systems this spring crossed the South in April and early May, then moved northward later in May. Typically, that air current passes over the Great Plains during the spring, bringing twisters to the so-called Tornado Alley.

Instead, the twisters hit Texas, Arkansas, Tennessee, Mississippi, Alabama, Georgia, the Carolinas and Virginia early in the season, then slipped northward across Missouri, Illinois, Indiana, Ohio, Pennsylvania, New York and Massachusetts afterward.

All of those 15 states have heavily populated areas, and killer tornadoes struck populated areas like Tuscaloosa, Birmingham, Dallas, Jackson, Bristol (Va.), Raleigh, Joplin (Mo.), and Springfield (Mass.), among other places.

I wrote earlier this year -- strangely, just a few days before the Raleigh-area tornadoes -- that twisters sometimes strike populated areas. In many people's minds, tornadoes are a rural event, and that's because they're so common in the sparsely populated areas of the Midwest.

Looking back through the archives, here are a few other killer storms that struck populated areas:

-- A tornado in May 1840, killed 340 people in Natchez, Miss. At the time, Natchez was still a major trading center in the region. Most of those killed (269) were on flatboats in the Mississippi River.

-- In May 1896, a tornado ripped through St. Louis, killing 255. Officials say the death toll might have exceeded 400, with many people being killed on boats in the Mississippi River. But their bodies were never found.

-- A June 1953 twister in Flint, Mich., left 115 dead.

-- And the day after the Flint tornado, a twister in Worcester, Mass., had a death toll of 94. Tornadoes aren't common in Massachusetts, but the 1953 storm and the twister last week are proof that they can take place anywhere (yes, there's even been a tornado in Alaska).

You can find Alex Sosnowski's article here.

Thursday, June 2, 2011

Summer forecast ... several versions

The meteorologists who specialize in long-range forecasts are riding a hot streak.

Most of them correctly predicted winter would start with cold weather and then become more moderate. That's exactly what happened in the East and lower Midwest. We froze from early December until Valentine's Day, and then it warmed up.

And several forecasters correctly saw a battle zone between warm air and colder Canadian systems this spring in the Midwest and East. Sadly, that battle zone developed, in the form of killer tornado outbreaks in eastern North Carolina, the Alabama-Tennessee-Georgia area, and then in Missouri (and Thursday in Massachusetts).

So what's ahead this summer?

I looked at four or five forecasts, and there seems to be general agreement again. A couple points in which there was some consensus:

1. The start of summer will be hot, with temperatures above average. (Someone will probably comment that it's silly to predict hot weather, because it's the South. I'm talking about hotter-than-average).

2. Precipitation in June and July will be about average.

3. Later summer, from mid August through September, could be wetter than average. That reflects the opinion by many meteorologists that tropical storms and hurricanes are more likely to impact the Southeast coast this year than the last two or three years.

The Climate Prediction Center, operated by NOAA, calls for average temperatures and precipitation early this summer, although it has a zone of below-average rainfall not far from the Charlotte region. That might hint at a chance of dry conditions in June and early July for us, but I might be reading too much into the forecast.

Paul Pastelek at Accu-Weather predicts hot and dry early this summer in the Southeast, with increasing thunderstorm activity after mid July. He says this year's hot weather in the Carolinas won't be quite as bad as last summer's.

Another long-range specialist, Dave Tolleris, is calling for a hot and dry June, an average July, and a wet August with average temperatures. He also predicts two main hurricane tracks -- one into the Gulf of Mexico, and the other bringing storms into Florida and then up the eastern United States. That's similar to 2004, when the Carolinas felt the wrath of dying hurricanes Frances, Jeanne and Ivan.

We'll see what happens.

Wednesday, June 1, 2011

Too early for tropical trouble?

The answer to the question in the headline is "yes, probably."

But a weak but persistent low pressure system formed in the Caribbean on Tuesday and is drifting across Florida today.

Southwesterly winds are trying to shear apart the system, and forecasters can't agree on whether the low will survive its trip over the Sunshine State.

Jeff Masters, the Michigan-based tropical weather specialist, said the computer models are having a tough time predicting the system's path or possible development, because it's so small. "They can't see it," he said of the computer models and the low.

Richard Knabb, a former National Hurricane Center staff member who is now the tropical weather specialist for the Weather Channel, doesn't think the low will survive its Florida trip and will be sheared apart.

The National Hurricane Center gives the low a 30 percent chance of developing into a tropical depression.

As you might know, today is the start of the 2011 Atlantic tropical weather season.

Just two weeks ago ... I was talking this morning to John Tomko, a meteorologist at the National Weather Service office in Greer, S.C., and we noted how fast the weather can change.

It was just two weeks ago -- May 17 -- when the high temperature in Charlotte was only 57 degrees. Tomko said it only reached 51 that day at the Greenville-Spartanburg airport.

"That's the power of an upper-level low," Tomko said, referring to the system that caused clouds and rain, keeping temperatures well below averages for that time of year.

That was a clear-cut springtime system, and now we're dealing with big-time summer weather. And it took only two weeks for the change to come about.