bluewave

Most storms over the last seven years have been falling into the cutter, I-78 to I-84 hugger and suppressed Southern stream. Strong benchmark storm tracks have been missing. This very strong Northern stream of the Pacific Jet has been leading to these groupings. One group of storms gets suppressed to the south as kicker lows in the fast Pacific flow come into Western North America. This was the case last winter with the big Gulf snowstorm which went OTS to our south instead of coming up the coast. The second group is the Great Lakes cutter like we got in mid-February during the -5 SD Greenland block. The jet was so strong and the SSTs to our east so warm that it forced a Southeast ridge rather then getting a benchmark track. Instead Toronto got the historic snows. Enough room between the shortwaves so one system can really amplify and cut to our west like later this week. That was originally forecast to be a coastal storm. Then the third track is the hugger which can produce some lighter snow events like we got last February. But there was still too much Southeast ridging for NYC Metro so the heaviest totals were to our NW. Plus the there are often too many shortwaves in the fast Pacific flow leading to poor wavelength spacing. It would be great in the coming winters if we can at least see a few very deep benchmark tracks. But the last time we were able to pull this off was in January 2022 and February 2021.

The starting point is when the climate began to warm more rapidly along with the oceans. So one of the predictions made years ago was that we would see an increase in the strongest of hurricanes but not necessarily the total number of storms. Has to do with dueling influences as the oceans reach all time record warmth. Stability can limit the total numbers but lead to the storms that do form being more intense. First, we have seen a record concentration in Cat 5 hurricanes in the last decade due to the warmest SSTs ever observed in the Atlantic and other basins. Second, uneven warming of these basins also lead to stability issues at varying points in the season such as what used to be thought of as the peak from late August into early September. So recently we have seen an early burst of activity followed by a late August into early September lull and followed by unusually late season development. When we get these very warm SSTs at the higher latitudes during mid-summer it has lead to stability issues in the tropics. But later in the session these stability issues have been resolving leading to this record late season activity.

The WPAC to the east of Japan is different from the EPAC since the Kuroshio Current like the Gulf Stream waters are certainly warm enough to cause a feedback process. But the wam blob off the West Coast during the 2010s was the result of the forced pattern emanating in the subtropical or tropical WPAC . So once the fall pattern in 2019 shifted the warm blob easily disappeared. This is why 19-20 wasn’t a repeat of 13-14 like some were speculating about that fall. So more remotely forced. The WPAC warm pool is much more stable and longer lasting since both the forcing and SST feedback are at play for pattern maintenance. This is why the Aleutian ridge and Southeast ridge have become such dominant features over the years.

We probably have to factor the summer drought stress during peak heating into the equation. This was the 4th driest and warmest summer here. Last year the summer was much wetter before the dry conditions last fall. Time Series Summary for NEW HAVEN TWEED AP, CT - Jun through Aug Click column heading to sort ascending, click again to sort descending. 1 1966 4.15 0 2 2022 4.29 0 3 2017 4.76 3 4 2025 4.99 0 Time Series Summary for NEW HAVEN TWEED AP, CT Click column heading to sort ascending, click again to sort descending. 1 2022 75.4 0 2 2024 75.2 0 3 2020 74.9 2 4 2025 74.5 0 5 2010 74.3 0

It’s very challenging to guess ahead of time how vibrant the foliage will be during any given year. Not really noticing colors quite a vivid up here compared to years past here and back on Long Island. The best fall color that I can remember back on Long Island was actually the late very vibrant foliage back in 2007. Went to a friends house in Mt. Sinai for Thanksgiving that year and the colors were gorgeous for that late in the season.

I get it that people on here are eager to see some type of shift with the SST and atmospheric state in the WPAC. But what we we are seeing now is only a reduction from very high summer levels to a still very warm level. It’s primarily a result of the recurving typhoons and unusually strong +WPO for October. Plus the subsurface is still plenty warm. So like after the cooling last winter, it didn’t take long for the surface to warm back up in the following months since the subsurface has so much stored heat energy. This is why the PDO has been fluxuaring between deeply negative states and levels and readings which aren’t as negative. But the orientation of the entire sea and atmospheric state results in the -PDO persisting at varying levels. Even with the decline from the extremely warm surface levels to still very warm, this October has produced one of the strongest East Asian to North Pacific Jets on record for the month of October. So it’s really the gradient between Siberia and the entirety of the Western and Central Pacific Ocean SST warmth.

Snowfall season starting at the higher elevations with some still great fall foliage even in the more northerly spots that are just past the peak.

Even with the +PNA -EPO pattern during January, the coldest departures were displaced further south toward the Mid-Atlantic and Southeast since Canada was so warm.

No it wasn’t prior to 2018-2019. Maybe since you live west of I-95 you are unfamiliar with the coastal areas. We had numerous events prior to 2018-2019 which were all or mostly snow. That mid-October storm track would have been mostly rain or mixed near the coastal plain during the winter. Too many storms to count prior to 2018-2019 which were the opposite.

It’s coming near the tail end of a -NAO period which began around the 15th. Not really sure how to define a classic -NAO since there have been many versions over the years with blocking near Greenland. It’s just that during the 2020s we are finding more ways for higher latitude blocking to merge with the subtropical ridge especially at storm time.

I am using the term early season to describe the activity prior to what is considered the late August into early September traditional peak we used to get more often. Erin went Cat 5 on August 16th which is early in the season for Cat 5 development. The record SSTs are why we haven’t had any really low ACE seasons since 2013 and 2014. This lead some to speculate that the AMO was going to shift colder back then. But instead the Atlantic SSTs reached all warmth over the last decade with the historic run of Cat 4-5 systems.

Yeah, that was an amazing late season snowfall pattern. Islip had 36.5” of snow from 3-7-18 to 4-2-18. But Islip has only had a total of 27.6” during 22-23, 23-24, and 24-25 combined.

Noticing the continuing pattern with these cool downs. The coldest departures will be found more to the south closer to where you live as Canada remains very warm relative to their means. Then we are already seeing a big PAC Jet extension in early November forecasts so expect the temperatures to warm up during the 2nd week of November.

I was talking about coastal sections from NJ out across LI. I agree about a heavy wet snow potential somewhere on the more inland side of that heavy rainfall zone in SE MA. Just a little latitude in a marginal setup makes a big difference.

The flow was ENE here near the coast so it would have pulled in too much warm air at the start. The lack of strong deepening would have meant that the coast couldn’t cool down enough at the tail end of the storm for a significant shift to snow. But interior areas would have done well.

The issue with the last coastal is that it remained strung out with two weaker low centers. So even during the peak of winter it still probably would have been more of a high elevation interior event. Not enough deepening to prevent mixing issues near the coast.

I had my first frost on Saturday morning but was very patchy.

Even before we get to the cold season these strong -NAOs are still finding a way to link up with the Southeast ridge or WAR. The storm for this week was originally forecast to be a coastal storm track. But it has shifted to a warmer cutter track to our west. In the old days a -NAO +PNA would nearly always result in a classic coastal storm track since there wouldn’t have been a Southeast ridge or WAR. New run -NAO linking up with the WAR Old run no WAR

This has been the pattern over the last decade. Early start to the season followed by a lull from late August into early September. Followed by a very strong late September to late October. So very challenging to get a low ACE season anymore with the record Atlantic SSTs and these historic RI and so many Cat 4-5 hurricanes.

It’s really interesting how we also had great 11 year runs for snowfall in December and March also. OCT-NOV 2008 to 2018…DEC 2000 to 2010….MAR 2009 to 2019. Following each of those runs it was like someone shutting off a switch during the respective months. OCT and NOV haven’t featured any early season snows since 2018. Our last historic December snowstorm was Boxing Day in 2010. Interior sections near BGM in 2020 got their historic December snowstorm near 40” since the storm hugged the coast too close near ACY for us to get the really heavy totals. Then the big cutter a week later on Christmas with all the damage and flooding at the ski resorts. Then our least really big March with 30” on Long Island was 2018 and some areas did well in March 2019. Since then coastal sections have had nearly no March snow in the last 6 years.

That was a great run of early season snowfall from 2008 to 2018. The higher elevation event later in October 2008 followed by the historic late October 2011 snowstorm. Then the post Sandy snowstorm in 2012 and the SWFE in November 2018.

What I have been saying is that the faster Northern Stream of the Pacific Jet driven by the gradient formed between the record SSTs over the WPAC and Siberian cold has lead to the dominant cutter, hugger, and suppressed Southern Stream since 2018-2019 producing the record low 7 year snowfall totals along the I -95 corridor. My early guess for this winter is that average DJF temperatures will be warmer than last winter was based on the tropical forcing that we are currently experiencing. I was able to identify the factor last October which lead to the colder winter which I discussed in the main forum. This feature isn’t there this October. But since the snowfall was so low last winter, can’t be sure whether we see something similar again or we get a short term favorable MJO leading to higher snowfall totals than last winter. Since we could beat last winters snowfall totals with a few good storm tracks. But the December 4” rule will probably be in effect again for La Ninas. Nearly all La Niña winters since 1991 with under 4” at places like NYC and Newark in December finished the season below. And all above this level went into snowy seasons. Last December we came in under which lead to my December guess for another below average snowfall season which worked out.

Each event is constrained by the overall pattern and not the other way around.

This has been one of the model forecast error patterns for years now of underestimating the WAR or Southeast ridge in the longer range. It’s what has been happening with such a strong Pacific Jet and near record SST warmth over the Gulf Stream and Atlantic. The models were originally forecasting the main low to be a coastal track to our east. But now the -NAO is linking up with the Greenland block again so the low is cutting to our west. So we haven’t any really deep lows taking a benchmark track since January 2022 during the winters. Even the coastal a few weeks ago were two weaker lows instead of one consolidated one. Our primary storm track since 2018-2019 has been cutter, hugger, and suppressed Southern Stream leading to the record 7 year low snowfall totals along the I-95 corridor. I am hoping one of these winters we can get a great MJO 8 month like January 2022 again with the strong benchmark tracks. But each of the times the MJO is approaching phase 8 it has weakened and reloaded into the warmer phases again. So this will probably be a short term modeling surprise if it happens again and not really seen from weeks out. New run stronger WAR Old run weaker WAR

Tom Skilling and Matt Lanza have a nice in depth discussion here on what the lack of balloon soundings may mean for the accuracy of weather model forecasts. https://www.facebook.com/TomSkilling/posts/weather-forecast-models-produce-forecasts-of-varying-accuracy-interestingly-some/1319935109491429/ With weather balloon observations regularly going off line at a whole series of key observation stations, we're moving into uncharted territory and hoping forecast models still behave. The concern is legitimate. Weather satellite and in flight aircraft data may help fill the void--but the data they provide is different than the more thorough balloon measurements. We may not see issues with model accuracy each day. But it's been established in some research work--and we know for a fact---that the upper air observations gathered by weather balloons carry disproportionate weight in influencing model accuracy. That's because their measurements of the atmosphere are in many ways more complete than other sources--such as satellite or in flight aircraft. NASA runs a global weather forecast model--the GEOS model. Among its roles is to look at the impacts of and distribution of gases and particulates in the atmosphere. It's also been useful in studying greenhouse gases and also the movement of dust and other particulates off the Sahara Desert westward out over the Atlantic and all the way to South and North America. It could also be used, were, God forbid, biological agents released into the atmosphere or a nuclear accident sent a huge amount of radioactivity into the atmosphere to track these agents and where they might go. So the NASA GEOS model isn't exclusively used for weather forecasting alone. But it IS an atmospheric forecast model and the data fed into it is comparable to the data fed into the full range of weather forecast models. You might have asked when you hear discussions of the fact different models come up with varying forecasts at times---"why is it they employ multiple models in the weather forecast process? Why not just one??" It's a reasonable question--and the answer is quite simple. It's because NO single model is perfect. Nor are our measurements of the atmosphere. Having multiple solutions from multiple models, each making slightly varied assumptions on how to handle the physics of the imperfectly measured atmosphere, offers human forecasters a range of possible forecasts scenarios--each valid yet some more likely to work out than others. When a common set of forecast solutions appears from varying models, it makes it easier to "cull" the less likely forecasts from the mix settling on the most accurate of the varied forecasts. NASA modelers have spent time looking at the observations fed into their model. By studying how the model behaves when certain data is flawed or missing, they've produced a ranking of which of the 210-million observations which go into many global forecasts based on their importance to the forecasts these models generate. A graphic I'm posting with this post lays out what they found. And interestingly, radiosonde data--in other words, weather balloon data--comes out as 2nd most influential of the different data sets which go into computer weather forecast models. This places weather balloon data in a uniquely powerful position. Eliminating balloon data from a set of stations, which has begun happening in greater numbers in recent months due to budget cuts, won't be something which messes up model predictions every day or in the same way. What it DOES suggest is that unexpected, hard to identify impacts may well occur. And who's to say that won't happen on a day when tornadoes or a snowstorm is a occurring and you need an accurate model read on how the extreme weather situation is evolving----or, equally scary, when a hurricane is approaching. That unpredictable and varying accuracy is introduced into the weather forecast environment is very concerning. Also, since many of the stations which have been pulled off line by budget cuts are in tornado and severe weather prone areas, the uniquely accurate 3-D measurements of the atmosphere weather balloons provide is worrisome. ----------------------------------------------- One other period provided meteorological forecast modelers a unique opportunity to check out the impact of losing upper air data from weather balloons--and it resulted in a measurable loss in computer model accuracy. The world lost Russian weather balloon soundings during an outage in 2015. European Centre researchers studied the impact on the loss of these balloon reports during that outage. This was a much broader loss of weather balloon data than what is happening now. But the outage led to a significant loss in model forecast accuracy. Because global weather is part of a vast, interconnected system, the loss of a critical data set produces forecast accuracy issues upstream and downstream of the regions where such data is usually taken. The 2015 outage provided a rare glimpse of what happens when weather balloon data is lost. That was a much different era in meteorological science so it's difficult to precisely anticipate the sort of problems such an out would produce today. But the loss of data as critical as that which is provided by our radiosonde (i.e. weather balloon) network can't be dismissed. ---------------------------------- https://theeyewall.com/weather-balloon-launch-cuts-an-honest-look-at-how-it-should-impact-forecasts/