40/70 Benchmark Posted September 19, 2023 Share Posted September 19, 2023 10 minutes ago, bluewave said: The two El Niño years when ONI never got higher than ASO were 04-05 and 53-54 so it wouldn’t be a first. 04-05 was an example of a very active hurricane season with a MEI peak in JA for the fall into winter season. The OHC having trouble getting above the June levels may be another tell that things may level off earlier than we usually see. As much as I love me some 2004-2005, I believe raindance mentioned that ACE only matters during la Nina. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted September 19, 2023 Share Posted September 19, 2023 6 hours ago, GaWx said: Has anyone seen this map of the correlation between DJF ONI and DJF snowfall? I’ve studied Atlanta extensively and I can vouch for the ~+0.25 there. What about other locations? I am in that sliver in which ENSO doesn't really matter, but I would still take a weak to moderate El nino, all things equal. 1 Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted September 19, 2023 Share Posted September 19, 2023 2 hours ago, bluewave said: Yeah, my guess is that is why the CFS thinks the El Niño is peaking now and doesn’t show the typical increase that we usually get in the late fall. Not that the CFS or any of these seasonal models are that great since they just seem to repeat the initial conditions. But it is enough for the CPC to mention with all the other model data in their latest weekly update. If the El Niño doesn’t get much stronger or just levels off instead of declining, then the MEI may not get much above the weak to maybe moderate range. Our winter forecast could again come down to competing influences with perhaps a mix of Nino-like and La Niña elements. So getting a -AO and +PNA will be necessary as an insurance policy if the tropical forcing becomes more variable. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf What this may mean is more periods in which the N stream steals the show. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted September 19, 2023 Share Posted September 19, 2023 1 minute ago, bluewave said: What does that mean? The higher the ACE, the lower the influence of the El Niño on the Atlantic hurricane activity. It has been no match for the record SSTs in the Atlantic basin. Plus the record WPAC warmth west of the Dateline has shifted the forcing further west. The El Niño is only one player in the crowded global forcing regime. I think what he means is that ACE is irrelevant within the context of a winter forecast for an el nino season. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted September 19, 2023 Share Posted September 19, 2023 Going through some of my methodologies now and there is definitely some value in the 1982-1983 analog, but its clear that el nino will functionally be significantly weaker. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted September 19, 2023 Share Posted September 19, 2023 33 minutes ago, 40/70 Benchmark said: I think what he means is that ACE is irrelevant within the context of a winter forecast for an el nino season. This is what I am saying. 30 minutes ago, bluewave said: But that is more driven by the WPAC warm pool more than the Atlantic seasonal ACE. Not much relationship between the ACE and the kind of winter we get. But you could probably draw some parallels to SST anomaly distribution in the Atlantic and the state of the NAO or AO. I have seen different studies on impacts from various regions. My comment about more N stream involvement this winter has nothing to do with ACE...two discrete comments. All meant was a weaker el nino could maintain more N stream involvement. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted September 19, 2023 Share Posted September 19, 2023 4 hours ago, snowman19 said: @Gawx @griteater @Bluewave @so_whats_happening @40/70 Benchmark @brooklynwx99 @raindancewx @Terpeast @mitchnick The BOM has just declared that an El Niño is underway and that it is coupling with the atmosphere. They have also declared that a coupled +IOD is underway. Here is the new detailed discussion: http://www.bom.gov.au/climate/enso/ They are expecting a super, trimonthly (NDJ) ONI event, here are the month by month graphs: ENSO: http://www.bom.gov.au/climate/model-summary/#region=NINO34&tabs=Pacific-Ocean IOD: http://www.bom.gov.au/climate/model-summary/#tabs=Indian-Ocean I still don't think the ONI ever hits 2.0, but I'm not that concerned about it because I'm convinced that it doesn't really matter. 2 Link to comment Share on other sites More sharing options...
A-L-E-K Posted September 19, 2023 Share Posted September 19, 2023 lol Link to comment Share on other sites More sharing options...
so_whats_happening Posted September 19, 2023 Share Posted September 19, 2023 4 hours ago, snowman19 said: @Gawx @griteater @Bluewave @so_whats_happening @40/70 Benchmark @brooklynwx99 @raindancewx @Terpeast The BOM has just declared that an El Niño is underway and that it is coupling with the atmosphere. It has also declared that a coupled +IOD is underway. Here is the new detailed discussion: http://www.bom.gov.au/climate/enso/ They are expecting a super, trimonthly (NDJ) ONI event, here are the month by month graphs: http://www.bom.gov.au/climate/model-summary/#region=NINO34&tabs=Pacific-Ocean I would assume these values are based off the BOMM/ BOMA model? If so this is the same model that has been having wild MJO swings when we did have MJO activity it showed amplitudes much greater than anything actually occurring and when we had null or very low amplitude for MJO the model was always pushing it to go over to 7-8-1-2 region with moderate amplitude when we have barely poked out from null most of late spring and summer. I respect BOM as they have a great catalogue of information to use and monitor everything within their website instead of going to several different sites for info, but I will say the model has been off by quite a bit all season just as much as the infamous CFS has been off. It is still reasonable to think that models just happened to get this one wrong and that is perfectly fine. Models are meant to be used as guidance for an outcome not certainties for a forecast. I will personally wait to see how things go but if by mid to late October (which is a little less than month from now) we don't see rather drastic changes having occurred into more persistent WWB events (which are a rather important aspect in El Nino formation and sustainability) to sustain subsurface and surface temps regardless of SOI or IOD connections we can surely look back and say models were a little too overzealous. What this means for winter well that is anyone's guess as we have very few scenarios with such an occurrence as we have seen. Link to comment Share on other sites More sharing options...
so_whats_happening Posted September 19, 2023 Share Posted September 19, 2023 4 hours ago, bluewave said: Yeah, my guess is that is why the CFS thinks the El Niño is peaking now and doesn’t show the typical increase that we usually get in the late fall. Not that the CFS or any of these seasonal models are that great since they just seem to repeat the initial conditions. But it is enough for the CPC to mention with all the other model data in their latest weekly update. If the El Niño doesn’t get much stronger or just levels off instead of declining, then the MEI may not get much above the weak to maybe moderate range. Our winter forecast could again come down to competing influences with perhaps a mix of Nino-like and La Niña elements. So getting a -AO and +PNA will be necessary as an insurance policy if the tropical forcing becomes more variable. https://www.cpc.ncep.noaa.gov/products/analysis_monitoring/lanina/enso_evolution-status-fcsts-web.pdf Maybe? Unfortunately I have not followed much about how models have been predicting things over the spring and summer other than what is posted on here. There have been a few instances in which the 3.4 region has peaked early, but im not sold yet that has occurred this go around. Almost feel like what may happen is overall rate of warming may be slowing a bit and subsurface continues to slosh around helping sustain things, maybe we poke close to 2C for a month but at this point I would bet the under to come to fruition. If we do indeed see any bit of cooling occur in 3.4 over the next 2-3 weeks we can safely assume we probably are damn near peak. The lack of anything showing up in long range is rather interesting to watch unfold though, have yet to see the typical westerly anomalies show up in the eastern IO which has been the thing for this season. Just the very idea that WWB have been originating in the Eastern IO versus maritime/ extreme west Pacific tells me already the forcing is going to be west of the typical El Nino placement. Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted September 19, 2023 Share Posted September 19, 2023 I'm done with my first draft of seasonal composites.....will just check against actual weather over the next 6 weeks or so before publishing. I think some around here get the idea that I am going wall-to-wall snow and cold and that simply is not the case. 2 Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted September 19, 2023 Share Posted September 19, 2023 16 minutes ago, so_whats_happening said: Maybe? Unfortunately I have not followed much about how models have been predicting things over the spring and summer other than what is posted on here. There have been a few instances in which the 3.4 region has peaked early, but im not sold yet that has occurred this go around. Almost feel like what may happen is overall rate of warming may be slowing a bit and subsurface continues to slosh around helping sustain things, maybe we poke close to 2C for a month but at this point I would bet the under to come to fruition. If we do indeed see any bit of cooling occur in 3.4 over the next 2-3 weeks we can safely assume we probably are damn near peak. The lack of anything showing up in long range is rather interesting to watch unfold though, have yet to see the typical westerly anomalies show up in the eastern IO which has been the thing for this season. Just the very idea that WWB have been originating in the Eastern IO versus maritime/ extreme west Pacific tells me already the forcing is going to be west of the typical El Nino placement. Bingo. I think what gets lost in the shuffle is that the weather is the product of gradients resulting from the interaction of competing forces....people are focusing too much on one force when the ambient environment is just as integral a part of the equation. Its not low pressure that creates the storm, but rather the imbalance of pressure...same thing with respect to forcing. It is the result of the SST gradient, not the absolute value within the ENSO region, as this is only part of the equation. Link to comment Share on other sites More sharing options...
snowman19 Posted September 19, 2023 Share Posted September 19, 2023 I would assume these values are based off the BOMM/ BOMA model? If so this is the same model that has been having wild MJO swings when we did have MJO activity it showed amplitudes much greater than anything actually occurring and when we had null or very low amplitude for MJO the model was always pushing it to go over to 7-8-1-2 region with moderate amplitude when we have barely poked out from null most of late spring and summer. I respect BOM as they have a great catalogue of information to use and monitor everything within their website instead of going to several different sites for info, but I will say the model has been off by quite a bit all season just as much as the infamous CFS has been off. It is still reasonable to think that models just happened to get this one wrong and that is perfectly fine. Models are meant to be used as guidance for an outcome not certainties for a forecast. I will personally wait to see how things go but if by mid to late October (which is a little less than month from now) we don't see rather drastic changes having occurred into more persistent WWB events (which are a rather important aspect in El Nino formation and sustainability) to sustain subsurface and surface temps regardless of SOI or IOD connections we can surely look back and say models were a little too overzealous. What this means for winter well that is anyone's guess as we have very few scenarios with such an occurrence as we have seen. No, it’s off the international average of models. Link to comment Share on other sites More sharing options...
GaWx Posted September 19, 2023 Share Posted September 19, 2023 The SOI is at 31 days in a row of negative dailies, the longest streak so far this year. The 30 day average is back down to ~-15, indicative of solid El Niño atmospheric conditions. In general, Nino 3.4 has tended to warm during the several weeks following long solid -SOI periods like this although there’s lots of variation. The OISST SSTa daily graph shows new highs in both 3.4 and 4 today with 3.4 near +1.7. I expect warming to dominate for the next few weeks meaning a decent shot at 3.4 reaching +2.0 on the OISST dailies in early Oct: https://www.longpaddock.qld.gov.au/soi/ ##Corrected to say new highs in 3.4 and 4 3 Link to comment Share on other sites More sharing options...
snowman19 Posted September 19, 2023 Share Posted September 19, 2023 The SOI is at 31 days in a row of negative dailies, the longest streak so far this year. The 30 day average is back down to ~-15, indicative of solid El Niño atmospheric conditions. In general, Nino 3.4 has tended to warm during the several weeks following long solid -SOI periods like this although there’s lots of variation. The OISST SSTa daily graph shows new highs in both 3.4 and 4 today with 3.4 near +1.7. I expect warming to dominate for the next few weeks meaning a decent shot at 3.4 reaching +2.0 on the OISST dailies in early Oct:https://www.longpaddock.qld.gov.au/soi/ ##Corrected to say new highs in 3.4 and 4Agree. I think it hits +2.0C on the weeklies next month. The CFS is out to lunch, as usual. The BOM would not have issued that new disco if they weren’t very confident. They have been ultra conservative with this Nino event and the IOD. IMO this one goes super trimonthly ONI….this one is coming. As for where the forcing is in DJFM? That’s another matter….. 3 1 Link to comment Share on other sites More sharing options...
Stormchaserchuck1 Posted September 19, 2023 Share Posted September 19, 2023 LR +PNA came in stronger today, 3 contours. https://ibb.co/9pDwnWQ In October, I start looking to see if ENSO is impacting the cooler season wavelengths. In this case, it's yes, but I still think that the ENSO is acting like a Weak event. Link to comment Share on other sites More sharing options...
snowman19 Posted September 19, 2023 Share Posted September 19, 2023 @GaWx Looks like the Euro is doing well with Nino 1+2 so far….it showed the peak and drop this month, followed by the warmup (it’s up to almost +2.7C on OISST). It forecasts it remaining steady from here on out at just below +3.0C through January Link to comment Share on other sites More sharing options...
mitchnick Posted September 19, 2023 Share Posted September 19, 2023 12 hours ago, snowman19 said: @Gawx @griteater @Bluewave @so_whats_happening @40/70 Benchmark @brooklynwx99 @raindancewx @Terpeast @mitchnick The BOM has just declared that an El Niño is underway and that it is coupling with the atmosphere. They have also declared that a coupled +IOD is underway. Here is the new detailed discussion: http://www.bom.gov.au/climate/enso/ They are expecting a super, trimonthly (NDJ) ONI event, here are the month by month graphs: ENSO: http://www.bom.gov.au/climate/model-summary/#region=NINO34&tabs=Pacific-Ocean IOD: http://www.bom.gov.au/climate/model-summary/#tabs=Indian-Ocean Could it be right? I suppose, but the problem it's been having is putting the MJO on steroids. It did it a few weeks ago and I recall you posting how the MJO was finally kicking in and failed as it has all year. So I've posted the latest on the site BOM MJO forecast on top then the Euro and JMA since they've been fairly unimpressed with the MJO waking up. As you can see, BOM is on its own ending the run in left field...literally! Lol EDIT: I do note that the BOM plot is 2 days old, so I'll post the updated forecast when available, but I doubt it will be anywhere near the other 2 models. Link to comment Share on other sites More sharing options...
GaWx Posted September 19, 2023 Share Posted September 19, 2023 16 minutes ago, mitchnick said: Could it be right? I suppose, but the problem it's been having is putting the MJO on steroids. It did it a few weeks ago and I recall you posting how the MJO was finally kicking in and failed as it has all year. So I've posted the latest on the site BOM MJO forecast on top then the Euro and JMA since they've been fairly unimpressed with the MJO waking up. As you can see, BOM is on its own ending the run in left field...literally! Lol EDIT: I do note that the BOM plot is 2 days old, so I'll post the updated forecast when available, but I doubt it will be anywhere near the other 2 models. The BOM and CFS have both been overdoing the MJO, especially in and near phase 5, since at least spring. The CFS has recently been forecasting a phase 5 in early OCT but is now staying inside the COD. Link to comment Share on other sites More sharing options...
mitchnick Posted September 19, 2023 Share Posted September 19, 2023 4 minutes ago, GaWx said: The BOM and CFS have both been overdoing the MJO, especially in and near phase 5, since at least spring. The CFS has recently been forecasting a phase 5 in early OCT but is now staying inside the COD. Agree, and unlike the BOM, the CFS has been lowering the ONI in response. I do note that today's run did have a few ensemble members warmer than the mean. First day it showed that in a while. Link to comment Share on other sites More sharing options...
snowman19 Posted September 19, 2023 Share Posted September 19, 2023 Could it be right? I suppose, but the problem it's been having is putting the MJO on steroids. It did it a few weeks ago and I recall you posting how the MJO was finally kicking in and failed as it has all year. So I've posted the latest on the site BOM MJO forecast on top then the Euro and JMA since they've been fairly unimpressed with the MJO waking up. As you can see, BOM is on its own ending the run in left field...literally! Lol EDIT: I do note that the BOM plot is 2 days old, so I'll post the updated forecast when available, but I doubt it will be anywhere near the other 2 models.That new BOM forecast I posted is not based on the POAMA (BOM) model, if you read it, they are basing it off of the International average of models Link to comment Share on other sites More sharing options...
Typhoon Tip Posted September 19, 2023 Share Posted September 19, 2023 Has any seasonal outlook ever ‘cast the winter as much below normal snow fall with temps above normal? seems not but who knows. You wonder if no one has ever gotten that right … yet it characterizes more winters than half in the last 30 years. Lol Link to comment Share on other sites More sharing options...
GaWx Posted September 19, 2023 Share Posted September 19, 2023 1 hour ago, Typhoon Tip said: Has any seasonal outlook ever ‘cast the winter as much below normal snow fall with temps above normal? seems not but who knows. You wonder if no one has ever gotten that right … yet it characterizes more winters than half in the last 30 years. Lol Yes, in locations away from where the forecaster lives. That’s the key. Not necessarily exactly as you stated, but a “benign” winter. For example, literally every amateur forecast I’ve seen so far for this winter from those not living in the W, which includes just about every forecast I’ve seen, has the W mild/benign and the E cold along with AN snow. They’re all almost carbon copies of each other’s forecast. Their forecasts are much more predictable than what they’re trying to predict. This is influenced a lot by weenieism as well as the desire to get more clicks. Their bias dominates. I should emphasize that I’m talking about the amateur forecasters that I’ve seen so far. I’m not at all talking about objective amateur and pro forecasters without a hidden agenda who put the desire for accuracy ahead of weenieism and getting clicks. Link to comment Share on other sites More sharing options...
mitchnick Posted September 20, 2023 Share Posted September 20, 2023 1 hour ago, snowman19 said: That new BOM forecast I posted is not based on the POAMA (BOM) model, if you read it, they are basing it off of the International average of models There's no new information in it except for their declaration there's a coupled Nino (barely per MEI) and +IOD. I thought we knew that already. Honestly, your post sounded like there was something new which is why I thought you were referring to the BOM model. 1 Link to comment Share on other sites More sharing options...
GaWx Posted September 20, 2023 Share Posted September 20, 2023 8 hours ago, GaWx said: Yes, in locations away from where the forecaster lives. That’s the key. Not necessarily exactly as you stated, but a “benign” winter. For example, literally every amateur forecast I’ve seen so far for this winter from those not living in the W, which includes just about every forecast I’ve seen, has the W mild/benign and the E cold along with AN snow. They’re all almost carbon copies of each other’s forecast. Their forecasts are much more predictable than what they’re trying to predict. This is influenced a lot by weenieism as well as the desire to get more clicks. Their bias dominates. I should emphasize that I’m talking about the amateur forecasters that I’ve seen so far. I’m not at all talking about objective amateur and pro forecasters without a hidden agenda who put the desire for accuracy ahead of weenieism and getting clicks. More on these amateur forecasts with most warm, dry in the NW and cold, snowy E coast: Weather Watcher: what a winter along E coast! Weather William: winter will be rockin’ in the east! Direct Wx: get your shovels ready in the east! America Climate Channel: amazing winter for the east! NWW116 goes big in the east! AWF: Lives in GA and has their coldest and one of snowiest winters of last 45 yrs 2009-10 as top analog! Weather At A (15 minute long) Glance: David S for NE: probably one of worst winters; “big, deep trouble, almost historic, winter-mageddon”! MBGC says wild winter coming, especially NE; 2009-10 favorite analog! Direct Wx’s favorite video of year: official snowfall forecast with snow to Savannah!! 1 1 Link to comment Share on other sites More sharing options...
Terpeast Posted September 20, 2023 Share Posted September 20, 2023 14 minutes ago, GaWx said: More on these amateur forecasts with most warm, dry in the NW and cold, snowy E coast: Weather Watcher: what a winter along E coast! Weather William: winter will be rockin’ in the east! Direct Wx: get your shovels ready in the east! America Climate Channel: amazing winter for the east! NWW116 goes big in the east! Yo, Adrian! Weather At A Glance: David S: wow! MBGC says wild winter coming! Direct Wx’s favorite video of year: official snowfall forecast with snow to Savannah!! Now we know why our winters have sucked lately. They keep jinxing them with these silly weenie forecasts 2 Link to comment Share on other sites More sharing options...
raindancewx Posted September 20, 2023 Share Posted September 20, 2023 Here is what BOM says about declaring El Nino. For my purposes, this El Nino started in March, and is already half over. So it's actually peaking at the surface between now and 11/1. Subsurface will have fits and starts through Oct/Nov before steadily weakening. Unlike winter, the greatest Spring periods for severe cold and precipitation in the West are during the most rapid ENSO transitions. You can look back at Spring 1973, 1988, 2005, 2017, 2019, 2023, etc to see this effect. The joke is the Summer temp profile was a pretty strong match to actual Nino 3.4 SST correlations in the Pacific, despite the constant bitching about how there is no forcing. Who cares? If you're getting El Nino conditions in the expected way, does it matter if not all the signals show up as you'd expect? Given how weak the correlation is, in theory it takes remarkably warm SSTs to drive such a good match - which of course we had in June-August. El Niño and positive Indian Ocean Dipole underway An El Niño and a positive IOD are underway. The declaration of these events, and their concurrence over spring, reinforces the Bureau's long-range rainfall and temperature forecasts, which continue to predict warmer and drier conditions for much of Australia over the next three months. The confirmation of an established El Niño increases the likelihood that the event will be sustained through the summer period. Oceanic indicators firmly exhibit an El Niño state. Central and eastern Pacific sea surface temperatures (SSTs) continue to exceed El Niño thresholds. Models indicate further warming of the central to eastern Pacific is likely. Broadscale pressure patterns over the tropical Pacific reflect El Niño, with the 90-day Southern Oscillation Index (SOI) at −7.7. Recent trade wind strength has been generally close to average, but was slightly weaker than average across the tropical Pacific in August 2023 for the first time since January 2020. Overall, there are signs that the atmosphere is responding to the pattern of SSTs in the tropical Pacific and coupling of the ocean and atmosphere has started to occur. This coupling is a characteristic of an El Niño event and is what strengthens and sustains an event for an extended period. Climate models indicate this El Niño is likely to persist until at least the end of February. El Niño typically leads to reduced spring and early summer rainfall for eastern Australia, and warmer days for the southern two-thirds of the country. A positive Indian Ocean Dipole is underway. The Indian Ocean Dipole (IOD) index is +1.25 °C for week ending 17 September. This is its fifth week above the positive IOD threshold (+0.40 °C). The longevity of this trend, combined with the strength of the dipole being observed and forecast, indicate a positive IOD event is underway. All models predict this positive IOD will persist to at least the end of spring. A positive IOD typically leads to reduced spring rainfall for central and south-east Australia. When a positive IOD and El Niño occur together, their drying effect is typically stronger and more widespread across Australia. 1 Link to comment Share on other sites More sharing options...
bluewave Posted September 20, 2023 Share Posted September 20, 2023 The reason we were discussing the coupling and MEI is due to the difference between a weak and strong MEI El Niño summer composites for the NPAC and North America. For one thing, the blocking has been much stronger during summers with a MEI around +0.5 like we had this summer. That was the case this summer with the strong -EPO +PNA -AO blocking. Also at least one of the summers had a very active hurricane season. The more positive MEI summers around +2.0 had less blocking and a more dominant Aleutian low and quiet hurricane seasons. The Aleutian low was very weak this summer. The other difference this year is the much warmer background state with record global temperatures. This muted the cooling influence that we usually get in the CONUS during a developing El Niño of any degree of coupling. Several locations had their warmest summer on record. JJA 2023 Weakly coupled MEI composite Strongly coupled MEI summer composite 4 1 Link to comment Share on other sites More sharing options...
snowman19 Posted September 20, 2023 Share Posted September 20, 2023 Here is what BOM says about declaring El Nino. For my purposes, this El Nino started in March, and is already half over. So it's actually peaking at the surface between now and 11/1. Subsurface will have fits and starts through Oct/Nov before steadily weakening. Unlike winter, the greatest Spring periods for severe cold and precipitation in the West are during the most rapid ENSO transitions. You can look back at Spring 1973, 1988, 2005, 2017, 2019, 2023, etc to see this effect. The joke is the Summer temp profile was a pretty strong match to actual Nino 3.4 SST correlations in the Pacific, despite the constant bitching about how there is no forcing. Who cares? If you're getting El Nino conditions in the expected way, does it matter if not all the signals show up as you'd expect? Given how weak the correlation is, in theory it takes remarkably warm SSTs to drive such a good match - which of course we had in June-August.El Niño and positive Indian Ocean Dipole underway An El Niño and a positive IOD are underway. The declaration of these events, and their concurrence over spring, reinforces the Bureau's long-range rainfall and temperature forecasts, which continue to predict warmer and drier conditions for much of Australia over the next three months. The confirmation of an established El Niño increases the likelihood that the event will be sustained through the summer period. Oceanic indicators firmly exhibit an El Niño state. Central and eastern Pacific sea surface temperatures (SSTs) continue to exceed El Niño thresholds. Models indicate further warming of the central to eastern Pacific is likely. Broadscale pressure patterns over the tropical Pacific reflect El Niño, with the 90-day Southern Oscillation Index (SOI) at −7.7. Recent trade wind strength has been generally close to average, but was slightly weaker than average across the tropical Pacific in August 2023 for the first time since January 2020. Overall, there are signs that the atmosphere is responding to the pattern of SSTs in the tropical Pacific and coupling of the ocean and atmosphere has started to occur. This coupling is a characteristic of an El Niño event and is what strengthens and sustains an event for an extended period. Climate models indicate this El Niño is likely to persist until at least the end of February. El Niño typically leads to reduced spring and early summer rainfall for eastern Australia, and warmer days for the southern two-thirds of the country. A positive Indian Ocean Dipole is underway. The Indian Ocean Dipole (IOD) index is +1.25 °C for week ending 17 September. This is its fifth week above the positive IOD threshold (+0.40 °C). The longevity of this trend, combined with the strength of the dipole being observed and forecast, indicate a positive IOD event is underway. All models predict this positive IOD will persist to at least the end of spring. A positive IOD typically leads to reduced spring rainfall for central and south-east Australia. When a positive IOD and El Niño occur together, their drying effect is typically stronger and more widespread across Australia. Besides the summer profile, this September’s 500mb pattern over the mid latitudes is matching other strong El Niño September’s (‘82, ‘91, ‘97, ‘09, ‘15) to a tee 3 Link to comment Share on other sites More sharing options...
40/70 Benchmark Posted September 20, 2023 Share Posted September 20, 2023 2 hours ago, snowman19 said: Besides the summer profile, this September’s 500mb pattern over the mid latitudes is matching other strong El Niño September’s (‘82, ‘91, ‘97, ‘09, ‘15) to a tee I definitely agree with you and raindance on this....the largest issue I see with people, including myself, is that our stances tend to be too polarized. This causes us to view issues as too "black and white", when the reality is much more nuanced and more of a compromise. I definitely see some summer-season commonality with stronger el nino events, such as 1972, 1982, 2009 and 2015, but I think its also important to consider the -vp pattern and MEI/RONI because those metrics also offer insight into the overall character of the developing el nino event. There are some stark differences between those 4 seasons. Dismissing how the forcing is manifesting itself is every bit as silly and equally detrimental to seasonal forecasting efforts as failing to fully appreciate the existence of an appreciable nino. 5 1 Link to comment Share on other sites More sharing options...
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