BethesdaWX Posted April 5, 2011 Share Posted April 5, 2011 The SOI isn't really a good metric when there is a monsoon low sitting over Darwin. Wouldn't it still reflect the overall "nina signal" in being there? I'm not knowledgable here, just think the globe looks somewhat Nina. Link to comment Share on other sites More sharing options...
am19psu Posted April 5, 2011 Share Posted April 5, 2011 Wouldn't it still reflect the overall "nina signal" in being there? I'm not knowledgable here, just think the globe looks somewhat Nina. Not really. The SOI was being overwhelmed by the TC signal. No doubt it's mostly Nina right now, but AAM anomalies went >0 last week for the first time in 8 mos, so the Nina isn't as strong in the atmosphere as we had seen. Link to comment Share on other sites More sharing options...
nzucker Posted April 5, 2011 Author Share Posted April 5, 2011 Yeah just to throw out some stats which most people are already pretty familiar with: Since 1950 there are 5 cases of a moderate Nino or stronger transitioning to a moderate Nina or stronger (63-65, 72-74, 87-89, 97-99, 06-08). In only 1 of these cases was the Nina followed by a Nino event. (63-65 was followed by the 65-66 Nino). 63-64 was a boderline weak El Niño...it only had 2 trimonthlies at 1.0C and most of the others were like 0.8C, so some people consider it weak. The pattern in the US was certainly very typical of weak. 64-65 was also a bit weaker of a Niña than the other ones being discussed (73-74, 88-89, 98-99)...so it had more room to go back to El Niño. Link to comment Share on other sites More sharing options...
skierinvermont Posted April 5, 2011 Share Posted April 5, 2011 63-64 was a boderline weak El Niño...it only had 2 trimonthlies at 1.0C and most of the others were like 0.8C, so some people consider it weak. The pattern in the US was certainly very typical of weak. 64-65 was also a bit weaker of a Niña than the other ones being discussed (73-74, 88-89, 98-99)...so it had more room to go back to El Niño. Yes I mentioned later in the post that the 64-65 Nina had already subsided by this point giving it more "room" to transition to Nino. As I noted, no moderate Nino has developed with a preceding JFM ONI of -1C or colder. Only 1 weak Nino has developed with a JFM of lower than -.9C (76-77). To go to a Nino from our current -1.2 JFM ONI would be nearly unprecedented. There are 9 cases of a JFM of -1C or colder, only 1 transitioned to a Nino and it was a weak one. Link to comment Share on other sites More sharing options...
VAwxman Posted April 5, 2011 Share Posted April 5, 2011 Statistically, it's definitely least likely following a moderate/strong Nina, especially a first year one. The fact we are in a -PDO phase weighs further against a Nino. Sure. Of course we can clearly see the stats do not favor a nino, and I'm definitely not saying I "favor" it either, but there are some unique characteristics of this event that make it trickier, so I'd make sure all options are on the table. Link to comment Share on other sites More sharing options...
Supercane Posted April 7, 2011 Share Posted April 7, 2011 Feb-Mar MEI just came in at -1.548...a strong La Niña reading, and essentially no change from Jan-Feb. http://www.esrl.noaa...lation/mei.data Link to comment Share on other sites More sharing options...
Amped Posted April 10, 2011 Share Posted April 10, 2011 Holy Coriolis torque Link to comment Share on other sites More sharing options...
nzucker Posted April 10, 2011 Author Share Posted April 10, 2011 Holy Coriolis torque What does this mean? Can you explain the diagrams? Link to comment Share on other sites More sharing options...
OKpowdah Posted April 10, 2011 Share Posted April 10, 2011 The daily AAM tendency from 4/7/2011 is the 4th lowest ever recorded (out of 19455 days) Link to comment Share on other sites More sharing options...
Amped Posted April 10, 2011 Share Posted April 10, 2011 What does this mean? Can you explain the diagrams? Low Angular Momentem is when the Jet/ westerlies are further north. High AAM is when the Jet/Westerlies are further south. Frictional Torque and Montian Torque are self explainatory. I have no idea what coriolis torque is and how it would transfer momentum from the atmosphere to the earth. Link to comment Share on other sites More sharing options...
gil888 Posted April 10, 2011 Share Posted April 10, 2011 Not really. The SOI was being overwhelmed by the TC signal. No doubt it's mostly Nina right now, but AAM anomalies went >0 last week for the first time in 8 mos, so the Nina isn't as strong in the atmosphere as we had seen. The AAM anomalies are due to the MJO, i think. We haven't had one that well-defined in quite some time. The anomalies are crashing hard again this week so I think it was just a blip upward.... Link to comment Share on other sites More sharing options...
OKpowdah Posted April 10, 2011 Share Posted April 10, 2011 Low Angular Momentem is when the Jet/ westerlies are further north. High AAM is when the Jet/Westerlies are further south. Frictional Torque and Montian Torque are self explainatory. I have no idea what coriolis torque is and how it would transfer momentum from the atmosphere to the earth. Could be BSing this ... the Coriolis torque is a product of the Coriolis force acting to the right of the meridional wind. So net poleward flow produces a positive torque, and net equatorward flow produces a negative torque. If this is the case, it must be a product of the ageostrophic wind (since in geostrophic flow there is no net poleward component), which is usually directed from higher to lower pressures. So if we roll with that idea, the Coriolis torque is a product of the Hadley circulation, which is related to tropical convection and the annular mode. In a high index state, we see a stronger Hadley circulation with net poleward flow and a positive torque. In a low index state (high latitude blocking situation), we see a weakened Hadley circulation with net equatorward flow and a negative torque. Right now, we've seen a strong negative AAO develop in the last week, which may correspond to the negative Coriolis torque we see centered around 50S. We're seeing a combination of forces right now with this large negative tendency. We have seen a decent North American mountain torque in the last week, superimposed on a negative friction torque, and this negative coriolis torque. The mountain torque, centered near 50N is most certainly a product of the digging trough out west. In addition, this trough has acted to transport higher momentum air poleward, lifting the zonal flow we had across the northern tier of the US last week, north into Canada. In accordance, we're also about to see a nice spike in the NAO. Link to comment Share on other sites More sharing options...
Amped Posted May 9, 2011 Share Posted May 9, 2011 Heating up in regions 1 and 2. The SOI has been Negative the last few days also http://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/30daysoivalues/ Link to comment Share on other sites More sharing options...
JBG Posted May 9, 2011 Share Posted May 9, 2011 Are some people wishcasting a Niño? Aren't Niñas usually multi-year rather than 10 month events? Link to comment Share on other sites More sharing options...
Amped Posted May 9, 2011 Share Posted May 9, 2011 Are some people wishcasting a Niño? Aren't Niñas usually multi-year rather than 10 month events? No they weaken to neutral a lot of times for the next year. The warm SSTs lurking below the surface likely rules out anything more than a weak nina next year. Link to comment Share on other sites More sharing options...
am19psu Posted May 9, 2011 Share Posted May 9, 2011 Daily SOI is -17.06 GWO heading toward the +AAM phases Strong MJO pulse headed toward P8 Hmmm... Link to comment Share on other sites More sharing options...
uncle W Posted May 9, 2011 Share Posted May 9, 2011 the oni index for FMA was -0.9...This is a list of years with a minus oni for FMA and what it was the following NDJ... year.....FMA.....NDJ... 1950.....-1.3.....-1.0 1951.....-0.6......0.6 1955.....-0.9.....-1.9 1956.....-0.7.....-0.8 1968.....-0.8......0.9 1971.....-1.1.....-0.7 1974.....-1.3.....-0.7 1975.....-0.7.....-1.7 1976.....-0.8......0.7 1985.....-0.7.....-0.4 1989.....-1.1.....-0.1 1996.....-0.5.....-0.4 1999.....-0.9.....-1.6 2000.....-1.0.....-0.7 2001.....-0.4.....-0.1 2008.....-1.1.....-0.6 2011.....-0.9.....????? Link to comment Share on other sites More sharing options...
phil882 Posted May 10, 2011 Share Posted May 10, 2011 the oni index for FMA was -0.9...This is a list of years with a minus oni for FMA and what it was the following NDJ... year.....FMA.....NDJ... 1950.....-1.3.....-1.0 1951.....-0.6......0.6 1955.....-0.9.....-1.9 1956.....-0.7.....-0.8 1968.....-0.8......0.9 1971.....-1.1.....-0.7 1974.....-1.3.....-0.7 1975.....-0.7.....-1.7 1976.....-0.8......0.7 1985.....-0.7.....-0.4 1989.....-1.1.....-0.1 1996.....-0.5.....-0.4 1999.....-0.9.....-1.6 2000.....-1.0.....-0.7 2001.....-0.4.....-0.1 2008.....-1.1.....-0.6 2011.....-0.9.....????? Yea it still looks like climo is quite against a resurgence in El Nino. While the animation of the sub-surface temperatures above is interesting as Nino 1+2 seem to be warming, also noted in the last few frames is another area located over near Nino 3.4 that no longer has any subsurface positive anomalies between 140-180 degrees west. If we are going to see a full blown El Nino, I think we are gonna need to see a more substantial WWB that propagates further eastward. If you guys can recall for the 09-10 El Nino, the wheels were in motion already by this point. The image below, however, doesn't really scream a major pattern shift in wind anomolies. Link to comment Share on other sites More sharing options...
skierinvermont Posted May 10, 2011 Share Posted May 10, 2011 Although I pointed out earlier in this thread from a statistical ONI perspective, neutral neg, or weak Nina seems most likely, OHC is substantially higher than most Ninas including 2nd year ones. So we have conflicting signals. Over the past few weeks the CFS forecast has steadily risen about .4C and now shows peaking in the weak Nino category. The CFSv2 almost makes it but then drops back neutral neg. Personally I think the CFSv2 looks pretty realistic. Link to comment Share on other sites More sharing options...
VAwxman Posted May 10, 2011 Share Posted May 10, 2011 Although I pointed out earlier in this thread from a statistical ONI perspective, neutral neg, or weak Nina seems most likely, OHC is substantially higher than most Ninas including 2nd year ones. So we have conflicting signals. Yeah the OHC is what makes it interesting, especially with this big MJO jolt into p7-p8 and the massive AAM spike that is underway. Stats definitely favor a dip back into Nina this coming fall / winter, but in looking at the OHC, this April's values are higher than they were in the April of every year that saw a Nino develop (since 1980) except for the two super ninos. Link to comment Share on other sites More sharing options...
Ed Lizard Posted May 13, 2011 Share Posted May 13, 2011 Daily SOI has been negative for a week. Edit to Add- missed it, also posted on here http://www.americanwx.com/bb/index.php/topic/13537-la-nina-soi-number-continue-to-drop/page__st__60 Link to comment Share on other sites More sharing options...
tacoman25 Posted May 13, 2011 Share Posted May 13, 2011 Although I pointed out earlier in this thread from a statistical ONI perspective, neutral neg, or weak Nina seems most likely, OHC is substantially higher than most Ninas including 2nd year ones. So we have conflicting signals. Over the past few weeks the CFS forecast has steadily risen about .4C and now shows peaking in the weak Nino category. The CFSv2 almost makes it but then drops back neutral neg. Personally I think the CFSv2 looks pretty realistic. Looks like latest runs have trended colder again. Link to comment Share on other sites More sharing options...
skierinvermont Posted May 13, 2011 Share Posted May 13, 2011 Looks like latest runs have trended colder again. Yeah, about .1C. The CFS went from peaking at .6 to .5 now. And V2 went from around .3 to .2 now. Link to comment Share on other sites More sharing options...
wxmx Posted May 14, 2011 Share Posted May 14, 2011 Yeah, about .1C. The CFS went from peaking at .6 to .5 now. And V2 went from around .3 to .2 now. I think he is comparing blue vs red lines, not current vs previous runs Link to comment Share on other sites More sharing options...
Deck Pic Posted May 14, 2011 Share Posted May 14, 2011 la nina Link to comment Share on other sites More sharing options...
MN Transplant Posted May 25, 2011 Share Posted May 25, 2011 BOM calls time of death The 2010−11 La Niña event has ended, with climate indicators of the El Niño - Southern Oscillation (ENSO) having returned to average levels. Climate models surveyed by the Bureau of Meteorology suggest that the Pacific Ocean will continue to warm over the coming months, with neutral conditions likely to persist through the austral winter; that is, neither La Niña nor El Niño. Link to comment Share on other sites More sharing options...
tacoman25 Posted May 25, 2011 Share Posted May 25, 2011 BOM calls time of death Every other Nina event that died by May/June was not followed by another Nina the following winter. Since very few first year Ninas have been followed by Ninos, I would say the odds strongly favor neutral ENSO next winter. Link to comment Share on other sites More sharing options...
A-L-E-X Posted May 26, 2011 Share Posted May 26, 2011 Every other Nina event that died by May/June was not followed by another Nina the following winter. Since very few first year Ninas have been followed by Ninos, I would say the odds strongly favor neutral ENSO next winter. I agree... I'd say neutral next winter and an el nino the winter after that based on prior analogs. Neutral after la nina winters usually suck for us (89-90, 01-02). Link to comment Share on other sites More sharing options...
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