Why Extreme Cold Has Hit U.S.

What's going on? Blame the so-called lake effect, the polar vortex, a kink in the jet stream—and an old super typhoon.

The lake-effect snow comes from west-southwesterly winds of a storm aligning neatly with the lengths of Lakes Erie and Ontario, which sit between the American Midwest and Canada. That alignment is "allowing the air to pick up large amounts of moisture," writes Jeff Masters, director of meteorology at Weather Underground, on his blog.

Lake-effect snow tends to result from cold, dry winter winds sweeping from Canada across unfrozen lakes. As they cross open water, the winds pick up moisture and become warmer. When that moist air reaches the eastern sides of the lakes, it's forced to rise abruptly over the land and over the colder air above the land.

The results are exceptional snowfalls in bands along the southeastern sides of the lakes, often accompanied by the unusual winter phenomena of thunder and lightning. But even by those standards, this week's snow stands out. "I can't remember and I don't think anyone else can remember this much snow falling in this short a period," Erie County, New York, executive Mark Poloncarz told CNN.

The most dramatic effect normally extends up to 70 miles (113 kilometers) inland from the lakes, but bands of light snow and flurries can extend hundreds of miles inland.

Now about that extreme cold...

Temperatures in much of the country have dipped 15° to 35°F (8 to 19°C) below average as a blast of Arctic air from the polar vortex—which normally circles the North Pole—has drifted southward over the eastern two-thirds of the United States. Cold temperatures this week reached south all the way into the Florida Panhandle, where Pensacola hit 28°F (-2°C).

Masters also blames what he calls "an unusually extreme jet stream pattern," which is seeing a collision of high and low pressure. The meteorologist describes a "sharp ridge of high pressure along the U.S. West Coast and a deep trough of low pressure diving to the south over the central United States."

The juxtaposition has allowed cold air to spill out of the Arctic, behind the trough, and into the central U.S.

The extreme early chill is also due in part to the impact of Super Typhoon Nuri, which warmed up waters west of Alaska ten days ago and "caused a ripple effect on the jet stream," Masters wrote.

http://news.nationalgeographic.com/news/2014/11/141119-snow-cold-weather-polar-vortex-weather-jet-stream-science/

Climate Change Due To Global Warming

The Impact of Climate Change on Natural Disasters
	Climate change may not be responsible for the recent skyrocketing cost of natural disasters, but it is very likely that it will impact future catastrophes. Climate models provide a glimpse of the future, and while they do not agree on all of the details, most models predict a few general trends. First, according to the Intergovernmental Panel on Climate Change, an increase of greenhouse gases in the atmosphere will probably boost temperatures over most land surfaces, though the exact change will vary regionally. More uncertain—but possible—outcomes of an increase in global temperatures include increased risk of drought and increased intensity of storms, including tropical cyclones with higher wind speeds, a wetter Asian monsoon, and, possibly, more intense mid-latitude storms. (For more information, see Global Warming: Potential Effects of Global Warming)
	Global warming could affect storm formation by decreasing the temperature difference between the poles and the equator. That temperature difference fuels the mid-latitude storms affect the Earth’s most populated regions. Warmer temperatures could increase the amount of water vapor that enters the atmosphere. The result is a hotter, more humid environment. At the equator, where conditions are already hot and humid, the change isn’t expected to be large. At the poles, however, the air is cold and dry; a little extra heat and water vapor could raise temperatures greatly. As a result, global warming may cause the temperature difference between the poles and the equator to decrease. and as the difference decreases, so should the number of storms, says George Tselioudis, a research scientist at NASA Goddard Institute for Space Studies (GISS) and Columbia University. But even as a warming climate might decrease the overall number of storms that form, it could increase the number of intense storms. As temperatures continue to rise, more and more water vapor could evaporate into the atmosphere, and water vapor is the fuel for storms. “If we are creating an atmosphere more loaded with humidity, any storm that does develop has greater potential to develop into an intense storm,” says Tselioudis. http://earthobservatory.nasa.gov/Features/RisingCost/rising_cost5.php

Hottest year on record

It’s official: 2014 has taken the title of hottest year on record. That ranking comes courtesy of data released Monday by the Japan Meteorological Agency (JMA), the first of four major global temperature recordkeepers to release their data for last year.

The global average temperature record from 1891-2014.
Credit: JMA

The upward march of the world’s average temperature since 1891 is a trademark of human-influenced global warmingwith 2014 being the latest stop on the climb. All 10 of the hottest years have come since 1998.

The average temperature was 1.1°F above the 20th century average according to JMA’s data. That edges 1998, the previous warmest year, by about 0.1°F.

RELATED	Climate Change’s Calling Card in 2014: Heat Europe’s Record Heat Directly Tied to Climate Change Seventeen U.S. Cities on Track for Hottest Year

One big difference between 2014 and 1998 is that the latter was on the tail end of a super El Niño, which has the tendency to spike temperatures. In comparison, 2014 was the year of the almost El Niño.

Instead, record warmth in other parts of the Pacific as well as the hottest year on record in Europe were some of the main drivers in fueling the heat. Joe Romm of Climate Progress also notes that heat in Australia early in the year and California’s hottest year further contributed to the heat.

A comparison of 2014, the hottest year on record, and 1998, the previous record holder.
Credit: JMA

Seasonal temperatures also paint a picture of a planet that didn’t get a break. Spring, summer and fall were all record-setting hot. Last winter was the only season not to set a record, and even that was still the sixth-warmest winter.

JMA is one of the four major groups that use both ground measurements and satellites to compute the planet’s average temperature. The other three include NASA and the National Oceanic and Atmospheric Administration in the U.S. and the Hadley Center in the U.K. There are subtle differences in how they analyze temperature data, but there’s generally broad agreement, particularly the upward trend in temperatures over the past century.

The other groups are expected to release their data in the coming weeks and confirm that 2014 was indeed the hottest year on record. And some scientists think it could get even hotter sooner. Strong trade winds in the Pacific have likely had a dampening effect on the global average temperature by essentially allowing the ocean to store more heat, but those winds are expected to weaken in the near future as part of a natural fluctuation.

Billion Dollar Disasters

2014 in Context

In 2014, there were 8 weather and climate disaster events with losses exceeding $1 billion each across the United States. These events included a drought event, a flooding event, 5 severe storm events, and a winter storm event. Overall, these events resulted in the deaths of 53 people and had significant economic effects on the areas impacted. Further cost data and figures on individual events in 2014 will be announced in mid-2015.

Methodology and Data Sources

In 2012, NOAA's National Climatic Data Center reviewed its methodology on how NCDC develops Billion-dollar Disasters. NCDC held a workshop with economic experts (May, 2012) and worked with a consulting partner to examine possible inaccuracy and biases in the data sources and methodology used in developing the loss assessments (mid-2013). This ensures more consistency with the numbers NCDC provides on a yearly basis and give more confidence in the year-to-year comparison of information. Another outcome is a published peer-reviewed article "U.S. Billion-dollar Weather and Climate Disasters: Data Sources, Trends, Accuracy and Biases". This research article found the net effect of all biases appears to be an underestimation of average loss. In particular, it is shown that the factor approach can result in an underestimation of average loss of approximately 10–15%. This bias was corrected during a reanalysis of the loss data to reflect new loss totals.

It is also known that the uncertainty of loss estimates differ by disaster event type reflecting the quality and completeness of the data sources used in our loss estimation. In 2014, two of the eight billion-dollar events (i.e., the drought and flooding event) have higher potential uncertainty values around the loss estimates due to less coverage of insured assets. The remaining 6 events (i.e., 5 severe local storms and a winter storm) have lower potential uncertainty surrounding their estimate due to more complete insurance coverage. To that end, we have temporarily rounded our loss estimates to the nearest billion dollars while developing research to define uncertainty and confidence intervals surrounding these estimates.

In performing these disaster cost assessments these statistics were taken from a wide variety of sources and represent, to the best of our ability, the estimated total costs of these events -- that is, the costs in terms of dollars that would not have been incurred had the event not taken place. Insured and uninsured losses are included in damage estimates. Sources include the National Weather Service, the Federal Emergency Management Agency, U.S. Department of Agriculture, other U.S. government agencies, individual state emergency management agencies, state and regional climate centers, media reports, and insurance industry estimates.

http://www.ncdc.noaa.gov/billions/

Forecast for Snow in the South

Low pressure is expected to track from near the Gulf Coast to off the Southeast coast in response to an energetic upper-level system kicking out of the Southwest. With sufficiently cold air in place, the low will help pull moisture northward across the South, resulting in snow for some locations, and a cold rain for others.
Wintry precipitation becomes more widespread and expands eastward through the day. In general, snow or a rain and snow mixture is possible between I-20 and I-40 from northeast Texas, southern Arkansas and northern Louisiana to northern Mississippi, northern Alabama, northern Georgia, far southern Tennessee, Upstate South Carolina and eventually North Carolina. Poor travel conditions are likely in this swath.
Below is an overview of the forecast for Winter Storm Remus, which starts Tuesday night and goes through Wednesday night. However, keep in mind that this forecast will likely change leading up to the event, so check back for updates.
Link:http://www.weather.com/storms/winter/news/winter-storm-remus-south-snow

Winter Storm Quantum: At Least 2 Dead on Hazardous Roads; Schools Closed throughout the South

Winter Storm Quantum glazed over roadways throughout the South early Tuesday morning, which made for a treacherous commute for travelers and killed one in Mississippi. 

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A driver in Mississippi died after his car (pictured) was struck by an ice cream truck on slick roads.   (Mississippi Highway Patrol )

A 24-year-old man died on Highway 18 in Utica, Mississippi after driving on an icy patch and being struck by an ice cream truck. 

In Texas, a driver died after colliding with an 18-wheeler in the Dallas-Fort Worth Metroplex.  

Georgia

Freezing rain and ice stuck to roadways in the Metro Atlanta area early Tuesday morning and prompted school districts to shut down or run delays. Parents were angered as warnings from some school districts came when students were already on their way to school. 

Cobb County Schools were the first to announce a two hour delay: 

Hours later, the district announced a closure. 

Paulding County Schools canceled class altogether as the wintry mix gained a foothold on the area's major highways, including I-75. 

http://www.weather.com/storms/winter/news/winter-storm-quantum-impacts-news

Poenix, Arizona Flash Flood

This article reports on the flash flood that hit Phoenix on August 20, 2014 and is ranked the 3rd most hazardous storm on 2014, by USA Today. The video in the link includes the dramatic rescue of an elderly woman from a van trapped in the flood. All of the rain, flooding and debris forced authorities to close nearly two dozen roadways is Maricopa County response to the threat of additional rainfall that could cause problems on the roads in the next few days. Authorities responded to multiple water rescue scenes involving stuck drivers. There was reported two people dead after the massive rainfall over Phoenix, AZ.

http://www.usatoday.com/story/news/nation/2014/08/19/flash-floods-force-water-rescues-in-phoenix-area/14299629/