Saturday, November 22, 2014

Problems ahead for big Thanksgiving travel day?

A few days ago, we were giving Thanksgiving travelers the all-clear signal for Tuesday and Wednesday. Now that outlook isn't so rosy.

Both the Europeans and Global computer models are predicting the development of a low pressure system along the Carolinas coast Wednesday, and that spells possible trouble for travelers.

"There definitely will be a coastal low," National Weather Service meteorologist Scott Krentz said Saturday evening. "The big question is how close to the coast it will be."

The closer to the coast, the farther inland for precipitation.

Wednesday is the biggest travel day of the year, and rain will make a mess of things for those flying or driving somewhere for Thanksgiving. Right now, it appears as if the biggest problems will be for anyone headed toward eastern North Carolina, including the Raleigh area, or up into central and eastern Virginia.

I must point out that temperatures will be chilly Wednesday, and although the precipitation almost certainly will fall as rain, some of the information being churned out by the computers says "snow," especially for northeastern North Carolina and farther to the west in the N.C. mountains.

I've traveled on a rainy Wednesday before Thanksgiving, and it was miserable.  A steady rain turned a trip up I-85 to Richmond into an ordeal.

We should have a better idea on the makeup of the storm, including its path, by later Sunday or early Monday.

But it's definitely a new -- and unwanted -- wrinkle in the Thanksgiving travel picture.

Thursday, November 20, 2014

Good news for Thanksgiving?

It looks as if weather patterns across the eastern United States are shaping up nicely for Carolinas residents during the Thanksgiving holiday week.

Translated ... travelers apparently won't have to deal with big storms, and those who enjoy a winter-like feel to the air will get their wish on Thanksgiving Day.

If your preference is for shorts and T-shirts on Thanksgiving, sorry!

Thanksgiving week will be ushered in with a fairly significant storm system across the eastern United States. Low pressure will move up the Ohio Valley late Saturday and Sunday. A weak cold air damming event could develop in the Carolinas Piedmont and Foothills on Sunday, but it probably won't last long -- especially in the Piedmont.

That will set the stage for a rainy Sunday, with temperatures in the 60s.

By the way, the atmosphere will have one element needed for severe weather Sunday -- wind shear. But instability will be lacking, so we're probably looking at showery weather.

The showers will taper off Monday, and we'll be in a warm sector for the day before another cold front arrives. That means highs in the upper 60s and lower 70s.

The next cold front arrives Monday night, and it will be followed by another front later in the week. By Thanksgiving, we're probably looking at high temperatures in the low to mid 40s for Charlotte, with sub-freezing morning lows. But there are no signs of major storm systems, even for the weekend after Thanksgiving.

Incidentally, our warm-up Sunday and Monday will sweep into the North. Highs in the 60s are possible for New York and Philadelphia.  Places along the Great Lakes that were hit with heavy snow this week will see a rapid melt-off Sunday and Monday.

For Thanksgiving holiday travelers, the advance outlook is good.

"I don't see anything that will be a problem in the Southeast for travelers on Tuesday and Wednesday," said Chris Horne, of the National Weather Service office in Greer, S.C.

Wednesday, November 12, 2014

Cold? Absolutely! Record-breaking? No!

A lot is being made by weather watchers -- including me -- of the cold wave arriving in the Carolinas later Wednesday.

For several nights, we've watched national newscasts showing heavy snow and bitter cold in the Rockies and Midwest. Even Texas has gotten into the act, with temperatures taking a 40-degree nose dive.

Terms like "polar vortex" and "arctic blast" are being thrown around, and you'd almost think we were in the thick of winter.  That's not the case.

First, here are a couple things that the cold wave will do:

1. Last a while.  This pattern change will last at least two weeks, until around Thanksgiving. A couple reinforcing surges of cold air will push into the United States and reach the Southeast next week and early the following week.

2. Drop temperatures considerably.  We've been in the 70s for several days, and that will end after today.  Thursday will be a cross-over day, with highs in the 50s as colder air filters in. A secondary cold front will arrive later Thursday, dropping Friday's highs to the 40s.  That's a lot colder than anything we've had for a while, and it's well below the seasonal average high in Charlotte for this time of year -- 63 degrees.

3. Bring snow -- to parts of the North.  The traditional "lake-effect" snow areas around the Great Lakes will get a lot of snow from these various surges of cold air. We're talking about upstate New York (from Lake Ontario); the area from Cleveland's eastern suburbs to Buffalo (Lake Erie); Michigan's Upper Peninsula (Lake Superior); and the corridor from South Bend, Ind., up along western Michigan's shore (Lake Michigan).

But here are some things the cold wave is not:

1. A record-breaker.  A few records might be broken, but here's something to think about. The coldest morning low temperature in the first surge of cold air this weekend in Charlotte will be 24 or 25 degrees Saturday. The record low for Saturday is 20, set in 1969.

2. Unusual.  "The upcoming pattern will feature a trough in the eastern United States, and that's typical in winter," said John Tomko, of the Weather Service's Greer, S.C., office. "It's just a few weeks earlier than usual. But it's the kind of pattern we always see."

3. Aiming at the Southeast.  Tomko said the trough will be strong but broad, rather than deep. What does that mean?  Instead of the coldest of the air surging all the way into the Deep South, it will run out of steam to our north -- over Kentucky, West Virginia and Virginia. "Certainly, colder air will reach our area," Tomko said. "But the coldest air will be held to our north."

Monday, November 10, 2014

As advertised, the cold air is coming

The weather pattern change that we started talking about early last week is unfolding Monday across the northern part of the United States.

A very strong storm system that battered western Alaska last Friday helped create a kink in the jet stream, and that is allowing an outbreak of arctic air to blast into much of the United States.

The cold air will reach the Charlotte region Thursday, but the heart of the arctic outbreak appears to be aimed at the central third of the United States. Places like Des Moines, Iowa, are not forecast to climb above freezing for much of the week. In Dallas, where the front is expected to arrive Tuesday, post-frontal high temperatures will only reach the 40s.

The cold air will trigger an outbreak of heavy lake-effect snow squalls in the Great Lakes.

And forecasters said long-range guidance from the computer models points to a second surge of cold air about a week from now. The coldest of that air might be aimed farther eastward, toward the eastern Great Lakes, the Northeast, and the Southeast.

This change in the pattern will last a while -- probably two weeks and maybe a bit more. That will take us into the beginning of Thanksgiving week.

So far, there are no strong indications that storm systems will form in the Southeast while the heart of the cold is around. And that will prevent an early-season snow or ice event, although there is a chance that a low pressure system expected to form in the Gulf of Mexico on Friday could bring snow to the North Carolina mountains Sunday.

We said good-bye to the 80s with the arrival of a strong cold front a few days before Halloween. Now it looks as if the next outbreak of very chilly air will mark an end to the 70s, at least for a while.

Thursday, November 6, 2014

Still looking cold for later next week

Computer guidance still indicates an outbreak of unseasonably cold air will push into the Carolinas next week, although it now appears as if the really chilly conditions might not arrive until Wednesday or even Thursday.

But everything basically looks the same as it did 24 hours ago.

A huge storm system is forecast to develop in the Aleutians on Friday, bringing winds of 75 mph and 45-foot waves into the Bering Sea. That system then will contribute to a kink in the jet stream, allowing polar air to dive southward into the continental United States.

This is a big change in our pattern, and computer models tend to have problems locking onto a solution. That means you might see a lot of changes in advanced forecasts over the next few days.

But barring something unexpected, it appears likely that we'll see temperatures later next week that are more like January than November.

There also are some hints of a storm system developing along the polar front later next week, but let's not get excited about that yet.

Wednesday, November 5, 2014

Alaska super storm could mean cold November for us

The remnants of a strong typhoon are expected to develop into a super storm off southwest Alaska and then could help bring the Carolinas some of its coldest November weather in years, starting next week.

That is the scenario gaining favor among meteorologists and computer models this week,

Some guidance from the trusted Global and European computer models paint a picture of daytime highs in the 30s and morning lows around 20 degrees in the Charlotte area by the middle of next week, in fact.

How will all this happen?

It starts with Typhoon Nuri, which was a Category 5 storm with 180 mph winds before weakening northeast of Japan during the past day. Nuri is forecast to swing northeast, into the north Pacific, and head toward the Bering Sea as it morphs into a very powerful non-tropical system.

In its morning summary, the National Weather Service office in Anchorage said the Aleutians storm could set a record for lowest barometric pressure Friday. Winds in the western Aleutians are forecast to be at hurricane force, with waves of 43 feet or more.

This is where the forecast moves into the "theory" category.

Meteorologists have noticed in recent years that strong storm systems near Alaska can ripple the jet stream, causing a big dip from Alaska across western Canada and into the eastern United States. That is the recipe for blasts of cold air to push into areas east of the Mississippi River.

You can find a write-up of this situation here and there's another one here.

The computer models are picking up on this situation and are predicting a surge of cold air into the United States around Tuesday or Wednesday of next week. Typically, a pattern shift like this doesn't go away quickly, and this could persist through the month of November.

Last weekend's snowfall in the Carolinas, interestingly, was the work of the remnants of another former tropical system, Hurricane Ana, which had threatened Hawaii earlier.

We'll be watching this situation over the next week.

Thursday, October 30, 2014

Maybe some snow for Charlotte, after all

Bulletin boards on meteorology websites have come alive in the past 24 to 48 hours in advance of the arrival of an unusual autumn storm system that appears likely to bring a real taste of winter to parts of the Carolinas.

The approaching system is an early wake-up call for snow-lovers, who probably thought they'd have to wait another month.

Let's start out by saying that you won't need to worry about shoveling snow in Charlotte. There hasn't been accumulating snow here before Nov. 11 since 1878, according to the National Weather Service.

But at least some of the computer guidance used by the Weather Service and other professional meteorologists continues to insist that the ground might get coated Saturday in areas not far from Charlotte.

The National Weather Service has jumped aboard the Snow Express and decided Thursday afternoon to mention snow as part of the forecast for Charlotte on Saturday morning. The official forecast calls for "little or no accumulation," but it's amazing that the Weather Service even has to deal with the possibility of accumulating snow this early in the season.

The likely scenario is that some folks near Charlotte will see snowflakes mixing with the rain showers at times Saturday morning.

It looks as if it will be a much more wintry picture in the mountains.

The storm system is in western Canada on Thursday. It is forecast to push quickly across Canada and then dive southeast, wrapping around a kink in the jet stream. The storm system, which computer models predict will be quite strong, is predicted to across the Carolinas on Saturday and then intensify when it reaches the coast. After that, it might push up the East Coast, possibly as some version of a nor'easter.

One National Weather Service report indicated Saturday's storm system -- considering the strength and the cold temperatures accompanying it -- is a once-in-50-years event.

Winter storm warnings are posted for the North Carolina mountains bordering Tennessee, where 4 to 6 inches of wet snow is a good bet Saturday. Appalachian State University has a home football game at 3:30 p.m. Saturday against Georgia State.  Conditions in Boone might be interesting.

Winter weather advisories are in effect for lower mountain elevations, including Asheville. But since the ground is still quite warm and Saturday is only the first day of November, it just seems too early for an accumulating snow event in non-mountain areas.

So forecasters are hedging their bets a bit about snow in places like Asheville.

In Charlotte, Saturday is likely to be a raw day. We'll have mostly cloudy skies, off-and-on rain (with maybe a few snowflakes mixed in), cold temperatures and a gusty breeze. Highs might not climb out of the lower 40s, especially if it stays cloudy all day.

It was in the 80s Tuesday. It seems weird to be talking about snow on Saturday. But as longtime Carolinas' residents know, that's often how it works out.