Friday, October 29, 2010

First frost almost on schedule

Temperatures in the mid to upper 30s, little or no wind, and clear skies are good ingredients for a light frost, and that's what the National Weather Service is predicting for the immediate Charlotte area Saturday morning.

A frost advisory, which means scattered light to moderate frost, is in effect for Mecklenburg, Union, Cabarrus, Rowan, Catawba, Lincoln, Cleveland and Gaston counties of North Carolina, and for Chester and York counties of South Carolina.

A freeze watch, meaning actual freezing temperatures, has been posted for Iredell, Alexander, Caldwell, Burke, McDowell and Rutherford counties.

The chance of freezing temperatures in Iredell County is probably to the north of Interstate 40, so the southern part of the county is more likely to get frost than a freeze.

No advisories have been posted for Stanly County in North Carolina or for Lancaster County in South Carolina, but scattered frost is possible there, too -- especially in the Lancaster County "panhandle."

First, a little class on frost.

Frost is caused when water vapor in the air freezes. If you see frost on an object, that means the temperature on that object reached 32 degrees.

Temperatures are not uniform. There can be a difference of a few degrees within 100 or 200 feet. Low-lying area tend to be cooler.

So it's possible to have an official air temperature of 35 degrees, yet see frost on some objects. Likewise, it can drop to 32 degrees officially, yet frost doesn't form.

If frost develops Saturday morning in Charlotte, it will be six days early, technically. That's because the N.C. Cooperative Extension Service, out of N.C. State University, says the average first frost in Charlotte (at the airport) comes Nov. 5. But there is a variation of 13 days on either side of that date, so an Oct. 30 frost is not really out of the ordinary.

According to the Extension Service, here are some other average first frost dates for the area:

Albemarle: Oct. 25.

Concord: Nov. 2.

Gastonia: Nov. 1.

Hickory: Oct. 20.

Lenoir: Oct. 21.

Monroe: Oct. 25 (this seems early, given that Monroe is southeast of Charlotte; but the National Weather Service's official observer is in a rural area south of Monroe, so it's possible measurements are made in a low-lying area).

Morganton: Oct. 18.

Salisbury: Oct. 26.

Shelby: Oct. 25.

Statesville: Oct. 19.

Wadesboro: Nov. 4.

The only South Carolina dates I could find came from a seed company, which said the average first frost date in Chester, S.C., is Oct. 20. That seems too early to me, so I discounted that. I'd assume the average date in Rock Hill and Lancaster would be somewhere around the Nov. 5 date.

TROPIC TROUBLE: The tropics are not finished for 2010. Tropical Storm Shary, a relatively weak system, is expected to move into the open Atlantic, encounter cooler water and strong wind shear, and dissipate this weekend.

But there is a stronger system in the deep southern Caribbean that is likely to become a named tropical storm, according to the National Hurricane Center. That system will affect Aruba, Bonaire and Curacao in the next day or two, then slide into the southern Caribbean.

Some long-range forecasters say this system eventually could be a Gulf of Mexico player by late next week. But late-season storms in the Caribbean are difficult to predict, so I wouldn't put much stock in any forecasts yet.

Thursday, October 28, 2010

A storm to remember

Finally, after two solid days of severe weather, calmer conditions are returning to the Charlotte region today.

Autumn weather is returning, too (see below), but the storm system responsible for the damage across our area will not be forgotten. It's become a part of weather history.

The center of the trouble was a low pressure system that deepened rapidly Monday over the Dakotas and Minnesota, then eventually pushed northeast into Canada. It was storm of epic proportions, and its impact was felt all the way into the Southeast.

Shortly after 6:30 p.m. Tuesday, the barometric pressure in Bigfork, Minn., dropped to 28.20 inches. That's the equivalent of 955 millibars of pressure -- the same as you'd get in a Category 3 hurricane with winds of 110 to 120 mph.

Nearby International Falls, Minn., had a pressure of 28.24 inches at 4 p.m. Tuesday.

Bigfork's low pressure broke the record for the deepest storm system in Great Lakes history. The previous record was 28.27, set in the Ohio blizzard on Jan. 28, 1978. I lived through that event, and maybe one day I'll write about it.

The storm had a tragic impact. On Wednesday afternoon, a Notre Dame University student was killed while video-taping the football team's practice session. Declan Sullivan, 20, was standing on the 50-foot tower when a wind gust blew it over. The South Bend Regional Airport, 5 miles away, reported a 51 mph wind gust about the same time.

On Lake Superior, a reporting station recorded sustained winds of 68 mph and gusts of 78 mph early Wednesday morning. Waves were 20 feet on the lake -- the kind of waves you see in storms on the open ocean.

With the pressure so low, winds whipped around the system in a counter-clockwise motion. Those winds helped create tremendous shear in the atmosphere, so the thunderstorms that formed along a cold front being dragged eastward by the low pressure system turned into tornadic storms.

On Tuesday, there were 373 reports of tornadoes, damaging wind and hail. Among those were 46 tornado reports, including those from Lincoln, Catawba and Stokes counties near Charlotte.

On Wednesday, there were 32 more reports, including 14 tornadoes.

First Frost coming?: You might want to start planning ahead for the possibility of our first frost of the season, on Saturday morning.

It appears as if temperatures will fall into the mid 30s to the north and west of Charlotte, and the mid to upper 30s near Charlotte. Winds are forecast to be light, so frost is a possibility.

Halloween Outlook: It looks great. Temperatures will rebound from the chilly conditions expected Friday and Saturday morning, with highs Sunday around 70 degrees. Conditions should be clear to partly cloudy Sunday evening, with temperatures in the 60s.

Tuesday, October 26, 2010

Massive storm, and we're on the edge

Weather geeks are really in a frenzy about the deep storm system that is crossing the northern part of the United States today and Wednesday.

Although the Charlotte region will be 600 to 700 miles south of the storm's center, we'll get a bit of the action from this massive system that will make news headlines for the next day or two.

First of all, the worst of the storm will be felt in the Great Lakes -- Illinois, Wisconsin, Indiana, Michigan and Ohio. And the storm will be multi-faceted, with tornadoes on the southeast side, some snow on the western (cold) side, and strong winds on all sides.

The barometric pressure in this system is really low, if you can believe some of the numbers we're seeing today from Minnesota and Wisconsin.

I've seen a number of barometric pressure readings today in the lower 28's. That's the equivalent of about 955 millibars -- similar to a Category 2 hurricane.

Few of the hurricanes we've seen this year have had lower barometric pressures than the storm system crossing the Upper Midwest and Great Lakes.

As you might imagine, winds are whipping around this storm, because it's tightly wound.

What will it mean in the Charlotte region?

Today will be rather calm, actually. The clouds and fog this morning probably will break for some partial sunshine this afternoon, and temperatures will climb into the lower 80s. Dewpoint temperatures are in the 60s, as the southerly flow around the southeast side of the deep storm system drags warm air northward.

There'll be 70-degree readings up to the Canadian border today, east of the storm.

But severe weather will break out today, and the National Weather Service expects squall lines of thunderstorms to reach the mountains by tonight. Some of those storms probably will move into the Charlotte area by Wednesday morning.

The best chance for severe weather in our area probably will be Wednesday morning. Some showers will remain after a cold front pushes across the area sometime Wednesday, but look for partial clearing Thursday.

Next will come the cold air, dragged southward by the counter-clockwise flow around the back side of the storm system. Temperatures on Saturday morning probably will reach the middle 30s in some places around Charlotte, and that should mean the first frost of the season in parts of the Piedmont.

UP NORTH: The Storm Prediction Center has taken the unusual step of putting parts of Indiana and Ohio in the "high risk" category for severe thunderstorms and tornadoes today.

Sustained winds of 40 to 50 mph, with gusts to 70 mph, are expected today across the Great Lakes. Thousands of power outages already are being reported in Kentucky and Illinois, and you can look for those to spread eastward and northward during today and tonight.

One other thing to consider ... if you're planning to fly today to Chicago, Minneapolis or Detroit, plan on delays. Strong winds and severe storms could play havoc with aviation schedules up there.

Monday, October 25, 2010

Severe storm threat fades, but more rain coming

Just an update to my earlier post today ... the severe weather threat has ended for the Charlotte area, as the strongest energy with the low pressure system has drifted off to the east.

Despite all the thunder, lightning and warnings, less than 1/5 of an inch of rain has fallen so far today at Charlotte Douglas International Airport. But additional showers are likely later today, and we need them.

After a warm and partly sunny day Tuesday, we'll probably get another round of showers and thunderstorms Wednesday with a cold frontal's arrival.

Severe thunderstorm watch issued

An area of strong thunderstorms is crossing the Charlotte metro region Monday morning, and more thunderstorm activity is possible for the next few hours.

Severe thunderstorm warnings that were in effect earlier for several counties west of Charlotte have expired, and there were no reports of significant damage.

Bryan McAvoy, at the National Weather Service office in Greer, S.C., says strong storms are crossing northern Mecklenburg and adjacent counties shortly before noon. McAvoy says those storms could produce wind gusts of about 40 mph.

Heavy rain is falling in a number of places across Mecklenburg County.

A severe thunderstorm watch remains in effect until 1 p.m., covering all of the Charlotte area. The storm threat is being caused by a rather powerful autumn low pressure system that triggered 174 reports of tornadoes, damaging winds and hail Sunday.

Farther to the south, a tornado watch is in effect until 1 p.m. for parts of Georgia and South Carolina.

We'll continue to stay on top of the stormy conditions today.

A line of severe storms plowed into the North Carolina mountains around daybreak Monday, causing reports of damage in Swain, Franklin, Jackson and Macon counties. Those storms weakened considerably as they moved into slightly more stable air in the foothills.

The atmosphere is primed for trouble, and if you want proof, just take a step outdoors. After several days (weeks, really) of very dry conditions, it is quite humid. Dewpoint temperatures, a measure of humidity, have been in the 20s and 30s for the last several days. This morning, they're in the 60s. Those are summer-type readings.

And unlike some severe weather episodes, the warm and muggy conditions won't come to an end when the storm system passes our area later today.

It will remain warm and humid Tuesday, with high temperatures reaching 80 degrees under partly sunny skies. More 80-degree weather is likely Wednesday, but showers and thunderstorms will return. Then a cold front will move across the region, bringing a return of conditions more appropriate for late October.

Thursday, October 21, 2010

When is cold air coming?

Don't get me wrong ... I enjoy warm -- even hot -- weather. But I also have a calendar on the refrigerator, and it says we're in the final third of October. And like a lot of other people, I'm wondering when that first blast of cold air will arrive.

And since my aerated, fertilized and seeded lawn could use more water (Wednesday's .11 of an inch is merely a start), I also wonder when rain will return.

There won't be cold weather or rain over the next several days. It'll reach the upper 70s today, cool to the lower 70s Friday behind a weak cold front, then recover to near 80 degrees Saturday, Sunday and Monday. And it'll be dry.

So when is the change coming?

You won't find the answer in the long-range forecasts.

This morning, I checked the 10-14 day predictions from the federal government (NOAA) and two of the best-known private companies, Accu-Weather and the Weather Channel. See if this sounds like a consensus:

NOAA: Above-average chance of rain, with above-average temperatures over the next 6-10 days and average temperatures overall over 10-14 days. That seems to indicate NOAA meteorologists think it'll be warm for 6-10 days, then cool down.

Weather Channel: Basically average to above-average temperatures for the next 10 days, with a good chance of rain next Tuesday and Thursday.

Accu-Weather: Solid chance of rain next week, but dry otherwise between now and Nov. 4 (the next two weeks). Their temperature forecasts differ widely from NOAA and the Weather Channel, with the prediction of a real cooldown for Halloween weekend. They're talking about daytime highs in the upper 50s on Oct. 30 and 31. Then they forecast a warmup in the first week of November.

I saw another forecast yesterday from New York-based Weather 2000 Inc., a private firm, and its meteorologists are calling for a cold air outbreak over the eastern United States for Halloween weekend.

There's a wild card in the forecast -- down in the Caribbean.

A tropical depression formed Thursday morning, and it probably will become Tropical Storm Richard by later today. Most computer models predict the system will become a hurricane in a few days.

The computers forecast the storm will cross Mexico's Yucatan Peninsula, and if it hasn't been wrecked by a trip over land and some southwest winds that could shear the top off the system, it could turn north or northeast in the Gulf of Mexico.

Should that system reach the Gulf coast of the United States, especially from Alabama eastward, it probably would link with a cold front that should be moving into the Southeast by the middle or end of next week. And that would bring a lot of rain to the Charlotte area.

Let's see ... by my quick count, the previous three paragraphs have the word "probably" twice; the words "could," "would" or "should" six times; and the word "if" once. So let's wait on that one, OK?

Monday, October 18, 2010

Woolly Worm's forecast: Snowy new year

I don't know if woolly worms gloat, but the winner of last year's Woolly Worm Festival in Banner Elk, Wilbur, did a pretty good job of predicting the winter of 2009-10.

Now we'll see if this year's winner -- a worm with a Charlotte-area connection -- is correct in his/her prediction that the winter of 2010-11 will have a cold and snowy start, a mild middle, and then finish with very cold temperatures.

The 33rd annual Woolly Worm Festival took place Saturday and Sunday in Avery County, and organizers estimate the event drew more than 23,000 people.

The festival features food, games and entertainment, but it's built around the woolly worm, a caterpillar who, according to folk legend, predicts the upcoming winter. That prediction is based on the hue of the creature's rings. Each ring represents a week of winter, and the darker the color, the worse the week.

Last year's winner, Wilbur of Chapel Hill, correctly predicted a cold and snowy winter.

Dr. Ray Russell, an Appalachian State University faculty member who operates the popular Ray's Weather website, says the winter of 2009-10 produced 134.3 inches of snow in Beech Mountain and 83.6 inches in Boone. He says it was the third-worst winter in history in the N.C. mountains.

So what about this year?

The winning worm in Sunday's championship race was owner and "trained" by 5-year-old Cole Peurifoy of Concord, above. I don't have the worm's name, but his rings indicate the Weeks 1-5 and 12-13 will be the worst.

Incidentally, the rings were interpreted this year by Tom Burleson, a 7-foot-2 former basketball standout with North Carolina State University and in the NBA. Burleson has legitimate woolly worm-interpreting credentials. He's from Avery County and still lives there.

The forecast, courtesy of Cole Peurifoy's worm:

Week 1 (Dec. 20-26): Cold with snow.
Weeks 2-4 (Dec. 27-Jan. 16): Extremely cold.
Week 5 (Jan. 17-23): Ice storm.
Weeks 6-11 (Jan. 24-March 7): Average to mild weather.
Weeks 12-13 (March 8-20): Very cold.

Ray Russell's Forecast: Russell doesn't agree with the woolly worm. Disdaining the color of the woolly worm's rings and paying heed to scientific factors such as La Nina and other short-term climate conditions, Russell is predicting the winter of 2010-11 will be mild and less snowy than last year.

His mountain and foothills snowfall predictions -- 75 inches at Beech Mountain; 32 inches in Boone; 11 inches in Asheville; and 7 inches in Hickory.

You can check out his information at

Thursday, October 14, 2010

Cooler and windy, but no frost in Piedmont

The strong cold front that pushed through the Charlotte area earlier Thursday (and produced a grand total of about 1/10 of an inch of rain) will bring windy conditions Friday and our coldest temperatures so far this season.

But the Piedmont should be safe from frost, this time around.

The biggest problem for the area could come Friday, when sustained northwest winds of 15 to 25 mph (with gusts to 35 mph) and low humidity will increase the fire danger.

The National Weather Service says it isn't expecting to issue a fire watch for the Piedmont but will do so for northeast Georgia and the South Carolina Upstate. However, forecasters say, the wildfire danger will be higher than usual in the Piedmont on Friday.

Daytime temperatures in this colder air mass will remain mild, actually. We'll have highs in the lower 70s for the next few days, and then into the middle 70s by early next week.

But with dry air and no clouds at night, the morning lows will be chilly. Some places around Charlotte will see readings in the upper 30s on Saturday, Sunday and Monday mornings. The frost threat is limited to higher elevations, the National Weather Service says.

This all means a beautiful weekend for seeing the fall colors in the mountains. And it also means that for the first time this football season, you'll need a coat at high school games Friday night and college games Saturday evening.

That also goes for fans headed to Charlotte Motor Speedway for the big races Friday and Saturday evenings.

That wet stuff? It's called "rain"

That strange wet stuff falling from the sky shortly before daybreak this morning is called "rain."

Once upon a time, we saw rain frequently, but since the middle of August, it has fallen only a few times. And it won't last long today.

A cold front is crossing the Charlotte region this morning, and it has touched off scattered showers and even a few thundershowers. People who live near Lake Norman and across the Cabarrus County line into Kannapolis got a middle-of-the-night wake-up call, about 3 a.m., when a small but strong thunderstorm crossed that area.

The storm produced winds of up to 40 mph, but it was short-lived.

The rain that's falling this morning across the region will move swiftly off to the east, and clearing will follow today. It could be the middle of next week before we have a solid chance of rain again.

We're also still watching for the possibility of gusty winds on Friday, especially in the mountains.

Winter Outlook: Brad Panovich, the chief meteorologist with our news partner, WCNC-TV, has come out with his winter forecast.

Brad is calling for rather mild temperatures and less snow than usual in the Charlotte area -- but a higher-than-average chance of ice storms.

Brad notes that we have a La Nina pattern this year, which typically means warm and dry winters in the Southeast. But there also is a negative Atlantic Oscillation (NAO) condition, which tends to drive cold air fairly deep in the eastern United States.

He predicts the main storm path will remain north of the Charlotte region, but we'll be close enough to get hit a few times. And if I'm translating his forecast properly, the NAO will drive cold air far enough south on occasion to leave us prone to ice storms. The threat would be freezing rain, rather than snow, because La Nina will prevent us from getting into the truly cold air.

His forecast also calls for dry and warm conditions along the eastern third of the Carolinas.

Here's a link:

Wednesday, October 13, 2010

No strong winds, please

A cold front will cross the Carolinas later tonight and early Thursday, and some computer models indicate Friday could be a very breezy day across the region.

We wouldn't want that.

Gusty winds Friday would be a problem for two reasons -- a fire threat across the entire region; and trouble for those planning to drive to the mountains and see the colorful leaves this weekend.

You don't need me to tell you how dry it's been recently. Many of us are praying that the cold frontal passage will trigger enough showers or thunderstorms to moisten the ground -- to either water the grass seed that some of us have planted, or make it wet enough for the lawn-work procrastinators to get their aerating and seeding done.

It's not likely, because there doesn't seem to be much chance of significant rain.

Very dry conditions since mid-August have put us in a position where gusty west or northwest winds could create a big-time wildfire threat. We've been lucky so far, with only a handful of wildfire outbreaks in recent weeks.

For those planning trips to the mountains this weekend, a windy Friday could ruin some of the color show by blowing leaves out of the trees. This figures to be one of the most colorful weekends of autumn 2010 in the North Carolina high country.

We should know more about the wind threat by Thursday morning.

Monday, October 11, 2010

Hot, but no record; and tropics still active

The temperature is soaring into the middle 80s this Monday afternoon, and while the National Weather Service says a record high is possible today at the Greenville-Spartanburg station (the record there is 86), nothing like that is expected in Charlotte.

Still, this mid-October heat wave is what you'd expect, given the type of steamy summer we just came through.

Today's high is expected to reach 85 or 86 degrees, and the record for the date is 90, set in 1939. More of the same is predicted Tuesday, when the record high is 89, set in 1919.

All of that got me wondering about the latest 90-degree and 80-degree days ever in Charlotte.

Our latest-ever reading of 90 degrees was on Oct. 13, in 1954. That was the year in which numerous heat records were set, and I've heard stories from old-timers that it was an absolutely brutal summer.

Our latest 85-degree day was on Nov. 2, 1961. That year featured a version of a heat wave at the beginning of November, with the temperature reaching the mid 80s daily from Nov. 1-4. Incidentally, in case you're wondering, we got 13 inches of snow that winter (1961-62) in Charlotte. It snowed three times in January 1962.

Finally, our latest 80-degree day happened just three years ago -- an 80-degree reading Dec. 10, 2007.

Our earliest 80-degree day was Feb. 2, 1989.

Tropical Update: As of 2 p.m. Monday, the National Hurricane Center still hadn't declared an area of stormy weather off the coast of Honduras to be a tropical storm, but it likely will happen later this afternoon. It will be Tropical Storm Paula, and the computer models are all over the board with predictions on where the system will go.

I haven't seen any predictions, however, that the system will affect the U.S. mainland. The three most likely scenarios seem to be: a.) Moving inland in Belize and Mexico's Yucatan peninsula, and falling apart; b.) Drifting southward into Central America; c.) Moving northeast, clipping the west coast of Cuba and then curving east, near the Bahamas, and then out into the open Atlantic Ocean.

The storm that will be Paula has formed in the same area of disturbed weather that produced Tropical Storm Otto last week, and it might not be finished. Some meteorologists think another system could develop in the same general area later this week.

Friday, October 8, 2010

Too early for mountain colors

The taste of autumn that we received in the past week brought out some new wardrobes and got many of us thinking about the arrival of fall, but don't race to the mountains this weekend, expecting a bright show of colors.

The latest check indicates leaves on some trees are changing colors, but you'll have to travel to the higher altitudes to see them.

As of Thursday, colors were being seen in the trees above 5,000 feet. That's mostly in the Mount Mitchell, Grandfather Mountain and Craggy Garden areas.

Forestry officials say it will be the middle of next week, or possibly even next weekend, before the autumn color show reaches the 3,500- or 4,000-foot level.

In other words, you'll probably see some spectacular yellows and reds next weekend along the Blue Ridge Parkway, near Boone and then down around Mount Pisgah. Dr. Howard Neufeld, an Appalachian State University professor who follows the changing of the leaves each year, says some yellows and oranges are being seen among the greenery in the Boone area, but it's still a bit too early there, too.

Some horticulturists had worried that our dry and hot late August and September would cause the leaves to turn brown and fall early. That happened in a few places, but late-September rain seemed to save the day.

The peak time in the mountains -- especially at elevations of 2,500 to 4,000 feet -- likely will be around Oct. 17 to 28.

Down in the Piedmont, naturally, it'll be later.

The latest prediction is that trees in the foothills will be at full color in the last week of October -- and a few days later in the Piedmont.

Changes Ahead: If you're a fan of warm weather, you'll love the next few days, as temperatures soar well above average in the Charlotte area. Under sunny skies, we'll have afternoon readings in the mid 80s this weekend.

But don't get too used to it, as some big changes are coming.

Most of the computer models indicate a change to much cooler and wetter weather, beginning around the end of next week. There are indications the chilly conditions could continue through the rest of the month.

Our afternoon highs by the end of next weekend probably will struggle to get out of the 60s.

Thursday, October 7, 2010

Arizona twisters, Atlantic hurricane, and our 80s

We've got a couple topics to cover today, and the first is the outbreak of tornadoes before daybreak Wednesday in Arizona.

It looks as if there were four twisters, mostly in the northern part of the state, around Flagstaff. A low pressure system that was parked over central California spun up the severe storms, and the tornadoes destroyed about 200 homes.

I heard someone mention on a TV newscast today that October tornadoes in Arizona are almost unheard of, so let's go to the record book.

In the decade from 2000 and 2009, there were 38 tornadoes reported in Arizona. Is that a lot? How about these figures, for the same 10 years:

Texas: 1,526

Oklahoma: 529

North Carolina: 319

South Carolina: 313

Alaska: 3

OK, so tornadoes are pretty rare in Arizona, unless you're comparing it to Alaska, in which case Arizona is like Tornado Alley.

On average, there are almost four tornadoes a year in Arizona. Of the 38 in the last decade, five were in October, including three on Oct. 18, 2005. Five twisters in a month is actually more than the state's average, so the point is that tornadoes any time of year in Arizona are rare.

By the way, the low pressure system responsible for the stormy weather out West is weakening and won't have such an impact as it moves into the upper Midwest this weekend.

The Tropics: As we mentioned yesterday, Subtropical Storm Otto has become Tropical Storm Otto and is crawling along at 2 mph. The National Hurricane Center still thinks Otto could become a hurricane, but the forecast track continues to be out into the open Atlantic.

My brother Michael, who is even more of a Weather Guy than the Weather Guy himself, points out that my comparison of subtropical and tropical storms in Wednesday's blog entry failed to mention a key difference -- the temperature of the atmosphere in the center of the storm systems at different altitudes.

As he notes, a subtropical system has warm air near the surface and cold air aloft. A tropical system is warm in the center, from bottom to top.

And For Us: It's the same old pattern we saw in August and September, and I'm betting it's the same pattern we'll see much of this winter. High pressure is locked over the Southeast, which means it'll be warm and dry for the foreseeable future.

Those morning lows near 40 degrees earlier this week will be replaced by lows closer to 50, over the next few days. But we'll see a real difference in the afternoon. It didn't reach 70 earlier in the week, but we'll be looking at highs near 80 through early next week.

In fact, it could reach 82, 83 or even 84 degrees in Charlotte on Saturday or Sunday. Maybe the Chicago Bears will have problems with our heat when they come to town for Sunday's game.

Baseball Playoff Weather: No problems for today's Major League Baseball playoff games. It'll be in the upper 60s and dry at gametime early this evening in Minneapolis, for the Twins' game (and probable loss, given their history) against the New York Yankees.

In San Francisco, it'll be in the upper 50s for the first pitch of the Giants' game against the Atlanta Braves.

And in St. Petersburg, it'll be 80 degrees and sunny when the Rays face Texas in Game 2 of their series. Of course, that game's being played in a dome, and from the looks of attendance at Rays' games, most everyone is outdoors enjoying the sunshine.

Wednesday, October 6, 2010

Subtropical storm? What's that?

A subtropical depression formed Wednesday morning east of the Bahamas, and since this system almost certainly will never affect the U.S. mainland, we can focus on something other than the storm's track.

For example, what does "subtropical" mean, and how is such a storm different from a "tropical" system?

Subtropical Depression 17 is expected to strengthen into a storm, and it'll get the name Otto. After that, all the computers agree that the system will move swiftly to the northeast, away from North America and out to sea.

It probably will convert to a tropical storm and might even become a hurricane.

And it's interesting to note that Otto would be the 15th named system this year. As I recall, that's pretty close to all the predictions, and it's indicative of a busy season. However, since no major storms actually made landfall in the United States, most people probably will think of 2010 as a quiet tropical season.

Anyways ... back to the issue at hand -- tropical vs. subtropical.

A tropical system gets its energy from the ocean's warm water. Its center, called the core, is warm. The strongest winds and heaviest thunderstorms tend to be near the center of a tropical system.

A subtropical system is different. Often, it's a low pressure area along a cold front that moves into the south Atlantic or Caribbean. Gradually, the storm system stops getting energy from the cold front and instead begins receiving fuel from the warm water below. Thunderstorms in the system give off latent heat, and that helps develop the warm core.

In a subtropical system, the strongest winds tend can be several hundred miles from the center. In other words, it's not organized quite as well. But subtropical storms can have sustained winds of up to 65 or 70 mph.

Often, subtropical systems develop a warm core and convert to tropical systems. The strongest winds and storms move closer to the center, and the system becomes better organized.

There's one more term to know -- extratropical storms. That's a system that was tropical in nature (either a tropical storm or hurricane) but moves into colder waters and loses its tropical characteristics.

Tuesday, October 5, 2010

Record heat to record cold?

Vince DiCarlo, who retired last year from the National Weather Service office, reminded me frequently that "averages are what you get from two extremes."

For example, Charlotte's rainfall total in September was about 4.1 inches -- above the monthly average.

But who thinks September was a wet month around here?

Our lawns turned brown in a relentless string of hot and dry days, until the last few days of the month, when it rained cats and dogs. Overall, though, rainfall was a big above average.

Our recent temperature swing is another example. A week ago Saturday, we broke a record (for Sept. 25) in Charlotte with a high of 94 degrees. Tomorrow (Wednesday) morning, we could be near record-low temperatures, with the thermometer in the vicinity of 40 degrees.

The record low for Wednesday is 38, set in 1935. This morning, we flirted with a record, dropping to 40 degrees (the record was 38, set in 1974).

The average high and low temperatures at this time of year are in the upper 70s and mid to upper 50s. But it seems as if we're mostly at one end or another of the extremes.

By the way ... I did a little checking of recent years, to see if our 40-degree reading this morning was unusual. Looking at the record book since 2006, it does appear as if it was a bit early to be that chilly.

Last year, our first day of 40 or colder was April 18 (35 degrees). October 2008 was a chilly month, as it dropped to 42 on Oct. 2 and got down into the upper 20s by the end of the month. In 2007, temperatures didn't fall to 40 or below until the end of the month. In 2006, it was the middle of October.

Either way, we can expect dry weather and a gradual warm up for the rest of this week. High pressure is taking control of the eastern United States, and we could be near 80 degrees for afternoon readings in a few days.

Talking Tropics: There's another system in the Caribbean, and the National Hurricane Center gives Invest 97L a 60 percent chance of becoming a tropical depression or tropical storm. It's north of the Virgin Islands, but the system is taking a beating from upper-level westerly winds (shear) and is not forming very quickly.

Some meteorologists speculate the area of disturbed weather could become two separate tropical systems -- one north of the Virgin Islands, carried back out to sea; and other south of the Dominican Republic and Haiti.