Along the leading edge of the invading polar blast, accumulating snow will spread from the Midwest to the East Coast on Tuesday.

The snow will come courtesy of yet another Alberta Clipper set to drop through the Dakotas and Ohio Valley on Monday through Monday night with accumulations on the order of a coating to 2 inches.

The snow will become heavier as it streaks across the mid-Atlantic on Tuesday, then makes a northeastward turn toward southern New England late in the day and evening.

Travel conditions will deteriorate with slippery roads and flight delays expected to unfold even in areas that avoid heavy snow. As colder air invades the storm, winds will increase and cause some blowing and drifting of the snow that has already fallen.

The polar vortex that gripped much of the country has moved on, but don't get too comfortable - another round of frigid air is expected to arrive next week across the northern U.S., from the Dakotas eastward to New England.

It'll be cold, but not the life-threatening cold of last week when subzero temperatures enveloped much of the country and contributed to at least a dozen deaths.

Temperatures will start falling over the weekend into Monday, said Bob McMahon, a meteorologist with the National Weather Service. The cold is expected to persist until Thursday, just in time for a second blast of frigid air to move in and keep temperatures about 10 degrees below average, he said.

The Sun's activity is at its lowest for 100 years, scientists have warned. They say the conditions are eerily similar to those before the Maunder Minimum, a time in 1645 when a mini ice age hit, Freezing London's River Thames. Researcher believe the solar lull could cause major changes, and say there is a 20% chance it could lead to 'major changes' in temperatures.

Conventional wisdom holds that solar activity swings back and forth like a simple pendulum. At one end of the cycle, there is a quiet time with few sunspots and flares. At the other end, solar max brings high sunspot numbers and frequent solar storms.

It's a regular rhythm that repeats every 11 years. Reality is more complicated. Astronomers have been counting sunspots for centuries, and they have seen that the solar cycle is not perfectly regular. 'Whatever measure you use, solar peaks are coming down,' Richard Harrison of the Rutherford Appleton Laboratory in Oxfordshire told the BBC.

'I've been a solar physicist for 30 years, and I've never seen anything like this.' He says the phenomenon could lead to colder winters similar to those during the Maunder Minimum. 'There were cold winters, almost a mini ice age. 'You had a period when the River Thames froze.'

As thousands of drivers and schoolchildren can tell you firsthand, Thursday's surprise snowfall created a near-standstill for Des Moines-area travel for hours.

At least 25 cars were involved in a pileup on Interstate Highway 80 near Waukee during the evening rush hour. Another 20-plus cars jammed U.S. Highway 169 between Adel and De Soto. Some people were without power for hours because roads laden with accidents kept crews from reaching the outage area.

And in Des Moines, at least one school bus was still taking students home after 9 p.m. because of poor road conditions.

"Those buses began their routes just as the worst of the storm was hitting the metro by surprise," district spokesman Phil Roeder said.

A bus that left Greenwood Elementary School at 4:30 p.m. was still en route to student houses at 9 p.m. Roeder said that he wasn't sure how long the route typically takes, but that students had always been home in time for dinner.

Another bus that left Windsor Elementary School at 4:30 p.m. didn't finish its route until 8:30.

Roeder said bus drivers remain in touch with dispatchers while on the road. Dispatchers then contact parents. Roeder said not every parent was contacted because of the unexpected conditions.

A series of avalanches in the Alps have claimed several lives over the past couple of days.

Despite repeated efforts to resuscitate him, a 24-year-old Frenchman died on his way to hospital on Thursday, at Bardonecchia in the Italian Alps above Turin.

He had been snowboarding and was apparently struck by an avalanche caused by other off-piste skiers.

Reports in Italian media say police have opened an investigation for manslaughter.

At Courchevel in the French Alps a mountain worker and his son were both hit by a wall of snow as they tried to reach their chalet refuge.

The boy survived but his father, an experienced mountaineer, was killed.

Two other teenage skiers died in separate avalanches, at Serre-Chevalier and at La Plagne.

Scientists are saying that the Sun is in a phase of "solar lull" - meaning that it has fallen asleep - and it is baffling them.

History suggests that periods of unusual "solar lull" coincide with bitterly cold winters.

Rebecca Morelle reports for BBC Newsnight on the effect this inactivity could have on our current climate, and what the implications might be for global warming.

We are about to enter a very interesting period, and while I know that many of you like the cold, this next Arctic outbreak could be dangerous and even historic. I put out an article about a week ago and then one before that that basically restated that I thought that mid to late January going into February could end up being dangerously cold for the central and eastern U.S. While I have really been putting myself out on the line over these last few weeks, I am now getting a lot of forecast model support to back up what I saw coming several weeks ago. Like I said on the Facebook page, the GFS model did not handle the last Arctic outbreak that well in predicting this in the long-range, so I absolutely had no reason to believe that anything would be different this time. Yet again, many fell into the trap of using the GFS as their model of choice for their long-range forecast, and they got burned. See, weather and climate works in cycles, and you have to be able to see those cycles. If you miss that, then you're left depending on a model that dictates your forecasts, and those forecasts can change A LOT! You're at the mercy of the forecast models, and I try to never put myself in that situation.

Now that I'm getting the support of the forecast models and we're much closer to the event, I want to show you what the models are predicting. In fact, if what the forecast models are predicting for the last week of January going into February comes to fruition, then we have a historic Arctic outbreak on our way that would give us brutal cold. The Canadian model also supports a big East Coast storm later in January, which I really think could happen. From the way things are starting to look, this cold pattern could lock in, which would continue into February, and we could also move into a very stormy pattern. Many of you have commented on the Facebook page (yes, I take the time to read almost all of your comments and messages) that you were disappointed that you didn't get any snow with this last Arctic outbreak. I'm really thinking things will be different this time. No, I'm not saying that Miami, FL will get snow, but I do think many areas in the Southeast and up the East Coast will.

It now appears that the stratosphere will kick off a number of indices that deem February to be the coldest prolonged period of winter thus far. In today's post, I will address multiple indices that favor a significantly colder than normal February.

Part I: The Stratosphere

- First Warming
In the opening days of January, we saw a stratospheric warming event occur. This event was minor, as the chart above (depicting temperature anomalies in the upper latitudes) shows. Nevertheless, this first warming event, coupled with the ongoing warming event is helping to destabilize the polar vortex in the stratosphere. So far this winter, the stratospheric polar vortex has been resistant to any and all attempts to be put down. We can attribute this to the positive phase of the Quasi-Biennial Oscillation (QBO), which is unfavorable for a weak polar vortex. These two first warmings are just tastes of what is to come. While the first warming was minor, it seems to have shaken up the vortex at least a bit, and this ongoing warming event right now is most likely helping with some slight (at the very least) destabilization of the polar vortex.

Global sea ice is supposed to be melting away. We are often led to believe that it is at or near record lows. It's global warming after all, and everyone knows that warmth melts ice. But if ice is growing, maybe it's a sign that things are cooling down.

From the chart that follows we do see that global sea ice did take a small hit in the 2000s, especially the Arctic. However the trend for the last three years is definitely a strong upward one.

Scientists have uncovered more evidence for a dramatic weakening in the vast ocean current that gives Britain its relatively balmy climate by dragging warm water northwards from the tropics. The slowdown, which climate modellers have predicted will follow global warming, has been confirmed by the most detailed study yet of ocean flow in the Atlantic.

Most alarmingly, the data reveal that a part of the current, which is usually 60 times more powerful than the Amazon river, came to a temporary halt during November 2004.

The nightmare scenario of a shutdown in the meridional ocean current which drives the Gulf stream was dramatically portrayed in The Day After Tomorrow. The climate disaster film had Europe and North America plunged into a new ice age practically overnight.

Although no scientist thinks the switch-off could happen that quickly, they do agree that even a weakening of the current over a few decades would have profound consequences.