Wednesday, January 7, 2015

First the cold; then a narrow escape Monday?

Exactly a year to the date of last year's coldest arctic outbreak in the Charlotte region, another burst of polar air is spilling into the Carolinas on Wednesday.

An arctic cold front is expected to cross the immediate Charlotte area sometime around midday, and temperatures will tumble from around 40 degrees late Wednesday morning to 10 degrees by daybreak Thursday. And forecasters said there will be even colder readings in some places not far from Charlotte.

The good news, according to meteorologists, is that long-range guidance indicates the Carolinas might escape a messy ice storm early next week.

It was a year ago today when the temperature dropped to 6 degrees in Charlotte. It's not expected to get quite that cold Thursday morning, but readings at daybreak probably won't be too far from the record of 8 degrees for the date.

A wind chill advisory is in effect for Wednesday evening and early Thursday. Winds will gust up to 30 mph from late afternoon until around midnight, causing wind chills of 5 to 15 degrees. Forecasters said the winds will abate overnight, but they'll still be blowing at up to 10 mph, causing wind chills slightly below zero in Charlotte.

In the mountains, wind chill readings could tumble to 10 or 15 degrees below zero.

There are two threats from this cold -- the wind chills, which will be a problem from about 6 p.m. Wednesday until midday Thursday; and the prolonged cold, which will be a problem for water pipes and heating systems.

The polar outbreak will send temperatures below freezing in the Charlotte area from about midnight until shortly before noon Friday. Some areas above 3,500 feet might not get above freezing until Saturday.

Thursday's highs in Charlotte will only reach the upper 20s.  Highs will be in the lower 40s Friday.

When temperatures are in the teens for many hours, as will be the case Thursday, frozen water pipes are the typical result.  Be sure to keep water dripping from a faucet tonight. Plumbers say it's best to use the faucet farthest from where water enters the house.

Heating systems obviously will be seriously taxed.  Assuming it's too late to get a system checkup on
Wednesday, you might want to consider putting towels around window sills that leak cold air. And make sure electrical outlets are covered.

Another tip ... on Thursday, when the sun is shining, be sure to keep your blinds open on sunny sides of the house. Even though the temperature is in the 20s, the solar heat will help warm the inside of your residence.

Looking ahead to next week ...

Moisture is expected to arrive Sunday and intensify Monday, but the computer guidance can't agree on whether that will pose a threat of wintry precipitation for the Charlotte region.

The moisture is coming, the computer models agree.  But they can't agree on the timing, and that's important.  One strong high pressure system over New England will be moving out to sea Sunday, to be follow by another late Monday or Tuesday.

Two of the three most heavily used computer models predict the precipitation will arrive in the "gap" between the two cold high pressure systems.  That means cold rain for the Charlotte region.  The Global weather model predicts the precipitation will arrive with enough cold air still around for freezing rain Sunday.

The National Weather Service is leaning toward the cold rain scenario.

Tuesday, January 6, 2015

Brutal cold could set stage for weekend headaches

The late Woody Hayes, longtime Ohio State University football coach, used to say that three things can happen when you throw the football, and two of them are bad.

That's sort of what it's like when an arctic air mass moves into the Carolinas. As long as the cold is here, or even nearby, we're at risk of trouble.

The cold air -- our coldest of the season -- will arrive Wednesday afternoon. The wind will pick up, and temperatures will fall late Wednesday afternoon and evening from about 40 degrees into the teens. By Thursday morning, many spots in the Charlotte region will be sitting at 10 degrees.

It won't get above 30 degrees in most areas Thursday afternoon, and it'll drop into the teens again Friday morning.

A second arctic air mass will arrive late Friday or Saturday, and although the temperatures with the second system won't be quite as cold, they'll be cold enough to leave us at risk of trouble Sunday.

That's when a low pressure system off the Mexican coast could push eastward and begin affecting the Southeast.

One heavily used weather computer model, the Global, is predicting that the storm system, while weak, will spread precipitation into the Carolinas on Sunday morning. At that point, temperatures will be cold enough for freezing rain.  I realize that some people enjoy wintry precipitation, but I don't think very many people want freezing rain.  Power outages with temperatures in the 30s are not fun.

The other major weather computer model, the European, is predicting that the energy will remain over Baja California a bit longer and not reach the Carolinas until Sunday evening. By that time, the cold dome of high pressure over New England is expected to have moved offshore, and temperatures will climb enough so any precipitation falls as rain.

This is what we'll be watching over the next few days.

By the way, some of the longer-range computer guidance indicates the cold air will be reinforced early next week, and a fairly strong storm system will form off the Southeast coast.  But that's more than a week away, and forecasts that far out are not terribly trustworthy.

Saturday, January 3, 2015

Arctic blast is heading this way

Charlotte-area weather will go through some weird twists and turns over the next 36 hours, but the big story is coming near the end of the week.

An arctic blast, featuring temperatures that are easily the coldest of the season, is poised to envelop the eastern United States and sink far into the South.

The cold air will arrive late Wednesday, as it now appears, and it will be a dry arrival -- no rain, no snow for the Piedmont.

The day of real change will be Thursday. Computer guidance on polar outbreaks is sometimes not extremely reliable, but if you believe what the computer models are forecasting, we might have a tough time climbing above freezing Thursday in Charlotte.

It will be windy, with wind chill temperatures probably at 10 degrees or lower for much of the day in the Charlotte region.  That, of course, means we're looking at morning lows Thursday and Friday in the low to mid teens.

There is nothing to indicate at this point that the cold outbreak will be anything but dry. Humidity levels are forecast to be very low, and it would seem that we're talking about clear-blue skies and cold temperatures.

Computer guidance indicates the shot of cold air will be transient, with temperatures back in the 40s by Friday. But some bitterly cold air will be bottled over Canada, and it's not far-fetched to believe that another push of polar air will move into the Southeast early the following week.

Tuesday, December 30, 2014

Panthers' game day weather looks colder, wetter






Monday, December 29, 2014

First look at Panthers-Cardinals: Wet, mild

If we've learned anything from weather computer models since early December, it's that they change frequently and are not terribly reliable beyond a few days.

But there seems to be agreement, five days away, that weather in the Carolinas this weekend will be unsettled.

The first guess for conditions at 4:30 p.m. Saturday, when the Carolina Panthers and Arizona Cardinals kick off their NFL wild-card playoff game, is for a chance of rain and temperatures above average for early January.

The various computer guidance input seems to agree on wet weather for the weekend, but the details are where everything gets tricky.

Will it rain all day Saturday?  Will the rain be light, sporadic, or heavy?  Those are questions we can't answer yet.

Very cold air is plunging into the continental United States this week, but the core of that cold will remain north of the Mason-Dixon line in the eastern United States. The Midwest and West will see a more southward push of the cold air.

Some of the cold will seep into the Southeast from Tuesday into Friday, but high temperatures those days will still reach the mid and upper 40s.

By the weekend, a moderating trend is likely. That's why the National Weather Service is predicting a high in the upper 50s Saturday.

In a few days, we'll have a better feel for exactly how wet it might be Saturday.

Friday, December 26, 2014

Coming up: A very mild January for Carolinas

Remember the other day, when I wrote that a few computer models were hinting that the much-publicized "pattern change" to cold and stormy weather might not be coming as expected at the beginning of the year?

I wrote that it was just a few runs of the models and not yet a trend.

Now it's a trend.

Most of the long-range guidance, including the pretty reliable Coupled Forecast System (CFSv2) operated by NOAA, is pointing to a mild January in the Southeast. In fact, temperatures could be well above average, if everything breaks the way it seems.

This marks a pretty big bust in many of the long-range forecasts that had called for a chilly and stormy winter, with the worst of the wintry weather arriving in early January.

First of all, this doesn't mean that it won't get chilly in the Carolinas, because it will -- next week. We're looking at several days of below-average temperatures before and immediately after New Years, although it won't be bitterly cold -- just highs in the mid and upper 40s for a few days.

Second, it doesn't mean arctic cold won't push into the United States. It looks like a blast of cold will slide southward from Canada into the Midwest, dumping cold air into Texas all the way to the Rio Grande next week.

But the computer guidance insists that the cold air won't push east of the Appalachians. Many of the forecasts show a persistent high pressure ridge off the Florida coast. Those southeast ridges are a death knell to wintry weather in the Southeast.

The Arctic Oscillation (AO) refuses to go negative, which keeps a steady west-to-east flow across the southern United States.

This doesn't mean our weather won't turn much colder in late January or February, but it means the computers certainly don't think it will happen anytime soon.

What caused the forecasts to go so wrong?  I've been reading a lot of possible explanations, but it's really a reminder that what the science of meteorology has improved a lot in recent years, there are still many things we don't understand. One theory I've seen thrown around the past few days is solar activity, with the theory being that strong solar activity overrides many of our other weather factors.

Greg Fishel of WRAL-TV wrote on his Facebook page on Friday afternoon that the last time we had a pattern like the one developing in early January was in 2005 and again in 2006. Both years, we had highs in the 60s and 70s.

Those two winters produced some of our lightest snowfall ever -- a trace in 2004-05 and 1 inch in 2005-06.

All it takes is one big storm to give us a big snowfall total, but it doesn't seem likely any time soon.

Monday, December 22, 2014

Winter ... now you see it ... now you don't

Those of you who follow weather very closely might be bored by what I'm saying today. Casual followers of weather might want to read on, however.

You all know about computer models -- the computer-based guidance that is a tool used by meteorologists in forecasting the weather.

The models update several times a day, and those who follow the updates closely are sometimes known by the term "model-huggers." Model-hugging can be a frustrating experience, and the last 48 hours is an example of that.

By following some of the output of the Global model, you'd have thought a few days ago that the Carolinas (and much of the central and eastern United States) were heading into arctic cold and winter storms, starting shortly before the end of the year.

Then on Sunday night came new models, indicating that maybe the very cold weather wouldn't be sinking far enough south and east to affect the Carolinas. Maybe it would remain bottled up in Canada, or perhaps moving no farther southeast than the Midwest.

In other words, forget about wintry weather for a while.

Experienced meteorologists tend to study the trends before making forecasts.

The trend late last week pointed to a pattern change for the Southeast. There were indications that we'd move from our December pattern -- with temperatures averaging around seasonal norms and no real threat of wintry weather -- to a wintry, stormy pattern.

One facilitator of that change would be the deep low pressure system that is expected to push northward from the Deep South into the eastern Great Lakes and southern Canada over the next few days.

Now, based on the last few model runs, all that is in doubt again. The most recent computer guidance says the current Carolinas weather pattern will continue, for the most part, into at least the first several days of January.  In other words, no pattern change.

But the model runs late Sunday hardly constitute a trend.  That will be determined from what the guidance tells us over the next few days.

Today's Christmas facts ... Last week, I wrote about the most successful (financially) Christmas movies. But what are the most popular?

The website What To Do With The Kids (which can provide ideas on keeping children busy during the holidays) says it interviewed people last year on their favorite holiday movies.  The response:

1. "How The Grinch Stole Christmas" (the 1966 animated version); 2. "The Polar Express" (2004 animated version); 3. "It's A Wonderful Life" (1946); 4. "Rudolph the Red-Nosed Reindeer" (1964, animation); 5. "Elf" (2004); 6. (tie) "A Charlie Brown Christmas" (1965, animation); "The Santa Clause" (1994); "Frosty the Snowman" (1969, animation); 9. "The Grinch" (2000); 10. "Miracle on 34th Street" (1947 version); 11. "National Lampoon's Christmas Vacation" (1989); 12. "A Muppet Christmas Carol" (1992).

Incidentally, "How The Grinch Stole Christmas" was also No. 1 in the last poll conducted by the website, in 2011.