Ji Posted February 8, 2012 Share Posted February 8, 2012 Donald, Do you think early March could offer a chance for an East Coast snowstorm or are we screwed till next winter? Link to comment Share on other sites More sharing options...
RCNYILWX Posted February 8, 2012 Share Posted February 8, 2012 Several quick thoughts: 1. Yesterday's AO was revised to -2.076. 2. Today, the AO rose somewhat further to -1.847. 3. The GFS ensembles are even more aggressive in forecasting a positive to perhaps strongly postive AO in the extended range. 4. The GFS continues to forecast a decline in the PNA in the extended range. As a result, the weekend/perhaps early week cold shot will likely quickly yield to moderation. Therefore, as has been the case all winter long, the cold won't lock into the East. Before then, some parts of the Mid-Atlantic region and perhaps extreme southern New England could experience a light snowfall or flurries later today and tonight. Another possibility for a light snow event could exist during the weekend should a system form along the boundary of a cold front that will be responsible for the temporary cooldown. Finally, there may be growing potential that the closing 7-10 days of the month could witness a return of cooler than normal readings in the Pacific Northwest. First of all, Don, great work all winter. Why aren't you working for CPC ? I had a question about the AO, since I've been trying to learn more about it myself. Stratospheric temperatures have taken a nosedive well up in the stratosphere, for instance at 5mb: http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/05mb9065.gif And at 10 mb: http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/10mb9065.gif Temperatures have begun to drop at 70mb, which is closer to the tropopause and thus closer where the response in terms of the strength and placement of the PV would occur, but they are still solidly above average for this time of year: http://www.cpc.ncep.noaa.gov/products/stratosphere/temperature/70mb9065.gif Given the above and that there was a lag time from the stratospheric warming in late December into January to flip from a +AO to a -AO regime, it is possible the ensembles are moving too quick back to a +AO regime? Link to comment Share on other sites More sharing options...
N. OF PIKE Posted February 8, 2012 Share Posted February 8, 2012 euro and gfs ensembles bring a -nao in about 3-4 days for several days after. Question for Don, Also since the recent blocking (-AO)was on the WRONG side of the globe for us to reap the benefits of the blocking ....why would decreasing blocking ("on the wrong side of the world") really heat us up that much if it never really cooled us off in the first place. I mean is this not holding any weight? Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 8, 2012 Share Posted February 8, 2012 First of all, Don, great work all winter. Why aren't you working for CPC ? I had a question about the AO, since I've been trying to learn more about it myself. Stratospheric temperatures have taken a nosedive well up in the stratosphere, for instance at 5mb: http://www.cpc.ncep....re/05mb9065.gif And at 10 mb: http://www.cpc.ncep....re/10mb9065.gif Temperatures have begun to drop at 70mb, which is closer to the tropopause and thus closer where the response in terms of the strength and placement of the PV would occur, but they are still solidly above average for this time of year: http://www.cpc.ncep....re/70mb9065.gif Given the above and that there was a lag time from the stratospheric warming in late December into January to flip from a +AO to a -AO regime, it is possible the ensembles are moving too quick back to a +AO regime? Thanks for the kind words. IMO, the ensembles are probably a little too quick and too aggressive, but the idea of a transition back to positive seems reasonable. Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 8, 2012 Share Posted February 8, 2012 euro and gfs ensembles bring a -nao in about 3-4 days for several days after. Question for Don, Also since the recent blocking (-AO)was on the WRONG side of the globe for us to reap the benefits of the blocking ....why would decreasing blocking ("on the wrong side of the world") really heat us up that much if it never really cooled us off in the first place. I mean is this not holding any weight? The points I'm trying to make is that once the AO+ returns, the anomalously mild weather looks to continue with only short-lived shots of cold and chances of a major snowstorm are likely to remain low. Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 8, 2012 Share Posted February 8, 2012 Donald, Do you think early March could offer a chance for an East Coast snowstorm or are we screwed till next winter? If the return of the AO+ plays out and an AO+ dominates in March, I doubt that there will be any such snowstorms. More than likely, Winter 2011-12 and Spring 2012 won't see a KU snowstorm. Link to comment Share on other sites More sharing options...
Ottawa Blizzard Posted February 8, 2012 Share Posted February 8, 2012 The points I'm trying to make is that once the AO+ returns, the anomalously mild weather looks to continue with only short-lived shots of cold and chances of a major snowstorm are likely to remain low. Don, you have to admit that this winter is turning out remarkably similar to 1905-1906 in terms of temperature and (up to now) snowfall. 1918-1919 is also a good match. Link to comment Share on other sites More sharing options...
uncle W Posted February 8, 2012 Share Posted February 8, 2012 Don, you have to admit that this winter is turning out remarkably similar to 1905-1906 in terms of temperature and (up to now) snowfall. 1918-1919 is also a good match. 1918-19 looks like another fading el nino that peaked in late Summer and fall... ftp://www.coaps.fsu.edu/pub/JMA_SST_Index/jmasst1868-today.filter-5 Link to comment Share on other sites More sharing options...
Ottawa Blizzard Posted February 8, 2012 Share Posted February 8, 2012 1918-19 looks like another fading el nino that peaked in late Summer and fall... ftp://www.coaps.fsu....-today.filter-5 sounds like we should never hope for a fading El Nino... Link to comment Share on other sites More sharing options...
Quakertown needs snow Posted February 9, 2012 Share Posted February 9, 2012 just wanted to say thanks don for all your posts and let's not forget his A+ Digital Snow Museum photo archives http://wintercenter.homestead.com/photoindex.html Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 9, 2012 Share Posted February 9, 2012 just wanted to say thanks don for all your posts and let's not forget his A+ Digital Snow Museum photo archives http://wintercenter....photoindex.html Many thanks, Andy. I greatly appreciate it. Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 9, 2012 Share Posted February 9, 2012 The guidance has come into general agreement that the Arctic Oscillation (AO) will be going positive down the road. The positive AO will help ensure that cold shots in the East are relatively short-lived. Looking farther down the road to March, the AO could make a critical difference as to what part of North America is cold vs. what part is warm. Using data for weak La Niña conditions and a neutral PNA, the following are some scenarios for a weak AO- vs. a weak AO+ for March. Link to comment Share on other sites More sharing options...
N. OF PIKE Posted February 9, 2012 Share Posted February 9, 2012 seems most models take the MJO into phase 8 in the next day or two....then into phase 1 over the following week or so.. seems Ao will surely rise to neutral levels (-5 to .5) but is a MJO propogating into phase 8-then 1 a red flag .......when thinking the AO will rise much higher than (neurtal levels) i.e > .5? Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 9, 2012 Share Posted February 9, 2012 seems most models take the MJO into phase 8 in the next day or two....then into phase 1 over the following week or so.. seems Ao will surely rise to neutral levels (-5 to .5) but is a MJO propogating into phase 8-then 1 a red flag .......when thinking the AO will rise much higher than (neurtal levels) i.e > .5? Not necessarily. For February, the AO was as follows during Phase 1: > 0: 65.6% days < 0: 34.4% days +1 or above: 46.7% days +2 or above: 21.1% days -1 or below: 27.8% days -2 or below: 14.4% days The average for the AO for such days is: +0.529. Link to comment Share on other sites More sharing options...
cbmclean Posted February 9, 2012 Share Posted February 9, 2012 The guidance has come into general agreement that the Arctic Oscillation (AO) will be going positive down the road. The positive AO will help ensure that cold shots in the East are relatively short-lived. Looking farther down the road to March, the AO could make a critical difference as to what part of North America is cold vs. what part is warm. Using data for weak La Niña conditions and a neutral PNA, the following are some scenarios for a weak AO- vs. a weak AO+ for March. I am just an amateur, so this may be a newbie type question, but I am extremely interested in the mechanisms of the fluctuations in temperature, especially during winter. Over, and over and over I have heard this winter about how the +NAO/AO configuration has lead to strenghended polar westerlies, thus leading to cold intrusions into the lower 48 and most of Canada being "transient". What I don't understand, is the unspoken assumption that always seems to come along with that analysis: namely that "transient" cold outbreaks = warmer than "normal" temperatures overall. This bothers me, because on a fundamental level, I don't see how the period of the fluctuations about the mean necessarily effects the averaged value of the system. Just because cold intrusions are short lived doesn't mean that it HAS to be warmer than normal averaged over a certain period of time. If every cold intrusion that we had was just a day long, we could still end up colder than "normal", just so long as the cold intrusions come at a sufficient frequency or have sufficient intensity or both. The point that I am trying to make is that I am just not satisfied withthe typical "lack of blocking" explanation for the anomalous warmth of this winter. Does anyone out there understand what I am getting at, or is my communication too garbled? Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 9, 2012 Share Posted February 9, 2012 What I don't understand, is the unspoken assumption that always seems to come along with that analysis: namely that "transient" cold outbreaks = warmer than "normal" temperatures overall. This bothers me, because on a fundamental level, I don't see how the period of the fluctuations about the mean necessarily effects the averaged value of the system. Just because cold intrusions are short lived doesn't mean that it HAS to be warmer than normal averaged over a certain period of time. If every cold intrusion that we had was just a day long, we could still end up colder than "normal", just so long as the cold intrusions come at a sufficient frequency or have sufficient intensity or both. I agree. In fact, even as I expect the upcoming cold shot this weekend into the first part of next week to be short-lived, I believe it will be of a magnitude that could lead to parts of the East being cooler than normal for the February 8-15 timeframe. The cold shot could rival what occurred in mid-January if everything comes together. My guess for that period was posted in Message #806 in this thread. Link to comment Share on other sites More sharing options...
RCNYILWX Posted February 9, 2012 Share Posted February 9, 2012 The guidance has come into general agreement that the Arctic Oscillation (AO) will be going positive down the road. The positive AO will help ensure that cold shots in the East are relatively short-lived. Looking farther down the road to March, the AO could make a critical difference as to what part of North America is cold vs. what part is warm. Using data for weak La Niña conditions and a neutral PNA, the following are some scenarios for a weak AO- vs. a weak AO+ for March. The La Nina/AO+ composite on the right is the recipe for a quick start to the spring severe weather season, considering that the GOM is running >1C above normal. Link to comment Share on other sites More sharing options...
Ginx snewx Posted February 9, 2012 Share Posted February 9, 2012 The guidance has come into general agreement that the Arctic Oscillation (AO) will be going positive down the road. The positive AO will help ensure that cold shots in the East are relatively short-lived. Looking farther down the road to March, the AO could make a critical difference as to what part of North America is cold vs. what part is warm. Using data for weak La Niña conditions and a neutral PNA, the following are some scenarios for a weak AO- vs. a weak AO+ for March. well I suppose the good news is the spread of ENS increased on the overnight runs with a good deal of members now keeping the AO negative or neutral Link to comment Share on other sites More sharing options...
Ottawa Blizzard Posted February 9, 2012 Share Posted February 9, 2012 Gee, what surprise - looks like the I-95 cities are under the gun for snow over the next few days. Honestly, this has to have been the most boring winter I can remember in southern Ontario. Even 2001-2002 had a moderate snowstorm on January 31st, 2002. It feels like spring outside today! Over the past few years places that are the most ill equipped for snow - i.e. Europe and the I-95 corridor in the US - have had more winter than places that are supposed to and which rely on winter weather for their economies.Also, looks like Don will be right. 12z GFS basically warms us all up next week. Bust for JB and bust of a pattern change. Link to comment Share on other sites More sharing options...
Ed Lizard Posted February 9, 2012 Share Posted February 9, 2012 The La Nina/AO+ composite on the right is the recipe for a quick start to the spring severe weather season, considering that the GOM is running >1C above normal. I wish the NW Gulf shelf waters were a bit warmer, I don't know how many apparently favorable Houston area severe outbreaks have been ruined by slow to burn off low clouds and limited daytime heating, and apparently breakable caps that never quite break. Link to comment Share on other sites More sharing options...
HM Posted February 9, 2012 Share Posted February 9, 2012 Gee, what surprise - looks like the I-95 cities are under the gun for snow over the next few days. Honestly, this has to have been the most boring winter I can remember in southern Ontario. Even 2001-2002 had a moderate snowstorm on January 31st, 2002. It feels like spring outside today! Over the past few years places that are the most ill equipped for snow - i.e. Europe and the I-95 corridor in the US - have had more winter than places that are supposed to and which rely on winter weather for their economies.Also, looks like Don will be right. 12z GFS basically warms us all up next week. Bust for JB and bust of a pattern change. A pattern can change to another pattern while still bringing little snow to a certain area. Pattern change does not equal snow. This is getting old. If you think the pattern now is the same as it was or that the -WPO period in January was the same pattern as before that then what can I say except you are flat out wrong. Link to comment Share on other sites More sharing options...
Ottawa Blizzard Posted February 9, 2012 Share Posted February 9, 2012 A pattern can change to another pattern while still bringing little snow to a certain area. Pattern change does not equal snow. This is getting old. If you think the pattern now is the same as it was or that the -WPO period in January was the same pattern as before that then what can I say except you are flat out wrong. I accept what you say, but - apart from the upcoming three days - there has been very little change in southern Ontario. We are on track for one of the mildest and most snowless winters of the past century. Link to comment Share on other sites More sharing options...
Ji Posted February 10, 2012 Share Posted February 10, 2012 nobody cares about a pattern change if it dosent change our lousy weather...which it hasnt Link to comment Share on other sites More sharing options...
mnweather Posted February 10, 2012 Share Posted February 10, 2012 The pattern change has been pretty much the same result as the previous pattern but it's just a different way of getting the same snow less result. Link to comment Share on other sites More sharing options...
cbmclean Posted February 10, 2012 Share Posted February 10, 2012 I agree. In fact, even as I expect the upcoming cold shot this weekend into the first part of next week to be short-lived, I believe it will be of a magnitude that could lead to parts of the East being cooler than normal for the February 8-15 timeframe. The cold shot could rival what occurred in mid-January if everything comes together. My guess for that period was posted in Message #806 in this thread. I understand exactly what you mean. I was just trying to stimulate discussion on the fundamental mechanics of what it takes to get a cold winter or a mild winter, which is topic in which I am extremely interested but don't know much about. It's probably a better topic for the Met 101 thread. Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 10, 2012 Share Posted February 10, 2012 Verification: From Message #694, which covered the February 1-7, 2012 timeframe: The following charts show the temperature anomalies for the February 1-10, 1950-2011 timeframe for all cases with a La Niña Region 3.4 anomaly in the -1.45°C to -0.65°C range, AO in the -1.5 to 0.0 range, and PNA in the -0.5 to +0.5 range (top); the bottom chart shows the observed decadal trend in temperatures. ...In sum, the composite temperature anomaly is what I expect for the February 1-7, 2012 timeframe except that Michigan, Ohio, Pennsylvania, New York, and New England would wind up milder than normal. The February 1-7, 2012 temperature anomalies were: As has been the case with my errors this winter, the areas in which errors occurred (western Great Lakes region, parts of western Canada, and eastern Alaska) had warmer, not colder, temperatures than I had anticipated. All in all, the idea of widespread warmth was a good one, but the warmth was even more widespread than I had anticipated. Finally, the much above normal readings across much of North America during the first week of February is consistent with the overall idea of widespread warmth during the month of February as a whole (#703 in this thread). The relevant map for North America was: Link to comment Share on other sites More sharing options...
QVectorman Posted February 10, 2012 Share Posted February 10, 2012 Don it's amazing. It's straight out of the play book for +AO despite us being in a -AO. I am baffled. Link to comment Share on other sites More sharing options...
Harry Posted February 10, 2012 Share Posted February 10, 2012 A pattern can change to another pattern while still bringing little snow to a certain area. Pattern change does not equal snow. This is getting old. If you think the pattern now is the same as it was or that the -WPO period in January was the same pattern as before that then what can I say except you are flat out wrong. I think he was referring to temps as well. But yeah that theme ( pattern has not changed ) has been running rampant and yes it IS old. As has been the same with those humping and or freaking out every time a GFS run shows warmth or whatever. That has gotten very old too. Oh look the GFS shows warmth so the pattern has not changed. ugh That sort of thing. Other then that i have greatly enjoyed reading your thoughts on all of this along with a few others too. Ignore the bs. Maybe it is me but i do not see us heading back to what we had and nor do i see the warmth returning and overpowering either as a few keep suggesting. Several reasons for that which maybe if i am feeling better later on i'll get into. Those stuck using analogs after 1950 are at most risk of busting. Amazes me that we have gone back to this same ole tired theme again of neglecting pre 1950 analogs but i suppose it is not surprising as people tend to do this more when warmth/above average temps happen. Those that say the data is not as reliable i say BS. Thus look at those who used them ( pre 1950 ) over the past 4-5 years or so vs those who have not and thus the results. Sorry if i come across as a dick or whatever. I don't mean to. Just frustrating to see the same thing keep happening over and over again when there is no need for it. Lastly.. Follow the trends even with the ensembles. Sure there will be hiccup runs ( always have been and always will be ) but i urge all to ignore them. Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 10, 2012 Share Posted February 10, 2012 Those stuck using analogs after 1950 are at most risk of busting. Amazes me that we have gone back to this same ole tired theme again of neglecting pre 1950 analogs but i suppose it is not surprising as people tend to do this more when warmth/above average temps happen. One can use pre-1950 analogs for SSTAs, ENSO, and ENSO-reconstructed data, among others. The ENSO-reconstructed NAO data proved useful last winter in highlighting a number of moderate-strong La Niña cases during which KU-type snowstorms occurred. Analogs from 1950-present are only possible for daily teleconnections data. The timeframe for daily MJO data is even more recent. Analogs offer insight. My view is that one should try to draw as broad and representative a sample as possible, keeping in mind the limitations inherent with analogs. Link to comment Share on other sites More sharing options...
donsutherland1 Posted February 10, 2012 Share Posted February 10, 2012 Don it's amazing. It's straight out of the play book for +AO despite us being in a -AO. I am baffled. Perhaps the stability in the strength of the La Niña, earlier prolonged AO+ regime, the MJO's remaining predominantly in Phases 4-6, among other factors led to a situation where responsiveness to the return of blocking was greater in Eurasia than North America? It's difficult to say for sure. Link to comment Share on other sites More sharing options...
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