Monday, December 30, 2013

Another wintry blast, another miss (or escape) for the Southeast

It's starting to sound like a broken record, but another shot of very cold air is moving into the United States. It's being accompanied by the threat of another winter storm, too.

But once again, upper atmospheric steering currents are allowing the Southeast to miss (or escape, depending on whether or not you enjoy wintry weather) the cold air and frozen precipitation.

Temperatures are brutally cold Monday in the upper Midwest. The forecast high temperature Monday in Minneapolis is 3 degrees, and after an overnight low of 10 below zero, the predicted high Tuesday is 3 degrees below zero.

It will be very cold in Chicago, too, but readings will remain above zero because the Windy City is expected to be hit with a snow-producing winter storm.

Lows below zero will be common place in the Midwest over the next few days.

But rather than dive into the Southeast, the strong high pressure system will slide eastward over the next few days. The storm track also will move along the Ohio Valley and into the Mid-Atlantic. If that sounds familiar, it's because cold high pressure systems have been following the same path regularly this winter.

The mechanism is not in place for high pressure to push into the Southeast and take hold there. For our part of the country, the cold air outbreaks have been brief, as there isn't a blocking pattern in the atmosphere to lock the arctic high pressure systems in place over the eastern United States.

There is considerable debate among weather followers, as to how long this pattern will continue. Computer models indicate no real change through the first 10 days of January, but meteorologists will tell you not to put a ton of faith in computer models beyond a few days.

The truth is, we don't know how long the pattern will continue.

Wednesday, December 18, 2013

Do you remember the 1989 tornadoes?

The year 1989 is memorable in the Carolinas because of Hurricane Hugo, which roared ashore near Charleston on Sept. 22 of that year and cut a path of destruction all the way into the Charlotte region.

But there was another major weather event that year -- one of the worst tornado outbreaks in Carolinas history.

It didn't rival the March 1983 tornadoes that ripped a path across South Carolina and the eastern portion of North Carolina. But the tornado outbreak of May 5, 1989, caused deaths and millions of dollars' worth of destruction. And the twisters impacted the Charlotte region.

Now the National Weather Service's office in Greer, S.C., is looking for people who have memories of those storms, which hit nearly 25 years ago. Specifically, they'd like to communicate with those who were affected. Those memories will be part of the Weather Service's observance this spring of Severe Weather Awareness Week.

The first tornado struck near Chesnee, S.C. Two people were killed there.

A tornado, perhaps from the same thunderstorm, then touched down near Lawndale in northern Cleveland County. That F4 twister, the second-strongest classification of tornado, stayed on the ground through the Vale area of western Lincoln County and into the Propst community in Catawba County. The tornado killed four people, injured 53, and caused millions of dollars' damage.

The second twister came from a different storm. It touched down in the early evening hours near Wesley Chapel in Union County. A young girl was killed, and the F4 tornado tore a path through Indian Trail, crossed U.S. 74 near a flea market, and then ripped through Unionville and Fairview.  There were six injuries and more than $8 million in damage.

A weaker tornado struck Anson and Stanly counties a short time later, and there also was an F3 twister in Winston-Salem that day.

The Weather Service's office in Greer is especially interested in the Cleveland-Lincoln-Catawba twister and the Union County tornado.

If you want to contribute to the Weather Service's report, contact meteorologist Justin Lane at

Tuesday, December 17, 2013

Arctic outbreak for Christmas? Scrap that idea!

The computer models giveth, and the computer models taketh away.

A few days ago, the models were showing an outbreak of bitterly cold arctic air plunging into the Rockies and upper Midwest, then descending all the way to the Gulf of Mexico.

That air mass threatened to bring frigid temperatures to places like Texas, western Louisiana, Arkansas and Oklahoma for the Christmas holidays. The model showed daytime highs around zero in parts of the Midwest.

But all that is changed now. The models show a strong high pressure system moving generally east, rather than south. That will keep the coldest of the air next week in Canada.

That means the bitter cold probably isn't headed for the Midwest. Conditions likely will be cool, but not frigid.

And it means the 2013 Carolinas Christmas likely will be average. At this time of year, "average" means highs in the low 50s and lows in the lower 30s.

For several weeks, we've been in a persistent pattern.  It gets quite cold for a few days, and then we have a mild trend. Precipitation falls as rain, not anything frozen. If you believe the models (and that can be a risky thing to do), the trend will continue for the forseeable future.

That means chances are quite low of anything frozen developing locally in the near future.

Monday, December 16, 2013

Christmas forecast starting to take shape

The evolving weather pattern across North America is taking better shape for Christmas week, and we're starting to get a better idea of what to expect during the busy holiday travel period.

No doubt some Carolinas residents will fret over the predicted 70-degree weather this weekend, fearing that could continue into Christmas and ruin their holiday spirit.  Have no fears. A cold front will do away with the 70s late Sunday or Monday, but don't look for arctic air to arrive next.

It now appears as if Christmas will be seasonal in the Carolinas, with highs somewhere in the vicinity of 50 degrees. And there are no signs of really cold weather coming our way through the end of the month. Rather, it looks as if it will be mild, with a few outbreaks of chilly air.

Before Christmas, things could get interesting around here.  More about that later.

The seasonal temperatures in the Carolinas won't be the case off to our west. It appears as if another surge of arctic air will descend into the Rockies and Midwest, then push down into Texas. Christmas week could be quite cold in that part of the country,

As for Christmas travel, I'd bet on the biggest potential for trouble coming in the Midwest and down into the Mid-South.  Snow, sleet or freezing rain would be a possibility at the southern edge of the cold air mass, in places like Texas, Oklahoma, Arkansas and Missouri.

We'll have to keep an eye this weekend on an approaching low pressure system. Some of the computer models are predicting a combination of conditions that could produce severe weather. At the bare minimum, heavy rain will be a possibility, with a strong surge of very mild air being pushed from the Gulf of Mexico into the Southeast.

Friday, December 13, 2013

Think it's been cold? The numbers say you're right

It's been cold so far this winter season.

I realize winter doesn't officially begin until next week, but tell that to anyone who shivered in 20-degree temperatures last month. In reality, our winter weather arrived in mid-November, with two straight mornings of 21-degree lows.

Since then, it's been more of the same.

The overall average temperatures in November and December have been a bit below average, but that's because we had a couple of very mild days, such as last Friday's mid 70s.

Last year, looking at the period from Nov. 1 through Dec. 12, Charlotte had six days with morning lows in the 20s. All of those came in November, as early December was quite mild. The lowest temperature during that period was 21 degrees.

This year, that same period has produced 14 days in the 20s or colder. It actually dropped to 19 degrees on Nov. 25 and 28, and it was 20 degrees on Tuesday morning this week.

The obvious question is whether this is a sign of things to come in January and February, the heart of winter. Don't bet on it necessarily.

Weather tends to follow patterns that last for several weeks.  So, following that theory, it might remain quite cold into January and perhaps beyond.

But remember three winters ago. Temperatures were well below seasonal averages from early December until Valentine's Day. Then, like someone flicked a switch, it got warmer. In fact, the latter part of February and March produced some of the warmest weather Charlotte has seen at that time of year.

Another shot of cold air is looming for Christmas week, so it appears safe to say that December will finish as a chilly month. What happens in January remains a big question mark.

Thursday, December 12, 2013

Bitter cold for Christmas ... but in Midwest?

The long-range weather computer models are painting a very, very cold picture for Christmas over parts of the United States, but if you believe those advance forecasts, the worst of the cold is headed for the same place that got it the last time -- the Midwest, down to Texas and northern Mexico.

If the models verify, it appears as if the Carolinas would get a glancing shot from the arctic outbreak, much as we did with last week's surge of cold air.

All of this is important, because any storm system that moves into or near this cold arctic air would produce frozen precipitation, and that could be a big deal during the Christmas holidays, with millions of people traveling. If you buy what the models are selling, the risk of snow, sleet and freezing rain would be in places like Texas, Oklahoma, Arkansas, Missouri and possibly western Tennessee.

If you remember, the last arctic outbreak dropped temperatures to what we'd call "chilly" levels here in the Carolinas, and a low pressure system produced a bit of freezing rain last Sunday before temperatures climbed above freezing.  Something similar would be possible with a storm system that is forecast to develop around Dec. 26 or 27.

All of this could change, however. And as one professional meteorologist told me Thursday, the winter computer models sometimes tend to exaggerate the amount of cold air in these situations. "When the time comes, temperatures often are not as cold as advertised," he said.

It seems safe to say that we won't be seeing an extended period of mild weather during Christmas week.

Instead, it looks -- for now, at least -- as if we can expect seasonal conditions from this weekend through much of next week, followed by stormy conditions and cool temperatures around Christmas.

Thursday, December 5, 2013

Will the ice, bitter arctic cold reach here?

A super-strong arctic high pressure system is blasting its way into the central part of the United States today, helping set the stage for what could be a crippling ice storm in parts of Texas, Oklahoma, Arkansas, Missouri and Tennessee.

Temperatures will struggle to get above freezing Friday in Dallas, and places like Austin and San Antonio will be in the mid 30s for most of the day.  Truly frigid weather is predicted for areas farther north.

Often, such arctic air masses push eastward and eventually cover the eastern part of the United States. But not always.

And it appears as if the Southeast might avoid the worst of the powerful cold this time around.

Some of that arctic air mass will seep into the Carolinas this weekend. You'll feel it Saturday, when temperatures tumble from around 60 degrees in the early-morning hours to the lower 40s by evening.

Planning to attend the ACC championship game Saturday night? Bring a heavy coat.

It'll be even worse Sunday, with temperatures near freezing during part of the day and a low pressure system bringing rain. This is when parts of the Charlotte region could experience freezing rain. Right now, it looks as if Charlotte won't see much in the way of glazing. But it could be a different story to the north, in places like Hickory and Statesville -- and especially Boone and other mountain locales.

Then the same cold front that pushes southward on Saturday will retreat northward late Sunday and early Monday as a warm front.

So guess what?  On Monday, we're back in the 60s, or at least near 60 degrees. In fact, there will be enough wind shear Monday (winds blowing from different directions at various levels of the atmosphere) that any thunderstorms developing along an approaching cold front could cause wind damage.  That front will bring another shot of cold air.

But we won't really get that cold next week, according to the computer models.  There probably will be a day or two with highs in the upper 40s, but it will be nothing like the 30-degree highs that cities to the west of us (at the same latitude) experience from the cold air mass.

So that's one system we might avoid.

It's a long winter, though.

We'll keep a close eye on this Sunday freezing rain scenario and let you know about any updates.

Wednesday, December 4, 2013

No ice storm, but cold rain ahead

You'll be hearing a lot in the next few days about a very strong arctic high pressure system that is barreling southward into the United States.

The good news for the Carolinas is that the heart of the cold is taking aim at the Midwest. That will prevent our region from being hit with an ice storm. Unfortunately, residents in the South Central United States might not be so lucky.

The arctic high is bring very cold weather and an amazingly abrupt change in conditions.

An example: Dallas could hit 80 degrees today. Freezing rain and temperatures near 30 degrees are forecast for Friday. The ice storm is expected across north Texas, Oklahoma, Arkansas, western Tennessee and possibly parts of Kentucky.

Earlier this week, the Carolinas seemed to be a possible target of freezing rain. But computer models now indicate not enough of the really cold air will spill across the mountains. It will turn much colder this weekend, but not cold enough for freezing rain.

Instead, we'll deal with our own abrupt temperature change. Forecasters expect highs in the mid 70s Thursday and Friday. By Sunday, when rain is falling for most of the day, temperatures might not get out of the upper 30s.

The changeover day will be Saturday, when temperatures are falling (along with rain). Conditions could be miserable Saturday night for the ACC championship football game at Bank of America Stadium.

Monday, December 2, 2013

Keeping an eye on next week

While we move through a one-week break from the cold weather, meteorologists and weather geeks will be looking closely at the always-waffling computer models for a hint about what will happen early next week.

The models show a strong cold high pressure system pushing southward from Canada into the United States in a few days. The models also show a low pressure system moving across the South.

That is a scenario for wintry precipitation, and some of the models show freezing rain and some sleet over parts of North Carolina and a few other spots in the Southeast. The time frame for the Carolinas would be late Sunday and Monday.

Regardless of whether it's frozen or not, plenty of precipitation appears to be in our future later this week. Rainfall chances will be increasing gradually every day.

The wintry scenario for the Carolinas depends on a strong cold air damming event to set up. That would mean strong high pressure over the Northeast or eastern Great Lakes, sending cold air on a northeast flow into the Carolinas. At the same time, low pressure would need to follow a track across the Southeast.

Some of the models show that. Others show the high pressure system not being that strong, or the low pressure system tracking up the Ohio Valley instead. If that happens, we would have a cold rain.

In recent winters, a strong high pressure system has established itself off the Southeast coast. That has served to fight off intrusions of cold air and keep conditions relatively mild in the Carolinas.
There are signs of such a ridge of high pressure strengthening in the near future.

If cold air damming looks likely and low pressure seems headed on a southerly track, you'll be hearing more about this ice threat soon.