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Everything posted by bluewave
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Warmer SSTs from Japan across to south of the Aleutians. Also stronger warm pool east of New England. More defined colder ENSO signal in Nino 3.4 and 4.
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He wrote a great article about this extreme event. https://www.daanvandenbroek.com/svalbards-3rd-consecutive-warmest-summer-on-record-august-shattering-multiple-records/ Southerly winds Besides global warming and its impacts (diminishing sea ice, warming oceans and atmosphere, etc.), the extremely warm Augst was caused by anomalously persistent southerly winds, advecting extremely mild air from lower latitudes to the region. This flow pattern was due to persistent high pressure systems towards Svalbard’s east, with low pressure systems coming up from the southwest, pushing mild (and often humid) air towards the Archipelago. Fastest warming place on earth Svalbard is one of the fastest warming places on Earth. The reason for the faster-than-average warming is due to several feedbacks, such as the ice-albedo feedback. Even more, Svalbard is strongly affected by changes in ocean currents and shifts in wind patterns. Specifically, Svalbard ends up on the ‘warmer side’ of cyclones more frequently, and relatively warm Atlantic water penetrates further into the Svalbard region and its fjords, a process known as Atlantification. read more about Longyearbyen’s climate here Most of Svalbard’s warming has been concentrated in the winter months. Nevertheless, the last few summers have been astounding, with the summer of 2024 defying every statistical norm.
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Solar influence isn’t strong enough to cause the disparity we saw this season since this is the greatest difference between the upper levels and surface since 1950.
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We don’t have the luxury of really large sample sizes that we used to enjoy in a much more stable climate of the past. So we just have to do the best with what we have. Non linear or threshold behavior doesn’t really become known until it’s already in the rear view mirror.
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I said alteration or reinterpretation filtered through competing marine heatwaves but not necessarily a discontinuation in a traditional sense.
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Our next warm up from mid to late September could get some enhancement when the flow eventually turns more SW and travels across the flash drought to our SW.
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Not in the manner which has manifested since around 2010.
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We have seen some counterpoints to the traditional AMO and PDO cycle discussions in recent years. The first one was when the AMO began shifting negative around 10 years ago especially more so on the Klotzbach index he developed. We noticed a strong warming of the NW Atlantic east of New England around this time which didn’t let the developing -AMO really take shape. Instead we shifted to all-time Atlantic warmth in the last few years which exceeded any historic precedent during +AMOs. Then we got the sharp and rapid shift to one of the strongest +PDO patterns in terms of SST and +NPM overlap in 13-14 into 15-16. Then this pattern suddenly reversed and transitioned to one of the strongest -PDOs off all time. But just as the warming of the NW Atlantic was different for past -AMOs, this is the first -PDO defined by the 2nd eof and record SST warmth to the east of Japan and south of the Aleutians. So in effect competing marine heatwaves have altered past -PDO, +PDO, -AMO, and +AMO expectations. My guess is that we continue to see competing marine heat waves alter past expectations of ENSO, AMO, and -PDO. While these indices can sway from negative to positive, it may not look like what we used to get in the past.
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These seasonal forecasts can give the temperature tendency fairly well. But the smaller details they really don’t see very well. Most seasonal model forecasts have been biased too cool with the exception of a mismatch like 20-21 and Jan 22. But the clues about those winters became slightly better known only after October in 2020 but not until nearly the start of January in 22. My guess is that the models can’t handle the MJO amplitudes and changes much before the 6-10 and 11-15 day forecasts. My work has been to identify these model deficiencies and add corrections to them.
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The CFS monthly forecast only becomes somewhat reliable as we approach the first of the given forecast month. My guess is this is because it’s mostly a repeater model. And does better when the early month pattern continues through the rest of the month.
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If the new Euro seasonal that just came out a few minutes ago is correct, then we’ll be looking at our 10th warmer winter in a row for the Northeast. Not really surprising given the very strong -PDO La Niña background state. The ridge axis near the Aleutians and near the East have become very persistent since the 15-16 super El Niño.
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Most Novembers since the 15-16 super El Niño have been cooler in the East. So there isn’t much we can draw from that specific forecast about the winter. Plus we don’t know yet whether we just revert to the recent November decadal mean or this year does something different. We’ll have better clues after October. It’s been the only month of the year which has gone against the much warmer pattern.
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Looks like our typical September endless summer pattern of recent years from mid to late month after an anomalous cool start.
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Those greenings were the result of the more gradual temperature change associated with the orbital precession. They are working on newer modeling to handle the faster warming climate of today. So the pattern may vary from what slower changes in the orbit caused. https://theconversation.com/the-sahara-desert-used-to-be-a-green-savannah-new-research-explains-why-216555#:~:text=These images depict a period,%2C Niger%2C Chad and Mali.
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Some of the model projections have wetter Sahara along the south and the drier edge encroaching north into Southern Europe. https://www.realclimate.org/index.php/archives/2022/02/future-rainfall-over-sahel-and-sahara/
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It’s looking like another over the top warm up. So it will start out with onshore flow and warm mins. But some of that heat building over the Midwest will eventually come east. So probably some more highs in the 85-90° range for the usual warm spots NJ later in the month once the flow turns more SW. It’s the type of warm up which could erase most of the early month cool departures.
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This could be the first time in the 2020s that the highest September temperature at Newark comes after September 15th. The high for the month so far at Newark was 86° on September 1st. Newark hasn’t had a September high this low since 2009. The cooler pattern is forecast to continue another week or so before we warm up later in the month. That’s when Newark has a chance to surpass the 86° high on the 1st. Newark warmest September temperatures 9-6-23….97° 9-4-22….93° 9-15-21….91° 9-3-20…..89° Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Sep max temperature Click column heading to sort ascending, click again to sort descending. 2024 86 27 2023 97 0 2022 93 0 2021 91 0 2020 89 0 2019 93 0 2018 98 0 2017 92 0 2016 94 0 2015 98 0 2014 95 0 2013 96 0 2012 92 0 2011 88 0 2010 98 0 2009 86 0
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One of the possibilities is that the record Mediterranean and North Atlantic SSTs can shift the ITCZ further north than usual.
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We haven’t had much success with -WPOs during La Ninas since 16-17 when the MJO has been phase 4-7. The only good -WPOs were during MJO phase 8 like in January 22. December 23 featured a strong -WPO but the MJO 4-6 helped pump the SE Ridge and we went snowless for the first time with one of the strongest December -AO patterns on record. We had the -WPO in February 2018 and the first winter 80° around NYC occurred as the MJO went through phases 4-7. The reason the February 2017 -WPO pattern featured a blizzard was also MJO phase 8. But the month was overall very warm due to the amplified MJO 4-7 prior to 8. Plus the more +PDO probably helped us out. December 22 MJO 4-6 Jan 22 MJO 8 Feb 2018 MJO 4-7 Feb 2017 MJO 8 after 4-7
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Good radiational cooling tonight for the usual spots.
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The last thing I want to do is make anyone sad. Just hoping we can get some degree of mismatch between this very strong -PDO and the pattern this coming winter. The 21-22 winter was a very interesting case. We didn’t get the strong MJO 5 signal that October which usually preceded our better La Niña winters. December was one of our warmest La Niña Decembers with the historic +13 at DFW. It was one of our strongest -PNA Decembers and the Aleutian ridge that month was one of the strongest on record. But we got the MJO 8 leading to the -EPO +PNA in January which really salvaged the winter from going the way that 22-23 did. That’s one example of a mismatch. But there could be a variety of other ways we haven’t seen yet since we are dealing in small sample sizes in this new much warmer era.While it may hard to shift the record 9 warmer than normal winters in a row pattern, I am hoping we get a chance next winter to better the 22-23 and 23-24 snowfall outcomes. Since there is more variance with snow we’ll just look for any opportunities we can get. But if the Aleutian Ridge and Southeast Ridge combo grows too strong yet again, then there is the chance that the winter could go the way of the last two. But not yet ready to give up on rolling the dice for at least a better snowfall outcome than the last two. Those details may not be known until we at least see how December goes.
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Yeah, the strongest forcing that month near MJO 5 was right before the coldest part of the month around the 20th. It occurred about 2-3 weeks later than we are seeing this year.
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The forcing shifting from the IO toward the Maritime Continent has been going on the last few weeks. The RMM charts have been pretty noisy. But the VP anomalies match the expected pattern progression this time of year. Plus there is often a lagged response so it’s no surprise the late August Maritime Continent forcing has manifested last few days.
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I am just trying to keep it real. The only time that optimism or pessimism are relevant is when you can have some impact on the outcome. We still haven’t devised a weather control device yet.
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The current cooler pattern in the East is due to the stronger MJO 5-6 region forcing than we have usually had in recent early Septembers. It’s one of the few times of the year when it’s actually a cool signal for us. Could also be combining with other factors previously discussed in this thread keeping the Atlantic unusually quiet. Since there continues to be sinking air and the AEW wave train is pushed further north than usual into the Sahara.