Sandy Update 10/29 early am
October 29, 2012
I’m jammed most of the day today, but here are some good Sandy links. Will try to stay current.
In part, the storm is feeding off of much warmer-than-average ocean waters located off the East Coast. Sea surface temperatures hit record highs off the New Jersey and New England coasts this summer, and warmer water can help maintain a hurricane, or hurricane-like hybrid storm, much farther north than they would typically be able to survive at this time of year. Sandy is tapping into energy from both the ocean and the jet stream, as researcher Adam Sobel explained.
The multifaceted storm is expected to dump upwards of 5-to-10 inches of rain or more along its path, potentially leading to extensive inland flooding. On top of that, as cold air wraps into its circulation, rain may change to snow in the higher elevations of Maryland, West Virginia, Virginia, and Pennsylvania, potentially dumping upwards of 2-to-3 feet in some locations.
Climate Change Connection?
The storm track is being influenced by an unusually strong “blocking” pattern in the upper atmosphere, with a massive dome of high pressure located southwest of Greenland. Without this blocking, the storm would have been able to turn out to sea, without harming the U.S. It’s an example of what can happen when blocking patterns appear at precisely the wrong time.
Additionally, there are many other ingredients that are converging to create a menacing situation, including a deep dip in the jet stream across the eastern U.S. that is playing a role in essentially capturing the storm and flinging it inland.
“History is being written as an extreme weather event continues to unfold, one which will occupy a place in the annals of weather history as one of the most extraordinary to have affected the United States,” wrote Weather Channel senior meteorologist Stu Ostro.
“A meteorologically mind-boggling combination of ingredients is coming together: one of the largest expanses of tropical storm (gale) force winds on record with a tropical or subtropical cyclone in the Atlantic or for that matter anywhere else in the world; a track of the center making a sharp left turn in direction of movement toward New Jersey in a way that is unprecedented in the historical database; a ‘warm-core’ tropical cyclone embedded within a larger, nor’easter-like circulation; and eventually tropical moisture and arctic air combining to produce heavy snow in interior high elevations,” Ostro said.
Recent studies, including Ostro’s own work, have shown that blocking patterns such as the one that is currently over the Atlantic have appeared with greater frequency and intensity in recent years. Some scientists think that may be related to the loss of Arctic sea ice, which is one of the most visible consequences of manmade global warming. The 2012 sea ice melt season, which ended just one month ago, was extreme, with sea ice extent, volume, and other measures all hitting record lows. The loss of sea ice opens large expanses of open water, which then absorbs more of the incoming solar radiation and adds heat and moisture to the atmosphere, thereby helping to alter weather patterns. Exactly how weather patterns are changing as a result, however, is a subject of active research.
Still, a few trends have become apparent. The Earth’s average global temperature has risen between 1.5 and 2 degrees Fahrenheit since industrial societies began to burn fossil fuels in great quantities in the late 19th century. The warmer temperatures mean that the atmosphere holds about 4% more moisture than it did in 1970, which could bring greater rainfall. By the end of this century, a typical hurricane could dump 20% more rain than it does now, Masters said.
Already, the U.S. Global Change Research Program, a federal initiative, reports that research shows “the destructive energy of Atlantic hurricanes has increased in recent decades. The intensity of these storms is likely to increase in this century.”
Hurricane Sandy is expected to barrel into the East Coast just as a cold front moves in from Canada, creating a hybrid “super storm.” The fact that the Atlantic is spawning hurricanes in late autumn may have to do with rising sea surface temperatures, recent research indicates.
Water temperature in the mid-Atlantic this year is in fact 5 degrees Fahrenheit higher than average, contributing to “an unusually large amount of water vapor available to make heavy rain,” Masters wrote on his blog.
I know what you’re thinking: who says that Hurricane Sandy has anything to do with climate change? Before recently there wasn’t enough strong scientific evidence that global warming might increase the destructive power of hurricanes. It wasn’t until the 1970s that satellites were able to monitor tropical storms and hurricanes. Before the 70s many tropical storms and hurricanes were poorly recorded, monitored only by unlucky planes or ships crossing the storm’s path. The period of time from the late 1970s to the present simply didn’t provide enough data to form accurate trends based on global warming. That is now changing.
A study published in the Proceedings of the National Academy of Sciencesby Aslak Grinsted of the University of Copenhagen and his colleagues devised a way around this time-lapse problem. Using data from storm surges, the “abnormal rise of water generated by a storm, over and above predicted astronomical tides,” Grinsted now had data from as far back as the 1920s. What did they find? “Using surges as an indicator we see an increase in all magnitudes of storms when ocean temperatures are warmer,” according to Michael D. Lemonick of Climate Central. But make no mistake, the storm surge data is not a perfect measurement because not all tropical storms and hurricanes make landfall.
What’s so unusual about Sandy and the timing of this hurricane? This late in the Hurricane season, by late October, the storm systems that materialize around the Caribbean usually move eastward away from the United States. Since Wednesday October 24, weather models have attempted to make sense of the predicted track of Sandy, but struggle because very little precedent exists in modern observations to drawn upon.
Andrew Freedman at Climate Central had this to say about Sandy: “Normally, hurricanes that form in Sandy’s location do head seaward, particularly in October, when strong cold fronts moving off the East Coast tend to sweep tropical weather systems away from the mainland. In fact, there may only have been a couple of cases in the historical record dating back to the 19th century when a hurricane took a track in October similar to the one Sandy may ultimately follow.”
So what has experts sounding the alarm on Hurricane Sandy, saying likely to be worse than 1991 “perfect storm?” An intense high-pressure system, unusual for this time of year, has formed over Greenland and much of Canada that will act as a “blocking high”, preventing the hurricane from moving in a typical trajectory away from the United States. Instead, this pressure disparity will most likely pull the storm system back toward New York, New Jersey, and Pennsylvania and as far into the mainland as Ohio.
Is this high pressure related to the unprecedented Arctic ice melting experienced this summer? Many scientists agree that increased melting of Arctic sea ice has allowed the sun’s energy to warm the oceans in the north a great deal. Others speculate the warming seas have altered the delicate balance of energy in the north, shifting weather patterns around the world. This exact complex relationship is still under scrutiny by scientists around the world.