bluewave

Florida is experiencing increasing flooding from higher sea levels and record rainfall as a warmer atmosphere holds more moisture.

The 0z GFS is also initially bringing the 100° heat to our north next Tuesday and Wednesday. The ridge is so strong that the surface high is east of New England instead of down near Bermuda like it used to be with these heatwaves in the past. So a large expansion of the subtropical ridge from the days past like we have frequently seen in recent years. We get just enough SSE flow from around NYC and east for a sea breeze influence instead of deep westerly flow at least Tuesday and Wednesday. I think the ensemble means are smoothing the ridge out too much. So these OP runs which show near record 600 dm heights could be correct. It’s possible that the 100° heat could sag south toward our area before the heatwave ends. But those details are still outside the best range of the guidance.

The 12z Euro is beginning to shift to another over the top warm up for next week like we have often seen in recent years. So like the GFS is showing, the warmest temperatures may initially go to our north. But we’ll have to see if the warmest day ends up being when the warmth begins to shift south before another cold front arrives. That may be the best chance of the locally onshore SSE flow shifting to the SW before the heatwave ends. New run 0z Thu 20 Jun Old run

Allentown also saw a steep decline from the 2010s into the 2020s. So it’s another station which had a fantastic snowfall outcome during the 2010s. State College had its peak during the 1990s. But the first 5 seasons of the 2020s so far are way down like all the other stations. Allentown 80s….31.0” 90s….29.8” 00s….32.1” 10s….39.7” 20s…22.9” State College 80s….38.8” 90s….55.1” 00s….39.9” 10s…..38.1” 20s….27.4”

My guess is that our snowfall peaked along the 1-95 corridor from BWI to BOS during the 2010s. The first 5 seasons of the 2020s so far have seen a steep decline. So we are going to need to see some big snowfall improvements next 5 years in order to avoid the 2020s becoming the lowest snowfall decade following the highest decade in the 2010s. Baltimore 80s….18.5” 90s….17.7” 00s….18.0” 10s….24.1” 20s….7.7” Philadelphia 80s….20.6” 90s….18.5” 00s…20.8” 10s….31.9” 20s….9.7” New York City 80s….19.7” 90s…24.4” 00s…28.0” 10s….37.9” 20s…14.2” Boston 80s…32.8” 90s…49.9” 00s…45.6” 10s….53.0” 20s…26.1”

The surface ridge axis on the CMC is further north. So we get SSE winds off the ocean. The Euro is further south allowing more westerly flow. Once within 120 hrs the models should start to agree on one solution or the other. But it’s been tough in recent years to get a strong westerly flow with our heatwaves. So the Euro would be a departure from recent experience. That’s why I would like to see some agreement in future runs.

Still plenty of spread with the models for the heatwave next week. It s the Euro vs the cooler GFS and CMC. The Euro has our first 600dm ridge for the month of June. The location of the maximum heights and specific wind direction varies across all the models also. So the details will have to wait until the models can come into better agreement.

I think the concept of what qualifies as a good or great La Niña winter has been diminishing over time as the winters have been steadily warming. For the posters around NYC Metro 95-96 was the gold standard in terms of wall to wall cold and snow from November into early April. This was followed by our first global temperature spike in 98. So while 10-11 was still an amazing winter, the snow cut off about a month too early to challenge 95-96 around NYC. Not as cold as 95-96 was from November into April but no complaints due to the epic snowfall from late December to late January. Then the next big global temperature spike in 15 and our next multiyear La Niña in 16-17 and 17-18. The 17-18 winter was very snowy but not up to the levels we saw back in 10-11 around NYC. March was really special though especially out east on Long Island. This was the first time we had an 80° reading in February around NYC and the record warmth allowed the decent cold anomaly from after Christmas into early January to essentially get erased. Our better La Niña winter in 20-21 featured the best snowfall outcome of the 2020s so far. But it was also our warmest winter around NYC with so many -AO days along with a -5 or daily AO reading. So even with such great blocking which could be likened to a weaker reflection of 10-11, we still finished a little above normal against an already warmest new 91-20 climate normals period. Plus we had the very warm Christmas flood cutter and flash melt which damaged the ski resorts. The warmer La Niña winter pattern began to emerge in 05-06. Great snowfall outcome around NYC but the January warmth was so strong the winter finished above normal. This was followed by the milder 07-08 La Niña and less snow but not so bad by modern day poor La Niña standards. Then the 11-12 La Niña winter with a combination of lack of snow and warmth. But still not bad as 22-23 for warmth and lack of snow. 16-17 had great blizzards but was still near a 40° winter around NYC. 21-22 was split with a good January for snow and cold in an otherwise sea of warm. So the better La Niña winters have been warming since 95-96 with a decline in snowfall. The poorest outcome La Ninas have also been warming and loosing snowfall. So 22-23 was about as bad as we have seen for both warmth and lack of snow. We have never seen any winter with a December -AO averaging under -2.000 put up such poor metrics for snow and cold. Now that we have seen another big global temperature spike and the 3rd since the late 90s, I am not sure what a good La Niña winter will look like after the most recent temperature spike. But I am also concerned what a poor outcome winter La Niña outcome will look like in the against this new higher global temperature baseline with the record global 23-24 global temperature rise. I would be happy if any of the potential La Niña winters in this new grouping put up better snowfall numbers than 22-23 did. But don’t have much expectation that the record 9 consecutive warmer winter streak in the Northeast will end based off of anything I am seeing now in regard to the La Niña and -PDO early development. Will check in after October to see if we get some early snowfall MJO clues based on past La Niña Octobers.

I am not sure why this relationship has worked for every La Niña year since 10-11. But the La Niña Octobers with a more amplified MJO 4-6 went on to have better snowfall than the years with weaker October MJO 4-7 activity. But all the La Niña years since 11-12 were warmer than normal regardless of what the MJO did in October. So it only seems to work for snowfall. The first grouping of years was 10-11 and 11-12. The October 2010 MJO 4-6 was much stronger in 2010 than 2011. This was followed by October 2017 having a more amplified 4-6 than 2016. More recently October 2020 had the strongest MJO 4-6 activity out of the 2020-2021 to 2022-2023 La Niña. It works for RMM and velocity potential anomalies. That being said, who knows if this pattern will continue again since it only began in 2010 and the oceans have seen such a big increase in heat last few years.

Yeah, the early indications based on the strength of this -PDO and forecast La Niña background state would argue for our 10th consecutive warmer than normal winter here in the Northeast. But not sure yet whether we can see some improvement in the snowfall department over the last two seasons. We may get some clues with the October potential early MJO indicator which has worked with all La Ninas back to 2010.

We are probably going to need some version of a weaker La Niña pattern correlation like we got in 20-21 in order to see any level of improvement over the last 2 winters. Our only successes with recent La Ninas were the +PNA intervals. -PNA periods haven’t worked out for us in recent years like they were able to back in the 1950s and 1960s. I have been researching the reason for the 20-21 deviation from the norm for such a robust La Niña. The only difference I could see was that the MJO 4-6 amplitude peaked in October rather than the winter through the beginning of February. Beyond that point it really didn’t matter much since we had such a good snowfall outcome already in the bank. Remember the seasonal models missed this pattern. So I will look at the MJO amplitude after we get through October in order to see if there is any positive indication there. I would be happy with just a small amount of what we got in 20-21 and even Jan 22. But absent that kind of influence, we would probably be looking at another very warm and relatively snowless -PNA Southeast ridge winter. Plus the new wild card is that will be our first winter following the record global temperature spike over the last year. https://www.climate.gov/news-features/blogs/enso/did-northern-hemisphere-get-memo-years-la-niña The pattern correlations are usually substantially positive for moderate-to-strong La Niñas, which indicates that most events share some basic similarity with the average La Niña pattern. This confirms that La Niña is a reliable source of predictability outside of the tropics (and a big reason that we have an ENSO Blog!). However, the pattern correlation for the December 2020 – January of 2021 is the lowest of the 13 events and is actually slightly negative. That means you can argue that the Northern Hemisphere atmosphere looked a little more like El Niño than La Niña!

All 3 models have the first 95° or higher temperatures of the season next week for the usual warm spots. But only the Euro goes over 100° and has a much stronger ridge. I like to wait and see if the other models come on board before knowing if the Euro is correct or overdone like it sometimes is beyond 120 hrs. Need to get the flow more SW and have the weak front further north for the Euro to be closer. The GFS has more convection and the CMC somewhere in middle.

I was using the 500 mb maps and not any CPC definition. The AMO index doesn’t really do justice to the extreme North Atlantic warming in recent years. The index doesn’t look nearly as impressive at the raw SSTs. This is probably why there were warm AMO periods in the 1950s to early 1960s without a Southeast ridge with a deep -PNA trough in the West and -AO -NAO Greenland block. I have actually been mentioning the rapidly warming Atlantic in relation to the record Southeast ridge since the 15-16 super El Niño.

So we agree then since my comment about the pattern was for the mid-Atlantic to CT/RI and not the MA pike and up.

The seasonal pattern leading up to the storm has a really big influence. The storm tracks were really poor for SNE from December on. So there was just too much of a Southeast ridge influence in March for the coast. The whole storm track was just to far north. It was the worst snowfall performance on record from NYC to Boston with a winter with such a low -AO in December. The only above normal snowfall season for NYC during the 2020s so far was 2020-2021. That December -AO pattern which produced the nice snowstorm along the coastal plain occurred during a +PNA. But since the block was so south based, the low tucked in close to ACY that BGM got the 40” jackpot instead of NYC to Boston. The late January into February period was the only productive productive -PNA pattern for the 2020s so far. My guess is the main reason that it worked out in places like NYC was that the PNA was positive for the first half of the season. After it flipped in late January the storm track still remained far enough south with Southeast ridge suppression continuing. So the favorable seasonal storm track established during the early part of the winter with the +PNA lingered after the the PNA turned negative.

March 2023 didn’t have much to do with luck. The -NAO was linked up with the Southeast ridge leading up to the storm. So the low tracked too far north and the interior Northeast jackpot instead of closer to the immediate coast. It was the same reason the near record -AO in December didn’t produce.

The -PNA -AO patterns from 1950 to 1970 didn’t have the Southeast ridge pattern that we have seen frequently during the 2020s so far.

The 0z Euro was more suppressed to the south with the major heat. We will need to see this period get within the 120 hr window for details. The GFS hasn’t been as warm. We have seen the models initially go really warm day 6-10 and 11-15 before dialing it back as we got closer. But even a compromise between the models could give the warm spots their first 95° of season.

There have been a few scenarios that we have been experiencing in recent years with these over the top warm ups. The first one is that heat builds from Mexico to the Western US and moves into Canada and the Northern Tier but never really gets here. This happens when the ridge is so strong to the north that it leaves a weakness underneath. This is where we get onshore flow here keeping the highs lower. Then the other is when this pattern is accompanied with enough height rises here that the warmth starts out in the West and travels into Canada and then southeast down to our area. Our traditional heatwaves from the past would start out in the Southern Plains and move across Chicago and the Great Lakes into our area a few days later.

With the showers coming through this morning Newark has had at least a T of rain on every weekend since the beginning of March. Newark Jun 8-9……….T Jun 1-2……….T May 25-25…..T May 18-19…..0.04 May 11-12…0.38 May 4-5…..0.31 Apr 27-28…0.11 Apr 20-21…0.05 Apr 13-14…0.04 Apr 6-7…….T Mar 30-31…0.01 Mar 23-24….3.10 Mar 16-17…..T Mar 9-10….1.46 Mar 2-3…..1.31

These over the top wam ups have become more common in recent years as the shore of Hudson Bay reached 95° before Newark did this year.

Yeah, the 2022-2023 winter had the lowest snowfall on record by a wide margin in NYC and BOS for such a strong December -AO pattern. December -AO lower than -2.000 and seasonal snowfall 2022…..-2.719…….NYC…..2.3”…..BOS….12.4” 2010..…-2.631…….NYC…..61.9”….BOS….81.0” 2009….-3.413…….NYC…..51.4”….BOS….35.7” 2005….-2.104……..NYC….40.0”….BOS…..39.9” 2000….-2.354…….NYC…..35.0”….BOS….45.9” 1995….-2.127……..NYC……75.6”….BOS…107.6” 1976…..-2.074……NYC…..24.5”…..BOS….58.0”

Another over the top warm up which allows for enough onshore flow to reduce the 90° potential.

First time that Newark started June in the top 5 warmest with no 90s. Newark June 1-7 warmest averages and maximum temperature 2010….77.9….94 1999…75.9….99 2024…75.8….89 1989….75.7….94 2021….75.4….97

We are still feeling the effects of the major stratospheric disruption back in March. That is pretty much the one thing holding back the arrival of any major 95°+ heat at this point. It has been such a strong pattern recently that the only cool patch in a record sea of warm Atlantic is to our east. New run Old run