The Daily Blog

Back-to-Back Storms, More Subzero Cold This Week.

Back-to-back storm systems and widespread cold will bring more harsh winter weather to the eastern two-thirds of the nation this week.

One storm will spread snow and rain along a path from the Tennessee Valley to the Northeast from today through Tuesday, while the next storm will bring significant snowfall to the central and southern Plains from late tonight into Wednesday.

Meanwhile, a new blast of arctic air will spread southward and eastward, with subzero low temperatures extending over a large area from the Plains to the Northeast on Tuesday night.The first storm will be too disorganized to produce the type of intense snowfall that has been common so far this winter, but snow — or rain changing to snow — will occur from Arkansas to New England. Some travel delays may occur, especially from Arkansas to western and northern Kentucky, where communities do not have as much snow removal equipment, and in interior New England, where snow will accumulate up to several inches.Sharply cold air will follow the passage of the storm, setting the stage for widespread bitter cold by Tuesday night and the likelihood of a significant accumulation of snow fairly far south into the Plains by Wednesday, including the Dallas region.

Winter storm watches are in effect in northern Texas and much of Oklahoma. Up to 10 inches of snow is expected in Oklahoma, where strong winds will create drifts of 2 to 3 feet. Wind chill temperatures are expected to approach minus 30 in western Kansas from later Tuesday night into Wednesday.

Accumulating snow is likely to occur as far south as north-central Texas by Wednesday, marking the third accumulating snowfall in this region in the past two weeks.Accumulating snow will likely spread eastward into Arkansas and northern Louisiana during the day Wednesday, and light snow or flurries are possible from northern Mississippi to the Carolinas Wednesday night as the storm weakens.

The cold air currently across the northern Plains and northern Rockies — high temperatures today will remain below zero in parts of Montana and North Dakota — will become more widespread across the Plains, upper Midwest and Northeast during the next couple of days.Low temperatures on Tuesday night will be below zero from western Kansas to northern Illinois, including Chicago, and many locations in Nebraska and Iowa will have low temperatures of at least minus 10. In the Northeast, temperatures will approach minus 15 in the coldest locations in interior New England and upstate New York, with temperatures in the teens in New York City.

The colder than normal weather will continue from the Plains to the East through at least Thursday, with a significant warming trend across the Plains by late in the week. Warmer air will begin to move into the Northeast late in the weekend or early next week.

Say It Ain’t Snow: Midwest, East to Get Socked Again.

A complex and intense winter storm will result in dangerous weather across a large portion of the country, from the Plains to the Eastern Seaboard, during the next couple of days, snarling road and air traffic, closing schools and causing power outages.

The dangerous weather will range from blizzard conditions in the Midwest, including Chicago, to a wintry mix in the cities along the Eastern Seaboard and dangerous thunderstorms along the Gulf Coast.

An initial band of snow, mixed with freezing rain, will race eastward through the Ohio Valley and mid-Atlantic region today and tonight, resulting in moderate accumulations of snow and some travel-related delays.The most intense snow and wind will occur from late tonight into Wednesday as the main part of the storm system gains strength and moves from the southern Plains into the upper Midwest. Snowfall will be more than 16 inches in some locations on the northern and western sides of the storm, where the combination of snow and wind will result in a full-fledged blizzard, with temperatures falling through the 20s.

The major cities in this corridor include Kansas City, Mo., Chicago and Detroit.Close to the track of the storm, a battle between the cold air to the north and unseasonably mild air to the south of the storm will result in a dangerous mixture of snow, sleet and freezing rain. A significant buildup of ice — locally more than .50 inches — will result in dangerous travel and the potential for downed trees and power lines.

This icy corridor will extend from the south-central Plains through the Ohio Valley into the mid-Atlantic and parts of the Northeast. The major cities along the Eastern Seaboard will be in the region where a mixture of precipitation will fall.

Washington, D.C., will have the least amount of icy precipitation, with an extended period of rain as temperatures race to near 50 degrees on Wednesday.

The precipitation will likely change over to plain rain for a time even in New York City, which established a monthly record for January snowfall with last week’s storm. The National Weather Service is expecting 2 to 5 inches of snow and perhaps a half-inch of ice before the changeover to ice and rain, however. Boston, being farthest north, is the most likely to have a mainly snow and ice event.From the Deep South to the Carolinas, the air will be much too warm for any frozen precipitation, but the storm will still pack a punch. Gusty thunderstorms — capable of producing flooding downpours, hail and damaging winds — will occur. Isolated tornadoes are even a threat, especially along the Gulf Coast on Tuesday through Tuesday night.

Bitterly cold air will accompany the storm in parts of the Plains and Midwest — daytime temperatures will be below zero as far south as western Nebraska on Tuesday afternoon, and temperatures will fall to below zero in Chicago by Wednesday night.

Subzero temperatures are possible in parts of the Northeast by Thursday night.

Massive Winter Storm to Sweep Much of Nation This Week.

In a winter that’s becoming known for its powerful storms, the one that’s about to form might be the most impressive of all in terms of the size and scope — affecting much of the eastern two-thirds of the country during the first half of the week.

Heavy snow, ice, rain, thunderstorms and bitter cold will occur along the storm’s path, with the likelihood of widespread travel interruptions, power outages and property damage.

The storm has yet to become organized, but the ingredients will be in place for rapid formation once the low pressure system begins to emerge from the Rockies on Monday. The huge temperature difference between the northern Plains and Gulf Coast will be fuel for the storm as two systems merge in the middle of the country.By early Tuesday, precipitation will likely extend from the eastern Rockies to the northern mid-Atlantic coast, with the most intense portion of the storm developing in the southern Plains. This low-pressure system will track from the Missouri Valley on Tuesday evening to off the New England coast by Wednesday evening.

More than a foot will fall on the northern and western sides of the storm, from the Plains and Missouri Valley through the Midwest and into northern New England. A corridor of accumulating ice will occur near the track of the storm, from the Missouri Valley through the Ohio Valley and into parts of the mid-Atlantic region.

As of Sunday morning, winter storm watches extended from Oklahoma to southern Michigan, including the cities of Kansas City, St. Louis, Chicago and Detroit.The precise track of the storm will determine the type of the precipitation for the major cities along the Eastern Seaboard, which have been pounded with several storms already this season. The National Weather Service is currently expecting a mixture of snow, ice and rain in New York City, Philadelphia and Washington, D.C., with a mixture of snow and ice in Boston.

Bands of rain and thunderstorms will occur south of the storm; the thunderstorms have the potential to reach severe levels, perhaps producing isolated tornadoes along the Gulf Coast on Tuesday and Tuesday night. The strong thunderstorms should remain to the north of central Florida, which was hit with damaging thunderstorms last week.

Winter weather advisories, warnings and wind chill warnings are currently in effect from Montana to Iowa and Minnesota for the northern part of the storm.

The very cold air in the northern Rockies and northern Plains — temperatures will approach minus 30 in northern Montana on Monday night — will move into the western part of the storm on Tuesday. Temperatures will be in single digits in the western Plains on Tuesday.

Temperatures will drop into the lower 20s even in Dallas by Tuesday night, with highs barely above freezing on Wednesday and Thursday. Temperatures late last week were in the middle 70s.

The bitterly cold air will not push as far south in the eastern part of the country, but by the second half of the week, sub-zero low temperatures are possible in parts of the Northeast.

Here Comes More Snow, From Deep South to New England.

Winter storm watches and warnings are in effect from the Deep South to New England for another significant winter storm system, one that will spread snow, sleet, rain and strong thunderstorms along its path during the next couple of days.

Snow amounts might reach a foot in the hardest-hit areas in the mountains of West Virginia, northwestern New Jersey, southeastern New York and southern and eastern parts of New England, including Boston, Hartford and Providence. The major cities farther to the south along the Eastern Seaboard will be spared the highest accumulation of snow, but even there, snow and ice are likely to produce travel delays by the time the storm winds down.

A number of storms this winter have brought the worst conditions to the Eastern Seaboard, but a slightly more inland track, combined with milder air from the south and east, will shift the focus of the current storm farther inland, except across New England, where enough cold air is expected to remain in place to result in mainly snow.The accumulating snow will begin as far south as northern Mississippi, northern Alabama and much of Tennessee this afternoon and tonight as cold air pours into the ongoing storm. Rain will change to heavy, wet snow, accumulating as much as a few inches.

The storm will ride northward through the mid-Atlantic region on Wednesday and through New England from Wednesday night through Thursday.

Washington, D.C., New York City and even most likely Philadelphia will experience a complete changeover to rain, with sleet and rain possibly mixing with the snow in Boston for a time. Regardless, the National Weather Service is forecasting 8 to 12 inches of snow in Boston.For New York, Philadelphia, Baltimore and Washington, the rain will change back to snow before the storm ends Wednesday night or Thursday, resulting in slippery roads. Any accumulation of snow will be light as far south as Washington, but a few inches of snow could quickly pile up in New York City.

The heaviest snow will occur where it will remain cold enough for snow during the entire event, and the combination of snow and wind will be fairly intense from northwestern New Jersey to eastern Maine as the storm begins to intensify on its northeastward track.

Along the Gulf Coast, the storm system will bring much-needed rain in the form of showers and thunderstorms. The thunderstorms, however, have the potential to produce damaging winds and isolated tornadoes, mainly across Florida this afternoon and tonight.

While a northwesterly wind following the storm will bring colder air into the Northeast and mid-Atlantic during the latter part of this week, it will not be as bitterly cold as it was last weekend through Monday, when numerous locations had low temperatures well below zero.

However, another bitter blast of Arctic air is likely to arrive during the first part of next week.

Widespread White Christmas Expected Across US.

For the second consecutive winter, a cold and stormy December has set the stage for a white Christmas across a significant part of the U.S. While snow cover is not likely to be quite as extensive as it was last year, a late-week storm might cover the ground in a magical white in parts of the East by the end of Christmas Day.

The depth of the current snow cover will guarantee a white Christmas in the Rockies and interior parts of the West, as well as in the northern Plains, much of the Ohio Valley, the Great Lakes and interior parts of the Northeast.Snow cover is spotty or completely lacking in parts of the mid-Atlantic region and coastal Northeast, but meteorologists are watching a late-week storm that could change that. Computer models are projecting a storm to move from the central Plains on early Friday to along the New England coast by later on Saturday, spreading snow along its path.

If this storm track materializes, fresh snow would be dumped from Iowa to parts of the Virginias, with a brand-new snow cover a possibility for the major cities along the Eastern Seaboard, from Washington, D.C., to Boston.Early-week storms moving through the West will increase the snow cover in the mountains of the West and Desert Southwest, expanding snow cover into some regions that are bare.

Even with the additional snow this week, snow cover was a little more extensive last Christmas when the combination of Arctic cold and a southern storm produced an abundance of snow.

Snow cover on Dec. 25, 2009, extended farther to the south in the Southwest and Plains than it will this year, with snow on the ground as far south as Dallas. Snow cover was also deep in the Virginias, Maryland, Delaware and southern New Jersey, following the first of a couple of monster snowstorms in what turned out to be the snowiest winter on record.Typically, a white Christmas is a virtual certainty in the high mountains of the West, the extreme northern Plains and interior parts of northern New England, with a likelihood of greater than 90 percent. The likelihood drops to just 5 to 10 percent along a line extending from the Texas Panhandle to southern Virginia.

This year, a white Christmas is likely in much of the region, where there is just a 26 to 40 percent chance on average.

A white Christmas is generally defined as having an inch or more of snow on the ground.

Lunar Eclipse Falls on Winter Solstice for First Time in Centuries.

As many as 1.5 billion people worldwide will be able to watch when the Earth’s shadow creeps across the moon’s surface early Tuesday morning, the first time in hundreds of years that a lunar eclipse will fall on the winter solstice.

With the full moon high in the winter sky, the lunar eclipse will be visible from four continents, with the best views from North America and Central America if weather permits, scientists say.”It’s a really democratic event,” Andrew Fraknoi, the chairman of astronomy at Foothill College in Los Altos Hills, told the San Francisco Chronicle, “because you don’t need an expensive telescope or any other sophisticated equipment to enjoy the spectacle — just your eyes or, if you like, a pair of binoculars.”

Unlike a solar eclipse, eclipses of the moon can usually be observed anywhere in the hemisphere where the moon is above the horizon.That means portions of this particular lunar eclipse could also be seen from northern and western Europe, and a small part of northeast Asia, including Korea and much of Japan. Totality will also be visible in its entirety from the North Island of New Zealand and Hawaii — a potential viewing audience of about 1.5 billion people, according to Space.com.

Total lunar eclipses in northern winter are fairly common -– NASA says there have been three of them in the past ten years alone. However, a lunar eclipse falling precisely on the date of the solstice is quite unusual.

Geoff Chester of the U.S. Naval Observatory inspected a list of eclipses going back 2000 years for NASA.

“Since Year 1, I can only find one previous instance of an eclipse matching the same calendar date as the solstice, and that is 1638 DEC 21,” Chester said, according to NASA. “Fortunately we won’t have to wait 372 years for the next one … that will be on 2094 DEC 21.”

This year’s event will take 3 hours and 38 minutes. The eclipse begins on Tuesday, Dec. 21, at 1:33 a.m. ET, according to NASA. At that time, Earth’s shadow will appear as a dark-red mark at the edge of the moon. It will take about an hour for the mark to expand and cover the entire moon. Totality begins at 2:41 a.m. and lasts for 72 minutes.During totality, the moon will be entirely immersed in the Earth’s shadow, but the moon will not disappear from sight. Instead, it should appear to turn coppery red, as Earth’s atmosphere refracts sunlight into the shadow.

Since the Earth’s shadow is cone-shaped and extends out into space for about 844,000 miles, sunlight will be strained through a sort of “double sunset,” all around the rim of the Earth, into its shadow and then onto the moon, according to Space.com.

If you’re planning to dash out for only a quick minute, NASA recommends that you choose this one: 3:17 a.m. ET. That’s when the moon will be in deepest shadow, displaying the most fantastic shade of copper red.

Weather Extremes in 2010 Shattered Slew of Records.

(Nov. 5) — Government forecasters highlighted the potential for “another winter of extremes” in the U.S. in their recently issued 2010-11 winter outlook, and that seems an appropriate assessment coming off a year in which numerous all-time records have been set, ranging from winter cold and snow to summer heat to thousand-year rainfall events.

Winter Snow and Cold

The combination of an active southern storm track and occasional arctic blasts from Canada resulted in a remarkable 2009-10 winter across much of the eastern two-thirds of the United States.All-time seasonal snowfall records were established in the mid-Atlantic region, including in Washington (56.1 inches at Reagan National Airport and 78.7 inches at Dulles International Airport), Philadelphia (78.7 inches) and Atlantic City, N.J. (58.1 inches). February alone resulted in nearly two dozen all-time monthly and single-storm snowfall records.The snow was not limited to the mid-Atlantic region. On Feb. 12, every state except Hawaii reported at least a trace of snow on the ground.

While snow was the focus in February, it was widespread cold that stole the weather headlines from December into early January, when arctic blasts from Canada resulted in bouts of extreme cold.

In early January, high temperatures remained below zero in parts of the northern Plains, and low temperatures plummeted well below freezing even into central Florida. West Palm Beach, Fla., experienced its coldest 12-day stretch since at least 1940, according to the National Weather Service.

The winter was one of the top 10 coldest on record in many Southern states, and it was the coolest December through March on record in Key West, Fla.

Summer Heat

The cold and snow were followed by intense summer heat, the result of a persistent and strong high-pressure system in the upper levels of the atmosphere, which was centered farther to the east than during a typical summer. In a dramatic turnaround, many of the places that had extreme winter cold experienced extreme summer heat.

June through August was the hottest on record in 11 states, from Mississippi to Rhode Island, and 35 of the 48 continental U.S. states had one of the top 16 hottest summers on record. Cities with all-time record-breaking summer heat included Washington, Baltimore, Philadelphia and New York.

The summer was normal or cooler than average in the Pacific Northwest and California, but a fall Western heat wave resulted in the hottest day on record in downtown Los Angeles. The temperature soared to 113 degrees on Sept. 27, breaking the old record of 112 set on June 26, 1990.

Flooding

Flooding is a common weather hazard in the U.S. every spring and summer, but a couple of events in the past year were particularly noteworthy.

The epic flood in Tennessee in early May is considered to be a 1,000-year event, which means the type of weather event that should occur only once per millennium. Nashville, having sustained more than $1 billion in damage on its own, is the defining location of the two-day storm that dumped about 40 percent of the average annual rainfall in two days. Massive flooding also occurred in much of western and central Tennessee, as well as in parts of Kentucky, northern Mississippi and Arkansas.Arkansas was also the site of a deadly flood a couple of weeks later, when over 10 inches of rain, most of which fell during the overnight hours, resulted in a torrent of water sweeping through campsites. It’s believed that 20 people were killed in the flood.

Possible Winter 2010 Extremes

The National Oceanic and Atmospheric Administration based its winter prediction of more extremes largely on the presence of a La Nina, which is a cooling of sea-surface temperatures in the equatorial Pacific that influences global weather patterns.

Across the United States, the most common extremes during a winter with a La Nina include heavier than normal rain and mountain snow in the Pacific Northwest and northern Rockies, drought conditions in the southern tier of the country and colder and stormier than normal weather in the northern Plains.