bluewave
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We haven’t been able to sustain a -EPO for more than shorter periods during the winters since 13-14 and 14-15 due to the overpowering Pacifc Jet influence with the record WPAC warm pool.
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It just shows how sensitive the pattern has been to forcing west of the Dateline. The old EPS run had more subsidence there. Now there is some forcing starting to show up again. While the warm pool has diminished there in recent weeks, there is still an area of +30°C SST warmth. New run some forcing showing up now west of the Dateline Feb 20 to 25th in the blue -2 near 160E. Old run
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The 0z EPS was moving in that direction with the forcing lingering longer than previous runs west of the Dateline.
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Our first 12 month period above +1.5°C.
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The SSW was needed in 2018 to flip the atmosphere back to its prior cold and snowy state which existed before the record 80° warmth in February.
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That Valentine’s Day storm was one of the more unusual ice storms that I ever saw on the Long Island South Shore. It started with several areas getting a ton of sleet. A gas station canopy collapsed in Island Park from the weight. Then the immediate south shore beaches turned to freezing rain. I picked up about .25 of ice back in Long Beach. The first time areas south of Merrick Road had more freezing rain than areas north. It was also one of the more impressive flash freezes in the afternoon after the brief warm up. Was one of the few times 2000- 2009 that a February cold blocking pattern disappointed.
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The biggest snowfall post SSW usually occurs when there was a higher snowfall during the season prior to the SSW. This was the case in years like 17-18 when we already had a snowy season before the SSW. So Long Island wound up with a record breaking 30” following the SSW in March. Other years like 06-07 had less snow following the SSW since there was hardly any snowfall before the event.
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SSWs only work out for us to get above normal snowfall seasons when the Pacific cooperates and its cold enough.
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Long range guidance really struggling with the fast Pacific flow. The EPS is backing off the cold that it was showing day 8-14. It now has milder temperatures than the previous run. New run Old run
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The snowfall measurements were spot on in those days at Central Park when the NWS crew would head over from 30 Rock to take the measurements themselves.
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On track for one of the warmest winters with a double SSW.
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We’ll probably never see another winter like 86-87 again since It may be one of the few times that Central NJ got 50” and NYC didn’t. Most of the the other 50” seasons in Central NJ extended north with NYC getting 50” also.
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Current North American snow extent at record lows for the date back to December levels.
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Not commonly enough anymore to reach 25” in a season without a big KU event.
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It seems like the increase in 6”+ days has masked the decline in 1-3”. So when we get the inevitable drop in larger events, there isn’t a small events cushion to fall back on. This has resulted in 5 out of the last 6 seasons in NYC with below average snowfall so far. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Oct Nov Dec Jan Feb Mar Apr Season Mean 0.0 1.1 2.2 3.9 5.5 2.2 T 14.4 2023-2024 0.0 T T 2.3 0.0 M M 2.3 2022-2023 0.0 0.0 T T 2.2 0.1 0.0 2.3 2021-2022 0.0 T 0.2 15.3 2.0 0.4 0.0 17.9 2020-2021 0.0 0.0 10.5 2.1 26.0 T 0.0 38.6 2019-2020 0.0 0.0 2.5 2.3 T T T 4.8 2018-2019 0.0 6.4 T 1.1 2.6 10.4 0.0 20.5
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The issue with much warmer winters is that we have become very KU dependent for NYC to get close to 25” on the season since the 1990s. During colder winters before then, it was easier for NYC to get closer to average with a bunch of small to moderate events. But snowfall seasons like that are pretty much non-existent these days.
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We can get small to potentially moderate events with a hostile Pacific like we saw in January. But I think we’ll need to see improvements in later model runs out West to have a chance for NYC to go over 10” on the season. There is still time to put something bigger together. But it’s not a guarantee.
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The improvements out West got pushed back as we have seen that we can’t just rely on the -AO without Pacific cooperation for major events. We still have time to put something together from later February into early March. But there are no guarantees with how hostile the Pacific has been in recent years.
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EPS correcting weaker with the ridge out West day 10 compared to the old day 15. So we may need to rely on short term improvements which may not show up until under 120 hrs. But the flip side of this is things keep getting pushed back. Hopefully we can put something together before the season ends. But there are no guarantees when the Pacific is this hostile. New run Old run
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Several factors lining up for a potentially very active Atlantic hurricane season.
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Unfortunately, the Pacific was too overpowering in those examples you cited for a big snow event. January had too much of a trough out West so we only got a few small events which was probably the best we could have hoped for. Last March the interior wound up with the big 40” special. December 2022 featured one the most negative -AO patterns we have seen during a La Niña. But the previous ones in 1995,2000, 2005, and 2010 did much better. Plus we had the block become more south based around storm time later in December 2022 linking up with the Southeast ridge .So I disagree that luck had much to do with this. It was a product of the type of patterns we have been getting in recent years which have been very hostile to snowfall. I still believe late February into early March will at least provide a window when NYC can get its first 4”+ or even 6”+ event or multiple events in years. But it’s not a guarantee. This is the first time we have a forecast for a solid STJ and blocking to combine in a while. We’ll just need the Pacific to back off for a long enough interval while the blocking pattern is still in effect. I think its doable.
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Enjoying the drier pattern here this week for as long as we can get it. It was the first time I walked on the grass and I didn’t start sinking into the mushy ground below in a while.
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Really impressive STJ event for SOCAL.
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It will be interesting to see if we can link this coming SSW with the very amplified MJO 6 like we did back at this time in 2018. https://wcd.copernicus.org/articles/1/657/2020/#:~:text=In the beginning of February,stratospheric warming (SSW) event. Mechanisms and predictability of sudden stratospheric warming in winter 2018 In the beginning of February 2018 a rapid deceleration of the westerly circulation in the polar Northern Hemisphere stratosphere took place, and on 12 February the zonal-mean zonal wind at 60∘ N and 10 hPa reversed to easterly in a sudden stratospheric warming (SSW) event. We investigate the role of the tropospheric forcing in the occurrence of the SSW, its predictability and teleconnection with the Madden–Julian oscillation (MJO) by analysing the European Centre for Medium-Range Weather Forecasts (ECMWF) ensemble forecast. The SSW was preceded by significant synoptic wave activity over the Pacific and Atlantic basins, which led to the upward propagation of wave packets and resulted in the amplification of a stratospheric wavenumber 2 planetary wave. The dynamical and statistical analyses indicate that the main tropospheric forcing resulted from an anticyclonic Rossby wave breaking, subsequent blocking and upward wave propagation in the Ural Mountains region, in agreement with some previous studies. The ensemble members which predicted the wind reversal also reasonably reproduced this chain of events, from the horizontal propagation of individual wave packets to upward wave-activity fluxes and the amplification of wavenumber 2. On the other hand, the ensemble members which failed to predict the wind reversal also failed to properly capture the blocking event in the key region of the Urals and the associated intensification of upward-propagating wave activity. Finally, a composite analysis suggests that teleconnections associated with the record-breaking MJO phase 6 observed in late January 2018 likely played a role in triggering this SSW event. How to cite. Statnaia, I. A., Karpechko, A. Y., and Järvinen, H. J.: Mechanisms and predictability of sudden stratospheric warming in winter 2018, Weather Clim. Dynam., 1, 657–674, https://doi.org/10.5194/wcd-1-657-2020, 2020.
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I realize that. I was just talking about the timeline. We usually get our snowstorms after the -AO begins rising after hitting a low for the period.
