Climate Change News and Article Collection

[Lauren Johnson]

In the Northern Atlantic south of Iceland, an extratropical storm that brought up to 6" of snow to Maryland on Thursday has put on a remarkable burst of rapid intensification over the past 24 hours, with the center pressure dropping 58 mb in 24 hours. The Free University of Berlin, which names all major high and low pressure systems that affect Europe, has named the storm "Jolle." This meteorological "bomb" was analyzed with a central pressure of 988 mb at 12Z (7 am EST) Friday morning by NOAA's Ocean Prediction Center, and hit 930 mb by 7 am EST Saturday morning. The storm may deepen a few more millibars today, but it is close to maximum intensity. A 930 mb central pressure is what one commonly sees in Category 4 hurricanes, and is one of the lowest pressures attained by an Atlantic extratropical storm in recent decades. Since extratropical storms do not form eyewalls, the winds of the massive Atlantic low are predicted to peak at 90 mph (Category 1 hurricane strength), with significant wave heights reaching 52 feet (16 meters.) The powerful storm brought sustained winds of 52 mph, gusting to 72 mph, to Vestmannaeyjar, Iceland at 6 pm local time Saturday. Fortunately, the storm is expected to weaken dramatically before Jolle's core hurricane-force winds affect any land areas.


Figure 1. Winter Storm Jolle, as seen at 10 am EST January 26, 2013. Three hours prior to this image, Jolle was analyzed with a central pressure of 930 mb--one of the lowest pressures in recent decades for an Atlantic extratropical storm. Image credit: [URL="http://www.nrlmry.navy.mil/htdocs_dyn_pregen_sat/PUBLIC/nexsat/pages/Europe/Latest.html"]Navy Research Lab, Monterey.

According to wunderground's weather historian Christopher C. Burt's post on [/URL]Super Extratropical Storms, the all-time record lowest pressure for a North Atlantic extratropical storm is 913 mb, set on January 11, 1993, near Scotland's Shetland Islands. The mighty 1993 storm broke apart the super oil tanker Braer on a rocky shoal in the Shetland Islands, causing a massive oil spill.

Other notable Atlantic extratropical storms, as catalogued by British weather historian, Stephen Burt:

920.2 mb (27.17") measured by the ship Uyir while she sailed southeast of Greenland on December 15, 1986. The British Met. Office calculated that the central pressure of the storm, which was centered some distance southeast of the ship, was 916 mb (27.05").

921.1 mb (27.20") on Feb. 5, 1870 measured by the ship Neier at 49°N 26°W (another ship in the area measured 925.5 mb)

924 mb (27.28") on Feb. 4, 1824 at Reykjavik, Iceland (the lowest on land measured pressure in the North Atlantic)

925.5 mb (27.33") on Dec. 4, 1929 by the SS Westpool somewhere in the Atlantic (exact location unknown)

925.6 mb (27.33") on Jan. 26, 1884 at Ochtertyre, Perthshire, U.K. (the lowest pressure recorded on land in the U.K.)

For comparison's sake, the lowest pressure measured on land during an extra-tropical storm in the United States (aside from Alaska) was 952 mb 28.10" at Bridgehampton, New York (Long Island) on March 1 during, the Great Billy Sunday Snowstorm.


Figure 2. Infrared satellite image of the North Atlantic Storm of January 11, 1993 at 0600Z when it deepened into the strongest extra-tropical cyclone ever observed on earth, with a central pressure of 913 mb (26.96"). Satellite image from EUMETSAT Meteosat-4.

Links
You can see a nice AVHRR image of the east side of the storm at the University of Bern. The raw MODIS pass is here.

The Meteorological Institute of Norway has a nice satellite animation of Jolle.

Wunderground's weather historian Christopher C. Burt's posts on Super Extratropical Storms and [URL="http://www.wunderground.com/blog/weatherhistorian/article.html?entrynum=50"]World and U.S. Lowest Barometric Pressure Records

Claudio Cassardo's January 23, 2013 post, [/URL]Very low minima of extratropical cyclones in North Atlantic

Read my story of what it was like to fly though a 936 mb Atlantic low pressure system on January 4, 1989.

Intense winter storms are expected to increase in number due to climate change
In my 2010 blog post, The future of intense winter storms, I discuss how evidence for an observed increase in intense wintertime cyclones in the North Atlantic is uncertain. In particular, intense Nor'easters affecting the Northeast U.S. showed no increase in number over the latter part of the 20th century. This analysis is supported by the fact that wintertime wave heights recorded since the mid-1970s by the three buoys along the central U.S. Atlantic coast have shown little change (Komar and Allan, 2007a,b, 2008). However, even though Nor'easters have not been getting stronger, they have been dropping more precipitation, in the form of both rain and snow. Several studies (Geng and Sugi, 2001, and Paciorek et al., 2002) found an increase in intense winter storms over both the North Atlantic, but Benestad and Chen (2006) found no trend in the western parts of the North Atlantic, and Gulev et al. (2001) found a small small decrease of intense winter storms in the Atlantic.

The U.S. Global Change Research Program (USGCRP), a scientific advisory board created by the President and Congress, concluded this in their 2009 U.S. Climate Impacts Report: "Cold-season storm tracks are shifting northward and the strongest storms are likely to become stronger and more frequent". The USGRP concluded that an increase of between four and twelve intense wintertime extratropical storms per year could be expected over the Northern Hemisphere by 2100, depending upon the amount of greenhouse gases put into the air (Figure 3). If we assume that the current climate is producing the same number of intense winter storms as it did over the period 1961-2000--about 53--this represents an increase of between 8% and 23% in intense wintertime extratropical storms. Two studies--Pinto et al. (2007) and Bengtsson et al. 2006--suggest that the more intense winter cyclones will affect only certain preferred regions, namely northwestern Europe and Alaska's Aleutian Islands. At least three other studies also find that northwestern Europe--including the British Isles, the Netherlands, northern France, northern Germany, Denmark and Norway--can expect a significant increase in intense wintertime cyclones in a future warmer world (Lionello et al., 2008; Leckebusch and Ulbrich 2004; and Leckebusch et al., 2006). None of these studies showed a significant increase in the number of intense Nor'easters affecting the Northeast U.S.


Figure 3. The projected change in intense wintertime extratropical storms with central pressures < 970 mb for the Northern Hemisphere under various emission scenarios. Storms counted occur poleward of 30°N during the 120-day season beginning November 15. A future with relatively low emissions of greenhouse gases (B1 scenario, blue line) is expected to result in an additional four intense extratropical storms per year, while up to twelve additional intense storms per year can be expected in a future with high emissions (red and black lines). Humanity is currently on a high emissions track. Figure was adapted from Lambert and Fyfe (2006), and was taken from Weather and Climate Extremes in a Changing Climate, a 2009 report from the the U.S. Global Change Research Program (USGCRP). The USGRP began as a presidential initiative in 1989 and was mandated by Congress in the Global Change Research Act of 1990, which called for "a comprehensive and integrated United States research program which will assist the Nation and the world to understand, assess, predict, and respond to human-induced and natural processes of global change".

Jeff Masters

http://www.wunderground.com/blog/JeffMas...rynum=2336