bluewave Posted November 8, 2012 Share Posted November 8, 2012 The increase in blocking during the month of October over the last decade or so has been a part of the record to historic weather events that the US and our region have been experiencing. October 2005 was remembered for the record breaking rainfall flooding that the Northeast recorded. Tropical moisture streaming northward near the end of the record breaking 2005 Atlantic hurricane season got caught under a strong block over SE Canada. http://www.erh.noaa...._sum/112005.txt During October 2006, Buffalo received a very intense and historic early season lake effect storm in conjunction with a strong blocking episode. http://www.erh.noaa....torm101206.html October 2008 featured a late October snowfall across portions of the Northeast around the time of another strong blocking episode. http://www.weather.c...permalink_month The big story of October 2009 was the record cold which invaded much of the US during a strong block focused over the North Pole. It was the 4th coldest October on record for the US. October 2010 produced the historic low moving through the Midwest under a strong blocking pattern. http://nws.met.psu.e...0/25Oct2010.pdf The record October snowstorm of 2011 followed a strong east based block near Europe. http://www.wundergro...l?entrynum=1978 The strong blocking pattern during this October turned the unprecedented and devastating Hurricane Sandy back toward the NJ Coast. http://www.wundergro...tml?entrynum=96 The blocking pattern lingered long enough for the recent record November snows here. http://capitalclimate.blogspot.com/2012/11/november-snowfall-records-broken-in-new.html Link to comment Share on other sites More sharing options...
CooL Posted November 8, 2012 Share Posted November 8, 2012 Nice post. I wonder if global warming or some other factor is leading to more extreme blocking, or if its just apart of a cycle. Hopefully it comes back in december lol Link to comment Share on other sites More sharing options...
uncle W Posted November 9, 2012 Share Posted November 9, 2012 I found my post which shows the winters lowest daily AO value and the weather around that time...Last October around the snowstorm and late January the AO was negative for a week or more...We just had a -3.195 on 10/24...We got Sandy and the noreaster just after that... lowest daily winter ao value since 1950...I hope I didn't miss a date...Weather at the time for NYC... season.......value.....date..... 1949-50......-2.854.....3/15/50......1.4" 3/14...record cold the beginning of the month... 1950-51......-4.353.....12/27/50....3" snow 12/27 and 9 degrees...the biggest snow and coldest temperature of the winter... 1951-52......-3.805.....3/4/1952....4" snow 3/2... 1952-53......-3.766.....12/27/52....12 degrees is the coldest temp. of the season...4" snow 12/31... 1953-54......-3.495.....1/30/54......cold continues...Cold snowy January... 1954-55......-3.064.....1/4/55........cold continues... 1955-56......-4.564.....2/15/56......1.4" 2/17 and 2/22...Big March snows...... 1956-57......-4.473.....2/21/57......2.6" snow 3/1... 1957-58......-4.030.....3/11/58......snow storms 3/14 and 3/21...... 1958-59......-4.026.....1/7/59........cold continues... 1959-60......-4.108.....1/28/60......18 degrees 2/3 is the coldest temp for Feb...Big March cold and snow..... 1960-61......-2.719.....1/10/61......greatest snowy and cold period followed 1/15-2/12..... 1961-62......-4.417.....3/4/62........record cold 3/2 and the Ash Wednesday storm 3/6... 1962-63......-5.010.....1/21/63......Near record cold 1/23 and 4" snow 1/26...Biggest snow of the season... 1963-64......-4.470.....12/20/63....1.4" 12/18...6.6" 12/23-24...11 degrees 12/20 coldest for that month...January Blizzard.... 1964-65......-3.973.....1/26/65......ice storm 1/24 and continued cold... 1965-66......-5.130.....1/28/66......8 degrees is the coldest temp. of the season 1/28...7" on 1/30... 1966-67......-4.147.....12/13/66....wet snow and rain 12/13-14 is the start of two weeks of snow and cold...7" snow 12/24-25... 1967-68......-3.490.....2/7/68........8 degrees 2/11...Cold and dry continues... 1968-69......-5.282.....2/13/69......17 degrees 2/17 is the coldest temp for the month...15" of snow 2/9-10...... 1969-70......-6.365.....3/5/70........20 degrees 3/10 coldest temp for the month...4" of snow 3/29... 1970-71......-2.821.....2/6/71........12 degrees max 2/2... 1972-73......-2.044.....12/17/72...24 degrees max 12/17... 1973-74......-2.792.....12/19/73...big ice storm 12/16-17...17 degrees 12/19 is the coldest temp of the month... 1974-75......-1.695.....12/18/74...some minor cold in a mild month...one of the few times the weather was benign at the ao minimum... 1975-76......-3.262.....1/24/76......-1 degrees 1/23 is the coldest temp of the winter...1" of snow 1/23... 1976-77......-7.433.....1/15/77......-2 degrees on the 17th is the coldest temp of the winter...5" snow 1/14-15... 1977-78......-5.291.....2/5/78........10 degrees 2/5 is the coldest temperature of the season...18" snow 2/6-7...... 1978-79......-4.387.....1/25/79......Very cold and snowy February...... 1979-80......-3.705.....1/24/80......continued cold and dry...longest stretch of cold that winter... 1980-81......-4.318.....3/4/81........largest snowfall for the winter...8.6" 3/5... 1981-82......-3.804.....12/30/81...January 1982 was very cold and snowy... 1982-83......-3.410.....2/6/83........4" of snow 2/6 and 18" 2/11-12...... 1983-84......-3.706.....3/13/84......record cold 3/10...7" snow 3/8-9... 1984-85......-6.226.....1/19/85.....-2 degrees 1/21 is the coldest temperature that winter... 1985-86......-3.894......2/6/86.......4.5" of snow 2/7 and 2/11...Snowiest period of the winter... 1986-87......-3.507.....3/9/87........2" snow 3/12...Near record cold 3/10... 1987-88......-2.314.....2/28/88......0.6" 2/27 is the last measurable snow...Thawing after... 1988-89......-0.318.....3/4/89........2.5" 3/6 and near record cold 3/7... 1989-90......-3.482.....12/10/89...One of the coldest Decembers on record... 1990-91......-3.381.....3/9/91.......24 degrees 3/12...benign after that... 1991-92......-2.597.....12/4/91.....0.7" 12/5...benign after that... 1992-93......-2.228.....3/2/93.......Super storm 3/13...Near record cold followed...... 1993-94......-3.503.....2/24/94.....2.6" 2/23...12 degrees 2/27...Feb KU... 1994-95......-3.116.....3/9/95.......20 degrees 3/10 is the coldest temp for the month...... 1995-96......-4.353.....12/19/95...8" of snow during a very cold period...January blizzard..... 1996-97......-3.377.....12/30/96...11 degrees New Years Day.... 1997-98......-4.269.....1/10/98.....14 degrees New Years day...Coldest of the winter... 1998-99......-3.856.....3/10/99......5" snow 3/14-15...17 degrees 3/8 is the coldest temp for the month... 1999-00......-2.118.....2/18/00......3" snow and ice 2/22...... 2000-01......-4.854.....2/25/01......6" snow 2/22 and 17 degrees...coldest for the month... 2001-02......-3.293.....12/28/01...Coldest period of the winter followed but benign... 2002-03......-3.575.....1/22/03......7 degrees 1/24 is the coldest for the winter... blizzard in February... 2003-04......-4.387.....1/17/04......1 degree 1/16 is the coldest temp of the season...6" of snow 1/15...Dec. ... 2004-05......-4.337.....2/26/05......6" of snow 2/25 and 8" 2/29...blizzard in January... 2005-06......-3.569.....12/5/05......2" snow 12/4...1" 2/6 and 6" 12/9...14 degrees 12/14 is the coldest temp of the season...... 2006-07......-2.184.....2/4/07........8 degrees 2/5 is the coldest for the winter... 2007-08......-2.468.....1/2/08........12 degrees 1/3 second coldest of the winter... 2008-09......-3.178.....2/3/09........4.3" 2/5 12 degrees... 2009-10......-5.821.....12/21/09...11" snow 12/19-20......16 degrees 12/18 is the coldest for the month... 2010-11......-5.172.....12/18/10...20" of snow 12/26-27...23 max on 12/14... 2011-12......-3.451.....01/28/12...4.3" of snow 1/21 largest snowfall of the season... 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uncle W Posted November 9, 2012 Share Posted November 9, 2012 The AO was at a low of -3.195 on October 24th...It's very positive now but will it get negative again when it counts?....If it does we will probably see some very cold weather or a stormy east coast...The following is a list of winters with their lowest AO daily index... year...AO index...date... 1976-77...-7.433...01/15/77 1969-70...-6.365...03/05/70 1984-85...-6.226...01/19/85 2009-10...-5.821...12/21/10 1977-78...-5.291...02/05/78 1968-69...-5.282...02/13/69 2010-11...-5.172...12/18/10 1965-66...-5.130...01/28/66 1962-63...-5.010...01/21/63 2000-01...-4.854...02/25/01 1955-56...-4.564...02/15/56 1963-64...-4.470...12/20/63 1956-57...-4.473...02/21/57 1961-62...-4.417...03/04/62 2003-04...-4.387...01/17/04 1978-79...-4.387...01/25/79 On or near the dates of these AO minimums it was either very cold, snowy or both...Fifteen of the sixteen years had a significant cold wave or major snowstorm around the dates of the AO minimum... Link to comment Share on other sites More sharing options...
Isotherm Posted November 9, 2012 Share Posted November 9, 2012 Good posts guys. Over the past several years we've been seeing a return to the predominately negative NAO/negative PDO cycle of the late 40s-late 70s. However, I do believe blocking has been stronger and more frequent compared to the last transition into the neg NAO cycle, largely b/c of the decreased solar output. Solar flux, ap indices, and activity in general has been the lowest we've seen in over a century. That has been shown to correlate well with enhanced northern latitude blockiness. As a result, we've been getting more major east coast storms than usual since about 2008 or so. Link to comment Share on other sites More sharing options...
Storm At Sea Posted November 9, 2012 Share Posted November 9, 2012 Good post as always. It would be interesting to determine the phase of the -NAO during the minimum events. Particularly, we might be able to determine cold streak versus snow event for the NYC area if we can determine the tendency of the NAO at that point in time. Also, I wonder whether the rate of chance in these indicies (NAO/AO) is more determinitistic of the outcome. For example, the NAO has been rising 0.2/day over the past ten days and should be peaking in within several days in the positive phase. It was during that period that we had two major storms blocked and drawn NW into the East Coast. The AO was at a low of -3.195 on October 24th...It's very positive now but will it get negative again when it counts?....If it does we will probably see some very cold weather or a stormy east coast...The following is a list of winters with their lowest AO daily index... year...AO index...date... 1976-77...-7.433...01/15/77 1969-70...-6.365...03/05/70 1984-85...-6.226...01/19/85 2009-10...-5.821...12/21/10 1977-78...-5.291...02/05/78 1968-69...-5.282...02/13/69 2010-11...-5.172...12/18/10 1965-66...-5.130...01/28/66 1962-63...-5.010...01/21/63 2000-01...-4.854...02/25/01 1955-56...-4.564...02/15/56 1963-64...-4.470...12/20/63 1956-57...-4.473...02/21/57 1961-62...-4.417...03/04/62 2003-04...-4.387...01/17/04 1978-79...-4.387...01/25/79 On or near the dates of these AO minimums it was either very cold, snowy or both...Fifteen of the sixteen years had a significant cold wave or major snowstorm around the dates of the AO minimum... Link to comment Share on other sites More sharing options...
green tube Posted November 9, 2012 Share Posted November 9, 2012 Nice post. I wonder if global warming or some other factor is leading to more extreme blocking, or if its just apart of a cycle. Hopefully it comes back in december lol maybe it's "global climate change" because every single weather event is now blamed on global climate change. how convenient that every meteorological outcome is evidence of proof for global climate change. Link to comment Share on other sites More sharing options...
Isotherm Posted November 9, 2012 Share Posted November 9, 2012 Good post as always. It would be interesting to determine the phase of the -NAO during the minimum events. Particularly, we might be able to determine cold streak versus snow event for the NYC area if we can determine the tendency of the NAO at that point in time. Also, I wonder whether the rate of chance in these indicies (NAO/AO) is more determinitistic of the outcome. For example, the NAO has been rising 0.2/day over the past ten days and should be peaking in within several days in the positive phase. It was during that period that we had two major storms blocked and drawn NW into the East Coast. You'd be correct regarding the rate of change being most important. The notorious "Archambault signal" coined from the research of Heather Archambault, who demonstrated that the modality transition from mod/strongly negative to positive NAO correlates strongly to east coast cyclogenesis. Many of I-95's largest snowstorms, like the 96 blizzard for example, occurred during a phase transition from - to + NAO. Usually when the NAO is deeply negative, we're primarily cold/dry or have clipper type / Miller B potential events. But the rise of the NAO (especially rapidly) generally results in a larger, moisture laden low, Miller A , coming up the east coast. Link to comment Share on other sites More sharing options...
earthlight Posted November 9, 2012 Share Posted November 9, 2012 Great post. On the topic of historic weather -- I think we may be living through one of the most remarkable periods, meteorologically, in this areas history. Over the last 5-6 years (and there are more beyond that, but we'll leave them out for now) the amount of anomalous events is almost becoming bizarre. Just in the last 1 1/2 to two or so years: December 26 2010 - Record setting snowfall, extreme impact event with record setting snow, wind, blizzard conditions. Winter of 2010-2011 - Record setting seasonal snowfall, periods of extreme cold and snow pack. Summer of 2011 - Record setting heat August 2011- Hurricane Irene with major impacts and damage October 2011 - Record setting early-season snowfall with over 15 inches of snow in some locations Winter of 2011-2012 - Equally anomalous, just not in the way we would have hoped. Incredibly low snowfall totals and wintry events. Summer of 2012 - 108 F at Newark and record setting heat throughout the northeast. October 2012 - Hurricane Sandy, possibly the most damaging storm we'll ever see in our lifetimes in this area November 2012 - One week later, anomalous early season snowfall event with widespread 6+ inch amounts and another strong surface low offshore. ---- When you look back even further, over the last few winters we have had a ridiculous amount of strong surface lows, nor'easters, and displays of classic CCB/frontogenic banding. This kind of stuff is not typical around here...we have experienced more than 10 storms that in the 80's and 90's would be considered "historic" or one of the "classics". One has to wonder if either a) this streak will end eventually, or b ) this is the new normal...the latter of which conversation I won't get into at the moment at the risk of bringing out the global warming alarmist hounds. But it certainly is interesting..and we're watching it unfold before our eyes. Link to comment Share on other sites More sharing options...
Brian5671 Posted November 9, 2012 Share Posted November 9, 2012 Excellent post and agree...it's getting bizarre. Link to comment Share on other sites More sharing options...
ag3 Posted November 9, 2012 Share Posted November 9, 2012 Great post. On the topic of historic weather -- I think we may be living through one of the most remarkable periods, meteorologically, in this areas history. Over the last 5-6 years (and there are more beyond that, but we'll leave them out for now) the amount of anomalous events is almost becoming bizarre. Just in the last 1 1/2 to two or so years: December 26 2010 - Record setting snowfall, extreme impact event with record setting snow, wind, blizzard conditions. Winter of 2010-2011 - Record setting seasonal snowfall, periods of extreme cold and snow pack. Summer of 2011 - Record setting heat August 2011- Hurricane Irene with major impacts and damage October 2011 - Record setting early-season snowfall with over 15 inches of snow in some locations Winter of 2011-2012 - Equally anomalous, just not in the way we would have hoped. Incredibly low snowfall totals and wintry events. Summer of 2012 - 108 F at Newark and record setting heat throughout the northeast. October 2012 - Hurricane Sandy, possibly the most damaging storm we'll ever see in our lifetimes in this area November 2012 - One week later, anomalous early season snowfall event with widespread 6+ inch amounts and another strong surface low offshore. ---- When you look back even further, over the last few winters we have had a ridiculous amount of strong surface lows, nor'easters, and displays of classic CCB/frontogenic banding. This kind of stuff is not typical around here...we have experienced more than 10 storms that in the 80's and 90's would be considered "historic" or one of the "classics". One has to wonder if either a) this streak will end eventually, or b ) this is the new normal...the latter of which conversation I won't get into at the moment at the risk of bringing out the global warming alarmist hounds. But it certainly is interesting..and we're watching it unfold before our eyes. Record snowfall for January in 2011. Record snowfall for February in 2010. Link to comment Share on other sites More sharing options...
ORH_wxman Posted November 9, 2012 Share Posted November 9, 2012 You'd be correct regarding the rate of change being most important. The notorious "Archambault signal" coined from the research of Heather Archambault, who demonstrated that the modality transition from mod/strongly negative to positive NAO correlates strongly to east coast cyclogenesis. Many of I-95's largest snowstorms, like the 96 blizzard for example, occurred during a phase transition from - to + NAO. Usually when the NAO is deeply negative, we're primarily cold/dry or have clipper type / Miller B potential events. But the rise of the NAO (especially rapidly) generally results in a larger, moisture laden low, Miller A , coming up the east coast. The storminess is actually greater during a phase change from positive NAO to negative, however, the snow chances tend to be greater from a -NAO to +NAO transition, but overall precipitation chances are actually lower than normal during that change. Its just when we do get storms that are occuring during the -NAO to +NAO phase change, they are much more likely to be snowstorms or winter precip. In the +NAO to -NAO transitions, precip is enhanced, but it can often be lakes cutters or inland runners. Link to comment Share on other sites More sharing options...
LongBeachSurfFreak Posted November 9, 2012 Share Posted November 9, 2012 Not being a pro met i have to agree with one of the best. Masters has been harping on the lack of arctic sea ice for very good reason. Not a political thing but a real thing. The lack of ice is lowering the difference in temps between the mid lats and arctic and hence leading to a snake like feast or famine jet pattern. Its either way to warm (last winter here) or to cold Europe last winter. Who in their right mid here would have thought we would have a truly (in my opinion) hurricane blast off the gulf stream in a westish track towards NJ????? Think about that... Add in its almost Novemberish. Think about that and the lack of ice and historical record. (tropical tracks in the past) Coincidence? I think not! Welcome to the NEW WORLD!!! Link to comment Share on other sites More sharing options...
nzucker Posted November 9, 2012 Share Posted November 9, 2012 Not being a pro met i have to agree with one of the best. Masters has been harping on the lack of arctic sea ice for very good reason. Not a political thing but a real thing. The lack of ice is lowering the difference in temps between the mid lats and arctic and hence leading to a snake like feast or famine jet pattern. Its either way to warm (last winter here) or to cold Europe last winter. Who in their right mid here would have thought we would have a truly (in my opinion) hurricane blast off the gulf stream in a westish track towards NJ????? Think about that... Add in its almost Novemberish. Think about that and the lack of ice and historical record. (tropical tracks in the past) Coincidence? I think not! Welcome to the NEW WORLD!!! The lack of arctic sea ice should actually reduce the strength of the jet stream by limiting the temperature gradient. It's the contrast between extreme cold in the Arctic and extreme warmth in the subtropical regions that leads to the jet stream forming and being so powerful. So this theory can't possibly work the way you see it. Link to comment Share on other sites More sharing options...
LongBeachSurfFreak Posted November 9, 2012 Share Posted November 9, 2012 The lack of arctic sea ice should actually reduce the strength of the jet stream by limiting the temperature gradient. It's the contrast between extreme cold in the Arctic and extreme warmth in the subtropical regions that leads to the jet stream forming and being so powerful. So this theory can't possibly work the way you see it. Okay sorry either you read it wrong or I explained it wrong. The lack gradient leads to a less powerful hence a more snakey jet. Hence the mega -noas +naos. Go back in history and find another Sandy in oct/nov. Link to comment Share on other sites More sharing options...
SnoSki14 Posted November 9, 2012 Share Posted November 9, 2012 The only theory that I really believe above global warming and the arctic sea ice melt is that warming temperatures in the arctic and lack of ice is what causes intense blocking episodes to form. Now it doesn't mean they are sustained, but when they do happen, they become very powerful and we get insane weather around here. Of course, things like timing play a major role (the involvement of the tropics and formation of Sandy in the Caribbean) but intense blocking greatly increases the chance of an east coast storm for our area. I guess that whole debacle "The Day After Tomorrow" wasn't completely wrong considering the transpiring weather events we've seen. Link to comment Share on other sites More sharing options...
LocoAko Posted November 10, 2012 Share Posted November 10, 2012 Great post. On the topic of historic weather -- I think we may be living through one of the most remarkable periods, meteorologically, in this areas history. Over the last 5-6 years (and there are more beyond that, but we'll leave them out for now) the amount of anomalous events is almost becoming bizarre. Just in the last 1 1/2 to two or so years: December 26 2010 - Record setting snowfall, extreme impact event with record setting snow, wind, blizzard conditions. Winter of 2010-2011 - Record setting seasonal snowfall, periods of extreme cold and snow pack. Summer of 2011 - Record setting heat August 2011- Hurricane Irene with major impacts and damage October 2011 - Record setting early-season snowfall with over 15 inches of snow in some locations Winter of 2011-2012 - Equally anomalous, just not in the way we would have hoped. Incredibly low snowfall totals and wintry events. Summer of 2012 - 108 F at Newark and record setting heat throughout the northeast. October 2012 - Hurricane Sandy, possibly the most damaging storm we'll ever see in our lifetimes in this area November 2012 - One week later, anomalous early season snowfall event with widespread 6+ inch amounts and another strong surface low offshore. ---- When you look back even further, over the last few winters we have had a ridiculous amount of strong surface lows, nor'easters, and displays of classic CCB/frontogenic banding. This kind of stuff is not typical around here...we have experienced more than 10 storms that in the 80's and 90's would be considered "historic" or one of the "classics". One has to wonder if either a) this streak will end eventually, or b ) this is the new normal...the latter of which conversation I won't get into at the moment at the risk of bringing out the global warming alarmist hounds. But it certainly is interesting..and we're watching it unfold before our eyes. The Newark 108F was in Summer of 2011. But your point still stands... Link to comment Share on other sites More sharing options...
earthlight Posted November 10, 2012 Share Posted November 10, 2012 The Newark 108F was in Summer of 2011. But your point still stands... Oops. Seemed closer than that. Didn't they get pretty high this summer too? Link to comment Share on other sites More sharing options...
JBG Posted November 10, 2012 Share Posted November 10, 2012 In the +NAO to -NAO transitions, precip is enhanced, but it can often be lakes cutters or inland runners. Well how would you count December 25, 1969, which was in +NAO to -NAO transition? It did switch briefly to rain but it was no cutter or inland runner. Link to comment Share on other sites More sharing options...
nzucker Posted November 10, 2012 Share Posted November 10, 2012 Okay sorry either you read it wrong or I explained it wrong. The lack gradient leads to a less powerful hence a more snakey jet. Hence the mega -noas +naos. Go back in history and find another Sandy in oct/nov. This does not make any sense. The lack of a gradient would make the jet weaker, and that would make storms weaker. Strong storm systems occur because of the phasing of powerful shortwaves in an amplified mid-latitude jet stream. If you have less of a temperature differential between the arctic and the tropics, there would be less energy in the jet to phase and yield mid-latitude cyclones. You also can't argue that a warming climate leads to more +NAO states and more -NAO states. There is no physical mechanism that makes the NAO both more positive and more negative at the same time. What you could argue is that the lack of arctic sea ice is causing wave transfer to the stratosphere, as in the propagation of Rossby waves. This theory seems contradictory to the idea of increased Siberian snow cover leading to the warmer stratosphere, but some papers have theorized that the declining arctic sea ice leads to a more -NAO/-AO. You might check out the Fang and Wallace paper from 1994, printed in Journal of Climate. The only problem is that winters following historic sea ice minimums, such as 07-08 and 11-12, had a very positive NAO and AO, so the correlation cannot be that strong. 2007 had the 2nd lowest sea ice on record, and 2011 had the third lowest sea ice on record, yet neither winter had a significant degree of high-latitude blocking. Link to comment Share on other sites More sharing options...
Chaser25973 Posted November 10, 2012 Share Posted November 10, 2012 I don't at all believe that man is the cause of climate change, but I'm not stupid. Something is definitely changing. Something is different that is making our storms stronger. Katrina and Rita, sub 900 mb hurricanes. Sandy phasing with a nor'easter and polar jet stream. The tornado outbreak two years ago.... the hurricane season where we had like 30 named storms. I don't know what the cause is, but something is definitely happening that's making our weather more violent. Link to comment Share on other sites More sharing options...
andyhb Posted November 10, 2012 Share Posted November 10, 2012 I don't at all believe that man is the cause of climate change, but I'm not stupid. Something is definitely changing. Something is different that is making our storms stronger. Katrina and Rita, sub 900 mb hurricanes. Sandy phasing with a nor'easter and polar jet stream. The tornado outbreak two years ago.... the hurricane season where we had like 30 named storms. I don't know what the cause is, but something is definitely happening that's making our weather more violent. We have had sub-900 mb (Labor Day 1935, Gilbert, Allen) hurricanes before (FYI, Katrina reached a minimum pressure of 902 mb, Wilma was the other sub-900 mb hurricane in 2005), and keep in mind we haven't had a Cat 3 or higher landfall in the US since 2005. If you mean the 4/27 tornado outbreak, that was a year and a half ago. 2003 had a similar pattern to April 2011, where there were multiple large tornado outbreaks within a two week span, and there have been tornado outbreak sequences like this before (May 1896; May-June 1917; May 1995; etc), although the April 9th-28th period last year was nothing short of insane, to be fair. Sandy was a very rare and essentially ideal scenario for a storm at this time of the year, and is not enough to include into larger scale climatological trends. Link to comment Share on other sites More sharing options...
Chaser25973 Posted November 10, 2012 Share Posted November 10, 2012 We have had sub-900 mb (Labor Day 1935, Gilbert, Allen) hurricanes before (FYI, Katrina reached a minimum pressure of 902 mb, Wilma was the other sub-900 mb hurricane in 2005), and keep in mind we haven't had a Cat 3 or higher landfall in the US since 2005. If you mean the 4/27 tornado outbreak, that was a year and a half ago. 2003 had a similar pattern to April 2011, where there were multiple large tornado outbreaks within a two week span, and there have been tornado outbreak sequences like this before (May 1896; May-June 1917; May 1995; etc), although the April 9th-28th period last year was nothing short of insane, to be fair. Sandy was a very rare and essentially ideal scenario for a storm at this time of the year, and is not enough to include into larger scale climatological trends. Well, Katrina which had 902, Rita which had 895 and Wilma which had 882 all happened the same year. When was the last time we had 3 tropical systems that each had sub 905 pressures in the same tropical season? And just because we haven't had a cat 3 or stronger hurricane make landfall on the US, just means we've been lucky and the steering patterns have been kind to us. Dean in 2007 could have split the uprights and made Katrina look like a joke if it hadn't been suppressed to the south. Link to comment Share on other sites More sharing options...
andyhb Posted November 10, 2012 Share Posted November 10, 2012 Well, Katrina which had 902, Rita which had 895 and Wilma which had 882 all happened the same year. When was the last time we had 3 tropical systems that each had sub 905 pressures in the same tropical season? And just because we haven't had a cat 3 or stronger hurricane make landfall on the US, just means we've been lucky and the steering patterns have been kind to us. Dean in 2007 could have split the uprights and made Katrina look like a joke if it hadn't been suppressed to the south. The bolded all rides on the word "if". 2005 was an anomaly within the system, essentially everything about that year was intensely active, which makes it a rather poor comparison when talking about tropical climatology. When composing means and trends, you usually get rid of the mins and maxes, the weakest and strongest years, to decrease noise. 2007, although it had two intense Cat 5s in Felix and Dean, was largely inactive otherwise. Link to comment Share on other sites More sharing options...
Chaser25973 Posted November 10, 2012 Share Posted November 10, 2012 The bolded all rides on the word "if". 2005 was an anomaly within the system, essentially everything about that year was intensely active, which makes it a rather poor comparison when talking about tropical climatology. When composing means and trends, you usually get rid of the mins and maxes, the weakest and strongest years, to decrease noise. Question: How many major anomalous events within a short time period do we need to have in order for it to become the new normal? Link to comment Share on other sites More sharing options...
andyhb Posted November 10, 2012 Share Posted November 10, 2012 Question: How many major anomalous events within a short time period do we need to have in order for it to become the new normal? Sandy was an anomaly (not in the fact that a hurricane struck the northeast, which is relatively rare as is, but its track and the baroclinic interaction between it and the amplifying s/w trough made is even more strange), the 2005 hurricane season was an anomaly, the 1993 Superstorm was an anomaly, the April 2011 tornado events were an anomaly, the Super Outbreak of 1974 was an anomaly, the Dust Bowl of the 1930s was an anomaly (although some conditions like this have occurred throughout the years, still nothing has come close to the Dust Bowl in terms of widespread US drought and dust storms). Over the period of decades climatological anomalies will make themselves present, this doesn't mean that they will become the "norm", although I'll admit areas of the Northeast have seen some strange events the past year and a half or so. Link to comment Share on other sites More sharing options...
bluewave Posted November 10, 2012 Author Share Posted November 10, 2012 These are some charts showing the general increase in heights and blocking over time. I also compared the recent October blocking to earlier years to show how anomalous it has been. Link to comment Share on other sites More sharing options...
bluewave Posted November 10, 2012 Author Share Posted November 10, 2012 The Perfect Storm of 1991 also occurred during a strong blocking pattern like Sandy. The October blocking around that time was more transient than the recent October era. The 1991 500 mb anomaly pattern featured 2 days with 400 meter or higher positive 500 mb height anomalies around the time of the storm. This October featured at least 4 days of 400 meter anomalies at the time of Hurricane Sandy. Perfect Storm Hurricane Sandy Link to comment Share on other sites More sharing options...
Weathergun Posted November 10, 2012 Share Posted November 10, 2012 ^The January 1992 Nor'easter, which caused alot damage over the Delmarva region, had block a huge block over SE Canada: The December 1992 Nor'easter, also had a block over SE Canada. It's seems that the most damaging storms for Mid-Atlantic and Northeast, come with strong blocks that develop somewhere over SE Canada: October 1992 had some blocking that month has well: Link to comment Share on other sites More sharing options...
Snow_Miser Posted November 10, 2012 Share Posted November 10, 2012 ^The January 1992 Nor'easter, which caused alot damage over the Delmarva region, had block a huge block over SE Canada: The December 1992 Nor'easter, also had a block over SE Canada. It's seems that the most damaging storms for Mid-Atlantic and Northeast, come with strong blocks that develop somewhere over SE Canada: SE Canada is exactly where the 6z GEFS shows a block in the longer range: Link to comment Share on other sites More sharing options...
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