bluewave

The NAO and AO have become really volatile over the years. With big swings from positive to negative over very short periods. So trying to do a detailed long range AO and and NAO forecast for next winter would probably be low skill at this point. This past winter the AO was negative and the NAO positive. This decoupling between the 2 indices has become more common during the 2020s. Plus on the days with .25 and more of precipitation around NYC this last winter the -AO and -NAO linked up with the Southeast Ridge. My guess is that this is related to surface pressures rising near the Azores during the winter. When the -AO links up with the Southeast Ridge the AO still registers as negative. But when the blocking near Iceland and Greenland links up with the East Atlantic or European Subtropical Ridge, the NAO registers as positive. So the rising pressures to the south near Europe have been preventing more -NAO winters in recent years. If we had lower pressures near the Azores this past winter, then it would have been a -NAO winter since pressures were above average near Iceland. Notice how much different it was from the pattern in 2010 with the record -NAO. The shift to a much more positive EA over time seems to have been also influencing the NAO. https://www.cpc.ncep.noaa.gov/data/teledoc/ea.shtml

While the records only go back to 1998, parts Orange County NY are already the 7th wettest May on record. Time Series Summary for MONTGOMERY ORANGE COUNTY AP, NY - Month of May Click column heading to sort ascending, click again to sort descending. 1 1998 6.80 0 2 2002 6.54 0 3 2011 5.39 0 4 2003 4.98 0 5 2024 4.94 0 6 2017 4.83 0 7 2025 4.77 23 8 2009 4.53 0 9 2021 4.50 0 10 2019 4.44 3

The jet stream weakening after the winter and plenty of blocking in Canada allowing lows to cutoff underneath.

We discussed this over the winter with the October to winter MJO relationship. La Niña mismatches with a strong +PNA out of the gate in December set the tone for those winters. We saw this in 1995-1996, 2000-2001, 2017-2018, 2020-2021, and 2024-2025. The La Niñas or cold neutrals surrounding these were warmer. But we missed out on the heavy snows last winter and much colder readings like we had in the past due to the much stronger Northern Stream of Pacific Jet. So the cold and snow last winter was a big underperformer in this new warmer and less snowy climate The data I am using suggests a rebound in temperatures for next winter based on what I am currently seeing. Plus we haven’t had back to back October MJO indicators like last year. But if we see more amplitude again next October then, I could reconsider my early first guess. But it would require a first in 30 years. The snowfall was so low from Philly to NYC last winter that it wouldn’t take much to come close or even exceed it. My final call on that will have to wait until I see the December early snowfall indicator. Also notice how scarce even months closer to average temperature to a little cooler than average like this past winter have become. We quickly saw a big rebound in temperatures this spring with the warm departures greatly exceeding the cold ones. This is to be expected since the geographic extent of the cold last winter was extremely limited. This is why the Northeast has seen over 50 top 10 warmest months since 2010 to only 1 top 10 coldest.

The extended EPS has this rainy pattern into late May. We may continue the recent years pattern of rain on at least one of the Memorial Day weekend days. As the upper low will still be near the Northeast.

My guess is that next winter will be warmer than this last one was from Philly to Boston. Every La Nina with such a strong +PNA in December had winters around it which were warmer. But since the snowfall was so low anyway, there is a chance that one larger snowstorm if it should occur could rival or exceed last winter from Philly to Boston. I will update again after we see what clues we get in October.

Yeah, the Southeast Ridge or WAR has been very strong this month. So the heaviest rains were pushed up further north than the I-78 to I-80 corridor. Looks like a repeat performance for the next few days.

It already has. The very strong 500mb ridge has returned to the east of Japan and south of the Aleutians this spring. Also notice the Southeast Ridge or Western Atlantic Ridge linking up again with the Greenland to Iceland blocking.

The strong onshore flow kept the upper 80s heat to our West. for May 1, 2025 through May 7, 2025 Click column heading to sort ascending, click again to sort descending. OCEAN COUNTY AIRPORT WBAN 89 Newark Area ThreadEx 88 NEWARK LIBERTY INTL AP WBAN 88 HARRISON COOP 88 TETERBORO AIRPORT COOP 87 TETERBORO AIRPORT WBAN 87 ESTELL MANOR COOP 87 SOMERSET AIRPORT WBAN 86 PHILADELPHIA/MT. HOLLY WFO COOP 86 New Brunswick Area ThreadEx 86 HIGHTSTOWN 2 W COOP 86 NEW BRUNSWICK 3 SE COOP 86 CALDWELL ESSEX COUNTY AP WBAN 86 Atlantic City Area ThreadEx 85 PENNSAUKEN 1N COOP 85 MILLVILLE MUNICIPAL AIRPORT WBAN 85 ATLANTIC CITY INTL AP WBAN 85 MOORESTOWN 4 E COOP 85 FREEHOLD-MARLBORO COOP 85 EWING 3 WNW COOP 85 FLEMINGTON 5 NNW COOP 85 SOUTH JERSEY REGIONAL AIRPORT WBAN 85 Trenton Area ThreadEx 84 MARGATE COOP 84 MANASQUAN 1 NW COOP 84 LONG BRANCH-OAKHURST COOP 84 TRENTON-MERCER AIRPORT WBAN 84 SUSSEX AIRPORT WBAN 83 CHARLOTTEBURG RESERVOIR COOP 83 SCHOOLEY'S MOUNTAIN 1 SW COOP 81 BOONTON 1 SE COOP 81 HIGHLAND LAKES 1SW COOP 80 Data for May 1, 2025 through May 7, 2025 Click column heading to sort ascending, click again to sort descending. NJ NEWARK LIBERTY INTL AP WBAN 88 NJ HARRISON COOP 88 NY LAGUARDIA AIRPORT WBAN 87 NJ TETERBORO AIRPORT WBAN 87 NJ TETERBORO AIRPORT COOP 87 NJ CALDWELL ESSEX COUNTY AP WBAN 86 NY NY CITY CENTRAL PARK WBAN 85 NJ CHARLOTTEBURG RESERVOIR COOP 83 NY SHRUB OAK COOP 83 NY WESTCHESTER CO AP WBAN 83 NY PORT JERVIS COOP 82 NY MONTGOMERY ORANGE COUNTY AP WBAN 82 CT DANBURY MUNICIPAL AP WBAN 82 NY CENTERPORT COOP 82 NY PORT AUTH DOWNTN MANHATTAN WALL ST HEL ICAO 81 NY BAITING HOLLOW COOP 81 CT MERIDEN MARKHAM MUNICIPAL AP WBAN 81 CT OXFORD WATERBURY WBAN 79 NY SYOSSET COOP 79 CT NORWICH PUBLIC UTILITY PLANT COOP 79 NY RIVERHEAD RESEARCH FARM COOP 78 NY JFK INTERNATIONAL AIRPORT WBAN 77 NY ST. JAMES COOP 76 NY ISLIP-LI MACARTHUR AP WBAN 76 NY FARMINGDALE REPUBLIC AP WBAN 75 NY SHIRLEY BROOKHAVEN AIRPORT WBAN 75 NY UPTON COOP - NWSFO NEW YORK COOP 75 CT NEW HAVEN TWEED AP WBAN 74 CT IGOR I SIKORSKY MEMORIAL AIRPORT WBAN 73 CT GUILFORD COOP 73 NY ORIENT POINT STATE PARK COOP 72 NY BRIDGEHAMPTON COOP 71 CT DANBURY COOP 70 NY WESTHAMPTON GABRESKI AP WBAN 70

We have seen a nice improvement since last fall as it’s tough to keep a really dry pattern going in this much wetter climate.

Top 5 warmth across the area for the 1st week of May. EWR…5th warmest LGA….5th HPN….5th JFK….5th ISP…..4th BDR….5th PHI…..5th

Unfortunately, the Pacific Jet has been too strong during the winter. So as the gradient weakens further into the spring, the weaker jet isn’t able to act as a kicker. So these closed lows get stuck in place when people are ready for sunny spring weather. But the good news is that the northern edge of the drought areas to the north of I-80 and into CT has improved with the soaking rains there in recent days.

It may turn out to be another case of the record WPAC warm pool driving the La Niña background more than what is occurring in the traditional ENSO regions east of the Dateline.

Very impressive omega blocking pattern this month.

Warm and wet pattern next few weeks as the cutoff lows undercut the ridge over Southeast Canada. So an early preview of the Euro summer forecast. Very close to our summers since 2018. Many days in the 60s and 70s with a few low 80s sprinkled in especially the closer you get to Philly and CNJ.

Here are some higher res Euro summer forecast maps showing the wetter pattern continuing through the summer.

7.36” max to our north is improving the drought conditions there.

Yeah, points east of NYC haven’t seen 100° heat since the 2010-2013 era. That was when the ridge was centered near the Great Lakes keeping the flow more westerly. These days we get a big ridges east of New England keeping the flow more onshore. So it’s more about the higher dew points for us.

It certainly has happened at times during recent summers like in June 2021 when the onshore flow kept the 100s to the west of Long Island. Monthly Data for June 2021 for Upton NY NWS CWA Click column heading to sort ascending, click again to sort descending. NJ NEWARK LIBERTY INTL AP WBAN 103 NJ HARRISON COOP 101 NY LAGUARDIA AIRPORT WBAN 100 NJ CALDWELL ESSEX COUNTY AP WBAN 100 NJ CANOE BROOK COOP 98 NY NY CITY CENTRAL PARK WBAN 98 NJ TETERBORO AIRPORT WBAN 98 CT MERIDEN MARKHAM MUNICIPAL AP WBAN 98 CT DANBURY MUNICIPAL AP WBAN 97 CT NORWICH PUBLIC UTILITY PLANT COOP 96 CT IGOR I SIKORSKY MEMORIAL AIRPORT WBAN 96 CT DANBURY COOP 96 NY CENTERPORT COOP 96 NY PORT JERVIS COOP 95 CT OXFORD WATERBURY WBAN 95 NY WESTCHESTER CO AP WBAN 95 NY SHRUB OAK COOP 94 CT NEW HAVEN TWEED AP WBAN 94 NY BAITING HOLLOW COOP 94 CT STAMFORD 5 N COOP 94 NY MONTGOMERY ORANGE COUNTY AP WBAN 93 NY SYOSSET COOP 93 NY MOUNT SINAI COOP 93 NJ CHARLOTTEBURG RESERVOIR COOP 92 NY RIVERHEAD RESEARCH FARM COOP 92 NY FARMINGDALE REPUBLIC AP WBAN 91 NY JFK INTERNATIONAL AIRPORT WBAN 91 NY MATTITUCK COOP 91 NY ORIENT POINT STATE PARK COOP 91 NY CARMEL 4N COOP 91 NY ISLIP-LI MACARTHUR AP WBAN 90 NY SHIRLEY BROOKHAVEN AIRPORT WBAN 90 CT GROTON COOP 90 NY UPTON COOP - NWSFO NEW YORK COOP 89

Looks we are on track for another year around 1.5C above preindustrial levels.

Not sure. But the Euro is usually more accurate with the summer than the winter forecast for us. Probably due to less moving parts in the summer so to speak. The reason it may be wet for us is that there are two ridge centers showing up for the summer forecast. One east of New England and another out West. So perhaps the model is trying to show a weakness in the ridge where there could be some moisture pooling. We’ll see if it has a clue. It’s the same idea as the CPC summer forecast. So probably more high dewpoints and onshore flow like we have been seeing in recent years if correct.

The Euro has two more rainy cutoffs after this one the next few weeks. The next once comes through later in the week. Then another one before the 15th. It will be interesting to see if the Euro is correct about a wet summer for us. As it would keep the strongest heat out West where the drought feedback really kicks in.

It was as if we crossed an invisible threshold in 2023. Perhaps the oceans just reached the point where they could no longer absorb the excess heat anymore. Almost like filling a glass with water and not seeing much of an issue until it starts spilling over the rim. So the excess heat is being released into the atmosphere instead of staying put in the oceans. Non-linear or threshold effects usually only become known once the barrier has been crossed. This is the risk of treating climate change solely as a linear gradual process which has lead to climate complacency.

It’s all relative to what the average rainfall is in any given area. Of course more arid and semi-arid regions experience less rainfall. But if you shut off the rainfall in a drier region like Southern California, then severe drought conditions will develop if it only a tiny fraction of what is normal for those local areas falls. In reality, those areas which burned last winter around LA used to be wild areas with very few inhabitants as recently as a couple hundred years ago. Now add the acceleration of the water cycle with wetter rainy periods spurring dense undergrowth from climate change followed by record drought and you saw what they were up against out there. Plus the changing 500mb and surface patterns lead to record winds. So poor land management practices combined climate change is a very dangerous combination.

We had one of the wettest springs on record in 1983 with extensive basement flooding in Long Beach. But the entire Eastern US had a very dry summer. So it can only take a few weeks during peak summer heating for drought conditions to develop when it doesn’t rain. Plus you have to take into account the source region of the heat which is moving into the area. 2011 had the worst drought since the dust bowl in Texas which extended up into our area through most of the East. If the whole region surrounding our local area is dry, then the drought feedback will affect our temperatures also since the flow is from those dry areas.