bluewave

We got lucky in 21-22 that the amplified MJO 4-7 during December kept progressing east of the Dateline into phase 8 in January. That’s why it was our last real month of winter for many near the East Coast. The Pacific Jet relaxed and the Pacific blocking was able to run the table for a whole month. But it’s still too early to be sure if we can get a clean progression into 8 or the MJO convection reloads in 4-7 again in January. We probably won’t know for sure which way things will go until we are near the start of January.

We actually want a slightly stronger Southeast Ridge so the heaviest rainfall offshore shifts west by 100-200 miles since we really need the rain. New run Old run

The December 2000 to 2010 era was our best for December snowfall. The snows really began to diminish after the Boxing Day Blizzard. With how warm Decembers have become you really need elevation for warning level events over 6”. Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean 8.9 8.9 2010 20.1 20.1 2009 12.4 12.4 2008 6.0 6.0 2007 2.9 2.9 2006 0.0 0.0 2005 9.7 9.7 2004 3.0 3.0 2003 19.8 19.8 2002 11.0 11.0 2001 T T 2000 13.4 13.4 Monthly Total Snowfall for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Mean 2.4 2.4 2024 T T 2023 T T 2022 T T 2021 0.2 0.2 2020 10.5 10.5 2019 2.5 2.5 2018 T T 2017 7.7 7.7 2016 3.2 3.2 2015 T T 2014 1.0 1.0 2013 8.6 8.6 2012 0.4 0.4 2011 0.0 0.0

Maybe the record SSTs in the Gulf can help boost the PWAT plume streaming north for some much needed rainfall next week. Plus a slightly stronger WAR could shift the storm track further west over time so the max totals are over the area instead of just to the East. We just don’t want too far a shift west since we really need the rain.

Strongest gusts on the Jersey Shore so far. Barnegat Inlet Light 54 MPH 0131 PM 12/05 WXFLOW

Not too shabby considering NYC and Boston’s 2 year snowfall totals combined were only 32”. Time Series Summary for NY CITY CENTRAL PARK, NY - Oct through Sep Click column heading to sort ascending, click again to sort descending. 2023-2024 7.5 0 2022-2023 2.3 0 Time Series Summary for Boston Area, MA (ThreadEx) - Oct through Sep Click column heading to sort ascending, click again to sort descending. 2023-2024 9.8 0 2022-2023 12.4 0

The gusts over 50 mph so far have been closer to CNJ. Ocean County... Lakehurst NAS 52 MPH 1021 AM 12/05 AWOS

Thanks for the very kind words. When the data I am looking at gets strong enough I do make forecasts beyond 2 weeks. Other times I provide a set of options that I think will be in play further out in time.

Nice snow squall in NJ.

Impressive to see lightning this far from the lakes with snow squalls.

The long range Euro and even GFS are probably struggling with the strength of the Pacific Jet again. Notice how the EPS keeps trying to retrograde the ridge axis long range and boost the heights over Western North America. This is why the model shifted so dramatically in its forecast for next week from earlier runs. It likes to show -EPOs beyond a week out which become weaker as we approach forecast time.We will need a solid MJO 8 to weaken that jet and allow the Pacific side to become more favorable. New run faster Pacific Jet near Alaska and ridge axis displaced further east Old run way too much -EPO and missed the jet and vort near Alaska and ridge axis too far to the west

We can hope that the MJO transits into 8 so we can get some version of a Jan 22 mismatch pattern with sustained Pacific blocking. But not sure yet if that will occur. We don’t want to see it weaken in earky Jan with another 10 day cooldown before reloading in the warmer 4-5-6 phases again.

I am not buying the weakening signal on the EPS. It’s probably just losing the signal like it did back on November 15th with both the RMM and VP anomalies. The GEFS was actually much better with both the RMM and VP anomalies. Our best bet would be to have the forcing shift into phase 8 regions east of Dateline in January. Otherwise it could just reload again in phases 4-5-6 like we have seen so many times in recent winters. Euro lost the signal a few weeks ago Verification much stronger closer to GFS VP anomalies also verified stronger Forecast Verification

The SST -PDO is a reflection of the predominant atmospheric 500mb state over extended periods of time. But this -PDO era is much different from past instances in that it’s being defined by the record warm pool from east of Japan and to the north of Hawaii as defined by the historic 2nd EOF values I posted a while back. My guess is that the SST -PDO is being driven by forcing closer to the equator such as the MJO getting stuck in phases 4-7 as has been the case for the last 10 years. The SSTs are just the reflection of the 500 mb atmospheric pattern. When the SST -PDO aligns with the atmospheric -PDO a feedback loop can develop and sustain the pattern. But sometimes when the forcing shifts like Jan 22 into MJO 8 we can get more of a +PDO atmospheric look even if the SST is still in negative mode. This is why I mention mismatch patterns when the 500 mb goes against the SST. Such a pattern tried to get established this week but the warmer MJO forcing is working to shift it quickly. If the +AAM could have had some assistance from a MJO 8 instead, then it could have been a more extended pattern. That’s why I will be tracking the MJO heading into January. If the WPAC warm pool slows the forcing there then we could see renewed warmth following the start of the New Year. But if the MJO can push strongly enough east of the Dateline closer to 8 than we would be able to revisit the first week of December against the colder January climo with improved snowpack for better Arctic air production.

Yeah, close to those areas around the equator. The warm pool east of Japan to north of Hawaii raises some interesting questions. I suppose you can make the argument that the forcing from the WPAC warm pool near the equator leads to stronger 500mb ridging across the North Pacific which warms the SSTs below. So the -PDO signature could be a result of the tropical forcing in the WPAC. When it aligns with the tropical forcing perhaps the subtropical -PDO marine heatwaves can lead to feedbacks which help to strengthen the pattern when in alignment.

It’s described in this story that I posted above. https://www.climate.gov/news-features/featured-images/warm-pool-indo-pacific-ocean-has-almost-doubled-size-changing-global

I posted the Pacific Jet correcting much stronger in the above post. The JMA site has the MJO jet composites. Just select the options for 200mb zonal wind anomaly. The jet increases across large swaths of the North Pacific when forcing is in the 4-7 regions. We are currently near a 4 composite for December with the jet pushing through the -EPO block this weekend. https://ds.data.jma.go.jp/tcc/tcc/products/clisys/mjo/composite.html

Yeah, we were discussing the issues with the much faster Pacific Jet and inability to sustain -EPO patterns. All the guidance has been underestimating this influence beyond a week out. This recent +AAM driven Pacific blocking pattern reverses fairy quickly. The forcing near the Maritime Continent accelerates the Pacific Jet, weakens the -EPO, and leads to a Southeast Ridge. New run faster Pacific Jet weakening -EPO block and leading to Southeast Ridge several days later Old run

Yeah, the nearly doubling of the Indio-Pacific warm pool has become a major climate driver especially for us in the East. https://www.climate.gov/news-features/featured-images/warm-pool-indo-pacific-ocean-has-almost-doubled-size-changing-global

The record warmth continues to defy expectations based on past El Niño events with the warming starting earlier and now continuing later.

I don’t devote separate threads to my discussions and forecasts. They are included in the NYC Metro and annual ENSO threads here. My sea ice and global temperature discussions are in the CC forum.

We are currently ENSO cold neutral as the La Niña is taking time to develop. But if we do follow the typical La Niña pattern, then 3 inches in December is the cutoff. Below that and NYC will have a below average snowfall season. December 2001 and 1996 were cold neutral and only had a T with below average seasons. The one early snowfall indicator which has worked for every La Niña winter in NYC going back to the 95-96 has been the December La Niña snowfall. Years with 3 or more inches December have gone on to above normal seasonal snowfall. Every December with under 3” has had a below average snowfall season. This is why December is so important with La Ninas around NYC. 22-23….Dec snow…..T……season….2.3 21-22…..Dec snow….0.2…season…..17.9 20-21…..Dec snow….10.5…season…38.6 17-18……Dec snow….7.7…..season…40.9 16-17…….Dec snow…3.2…..season…30.2 11-12…….Dec snow….0…….season….7.4 10-11…….Dec snow….20.1….season….61.9 08-09…..Dec snow….6.0……season….27.6 07-08…..Dec snow…..2.9…..season….11.9 05-06…..Dec snow…..9.7…….season…40.0 00-01……Dec snow….13.4……season….35.0 99-00…..Dec snow…..T……….season….16.3 98-99…..Dec snow…..2.0……..season….12.7 95-96…..Dec snow…..11.5……..season….75.6

The north-south bridges like the Throggs Neck will probably have more impressive crosswinds with the westerly flow.

I think that the winds will be the biggest story tomorrow. These will be some of the steepest low level lapse rates we have seen this time of year. Models usually underestimate wind gusts in these situations. So there could be gusts in the 50-60 mph range.

It’s no surprise the models have adjusted warmer going forward. The WPAC warm pool along the equator was the warmest for November at just over a +29.05°C. Forcing in these areas leads to a more pronounced Southeast Ridge.