Dr. Jeff Masters' WunderBlog

The future of intense winter storms

Posted by: Dr. Jeff Masters, 14:43 GMT le 03 Mars 2010

When Winter Storm Xynthia powered ashore over Europe last weekend, it brought hurricane-force wind gusts, flooding rains, and a 1-meter storm surge topped by 8-meter high battering waves that overwhelmed sea walls in France, killing scores of people. Today, AIR Worldwide estimated the insured damage from the storm at $1.5 - $3 billion. Intense extratropical cyclones like Xynthia, with central pressures below 970 mb, make up less than 20% of all wintertime cyclones in the Northern Hemisphere, but cause the vast majority of the devastation and loss of life. The ten deadliest winter storms to hit Europe over the past 60 years all had minimum pressures lower than 970 mb. The situation is similar for North America, though the storms generally do not get as intense as their European counterparts (the four major Nor'easters this winter have had central pressures of 968, 969, 978, and 972 mb). It is important, then, to ask if these strongest of the strong storms are changing in frequency, and whether a future warmer world will have more or less of these storms.

Figure 1. Winter Storm Xynthia, as captured by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite. Image was acquired in two separate overpasses on February 27, 2010. MODIS captured the eastern half of the image around 10:50 UTC, and the western half about 12:30 UTC. Forming a giant comma shape, clouds stretch from the Atlantic Ocean to northern Italy. Xynthia peaked in intensity at 18 UTC February 27, with a central pressure of 966 mb. Image credit: NASA.

Have intense Northern Hemisphere winter storms increased in number?
Most of the material for this post comes from three sources: the 2007 IPCC report, a 2009 review titled, Extra-tropical cyclones in the present and future climate: a review, and Weather and Climate Extremes in a Changing Climate, a 2009 report from the U.S. Global Change Research Program (USGCRP). An increasing number of intense winter storms in some regions of the Northern Hemisphere over the last few decades of the 20th century was a common theme of many of the studies reviewed. However, the studies used different measures as to what constitutes an "intense" storm, and have some disagreement on which areas of the globe are seeing more intense storms. A 1996 study by Canadian researcher Steven Lambert (Figure 3) found a marked increase in intense wintertime cyclones (central pressure less than 970 mb) in the latter part of the 20th century. Most of this increase occurred in the Pacific Ocean. Other studies (Geng and Sugi, 2001, and Paciorek et al., 2002) found an increase in intense winter storms over both the North Atlantic and North Pacific in the latter part of the 20th century. Benestad and Chen(2006) found an increase in the number of intense storms over the Nordic countries over the period 1955-1994, but no trend in the western parts of the North Atlantic. Gulev et al. (2001) found a small increase in the number of intense North Pacific storms (core pressure below 980 mb), a large increase in the Arctic, but a small decrease in the Atlantic. McCabe et al. 2001 found an increase at both mid-latitudes and high latitudes, particularly in the Arctic. Hirsch et al. (2001) found that the number of intense Nor'easters along the U.S. East Coast (storms with winds > 52 mph) stayed roughly constant at three storms per year over the period 1951 - 1997. Over the period 1900 to 1990, the number of strong cyclones (less than 992 mb) in November and December more than doubled over the Great Lakes of North America (Angel and Isard, 1998). With regards to Europe, Lionello et al. conclude, "the bulk of evidence from recent studies mostly supports, or at least does not contradict, the finding of an attenuation of cyclones over the Mediterranean and an intensification over Northern Europe during the second part of the twentieth century".

Figure 2. Trends in strong extratropical cyclones with central pressures less than 980 mb, for the period 1989 - 2009, as estimated using thirteen different methods, M02 - M22, defined in Neu et al., 2012. The error-bars represent the 95% confidence range of the trend estimate. A trend is significant at 5% level if the error-bar does not include zero. Four of the thirteen methods showed a slightly significant downward trend in both summertime and wintertime Northern Hemisphere strong extratropical cyclones during the period. None of the methods showed a statistically significant trend in Southern Hemisphere strong extratropical cyclones during either summer or winter. Image credit: U. Neu, M.G. Akperov, N. Bellenbaum, R. Benestad, R. Blender, R. Caballero, A. Cocozza, H.F. Dacre, Y. Feng, K. Fraedrich, J. Grieger, S. Gulev, J. Hanley, T. Hewson, M. Inatsu, K. Keay, S.F. Kew, I. Kindem, G.C. Leckebusch, M.L.R. Liberato, P. Lionello, I.I. Mokhov, J.G. Pinto, C.C. Raible, M. Reale, I. Rudeva, M. Schuster, I. Simmonds, M. Sinclair, M. Sprenger, N.D. Tilinina, I.F. Trigo, S. Ulbrich, U. Ulbrich, X.L. Wang, and H. Wernli, "IMILAST – a community effort to intercompare extratropical cyclone detection and tracking algorithms: assessing method-related uncertainties", Bulletin of the American Meteorological Society, pp. 120919072158001, 2012. http://dx.doi.org/10.1175/BAMS-D-11-00154.1

In summary, the best science we have shows that there has not been a statistically significant increase in the number of intense wintertime extratropical storms globally in the past two decades, but there has been and increase in the North Pacific and Arctic. Increased wave heights have been observed along the coasts of Oregon and Washington during this period, adding confidence to the finding of increased intense storm activity. The 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. Wintertime top 5% heavy precipitation events (both rain and snow) have increased over the Northeast U.S. in recent decades (Groisman et al., 2004), so Nor'easters have been more of a threat to cause flooding problems and heavy snow events. In all portions of the globe, tracks of extratropical storms have shifted poleward in recent decades, in accordance with global warming theory. Note that the historical data base for strong winter storms is in better shape than the data base we are using to try to detect long-term changes in hurricanes. The Ulbrich et al. (2009) review article states:

The IPCC AR4 (cf. Trenberth et al. 2007, p. 312) states that the detection of long-term changes in cyclone measures is hampered by incomplete and changing observing systems. Recent studies found, however, a general reliability of results for cyclones in the Northern Hemisphere. There are no sudden shifts in intensities that would indicate inhomogeneities, and also a comparison with cyclone activity estimated from regional surface and radiosonde data (Wang et al. 2006b; Harnik and Chang 2003) confirmed the general reliability of the data".

However, the data is not as good in the Southern Hemisphere, so the finding that intense winter storms are also increasing in that hemisphere must be viewed with caution.

Figure 3. Number of intense winter cyclones with central pressure less than 970 mb in the Northern Hemisphere, North Pacific, and North Atlantic between 1899 - 1991. Image credit: Lambert, S.J., 1996: Intense extratropical Northern Hemisphere winter cyclone events: 1899-1991. J. Geophys. Res., 101D, 2131921325.

Intense winter storms are expected to increase in number
General Circulation Models (GCMs) like the ones used in the 2007 IPCC Assessment Report do a very good job simulating how winter storms behave in the current climate, and we can run simulations of the atmosphere with extra greenhouse gases to see how winter storms will behave in the future. The results are very interesting. Global warming is expected to warm the poles more than the equatorial regions. This reduces the difference in temperature between the pole and Equator. Since winter storms form in response to the atmosphere's need to transport heat from the Equator to the poles, this reduced temperature difference reduces the need for winter storms, and thus the models predict fewer storms will form. However, since a warmer world increases the amount of evaporation from the surface and puts more moisture in the air, these future storms drop more precipitation. During the process of creating that precipitation, the water vapor in the storm must condense into liquid or frozen water, liberating "latent heat"--the extra heat that was originally added to the water vapor to evaporate it in the first place. This latent heat intensifies the winter storm, lowering the central pressure and making the winds increase. So, the modeling studies predict a future with fewer total winter storms, but a greater number of intense storms. These intense storms will have more lift, and will thus tend to drop more precipitation--including snow, when we get areas of strong lift in the -15°C preferred snowflake formation region. For completeness' sake, some of the studies that show more intense winter cyclones in a warmer world are Lambert (1995), Boer et al. (1992), Dai et al. (2001), Geng and Sugi (2003), Fyfe (2003), Lambert (2004), Leckebusch and Ulbrich (2004), Lambert and Fyfe (2006), Pinto et al. (2007), and Lionello et al. (2008). A review article be Ulbrich et al. provides a nice summary. However, 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. One interesting new study (O'Gorman, 2010) found that wintertime extratropical cyclones in the northern hemisphere would increase in intensity by 2100 primarily because the surface would heat up more than the upper air, making the atmosphere more unstable. In summer, the models predict a decrease in extratropical cyclones in the Northern Hemisphere. In the Southern Hemisphere, these storms were predicted in increase in intensity year-round. The models studied were the 2007 IPCC suite of climate models.

What the IPCC models say
The Lambert and Fyfe (2006) study, titled, "Changes in winter cyclone frequencies and strengths simulated in enhanced greenhouse warming experiments: results from the models participating in the IPCC diagnostic exercise", looked at thirteen models used to formulate the 2007 IPCC Climate Change report. Of these models, eleven simulated an increase in the number and intensity of the most intense cyclones (<970 mb pressure) in the climate expected by 2100. Two of the models did not, so it is fair to say that there is some uncertainty in these results. Nevertheless, the model results are compelling enough that 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.

Figure 4. 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".

Conclusion
The best science we have suggests that there has not been an increase in intense wintertime extratropical cyclones globally in recent decades, though there has been an increase in the Pacific and Arctic. Intense winter extratropical cyclones are expected to in increase in number and shift northwards in a warming climate, with northwest Europe at significantly higher risk of seeing an increase in intense storms. Research by Barredo (2010) suggests that Europe has not yet seen a significant increase in damaging winter storms, since normalized damages from severe winter storms did not increase between 1970 - 2008.

References
Auer, A.H. Jr. and J.M. White, 1982: The Combined Role of Kinematics, Thermodynamics, and Cloud Physics Associated with Heavy Snowfall Episodes. J. Meteor. Soc. Japan, 60, pp 500-507.

Barredo, J.I., 2010, "No upward trend in normalised windstorm losses in Europe: 1970–2008," Nat. Hazards Earth Syst. Sci., 10, 97-104, 2010, doi:10.5194/nhess-10-97-2010

Bengtsson L, Hodges KI, Roeckner E (2006): Storm tracks and climate change. J Clim 19:35183543

Boer GJ, McFarlane NA, Lazare M (1992) Greenhouse gas-induced climate change simulated with the CCC second generation general circulation model. J Climate 5:10451077

Dai, A., et al., 2001b: Climates of the twentieth and twenty-first centuries simulated by the NCAR Climate System Model. J. Clim., 14, 485519.

Fyfe, J.C., 2003: Extratropical southern hemisphere cyclones: Harbingers of climate change? J. Clim., 16, 28022805.

Geng, Q.Z., and M. Sugi, 2003: Possible change of extratropical cyclone activity due to enhanced greenhouse gases and sulfate aerosols - Study with a high-resolution AGCM. J. Clim., 16, 22622274.

Groisman, P.Y., R.W. Knight, T.R. Karl, D.R. Easterling, B. Sun, and J.H. Lawrimore, 2004, "Contemporary Changes of the Hydrological Cycle over the Contiguous United States: Trends Derived from In Situ Observations," J. Hydrometeor., 5, 64-85.

Komar, P.D. and J.C. Allan, 2007a: Higher waves along U.S. east coast linked to hurricanes. EOS, Transactions, American Geophysical Union, 88, 301.

Komar, P.D. and J.C. Allan, 2007b: A note on the depiction and analysis of wave-height histograms. Shore & Beach, 75(4), 1- 5.

Komar, P.D. and J.C. Allan, 2008: Increasing hurricane-generated wave heights along the U.S. East coast and their climate controls. Journal of Coastal Research, 24(2), 479-488.

Lambert, S.J., 1995: The effect of enhanced greenhouse warming on winter cyclone frequencies and strengths, J Climate 8:1447-1452

Lambert, S.J., 1996: Intense extratropical Northern Hemisphere winter cyclone events: 1899-1991. J. Geophys. Res., 101D, 2131921325.

Lambert S.J., 2004: Changes in winter cyclone frequencies and strengths in transient enhanced greenhouse warming simulations using two coupled climate models. Atmos Ocean 42:173 181

Lambert, S.J., and J.C. Fyfe, 2006: Changes in winter cyclone frequencies and strengths simulated in enhanced greenhouse warming experiments: results from the models participating in the IPCC diagnostic exercise. Clim. Dyn., 26, 713728.

Leckebusch, G.C., and U. Ulbrich, 2004: On the relationship between cyclones and extreme windstorm events over Europe under climate change. Global Planet. Change, 44, 181193.

Lionello P, Boldrin U, Giorgi F (2008) Future changes in cyclone climatology over Europe as inferred from a regional climate simulation. Clim Dyn 30:657671

Neu, U., M.G. Akperov, N. Bellenbaum, R. Benestad, R. Blender, R. Caballero, A. Cocozza, H.F. Dacre, Y. Feng, K. Fraedrich, J. Grieger, S. Gulev, J. Hanley, T. Hewson, M. Inatsu, K. Keay, S.F. Kew, I. Kindem, G.C. Leckebusch, M.L.R. Liberato, P. Lionello, I.I. Mokhov, J.G. Pinto, C.C. Raible, M. Reale, I. Rudeva, M. Schuster, I. Simmonds, M. Sinclair, M. Sprenger, N.D. Tilinina, I.F. Trigo, S. Ulbrich, U. Ulbrich, X.L. Wang, and H. Wernli, "IMILAST – a community effort to intercompare extratropical cyclone detection and tracking algorithms: assessing method-related uncertainties", Bulletin of the American Meteorological Society, pp. 120919072158001, 2012. http://dx.doi.org/10.1175/BAMS-D-11-00154.1

O'Gorman, P.A., 2010, Understanding the varied response of the extratropical storm tracks to climate change, Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1011547107

Pinto JG, Ulbrich U, Leckebusch GC, Spangehl T, Reyers M, Zacharias S (2007c) Changes in storm track and cyclone activity in three SRES ensemble experiments with the ECHAM5/MPIOM1 GCM. Clim Dyn 29:195210

Ulbrich, U., Leckebusch, G.C. and J.G. Pinto (2009), Extra-tropical cyclones in the present and future climate: a review, Theoretical and Applied Climatology, Volume 96, Numbers 1-2 / April, 2009 DOI 10.1007/s00704-008-0083-8

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601. Seastep 05:05 GMT le 05 Mars 2010
Quoting taco2me61: Hi all just getting off work and 1st time on here today.... But I was wondering did they raise enough money to send StormW to the Hurricane Con???? Taco :0) Yes. See 579. Member Since: 9 septembre 2008 Posts: 6 Comments: 3406

602. Skyepony (Mod) 05:28 GMT le 05 Mars 2010
GOES-P launch was spectacular. Always fun to see our new weather toys make it into orbit. From my yard.. Member Since: 10 août 2005 Posts: 144 Comments: 29293

603. Motttt 05:43 GMT le 05 Mars 2010
I saw it here in Sarasota Member Since: 10 septembre 2001 Posts: 0 Comments: 213

604. WaterWitch11 05:47 GMT le 05 Mars 2010
was the goes-p launch only visible on the east coast? ni-night everyone! Member Since: 11 août 2008 Posts: 3 Comments: 1266

605. Skyepony (Mod) 05:52 GMT le 05 Mars 2010
Sarasota is on the west coast of Fl. So looks like the west coast got to see too. It was really clear. Maybe too clear for nocolucent clouds from the contrail, right time of day.. It launched & went east. Member Since: 10 août 2005 Posts: 144 Comments: 29293

606. hydrus 06:12 GMT le 05 Mars 2010
Quoting PcolaDan: Interesting site I found here. Volcanoes, earthquakes and impact craters. You are right Dan. This sight is cool. :) Member Since: 27 septembre 2007 Posts: 1 Comments: 14281

607. xcool 06:37 GMT le 05 Mars 2010
hey Member Since: 26 septembre 2009 Posts: 2 Comments: 15501

608. tornadodude 07:31 GMT le 05 Mars 2010
Member Since: 28 juin 2006 Posts: 22 Comments: 7816

609. barbamz 09:35 GMT le 05 Mars 2010
Several video tapes of the hugh waves hitting the cruise ship in the Mediterranean. Click on the video link on the site of our regional newspaper. Good morning from Germany, Barbara Member Since: 25 octobre 2008 Posts: 24 Comments: 1592

610. CybrTeddy 10:40 GMT le 05 Mars 2010
If not already posted, the NHC released the changes to their products in 2010. Major difference will be the genesis probability, which will now be rounded to the nearest 10%. Link Member Since: 8 juillet 2005 Posts: 253 Comments: 20238

611. Sergej7 10:57 GMT le 05 Mars 2010
ScienceDaily (Mar. 5, 2010) %u2014 Geologists have found evidence that sea ice extended to the equator 716.5 million years ago, bringing new precision to a "snowball Earth" event long suspected to have taken place around that time. http://www.sciencedaily.com/releases/2010/03/100304142228.htm Today the minimum temperature Ilirney (Chukotka, Russia)-55.5C (-67,9 F) http://meteocenter.net/25248_fact.htm Chukotka near Alaska Member Since: 3 Mars 2010 Posts: 0 Comments: 35

612. Sergej7 12:44 GMT le 05 Mars 2010
Florida and U.S. temperature last night on March 5 (6 am), two maps http://yash-sergej.narod.ru/05mar2010US.html MIAMI low 44 WEST PALM BEACH low 39 the new record? Member Since: 3 Mars 2010 Posts: 0 Comments: 35

614. nrtiwlnvragn 13:10 GMT le 05 Mars 2010
Quoting Sergej7: Florida and U.S. temperature last night on March 5 (6 am), two maps http://yash-sergej.narod.ru/05mar2010US.html MIAMI low 44 WEST PALM BEACH low 39 the new record? So far: A DAILY RECORD LOW TEMPERATURE OF 37 DEGREES WAS SET AT ORLANDO INTERNATIONAL TODAY...MARCH 5 2010. THIS BREAKS THE OLD RECORD OF 38 SET IN 2002. A DAILY RECORD LOW TEMPERATURE OF 33 DEGREES WAS SET AT VERO BEACH TODAY...MARCH 5 2010. THIS BREAKS THE OLD RECORD OF 37 SET IN 1999. A RECORD LOW TEMPERATURE OF 39 DEGREES WAS SET AT WEST PALM BEACH TODAY. THIS BREAKS THE OLD RECORD OF 40 SET IN 1971. A RECORD LOW TEMPERATURE OF 44 DEGREES WAS TIED AT MIAMI INTERNATIONAL AIRPORT TODAY. THIS RECORD WAS PREVIOUSLY SET IN 1930. A DAILY RECORD LOW TEMPERATURE OF 35 DEGREES WAS SET AT MELBOURNE TODAY...MARCH 5 2010. THIS BREAKS THE OLD RECORD OF 36 SET IN 1960. THE MINIMUM TEMPERATURE AT THE KEY WEST INTERNATIONAL AIRPORT ON FRIDAY MARCH 5TH WAS 53 DEGREES. THIS TIES THE OLD RECORD LOW OF 53 DEGREES SET IN 1873. Member Since: 23 septembre 2005 Posts: 11 Comments: 8923

615. KEEPEROFTHEGATE (Mod) 13:56 GMT le 05 Mars 2010
:) Member Since: 15 juillet 2006 Posts: 143 Comments: 40497

617. nrtiwlnvragn 14:38 GMT le 05 Mars 2010
Quoting altesticstorm10: example (NOT a real NHC advisory) TROPICAL WEATHER OUTLOOK AUG 13 2010 205 AM EDT THE REMNANTS OF HURRICANE JULIA...NOW A WEAKENED EXTRATROPICAL CYCLONE...IS NOW LOCATED ABOUT 250 NM EAST-SOUTHEAST OF NEWFOUNDLAND...AND SHOULD BE ABSORBED BY A LARGE-SCALE TROUGH WITHIN 24 TO 36 HOURS AS IT HEADS OUT TO SEA AT A BRISK PACE. AS OF 200 UTC ADVISORIES ARE NO LONGER BEING ISSUED ON THIS STORM. THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON HURRICANE KARL...LOCATED 325/350 NM EAST-SOUTHEAST OF THE NORTHERNMOST LEEWARD ISLANDS. KARL IS CURRENTLY MOVING TO THE WEST-NORTHWEST AT 14 KT...16 MPH. MAXIMUM SUSTAINED WINDS REMAIN AT 85 MPH. SLOW TO STEADY STRENGTHENING IS LIKELY IN THE NEXT 24 TO 48 HOURS. A BROAD WAVE LOCATED NEAR 10N TO THE SOUTHWEST OF CAPE VERDE IS SHOWING SIGNS OF ORGANIZATION. CONDITIONS APPEAR FAVORABLE FOR FURTHER ORGANIZATION AT THIS TIME...AND THERE IS A 20 PERCENT CHANCE THAT TROPICAL CYCLONE FORMATION WILL OCCUR IN THE NEXT 48 HOURS. A MID-LEVEL DISTURBANCE LOCATED IN THE NORTHWESTERN CARIBBEAN SEA CONTINUES TO SHOW A BROAD DISPLAY OF CONVECTION. CONDITIONS APPEAR ONLY MARGINALLY FAVORABLE FOR DEVELOPMENT AT THIS TIME. THERE IS A 10 PERCENT CHANCE THAT TROPICAL CYCLONE FORMATION WILL OCCUR IN THE NEXT 48 HOURS. NHC will still use the categories Low, Medium and High in the TWO, they will add the %. This PDF has examples of all the hurricane products. Member Since: 23 septembre 2005 Posts: 11 Comments: 8923

618. weathermanwannabe 14:50 GMT le 05 Mars 2010
Good Morning........Only comment on the NHC changes is that I actually like the "low-medium-high" designations for development which sort of jive nicely with the nomenclature of "average-below average-above average" seasons when you are talking about something so hard to nail down exactly (cyclogenisis). However, I'm sure Dr. M is not complaining on this propsed change as he (and we go along with him every year) routinely gives percentages of possible development of emerging systems/waves in his Blogs.....I suppose this is still a "science" so more numbers and percentages just come with the territory....... :) Member Since: 8 août 2006 Posts: 0 Comments: 6691

619. Skyepony (Mod) 15:00 GMT le 05 Mars 2010
We mostly lacked a polar vortex this winter, Feb pretty much nonexistent.. very unusual.. The daily geopotential height anomalies at 17 pressure levels are shown for the previous 120 days as indicated, and they are normalized by standard deviation using 1979-2000 base period. The anomalies are calculated by subtracting 1979-2000 daily climatology, and then averaged over the polar cap poleward of 65%uFFFDN. The blue (red) colors represent a strong (weak) polar vortex. The black solid lines show the zero anomalies. Member Since: 10 août 2005 Posts: 144 Comments: 29293

620. TampaSpin 15:07 GMT le 05 Mars 2010
StormW FundRaiser for Hurricane Conference StormW FundRaiser Forum WoW!!!! You all did it. Just checked Google checkout and Paypal and we now have donations of $520 less fees its just over $500!!! Thank you all very much!!! I will get the $350 paid for Registration fees and give StormW the remaining amount for his travel expenses and needs. He is truly a tremendous asset with his knowledge! Again Thank you all! Member Since: 2 septembre 2007 Posts: 175 Comments: 19747

621. nrtiwlnvragn 15:10 GMT le 05 Mars 2010
March Monthly Ocean Briefing (Powerpoint) Member Since: 23 septembre 2005 Posts: 11 Comments: 8923

622. Patrap 15:13 GMT le 05 Mars 2010
Mayan Calenders still selling Briskly Worldwide. Got Doom ? Member Since: 3 juillet 2005 Posts: 371 Comments: 111397

624. AussieStorm 15:18 GMT le 05 Mars 2010
Quoting TampaSpin: StormW FundRaiser for Hurricane Conference StormW FundRaiser Forum WoW!!!! You all did it. Just checked Google checkout and Paypal and we now have donations of $520 less fees its just over $500!!! Thank you all very much!!! I will get the $350 paid for Registration fees and give StormW the remaining amount for his travel expenses and needs. He is truly a tremendous asset with his knowledge! Again Thank you all! Cool Member Since: 30 septembre 2007 Posts: 5 Comments: 13321

625. TampaSpin 15:20 GMT le 05 Mars 2010
Quoting Jeff9641: Take this video DOWN BEFORE YOU INFECT SOMEONE ELSE'S COMPUTER. I am tired of people posting junk on this blog and it has a virus. NO KIDDING!!!!!! Thanks Jeff!!! Member Since: 2 septembre 2007 Posts: 175 Comments: 19747

626. Ossqss 15:20 GMT le 05 Mars 2010
Psst -- new blog Member Since: 12 juin 2005 Posts: 6 Comments: 8154

627. AussieStorm 15:21 GMT le 05 Mars 2010
Quoting barbamz: Several video tapes of the hugh waves hitting the cruise ship in the Mediterranean. Click on the video link on the site of our regional newspaper. Good morning from Germany, Barbara whoa that's some video, geez big waves. Member Since: 30 septembre 2007 Posts: 5 Comments: 13321

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