bluewave
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The inconsistency is the fact that we haven’t gotten such a strong La Niña signal before in October with the RONI, ONI, or any other La Niña metric as low as it is. Past La Niña years with such a strong -PDO were much more robust in the Nina SSTs. So we are getting multiple disconnects across the board including the early MJO indicator. December 2020 was the best for NYC snowfall in over a decade. Some would argue it was the best December since 2010 but not of that magnitude of greatness. The unusual south based block resulted in NYC finishing warmer than average at +1.7 even with a trough in the East. I can remember commenting in the NYC thread how the October MJO was acting more like we saw in 17-18 and 10-11 later in October. But then the historic November warmth arrived exceeding 2015. So many back in the NY thread were very concerned about the winter after seeing so much November warmth like we saw in the Niña background years like 2011 and 2001. Then the Euro started forecasting a great looking December pattern as we got closer to the start of December. This was pretty much the opposite of the seasonal model issued back on November 5th. So the early MJO indicator beat the Euro seasonal forecast. But that was a much stronger La Niña than this year as per the RONI and ONI metrics. The -PDO wasn’t as strong as we are seeing now. So perhaps the strong La Niña influence is being realized more in the -PDO index this time than at any other time in the past. The October Euro forecast for December doesn’t look so great. It’s got a coast to coast warm ridge across the U.S. We’ll wait to see what it comes up with on November 5th. If it continues along the same lines as October 5th, then we’ll need as big a miss as it had back in 2020 for the early MJO indicator to keep working as it has each La Niña year since 10-11. http://seasonal.meteo.fr/content/PS-previ-cartes?language=fr Current Euro 500 mb forecast for December 2020 forecast big miss to the delight of the winter fans around NYC Forecast Verification
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With the dew points so low today, highs could beat guidance with low 60s possible in spots. This would result in lower RH values than forecast. So one of our driest days of the fall.
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In order for the MJO relationship to work again this year, all the seasonal models are going to have to be way off for December. The last 2 years when the MJO 5 amplitude was closer to this strong in October were 2020 and 2017. Right now none of the forecasts models look similar to those two years in December. The key to those seasons was a snowy and at times colder December around NYC with a mismatch pattern going against the La Niña and -PDO. Then the whole winter still averaged warmer than normal, but not as warm as our recent warmer La Niña winters like 16-17, and 22-23. Snowfall was much better those years. The fact that the La Niña is so weak now like 16-17 instead of the stronger years like 17-18 and 20-21 also is different since our best La Niña winters since 10-11 have been stronger.And it was those stronger La Niña Octobers that had the stronger MJO activity. Not such a weak event having a stronger MJO October response this year. This a reversal from 95-96 to 08-09 when the weaker La Ninas have been the better winters. So while the seasonal models haven’t been the most reliable during recent winters, I am not ready to yet buy that there is going to be a big mismatch right out of the gate in December. Remember, the good La Niña winters start out with great frontloaded results in December and then revisit it again at some point later on. They don’t start out warm and snowless in December in NYC and then turn great later on. So I am going to view these October MJO results with caution and will need to see the the models as we get closer into December really diverge from the seasonal forecasts. Otherwise it will be a case of this winter following the weaker La Niña script with warmer and less snow December and the early October MJO indicator not working for the first time since 2010.
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There is so much Pacific SST warmth west of the Dateline this fall that it’s driving the baseline much more than the meager ENSO region cooling.
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The MJO activity in MJO 5 is unusually strong for weaker La Niña this month. The latest RMM index is closer to 2020, 2017, and 2010 than 2022, 2021, 2016, and 2011. Whether we use the ONI or RONI this fall so far is closer to the weaker La Niña years like 2016. But for some reason we are still getting the stronger October MJO response which preceded the better La Niña winters. These Decembers like 2020, 2017, and 2010, had more of a mismatch pattern where the December patterns were snowier and in some cases colder like 2017 and 2010. Since we are getting this divergence between the strength of the La Niña and early MJO response not really sure what to make of it yet. Since our best La Niña winters were actually the stronger ones of the groupings and not the weaker ones. Plus there is no guarantee that this indicator will continue to work as it did in the past. As always, we may just have to wait until December actually gets underway in order to know for sure. Especially since there are other indicators signaling the potential for above to potentially well above normal temperatures and below average snowfall in NYC. It’s based on the MJO RMM amplitude and VP anomalies in phase 5-6 during La Niña Octobers since 2010. The stronger October MJO responses had better winters in NYC relative to the other La Ninas in the multiyear event group. Those stronger MJO 5-6 Octobers also had the more robust peak La Niña ONIs from fall into winter of the multiyear groups. All the La Niña winters around NYC since 11-12 have averaged warmer than normal. But even the warmer than average 17-18 and 20-21 winters had better snowfall than the other years in the multiyear group. In addition, we haven’t had any cold neutral ENSOs in the -0.1 to -0.5 peak range with a strong -PDO since 2010. So not sure how the relationship would work for any year with the official CPC ONI not getting colder than -0.5. The other thing to consider is that we don’t know how long this relationship will continue to work it. http://www.bom.gov.au/clim_data/IDCKGEM000/rmm.74toRealtime.txt https://origin.cpc.ncep.noaa.gov/products/analysis_monitoring/ensostuff/ONI_v5.php Multiyear La Niña groupings below with peak MJO 5-6 strength and the peak ONI from the fall into winter…….Strongest October MJO 5-6 and La Niña ONI leading to best NYC winters of the multiyear group bolded http://www.bom.gov.au/clim_data/IDCKGEM000/rmm.74toRealtime.txt October 2024….Phase 5 peak +2.762…ONI….latest weekly only -0.3 October 2022…Phase 6 peak +2.177…..ONI….-1.0 October 2021….Phase 5 peak +2.087….ONI….-1.0 October 2020…Phase 5 peak +2.818….ONI…..-1.3 October 2017….Phase 6 peak +3.353….ONI….-1.0 October 2016….Phase 5 peak +1.800….ONI….-0.7 October 2011….Phase 6 peak +1.674….ONI….-1.1 October 2010….Phase 5 peak +2.880…ONI…..-1.6
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If these preliminary daily AO values hold, then this will be the first 7+ sigma AO swing outside of the December to April period in around a month or less. The lowest reading back on 10-7-24 was -2.445 rising to +4.795 on 10-23 for a +7.240 sigma swing. 4 out of the top 5 greatest AO swings occurred since 2005. So this goes to how amplified and volatile the AO index has become in recent years. Greatest AO swings on record in around a month or less since 1950 and the date on which the maximum difference from low to high or high to low occurred with the numerical value of the swing https://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/norm.daily.ao.nao.pna.aao.gdas.120days.csv https://ftp.cpc.ncep.noaa.gov/cwlinks/norm.daily.ao.index.b500101.current.ascii #1……+10.790……3-11-21 #2…...+9.401…….1-16-16 #3……+9.256……3-2-56 #4……+9.039……4-21-13 #5……+8.522……1-25-05 #6…...+8.462…..1-15-77 #7…….+8.268….3-16-68 #8…….+7.793….2-25-01 #9…….+7.731….3-23-86 #10……+7.720…2-4-11 #11……+7.641…..3-5-70 #12…..+7.502…..1-19-85 #13……+7.387….3-20-78 #14……+7.240….10-23-24 #15……+7117……1-23-52 #16…..+7.066…1-24-08 #17……+7.043…3-19-15 #18……+7.038…2-10-76
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Sunday looks like the lowest afternoon dew points of the season with some spots possibly approaching 10° or lower.
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The actual +EPO 500 mb vortex near Alaska was pretty was pretty weak in 20-21. It was more of a +WPO Bering Sea low which cominbed with the +PNA at times and the -AO for a mild but snowy winter. 19-20 had a stronger +EPO vortex near Alaska which is why the winter was so mild and snowless combined with the +AO. Our last +EPO dominant 500 mb vortex winter during a La Niña was 2011-2012.
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It’s funny that the snowfall climo has actually been better December 1st through 17th since 2011 in NYC than later in the month. NYC hasn’t had a decent late December snowstorm since the Boxing Day blizzard in 2010. My guess is this is related to the warm up we have been getting every year during the 2nd half of the month since 2011. High temperatures of 55+ have been very reliable from the December 17th through 25th. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending snowfall 12-01 to 12-17 2023-12-17 T 0 2022-12-17 T 0 2021-12-17 T 0 2020-12-17 10.5 0 2019-12-17 1.8 0 2018-12-17 T 0 2017-12-17 7.0 0 2016-12-17 3.2 0 2015-12-17 0.0 0 2014-12-17 1.0 0 2013-12-17 8.6 0 2012-12-17 0.0 0 2011-12-17 0.0 0 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending snowfall 12-18 to 12-31 2023-12-31 0.0 0 2022-12-31 T 0 2021-12-31 0.2 0 2020-12-31 T 0 2019-12-31 0.7 0 2018-12-31 T 0 2017-12-31 0.7 0 2016-12-31 T 0 2015-12-31 T 0 2014-12-31 T 0 2013-12-31 T 0 2012-12-31 0.4 0 2011-12-31 0.0 0 Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending max temp December 17th through 25th 2023-12-25 62 0 2022-12-25 58 0 2021-12-25 60 0 2020-12-25 61 0 2019-12-25 57 0 2018-12-25 61 0 2017-12-25 55 0 2016-12-25 58 0 2015-12-25 72 0 2014-12-25 62 0 2013-12-25 71 0 2012-12-25 56 0 2011-12-25 62 0
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60°+ Octobers have become much more common in recent years. In the old days Octobers were closer to 55°. Julys used to average around 75° and now closer to 80°. Decembers at Newark used to be closer 35° and now 40°. So a 5° rise in the 10 year running means since the 1930s. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Oct Click column heading to sort ascending, click again to sort descending. 1 2021 64.4 0 2 2017 63.8 0 3 2007 63.5 0 4 1971 63.1 0 5 1990 62.4 0 6 2024 62.2 7 - 1984 62.2 0 7 2023 62.0 0 8 1949 61.6 0 9 1963 61.2 0 10 1995 61.0 0 - 1947 61.0 0 11 2019 60.4 0 - 1954 60.4 0 12 1973 60.3 0 13 1946 60.0 0
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Those 850 mb temps should be near +20C early Tuesday for the 70° lows around Iowa. But they should modify quite a bit coming east. Looks similar to the other day when the warm spots went 80-85 in NJ. That should be good for more record high potential at around Halloween as the surface forecast highs have been beating forecasts with the record dry pattern.
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The extreme +EPO pattern this month looks like a blend of influences. La Niña background forcing, marine heatwave east of Japan/-PDO, and some MJO. Notice how the MJO 6 composite is much weaker than the pattern we got. So the other influences are at work. Also notice how well defined the warm pool near Japan and the Cold SST pool near Alaska has become with the +EPO.
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The unusual thing about the airmass next week will be how warm the minimums will be to our west. Models have been hinting at lows near 70° in Iowa. This could be a first for so late in the season as the departures are forecast to be off the charts.
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01-02 only works as an analog if December comes out of the gate really warm and doesn’t trail off or reverse after. We got a very warm December in that range in 21 but the reversal in January took a +7 winter out of play. Then 22-23 started slightly cooler than avg in December before January and February averaged +7.5. Last winter started very warm again but the departures lagged in January and February. So it has been a challenge for NYC to get much beyond +5 in recent winters since it’s hard to sustain such high departures over a 3 month period. The bigger story has been the sustained above to near to record warmth since 15-16.
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A 01-02 repeat in this warmer climate would make the last few winters seem colder by comparison. The 01-02 winter went +7.1 in NYC against the much colder normals of that time. It averaged 41.5° and the same departure these days would yield a 43.3° average. Would be +1.8° warmer than 01-02 and +2.3° warmer than 22-23. Time Series Summary for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 1 2001-2002 41.5 0 2 2022-2023 41.0 0 - 2015-2016 41.0 0 3 2023-2024 40.6 0 4 2011-2012 40.5 0 5 1931-1932 40.1 0 6 1997-1998 39.6 0 7 2016-2017 39.3 0 8 2019-2020 39.2 0 9 1990-1991 39.1 0 10 1998-1999 38.6 0
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That was the only winter back in Long Beach that I was able to ride the boardwalk practically every day. Very few storms and mild temperatures. I couldn’t believe at the time how different it was from the 93-94 and 95-96 winters.
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If we were ever were able to repeat a 01-02 type warm and dry winter in this much warmer climate, then NYC would have a shot at their first under 1” snowfall season.
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Driest airmass of the season expected to arrive on Friday with dew points in the 20s during the afternoon peak heating.
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Newark only needs one more 80° day with next weeks warm up for the new all-time record after October 20th. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 1 2024-12-31 3 69 - 1979-12-31 3 0 - 1950-12-31 3 0 - 1947-12-31 3 0
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Strong +EPO patterns can be very dry this time of year like we also saw back in 1963.
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The longer that marine heatwave near Japan kept going you knew that it was only a matter of time before a big +EPO pattern emerged.
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Newark only needs 3 more days for the new longest dry streak record. Number of Consecutive Days Precipitation < .01 for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. 1 26 1949-06-24 2 25 1939-11-30 3 24 1995-09-08 - 24 1980-02-15 - 24 1963-10-27 - 24 1959-09-27 - 24 1942-05-05 4 23 2024-10-22 - 23 1991-11-09
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This may be the first time we had two separate 590+DM ridge events in late October with the next big warm up next week.
