donsutherland1 Posted November 1, 2013 Share Posted November 1, 2013 Not the kind of winter I'd like to see... My very early guess prior to data I look for in November for confirmation of some of my key assumptions is that odds favor a warmer than normal winter in the eastern third to half of the U.S./southern Canada (including Toronto and Montreal). The risk of warmth is lower for Ottawa and Quebec City. A warmer than normal outcome is perhaps a 70% probability in my thinking at this time and the risk of a much warmer than normal outcome is on or near the table. At this point, ENSO is extremely likely to be neutral. It is also very likely to be biased cooler than normal based on the statistical ENSO models that have continued to outperform the dynamical ones on a consistent basis. The Arctic Oscillation (AO) looks to be predominantly positive. Three AO statistical analogs are currently high in the mix 1975-76, 1978-79, and 1989-90. 1975-76 looks best. Both 1975-76 and 1989-90 saw early autumn positive figures in the midst of predominantly positive regimes. 1989-90 did experience strong blocking from late November into December, prior to making a strong flip to predominantly positive to strongly positive values. Ensemble forecasts suggest that early-winter 1989-90-style blocking is not likely. 1978-79 saw positive autumn figures in the midst of a predominantly negative regime. For that reason, even as 1978-79 appears in the mix based on recent AO figures, I do not consider it a strong analog. Odds of a positive average for Winter 2013-14: Around 75% Siberian snow cover has advanced fairly slowly across October. According to research by Dr. Cohen, that would suggest a positive AO. New research from Italy that led to the development of the October Pattern Index (OPI), which seems highly promising in forecasting the winter AO, also had been pointing to a positive AO In short, at least when it comes to the AO, multiple lines of evidence indicate a positive AO. The PDO is likely to average negative. I have no firm thoughts on the EPO at this time. I will note that for the better AO analogs (1975-76, 1989-90) it had been predominantly positive during the winter. Winter precipitation: Still uncertain. Odds somewhat favor normal or below normal precipitation. Timing could be critical if one is looking for a moderate or larger snowstorm. The one positive thing is that the Arctic has been running consistently colder than it has in recent years. If the AO+ regime keeps the cold locked up there, brief intrusions of cold might be somewhat sharper than they were the last few winters. The late September cold shot that sent the temperature into the 40s in NYC and 30s in some outlying areas offered a hint of what might be possible. However, there is a risk that the cold could be drained into Eurasia at some point, leading to above normal temperature anomalies in the Arctic region. Given some of the data, there is some prospect of near coast-to-coast warm anomalies this winter (perhaps 25%). Until some of the assumptions that would lead to that outcome are confirmed by subsequent data, it's too soon to make such a call (at least for me). I'll have my final thoughts in late November (probably to be posted in the general forum). I hope things change from my current thinking but things have been trending the wrong way since I've been paying close attention to the data beginning in September. Link to comment Share on other sites More sharing options...
NEG NAO Posted November 1, 2013 Share Posted November 1, 2013 Don - won't allow me to post the image here - but if you go to JB's twitter account - on oct 30 post he shows the NCEP 06Z CFS 2-meter temp graphic for December 1st -14th and it shows a cold east and warm west pattern shaping up - any thoughts ? Link to comment Share on other sites More sharing options...
The_Global_Warmer Posted November 1, 2013 Share Posted November 1, 2013 the OPI which is insanely accurate since 2000 is predicting a 1.64 AO this winter. I feel like I shouldn't know this. I don't want to know this. How am I supposed to look forward to that? It's depressing. But I suppose if we had this in 2009 we would all be happy. Link to comment Share on other sites More sharing options...
donsutherland1 Posted November 1, 2013 Author Share Posted November 1, 2013 Don - won't allow me to post the image here - but if you go to JB's twitter account - on oct 30 post he shows the NCEP 06Z CFS 2-meter temp graphic for December 1st -14th and it shows a cold east and warm west pattern shaping up - any thoughts ? A lot would depend on what happens when the current AO+ regime ends. 1975 saw the break occur in November, but then revert back to a predominantly positive regime by the beginning of December. 1989 saw a predominantly AO- regime set in during the 11/17-12/21 period. So, the possibility of a temporary period of blocking is feasible. I don't think we'll see something like 1989. The ensemble forecasts also seem to lean against such an outcome. A shorter period of blocking is possible once the current AO+ regime ends. Overall, though I think 1975 might offer better insight into December than 1989. So a warm December overall is probably more likely than a cold one. In fact, the latest CFSv2 December monthly map is really warm. Nevertheless, at this point in time, I think it's far too soon to try to pin down December's details, even as the I believe the winter overall is looking to be warmer than normal. Link to comment Share on other sites More sharing options...
Isotherm Posted November 1, 2013 Share Posted November 1, 2013 the OPI which is insanely accurate since 2000 is predicting a 1.64 AO this winter. I feel like I shouldn't know this. I don't want to know this. How am I supposed to look forward to that? It's depressing. But I suppose if we had this in 2009 we would all be happy. Where did you get this data from? I find it very difficult to believe we can predict the AO with such incredible accuracy using October. I can see .7 - .8 type correlations but that graph indicates a > .95 type correlation. Link to comment Share on other sites More sharing options...
donsutherland1 Posted November 1, 2013 Author Share Posted November 1, 2013 the OPI which is insanely accurate since 2000 is predicting a 1.64 AO this winter. I feel like I shouldn't know this. I don't want to know this. How am I supposed to look forward to that? It's depressing. But I suppose if we had this in 2009 we would all be happy. Has Ricardo posted the figure? I was looking forward to his forthcoming post and additional discussion. Link to comment Share on other sites More sharing options...
Isotherm Posted November 1, 2013 Share Posted November 1, 2013 Don, Nice post. Unfortunately it looks like the early indicators are suggesting a poor Arctic pattern for blocking development and maintenance. The EPO is something we'll have to monitor over the coming weeks as it's negative phase can often offset warming in the northern tier of the US during DJF. I'll probably winter outlook posted later in November after we've accumulated more data. Winter's really left the building since March 2011. Let's hope we see positive developments soon. Link to comment Share on other sites More sharing options...
uncle W Posted November 1, 2013 Share Posted November 1, 2013 I was looking at the highest daily winter AO value and came up with this list...Some plus AO years were fine...1988-89 had a plus ao most of the winter except for a few days...That winter was horrible... December........... January............... February........... March 1st to 22nd... +5.040 12/02/79...+5.582 1/14/89...+5.911 2/26/90...+4.917 3/16/68... +4.704 12/17/91...+5.245 1/20/57...+4.306 2/28/67...+4.692 3/02/56 +4.460 12/27/83...+5.078 1/15/05...+4.172 2/25/76...+4.172 3/20/78 +4.350 12/02/12...+4.703 1/28/08...+3.914 2/04/11...+4.143 3/22/86 Dec... 1979-80 was a bad winter... 1991-92 was a bad winter... 1983-84 was an average winter... 2012-13 was an average winter... Jan... 1988-89 was a bad winter... 1956-57 was an average winter... 2004-05 was a great winter... 2007-08 was a bad winter... Feb... 1989-90 was a bad winter... 1966-67 was a great winter... 1975-76 was a bad winter... 2011-12 was a bad winter... March... 1967-68 was an average winter... 1955-56 was a great winter... 1977-78 was a great winter... 1985-86 was a bad winter... Link to comment Share on other sites More sharing options...
The_Global_Warmer Posted November 1, 2013 Share Posted November 1, 2013 Has Ricardo posted the figure? I was looking forward to his forthcoming post and additional discussion. Crocodile23 posted it. He says Ricardo will be stopping by soon with their write-up and all that. I would assume Cohens SAI will come in a bit lower probably around a 1.25. Either way anything over a 1.0 in a 90 day period is pretty high. Over a 1.5 and it's stupidly high. Assuming we get 2-4 weeks of a negative AO the other time would be ridiculous. While it's hard to think it will be wrong. Hopefully an active STJ and the Pacific can balance it out some. Link to comment Share on other sites More sharing options...
SnoSki14 Posted November 1, 2013 Share Posted November 1, 2013 Yeah this is very depressing as the entire year has taken a break. Well there were plenty of years in the past where we saw several consecutive disappointing winters, I mean a large chunk of the 1990s were disappointing. I guess the best thing to do now is expect the worst, but hope for the best because even in a warm winter, snow events are possible. 2005-2006 was a textbook example of that. Link to comment Share on other sites More sharing options...
KEITH L.I Posted November 1, 2013 Share Posted November 1, 2013 A lot would depend on what happens when the current AO+ regime ends. 1975 saw the break occur in November, but then revert back to a predominantly positive regime by the beginning of December. 1989 saw a predominantly AO- regime set in during the 11/17-12/21 period. So, the possibility of a temporary period of blocking is feasible. I don't think we'll see something like 1989. The ensemble forecasts also seem to lean against such an outcome. A shorter period of blocking is possible once the current AO+ regime ends. Overall, though I think 1975 might offer better insight into December than 1989. So a warm December overall is probably more likely than a cold one. In fact, the latest CFSv2 December monthly map is really warm. Nevertheless, at this point in time, I think it's far too soon to try to pin down December's details, even as the I believe the winter overall is looking to be warmer than normal. Don..December 1975 was near normal..35.8 CPK and January 76 was cold and snowy..what made that winter mild was the major warmth in February..Great forecast Don,except don't hold your hat on the CFSV2..pretty inaccurate if you ask me Link to comment Share on other sites More sharing options...
donsutherland1 Posted November 1, 2013 Author Share Posted November 1, 2013 Crocodile23 posted it. He says Ricardo will be stopping by soon with their write-up and all that. I would assume Cohens SAI will come in a bit lower probably around a 1.25. Either way anything over a 1.0 in a 90 day period is pretty high. Over a 1.5 and it's stupidly high. Assuming we get 2-4 weeks of a negative AO the other time would be ridiculous. While it's hard to think it will be wrong. Hopefully an active STJ and the Pacific can balance it out some. Thanks. I missed it as I had been looking for Ricardo's post. Even as I would prefer a colder and, more importantly, snowy winter, I'm pulling for Ricardo and his team to be right. Their work seems very promising. If the promise is realized going forward in the forecasting realm, their work (coupled with SAI) will make an important contribution toward improving the reliability of winter forecasting. More reliable winter forecasts could aid with energy planning, among other economic considerations. Some forecasters remain hesitant to make assumptions about the AO on account of uncertainty, even as the AO is an important influence when it comes to Northern Hemisphere winter conditions. The same situation existed for ENSO forecasting in the past. The recent work by Cohen and the Italian researchers could change this. Link to comment Share on other sites More sharing options...
donsutherland1 Posted November 1, 2013 Author Share Posted November 1, 2013 Don..December 1975 was near normal and January 76 was cold and snowy..what made that winter mild was the major warmth in February..Great forecast Don,except don't hold your hat on the CFSV2..pretty inaccurate if you ask me Just so there's no confusion, 1975 is strictly an AO analog. Other conditions e.g., ENSO differed in 1975-76 (La Niña) vs. what is likely this time around (Neutral). I just looked at the CFSv2 on account of the reference to the CFS (I assume JB tweeted about the same model via WeatherBell's charts). I agree with you. I don't believe the model has demonstrated much skill in its monthly forecast from so far out. It does seem to have had some skill within 10 days of the coming month, but also has had some cases with large errors. Link to comment Share on other sites More sharing options...
donsutherland1 Posted November 1, 2013 Author Share Posted November 1, 2013 Yeah this is very depressing as the entire year has taken a break. Well there were plenty of years in the past where we saw several consecutive disappointing winters, I mean a large chunk of the 1990s were disappointing. I guess the best thing to do now is expect the worst, but hope for the best because even in a warm winter, snow events are possible. 2005-2006 was a textbook example of that. Many, but not all, bad (warm) winters have at least a stretch or two of colder, snowy weather. Even if the winter turns out warmer than normal, it's too soon for me to be able to have a good idea as to whether we'll be dealing with a 2001-02 or 2011-12-style disaster. Of course, I could still be wrong with respect to my overall thinking. Link to comment Share on other sites More sharing options...
Isotherm Posted November 1, 2013 Share Posted November 1, 2013 The DJF AO for 2011-12 was +0.66 (Jan and Feb slightly negative AO) DJF AO for 2001-02 was +0.45 (December -1.3 AO) DJF AO for 2006-07 was +1.0 (with February 2007 a -1 AO after +2 Dec and Jan) DJF AO 2007-08 was +0.86 (all three months about +.8) So if the OPI is correct, we'd be more positive than any winter since 2000. Most of the positive AO winters featured a one month period of negative values, except for 2007-08 on this list. 1990-91 was +0.37 for DJF AO, with one month negative. 1992-93 was +1.76 AO for DJF, looks close to the OPI forecast. That winter was actually a blockbuster for New England, and the superstorm of course. Link to comment Share on other sites More sharing options...
donsutherland1 Posted November 1, 2013 Author Share Posted November 1, 2013 I was looking at the highest daily winter AO value and came up with this list...Some plus AO years were fine...1988-89 had a plus ao most of the winter except for a few days...That winter was horrible... December........... January............... February........... March 1st to 22nd... +5.040 12/02/79...+5.582 1/14/89...+5.911 2/26/90...+4.917 3/16/68... +4.704 12/17/91...+5.245 1/20/57...+4.306 2/28/67...+4.692 3/02/56 +4.460 12/27/83...+5.078 1/15/05...+4.172 2/25/76...+4.172 3/20/78 +4.350 12/02/12...+4.703 1/28/08...+3.914 2/04/11...+4.143 3/22/86 Dec... 1979-80 was a bad winter... 1991-92 was a bad winter... 1983-84 was an average winter... 2012-13 was an average winter... Jan... 1988-89 was a bad winter... 1956-57 was an average winter... 2004-05 was a great winter... 2007-08 was a bad winter... Feb... 1989-90 was a bad winter... 1966-67 was a great winter... 1975-76 was a bad winter... 2011-12 was a bad winter... March... 1967-68 was an average winter... 1955-56 was a great winter... 1977-78 was a great winter... 1985-86 was a bad winter... Some of those winters e.g., 1977-78, had predominantly negative AO values despite a few notable to exceptional AO+ readings. 1/19/78 through 3/8/78 saw one of the great blocking regimes on record. During that time, much of that winter's excessive snows fell. By the time the AO soared to +4, winter was essentially finished. Link to comment Share on other sites More sharing options...
uncle W Posted November 1, 2013 Share Posted November 1, 2013 Some of those winters e.g., 1977-78, had predominantly negative AO values despite a few notable to exceptional AO+ readings. 1/19/78 through 3/8/78 saw one of the great blocking regimes on record. During that time, much of that winter's excessive snows fell. By the time the AO soared to +4, winter was essentially finished. The March +AO's are after the fact but 1956 had plenty of winter still...1968 went from cold to mild in March...1978's winter was over by then...1986 was warm the end of March...only 2005 had a great winter after such a high AO in before February... Link to comment Share on other sites More sharing options...
uncle W Posted November 1, 2013 Share Posted November 1, 2013 The DJF AO for 2011-12 was +0.66 (Jan and Feb slightly negative AO) DJF AO for 2001-02 was +0.45 (December -1.3 AO) DJF AO for 2006-07 was +1.0 (with February 2007 a -1 AO after +2 Dec and Jan) DJF AO 2007-08 was +0.86 (all three months about +.8) So if the OPI is correct, we'd be more positive than any winter since 2000. Most of the positive AO winters featured a one month period of negative values, except for 2007-08 on this list. 1990-91 was +0.37 for DJF AO, with one month negative. 1992-93 was +1.76 AO for DJF, looks close to the OPI forecast. That winter was actually a blockbuster for New England, and the superstorm of course. 1992-93 had the December super storm and the March super storm...February 1993 had a big change early in the month to colder and stormier...From February 1993 to March 1994 NYC saw many significant winter storms with snow sleet and rain... Link to comment Share on other sites More sharing options...
uncle W Posted November 1, 2013 Share Posted November 1, 2013 all the neutral negative Decembers with an oni between -0.1 and -0.5 had a munus AO on average for December...I hope it happens again this year...I think the DJF oni will be in that range... Link to comment Share on other sites More sharing options...
Stormlover74 Posted November 1, 2013 Share Posted November 1, 2013 all the neutral negative Decembers with an oni between -0.1 and -0.5 had a munus AO on average for December...I hope it happens again this year...I think the DJF oni will be in that range... I was looking at the highest daily winter AO value and came up with this list...Some plus AO years were fine...1988-89 had a plus ao most of the winter except for a few days...That winter was horrible... December........... January............... February........... March 1st to 22nd... +5.040 12/02/79...+5.582 1/14/89...+5.911 2/26/90...+4.917 3/16/68... +4.704 12/17/91...+5.245 1/20/57...+4.306 2/28/67...+4.692 3/02/56 +4.460 12/27/83...+5.078 1/15/05...+4.172 2/25/76...+4.172 3/20/78 +4.350 12/02/12...+4.703 1/28/08...+3.914 2/04/11...+4.143 3/22/86 Dec... 1979-80 was a bad winter... 1991-92 was a bad winter... 1983-84 was an average winter... 2012-13 was an average winter... Jan... 1988-89 was a bad winter... 1956-57 was an average winter... 2004-05 was a great winter... 2007-08 was a bad winter... Feb... 1989-90 was a bad winter... 1966-67 was a great winter... 1975-76 was a bad winter... 2011-12 was a bad winter... March... 1967-68 was an average winter... 1955-56 was a great winter... 1977-78 was a great winter... 1985-86 was a bad winter... 92 had 2 late season storms, 89 of course had snow on thanksgiving and a very cold December but a disaster for snowstorms, 86 had back to back events in February and 04-05 didn't get going until 2/3 of the way thru January ( I know alot of people were calling winter cancel by mid month before the activity got going) Link to comment Share on other sites More sharing options...
IsentropicLift Posted November 1, 2013 Share Posted November 1, 2013 The AO is much less of a factor for us than the NAO/PNA and the AO is most important during times of extremes one way or the other. Personally I feel as if we're in for a big, big winter. That doesn't mean that it's going to be all snow events, especially at the coast. If we end up with a mainly -PNA and slightly -NAO it would favor an active storm track for our area and anything can happen. Long range NAO forecasts point towards a nearly neutral to slightly negative NAO coming towards the third week of November or so. The PNA is a little more worrisome as it looks to stay negative till at least the end of November. This type of setup (+AO/-NAO/-PNA) should favor generally fast flow and quick hitting systems with the mean storm track up through the APS and into New England. Hopefully that will at least usher in a period of above normal precip through the end of the month. Link to comment Share on other sites More sharing options...
Isotherm Posted November 1, 2013 Share Posted November 1, 2013 Not going to put much stock in the OPI until I see how it performs this winter. With that being said, going into November, we have the OPI suggesting a +1.65 AO for winter. The SAI suggests moderately positive, maybe on par with 2007-08's +0.8 value. Our slope was very similar to that year. The next 30-40 days will be very important for pattern development IMO. I place the largest weight on the period late October-early December. Link to comment Share on other sites More sharing options...
Isotherm Posted November 1, 2013 Share Posted November 1, 2013 The AO is much less of a factor for us than the NAO/PNA and the AO is most important during times of extremes one way or the other. Personally I feel as if we're in for a big, big winter. That doesn't mean that it's going to be all snow events, especially at the coast. If we end up with a mainly -PNA and slightly -NAO it would favor an active storm track for our area and anything can happen. Long range NAO forecasts point towards a nearly neutral to slightly negative NAO coming towards the third week of November or so. The PNA is a little more worrisome as it looks to stay negative till at least the end of November. This type of setup (+AO/-NAO/-PNA) should favor generally fast flow and quick hitting systems with the mean storm track up through the APS and into New England. Hopefully that will at least usher in a period of above normal precip through the end of the month. Don't necessarily agree. We've seen a larger number of snowstorms with a +NAO than we have with a +AO. I place the greatest weight on the EPO, AO, followed by the NAO / PNA. The EPO is a key indicator for CONUS cold weather. Of course they are all a piece of the puzzle, but in my view the EPO is the biggest piece for temps, along with the AO. Link to comment Share on other sites More sharing options...
IsentropicLift Posted November 1, 2013 Share Posted November 1, 2013 Don't necessarily agree. We've seen a larger number of snowstorms with a +NAO than we have with a +AO. I place the greatest weight on the EPO, AO, followed by the NAO / PNA. The EPO is a key indicator for CONUS cold weather. Of course they are all a piece of the puzzle, but in my view the EPO is the biggest piece for temps, along with the AO. You can get a snowstorm with a +NAO when the PNA is also strongly positive, but a +NAO definitely favors inland locations for snow. Link to comment Share on other sites More sharing options...
donsutherland1 Posted November 1, 2013 Author Share Posted November 1, 2013 The AO is much less of a factor for us than the NAO/PNA and the AO is most important during times of extremes one way or the other. With respect to blockbuster snowstorms (12" or more), that's not the case. Since 1950, when daily records for the AO and NAO have been recorded, NYC has seen 21 storms that brought 12" or more of snow. In 71% of those cases, the storms began with a negative AO. In contrast, there was a near 50-50 split with respect to the NAO (48% began with a negative NAO). Below is the contingency table for such snowstorms: Link to comment Share on other sites More sharing options...
uncle W Posted November 1, 2013 Share Posted November 1, 2013 Not the kind of winter I'd like to see... My very early guess prior to data I look for in November for confirmation of some of my key assumptions is that odds favor a warmer than normal winter in the eastern third to half of the U.S./southern Canada (including Toronto and Montreal). The risk of warmth is lower for Ottawa and Quebec City. A warmer than normal outcome is perhaps a 70% probability in my thinking at this time and the risk of a much warmer than normal outcome is on or near the table. At this point, ENSO is extremely likely to be neutral. It is also very likely to be biased cooler than normal based on the statistical ENSO models that have continued to outperform the dynamical ones on a consistent basis. The Arctic Oscillation (AO) looks to be predominantly positive. Three AO statistical analogs are currently high in the mix 1975-76, 1978-79, and 1989-90. 1975-76 looks best. Both 1975-76 and 1989-90 saw early autumn positive figures in the midst of predominantly positive regimes. 1989-90 did experience strong blocking from late November into December, prior to making a strong flip to predominantly positive to strongly positive values. Ensemble forecasts suggest that early-winter 1989-90-style blocking is not likely. 1978-79 saw positive autumn figures in the midst of a predominantly negative regime. For that reason, even as 1978-79 appears in the mix based on recent AO figures, I do not consider it a strong analog. Odds of a positive average for Winter 2013-14: Around 75% Siberian snow cover has advanced fairly slowly across October. According to research by Dr. Cohen, that would suggest a positive AO. New research from Italy that led to the development of the October Pattern Index (OPI), which seems highly promising in forecasting the winter AO, also had been pointing to a positive AO In short, at least when it comes to the AO, multiple lines of evidence indicate a positive AO. The PDO is likely to average negative. I have no firm thoughts on the EPO at this time. I will note that for the better AO analogs (1975-76, 1989-90) it had been predominantly positive during the winter. Winter precipitation: Still uncertain. Odds somewhat favor normal or below normal precipitation. Timing could be critical if one is looking for a moderate or larger snowstorm. The one positive thing is that the Arctic has been running consistently colder than it has in recent years. If the AO+ regime keeps the cold locked up there, brief intrusions of cold might be somewhat sharper than they were the last few winters. The late September cold shot that sent the temperature into the 40s in NYC and 30s in some outlying areas offered a hint of what might be possible. However, there is a risk that the cold could be drained into Eurasia at some point, leading to above normal temperature anomalies in the Arctic region. Given some of the data, there is some prospect of near coast-to-coast warm anomalies this winter (perhaps 25%). Until some of the assumptions that would lead to that outcome are confirmed by subsequent data, it's too soon to make such a call (at least for me). I'll have my final thoughts in late November (probably to be posted in the general forum). I hope things change from my current thinking but things have been trending the wrong way since I've been paying close attention to the data beginning in September. checking the three analogs Don presented shows a very cold month happened in all three winters... 1975-76 averaged 27.1 for 30 days 1/2-1/31... 1978-79 averaged 26.0 for 30 days from the end of January to the end of February... 1989-90 averaged 25.3 for 30 days from the end of November to the end of December... If 2013-14 is anything like these analogs we could see a very cold month this winter... Link to comment Share on other sites More sharing options...
Absolute Humidity Posted November 1, 2013 Share Posted November 1, 2013 With the Exception of 93-94, +AO blows chunks. Even that winter featured more sleet than snow for many and its cold very well may have been more influenced by the eruption of Mt. Pinatubo in 1991. Link to comment Share on other sites More sharing options...
Isotherm Posted November 1, 2013 Share Posted November 1, 2013 checking the three analogs Don presented shows a very cold month happened in all three winters... 1975-76 averaged 27.1 for 30 days 1/2-1/31... 1978-79 averaged 26.0 for 30 days from the end of January to the end of February... 1989-90 averaged 25.3 for 30 days from the end of November to the end of December... If 2013-14 is anything like these analogs we could see a very cold month this winter... Good info Unc. Looking at 1989-1990 and 1975-76 since they were +AO overall... Dec 1989 was almost entirely -EPO driven, with a slightly negative AO as the high NPAC heights extended into the arctic. Jan 1976 was an interesting case. No extreme NAO/AO values. Just slightly negative. PNA slightly positive, EPO about neutral. The north atlantic and arctic ridging were more key in Jan 1976. Link to comment Share on other sites More sharing options...
Isotherm Posted November 1, 2013 Share Posted November 1, 2013 With the Exception of 93-94, +AO blows chunks. Even that winter featured more sleet than snow for many and its cold very well may have been more influenced by the eruption of Mt. Pinatubo in 1991. AO was actually slightly negative for 93-94 but it's another winter where the -EPO did most of the work. NAO was strongly positive. Link to comment Share on other sites More sharing options...
Isotherm Posted November 1, 2013 Share Posted November 1, 2013 Actually Unc, just looking at temp data now, 1975-76 finished slightly colder than normal for DJF due to the bitter January. 32.6F mean temp for DJF at New Brunswick off of the normal mean of 33F for DJF (26F mean temp for January). Nationwide 75-76: January 1976: Link to comment Share on other sites More sharing options...
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