jbcmh81 Posted December 19, 2010 Share Posted December 19, 2010 lowest daily winter ao value since 1950...I hope I didn't miss a date... season.......value.....date..... 1949-50......-2.854.....3/15/50 1950-51......-4.353.....12/27/50 1951-52......-3.805.....3/4/1952 1952-53......-3.766.....12/27/52 1953-54......-3.495.....1/30/54 1954-55......-3.064.....1/4/55 1955-56......-4.564.....2/15/56 1956-57......-4.473.....2/21/57 1957-58......-4.030.....3/11/58 1958-59......-4.026.....1/7/59 1959-60......-4.108.....1/28/60 1960-61......-2.719.....1/10/61 1961-62......-4.417.....3/4/62 1962-63......-5.010.....1/21/63 1963-64......-4.470.....12/20/63 1964-65......-3.973.....1/26/65 1965-66......-5.130.....1/28/66 1966-67......-4.147.....12/13/66 1967-68......-3.490.....2/7/68 1968-69......-5.282.....2/13/69 1969-70......-6.365.....3/5/70 1970-71......-2.821.....2/6/71 1971-72......-3.100.....2/5/72 1972-73......-2.044.....12/17/72 1973-74......-2.792.....12/19/73 1974-75......-1.695.....12/18/74 1975-76......-3.262.....1/24/76 1976-77......-7.433.....1/15/77 1977-78......-5.291.....2/5/78 1978-79......-4.387.....1/25/79 1979-80......-3.705.....1/24/80 1980-81......-4.318.....3/4/81 1981-82......-3.804.....12/30/81 1982-83......-3.410.....2/6/83 1983-84......-3.706.....3/13/84 1984-85......-6.226.....1/19/85 1985-86......-3.894......2/6/86 1986-87......-3.507.....3/9/87 1987-88......-2.314.....2/28/88 1988-89......-0.318.....3/4/89 1989-90......-3.482.....12/10/89 1990-91......-3.381.....3/9/91 1991-92......-2.597.....12/4/91 1992-93......-2.228.....3/2/93 1993-94......-3.503.....2/24/94 1994-95......-3.116.....3/9/95 1995-96......-4.353.....12/19/95 1996-97......-3.377.....12/30/96 1997-98......-4.269.....1/10/98 1998-99......-3.856.....3/10/99 1999-00......-2.118.....2/18/00 2000-01......-4.854.....2/25/01 2001-02......-3.293.....12/28/01 2002-03......-3.575.....1/22/03 2003-04......-4.387.....1/17/04 2004-05......-4.337.....2/26/05 2005-06......-3.569.....12/5/05 2006-07......-2.184.....2/4/07 2007-08......-2.468.....1/2/08 2008-09......-3.178.....2/3/09 2009-10......-5.821.....12/21/09 2010-11......-5.172.....12/18/10 as of 12/18 So the only other time in the last 60 years that saw two winters in a row with a value greater than -5 was 1976 to 1978. And apparently we have never had a La Nina this strong with an AO this negative. Which makes predicting the outcome of the winter a little difficult I would think. Link to comment Share on other sites More sharing options...
jbcmh81 Posted December 19, 2010 Share Posted December 19, 2010 So the only other time in the last 60 years that saw two winters in a row with a value greater than -5 was 1976 to 1978. And apparently we have never had a La Nina this strong with an AO this negative. Which makes predicting the outcome of the winter a little difficult I would think. Edit: Missed 1968-1970 as well. Link to comment Share on other sites More sharing options...
winter_warlock Posted December 19, 2010 Share Posted December 19, 2010 Edit: Missed 1968-1970 as well. yep 69-70 had the higher than last 2 yrs, 6.3 Link to comment Share on other sites More sharing options...
GaWx Posted December 19, 2010 Share Posted December 19, 2010 The -5.172 of 12/18/2010 absolutely obliterates the record daily low AO for December for a moderate to strong La Nina (other than the surrounding days within 12/2010). The old record prior to 2010 was the -2.792 of 12/19/1973! There have been 11 moderate to strong La Nina winters since 1950-1. Also, the -5.172 is actually a new record daily low AO for December for ANY strength La Nina. The old record low was the -4.688 of 12/29/2000. There have been 19 La Nina winters since 1950-1. Daily records go back to 1950. Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 19, 2010 Author Share Posted December 19, 2010 This morning, the AO was -4.980. That breaks the daily record of -4.651 set last year. The ensembles suggest that the AO will be rising over coming days. If things work out as happened with the earlier albeit weaker La Niña cases in December, the AO should continue to rise and perhaps become positive some time during the first week in January +/- a few days. As that happens, the La Niña typically begins to dominate the pattern. That outcome probably remains more likely than not, but there is some uncertainty that deserves some discussion. It should also be noted that this is the first super December block during any La Niña. Superblocks tend to decay more slowly and renewed blocking tends to redevelop soon after the initial superblock has broken. The experience with the December 1976 and December 2009 superblocks highlights that tendency. The 2009-2010 blocking was, by far, the dominant driver of the Northern Hemisphere synoptic pattern last winter. Whether or not intense and frequent blocking will again be the dominant pattern driver this winter remains to be seen. There is an intriguing hint on the latest GFS ensembles of a redevelopment of blocking. In addition, the 360-hour GFS ensemble mean 500 mb height anomalies have some similarities to the January 1-3, 1971 height anomalies, though the center of blocking is farther east on the GFS ensembles. January 1-3, 1971: GFS Ensembles: All of the above adds confidence to a likely cold March (and might increase the level of anticipation in snow-starved cities such as Ottawa and Montreal). It also suggests that while February might wind up with the warmest anomalies, the month won't be an all-out blowtorch. Finally, it muddies the picture for January, hinting that the month could still be in play. For now, I remain inclined to suggest moderation lies ahead beginning in the first week in January +/- a few days, but the level of uncertainty is higher than it was last winter. Link to comment Share on other sites More sharing options...
jbcmh81 Posted December 19, 2010 Share Posted December 19, 2010 For now, I remain inclined to suggest moderation lies ahead beginning in the first week in January +/- a few days, but the level of uncertainty is higher than it was last winter. Don, I would agree that moderation is probably likely, but that is also not saying a lot given the extreme negative departures we have been seeing so far this December. So moderation may just end up meaning less negative, but still negative overall. The possibility of the blocking redeveloping towards the first of January and beyond is interesting as you noted. It is why some of the La Ninas I brought up before, like 1903-04 and 1962-63 are still very much on my mind. Neither one of those winters had record-breaking snowfall or particularly large storms from what I can see, but just persistent cold and light to moderate snows that gradually piled up. Link to comment Share on other sites More sharing options...
uncle W Posted December 19, 2010 Share Posted December 19, 2010 Don, I would agree that moderation is probably likely, but that is also not saying a lot given the extreme negative departures we have been seeing so far this December. So moderation may just end up meaning less negative, but still negative overall. The possibility of the blocking redeveloping towards the first of January and beyond is interesting as you noted. It is why some of the La Ninas I brought up before, like 1903-04 and 1962-63 are still very much on my mind. Neither one of those winters had record-breaking snowfall or particularly large storms from what I can see, but just persistent cold and light to moderate snows that gradually piled up. 1903-04 had more snow than 1962-63...27.4".... 16.3"...The four storms 2"+ in 1962-63 were all mixed with or changed to rain... 1903-04 3.8" 12/3 1.3" 12/27 1.3" 12/29 8.0" 1/2-3 1.5" 1/8 0.3" 1/13 0.8" 1/26 2.0" 2/15 3.0" 2/19 1.0" 3/1 0.4" 3/11 2.0" 3/15 2.0" 3/18 1962-63 1.2" 12/9 0.3" 12/16 2.7" 12/21 0.3" 12/25 0.2" 1/23 4.2" 1/27 0.9" 2/1 2.5" 2/19 1.0" 2/24 0.2" 2/25 2.0" 3/1 0.8" 3/21 Link to comment Share on other sites More sharing options...
A-L-E-X Posted December 19, 2010 Share Posted December 19, 2010 Thanks Don-- your idea of a colder March, makes 1955-56 continue to be a possible analog, and perhaps we'll have that endangered species visit us again-- the rare March east coast snowstorm Another a nina winter where blocking redeveloped later on was 2005-06. Of course we also have 1966-67 and 1995-96, but they were weak la ninas. Link to comment Share on other sites More sharing options...
uncle W Posted December 19, 2010 Share Posted December 19, 2010 if you look at the weather in NYC at the time of each winters lowest -AO reading you will see either the coldest temperature for the winter or the month near or on the same date many times...Snowfalls on or around the same dates...Or the coldest temp. for the winter and the biggest snow on or around the same dates...12/27/1950 had its lowest -ao reading for the winter and NYC received it's largest snow that winter and coldest temperature on that date...Granted it was only a 3" storm and the temperature was only 9 degrees but it coincided together...When I have time I'll post what the weather was in NYC when the ao was at its minimum...Feb. 69 and 78 had their blizzards and coldest temps around the ao minimum...1/17/04 and on and on... Link to comment Share on other sites More sharing options...
Organizing Low Posted December 19, 2010 Share Posted December 19, 2010 Superblock!! Haha, I love it... Great work Don, your AO has absolutely dominated and controlled the weather over in these parts the past 2 winter seasons (temps and precip), thanks for the information and I look forward to more. Link to comment Share on other sites More sharing options...
uncle W Posted December 20, 2010 Share Posted December 20, 2010 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...KU...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...KU event...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...KU...1960-61......-2.719.....1/10/61......greatest snowy and cold period followed 1/15-2/12...three KU's...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...KU...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...Ku storm 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...KU...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...KU...1978-79......-4.387.....1/25/79......Very cold and snowy February...KU...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...KU...1983-84......-3.706.....3/13/84......record cold 3/10...7" snow 3/8-9...1984-85......-6.226.....1/19/85.....4.1" of snow 1/17/85...-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...KU...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...KU in Feb...1995-96......-4.353.....12/19/95...8" of snow during a very cold period...January blizzard..KU...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...KU in January...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...KU 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. KU...2004-05......-4.337.....2/26/05......6" of snow 2/25 and 8" 2/29...KU 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...KU in Feb...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...KU...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.....1/28/12...4.3" of snow 1/21/12 2012-13......-5.688.....3/20/13...3.0" of snow 3/18/13... 2013-14......-2.605.....1/27/14...11" of snow 1/21...very cold on the 28th... 2014-15......-1.280.....12/28/14.....as of 1/17/15 Link to comment Share on other sites More sharing options...
SACRUS Posted December 20, 2010 Share Posted December 20, 2010 [quote lowest daily winter ao value since 1950...I hope I didn't miss a date...Weather at the time for NYC... some memorable events on that list. Great info and great thread. Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 20, 2010 Author Share Posted December 20, 2010 Wonderful info., Uncle W. Link to comment Share on other sites More sharing options...
uncle W Posted December 20, 2010 Share Posted December 20, 2010 Wonderful info., Uncle W. thanks Don...I hope I didn't make any mistakes..if we see a lower AO reading later on in the winter we could see extreme cold with hopefully some snow... Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 20, 2010 Author Share Posted December 20, 2010 On yesterday's point that superblocks tend to decay more slowly and renewed blocking tends to redevelop soon after the initial superblock has broken, the latest run of the GFS ensembles is even more adamant about a rebuilding of the blocking. The debate as to whether typical December superblock experience (unprecedented until December 2010 for a La Niña) or typical La Niña blocking experience will define the path forward has increased with the latest run of the GFS ensembles. Whether or not Winter 2010-11 will follow a path more akin to Winter 1970-71 remains to be seen (one warm month in the East vs. the typical two or sometimes three). If the colder 1970-71-type scenario is to play out, a good signal would be a much longer duration of the current blocking regime (now being hinted at by the GFS ensembles). Link to comment Share on other sites More sharing options...
jbcmh81 Posted December 20, 2010 Share Posted December 20, 2010 On yesterday's point that superblocks tend to decay more slowly and renewed blocking tends to redevelop soon after the initial superblock has broken, the latest run of the GFS ensembles is even more adamant about a rebuilding of the blocking. The debate as to whether typical December superblock experience (unprecedented until December 2010 for a La Niña) or typical La Niña blocking experience will define the path forward has increased with the latest run of the GFS ensembles. Whether or not Winter 2010-11 will follow a path more akin to Winter 1970-71 remains to be seen (one warm month in the East vs. the typical two or sometimes three). If the colder 1970-71-type scenario is to play out, a good signal would be a much longer duration of the current blocking regime (now being hinted at by the GFS ensembles). Don, what makes 70-71 more of a possibility for this winter? Looking at the actual weather, December was warm in the OV down to the Gulf Coast, the exact opposite of this year. January was much colder for the northern Plains on east, and February looks +/- 2 degrees for much of the country. The winter overall was warm in the Southeast and OV, and cold for the far northern plains, with most other areas near normal. Are you talking about blocking alone? Even if we turn warm for a month or more across most of the East, it would be very hard at this point to end winter as a warm one (or even normal) similar to 70-71. If we see persistent blocking, I would think we are looking at a far colder winter overall than in 70-71. Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 20, 2010 Author Share Posted December 20, 2010 Don, what makes 70-71 more of a possibility for this winter? Looking at the actual weather, December was warm in the OV down to the Gulf Coast, the exact opposite of this year. January was much colder for the northern Plains on east, and February looks +/- 2 degrees for much of the country. The winter overall was warm in the Southeast and OV, and cold for the far northern plains, with most other areas near normal. Are you talking about blocking alone? Even if we turn warm for a month or more across most of the East, it would be very hard at this point to end winter as a warm one (or even normal) similar to 70-71. If we see persistent blocking, I would think we are looking at a far colder winter overall than in 70-71. !970-71 is merely a case where most of the winter was cold during a La Niña (ENSO Region 3.4 anomaly of -1 or below). December 1970 was generally warmer than normal in the East. But January through March 1971 was on the cold side of normal in most of the East. My point is that even if the La Niña remains near its current strength (something that appears likely through at least February), there is precedent for a colder outcome. Right now, I still favor moderation in early January (even if there is a quick cold shot early on) and then a generally warm regime for the second half of the month. February should be the warmest month. Several quick stats regarding January during La Niña conditions where the Region 3.4 anomaly is -1 or below for December and January: - Cold in the East during December: 3/4 (75%) were normal or colder than normal in the East in January - Blocky January (AO averaged -1 or below): 4/4 (100%) were normal or colder than normal in the East in January - Low or no blocking in January (AO averaged > -1): 4/7 (57%) were warmer than normal Link to comment Share on other sites More sharing options...
easternsnowman Posted December 20, 2010 Share Posted December 20, 2010 'm with DT in believing late Feb and early March will be cold and snowy. Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 20, 2010 Author Share Posted December 20, 2010 'm with DT in believing late Feb and early March will be cold and snowy. Late February into March has, during a number of La Niña winters, favored strong blocking. I continue to lean toward a colder than normal March at this stage. Odds of such an outcome are actually quite good should blocking redevelop for March. Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 21, 2010 Author Share Posted December 21, 2010 The following 500 mb and surface temperature anomaly maps illustrate the impact continued blocking might have in January. The cases were taken from La Niñas that had ENSO Region anomalies of -1 or below in both December and January. The "blocky" sample had a January AO of -1 or below. The "no blocking" sample had a January AO of > 0. All moderate/strong La Niña Cases: 500 mb: Temperature Anomalies: Blocking: 500 mb: Temperature Anomalies: No Blocking: 500 mb: Temperature Anomalies: Link to comment Share on other sites More sharing options...
Carvers Gap Posted December 21, 2010 Share Posted December 21, 2010 The following 500 mb and surface temperature anomaly maps illustrate the impact continued blocking might have in January. The cases were taken from La Niñas that had ENSO Region anomalies of -1 or below in both December and January. The "blocky" sample had a January AO of -1 or below. The "no blocking" sample had a January AO of > 0. Wow! That is pretty amazing data. Link to comment Share on other sites More sharing options...
nzucker Posted December 21, 2010 Share Posted December 21, 2010 This January may be much colder than many expected; already, long-range models are latching onto a huge ridge building into Siberia that will bring all the arctic air to drain into the Canadian Prairies and probably the US High Plains. ECM shows Siberian High developing at Day 10: 18z GFS at Day 10 shows very cold air developing in central Canada and moving towards the Northern Rockies/Northern Plains: Link to comment Share on other sites More sharing options...
uncle W Posted December 21, 2010 Share Posted December 21, 2010 These are the stats for NYC for the eleven January analogs that Don shows... Year.....Ave temp.....precip.....snowfall...greatest snowfall 1950............41.4..........2.26"..........0.4"..............0.4" 1955............31.0..........0.77"..........2.6"..............0.9" 1956............32.0..........1.54"..........1.2"..............0.5" 1971............27.0..........2.67"........11.4"..............6.4" 1974............35.3..........3.80"..........7.8"..............4.3" 1976............27.4..........5.78"..........5.6"..............1.9" 1985............28.8..........1.00"..........8.4"..............4.1" 1989............37.4..........2.29"..........5.0"..............5.0" 1999............33.9..........6.99"..........4.5"..............2.5" 2000............31.3..........3.24"..........9.5"..............5.5" 2008............36.5..........2.85"............T...................T..... 11yr ave.......32.9...........3.02"..........5.1".............2.9" 1971-00.......32.1...........4.13"..........8.1"................................ 55,56,85.......30.6..........1.10"..........4.1".............1.9" 50,71,74,76 89,99,00,08.. 33.8..........3.74"..........5.5".............3.3" the 11 January's temperature average is slightly above normal...Precipitation averages below normal and snowfall well below normal...1971 had the only 6" snowfall...The three January's with blocking were very dry...The average max snowfall for those months is only 1.9" and monthly snowfall is 4.1"... Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 21, 2010 Author Share Posted December 21, 2010 This morning, the AO stood at -4.104. A general slow rise is expected over the next few days. In terms of the possible weekend event, I still suspect a moderate event is possible for the Middle Atlantic and southern New England states. What is somewhat worrisome is the recent trend among the GFS ensembles to present a broader and broader turn to the north. If that trend has merit, it would not be surprising to see the 12z ECMWF and 12z ECMWF ensemble mean shift eastward. IMO, as the 12z ensemble suite hasn't come out, my best guess is that a track somewhere between the 0z ECMWF ensemble mean and 0z/6z GFS ensemble means is probably a reasonable idea at this time. The operational 12z GFS is east of that idea. While I don't believe that is the most likely outcome at this time, I don't believe it can be dismissed out of hand given the abnormally high level of uncertainty that is often present during moderate/strong La Niña events. Link to comment Share on other sites More sharing options...
ayuud Posted December 21, 2010 Share Posted December 21, 2010 This morning, the AO stood at -4.104. A general slow rise is expected over the next few days. In terms of the possible weekend event, I still suspect a moderate event is possible for the Middle Atlantic and southern New England states. What is somewhat worrisome is the recent trend among the GFS ensembles to present a broader and broader turn to the north. If that trend has merit, it would not be surprising to see the 12z ECMWF and 12z ECMWF ensemble mean shift eastward. IMO, as the 12z ensemble suite hasn't come out, my best guess is that a track somewhere between the 0z ECMWF ensemble mean and 0z/6z GFS ensemble means is probably a reasonable idea at this time. The operational 12z GFS is east of that idea. While I don't believe that is the most likely outcome at this time, I don't believe it can be dismissed out of hand given the abnormally high level of uncertainty that is often present during moderate/strong La Niña events. When do you think this storm track will change? we need some synoptic stuff here in upstate! Link to comment Share on other sites More sharing options...
Feb Posted December 21, 2010 Share Posted December 21, 2010 This morning, the AO stood at -4.104. A general slow rise is expected over the next few days. In terms of the possible weekend event, I still suspect a moderate event is possible for the Middle Atlantic and southern New England states. What is somewhat worrisome is the recent trend among the GFS ensembles to present a broader and broader turn to the north. If that trend has merit, it would not be surprising to see the 12z ECMWF and 12z ECMWF ensemble mean shift eastward. IMO, as the 12z ensemble suite hasn't come out, my best guess is that a track somewhere between the 0z ECMWF ensemble mean and 0z/6z GFS ensemble means is probably a reasonable idea at this time. The operational 12z GFS is east of that idea. While I don't believe that is the most likely outcome at this time, I don't believe it can be dismissed out of hand given the abnormally high level of uncertainty that is often present during moderate/strong La Niña events. Didn't happen. As usual it appears the GFS will be late to the party. Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 21, 2010 Author Share Posted December 21, 2010 Didn't happen. As usual it appears the GFS will be late to the party. Hopefully, the Euro will ultimately prove correct. My worry is that the Euro might be playing somewhat to its bias in holding back energy and that could be leading to a more wound-up, in-close solution that might otherwise result. I do like how the GGEM and UKMET offered support for a more robust solution than the GFS, but phased solutions can be fraught with peril especially during La Niñas. Saturday/Sunday is still a long way off. I'll be looking forward to the 12z Euro ensembles, 18z and 0z model runs. Link to comment Share on other sites More sharing options...
WhiteoutWX Posted December 21, 2010 Share Posted December 21, 2010 Hopefully, the Euro will ultimately prove correct. My worry is that the Euro might be playing somewhat to its bias in holding back energy and that could be leading to a more wound-up, in-close solution that might otherwise result. I do like how the GGEM and UKMET offered support for a more robust solution than the GFS, but phased solutions can be fraught with peril especially during La Niñas. Saturday/Sunday is still a long way off. I'll be looking forward to the 12z Euro ensembles, 18z and 0z model runs. Its good though that all the models are basically in agreement up until about 72 hrs. By that time the s/w is already past the rockies and the southwest where the Euro usually displays a bias. Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 21, 2010 Author Share Posted December 21, 2010 Its good though that all the models are basically in agreement up until about 72 hrs. By that time the s/w is already past the rockies and the southwest where the Euro usually displays a bias. I agree about the general similarity in solutions among most of the models. I still have low confidence in extreme solutions (12z Euro-esque event that possibly transitions to rain for at least a time in parts of the greater NYC area or largely a non-event). I have medium confidence in a moderate event. It will be interesting to see the ECMWF ensemble mean in a little while in terms of track and timing. Link to comment Share on other sites More sharing options...
donsutherland1 Posted December 22, 2010 Author Share Posted December 22, 2010 Earlier in this thread, I noted that the only KU-type snowstorm that occurred with a La Niña Region 3.4 anomaly around -1 was the December 1909 bomb. That is incorrect and I regret the error. The January 2000 snowstorm occurred in a month when the Region 3.4 anomaly was -1.86. The list of KU storms during La Niñas (1950-2009) follows: Interestingly enough, 6/9 (67%) of KU storms that occurred with a Region 3.4 anomaly of -0.25 or lower commenced when the GWO was either in Phase 4 or 5. 1 of those 9 storms began when the GWO was at Phase 2. Link to comment Share on other sites More sharing options...
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