April 2023

[bluewave]

4 hours ago, Volcanic Winter said:

I have to mention @psuhoffman because he demonstrated with clear data on the M/A forum how in the 20th century we snowed frequently in the previous -PDO cycle with a predominantly negative PNA. In order to accomplish that we needed -NAO blocking (basically a favorable Atlantic) that would overcome a hostile Pacific and produce snow, and it did. Granted there will be some differences between the DC area where he focuses and NYC, of course. But the general theme was pretty clear that the PNA wasn’t historically a death knell for east coast winters, and it’s concerning that it’s beginning to be. 
 

I think logically a chunk of that is temperature climo, we’re warming and missing borderline events that may have been mild to moderate events in colder decades. That’s just my thoughts on it, not his. It’s probably more complicated. 

But I found his presentations and analyses compelling and grounded in observable fact. It’s more the conclusions that are open to interpretation. Hopefully it’s just “bad luck” worsened by decadal warming. 

It’s a good observation. -PNA and +AO patterns of the 1950s and 1960s didn’t have the SE Ridge. So those patterns were colder and snowier than what we have been getting recently. The Gulf Stream is much warmer and pumps the SE Ridge.

 

 

 

[Stormlover74]

Up to 9

 

[SnoSki14]

Man spring is going to get to a hot start. Already seeing June like temperatures by mid April. 

[CIK62]

The next 8 days are averaging    57degs.(49/66) or +7.

Reached  52 here yesterday at 11:30pm.

Today:    64-69, wind e. to s., increasing clouds, 52 tomorrow AM.

50*(82%RH) here at 7am.     53* at 8am.      56* at 9am.      58* at Noon.       60* at 1pm.      Reached 63* at 3pm.        60* at 4pm.      57* at 5pm.

NB.  Average April  53.7

         Record April   57.9[+4.2] in 2010.

Using GFSEns. for the next 16 days  gives 58(49/67) or +6---a record pace---(already +3.7).      April looked BN on some LR outlooks and ended up Too Close to Call.

Clear sailing except near the 9th.

[SnowGoose69]

Will be interested to see if the Mets wimp out and postpone Thursday or not...models have not budged from a 4-6pm arrival on that front really which is late enough to not impact the starting pitcher but the Yanks canned opening day last year 24 hours out given the open date available as is customary...could see Mets just doing the same.  I'm not sure why the Euro seems so enthused with convective potential relative to other models.  I am not impressed with the instability overall

[bluewave]

The March -2.35 -PDO was the lowest in March since 1956 when the reading was -2.93. March 2009 was the last time below -2 in March at -2.06. Near record trough along the West Coast driving the SST pattern. So these are the warmest SSTs anomalies near the coast of South America in March for such a cold PDO.

https://www.ncei.noaa.gov/pub/data/cmb/ersst/v5/index/ersst.v5.pdo.dat

[SnowGoose69]

Its hard to say if the NATL SSTs are solely responsible for that change though, there may be some other factor we just are not aware of which is leading to it.  I know many in the meteorology world argue that SSTs really do not impact atmospheric heights and that its an overblown theory...we see this in the GOA every year when the argument breaks out whether its the chicken or the egg

[LibertyBell]

21 hours ago, BucksCO_PA said:

5/21/1992:

Indian Mills, NJ

High 88 / Low 28

Millville, NJ

High 82 / Low 30

ACY (Pomona, NJ)

high 84 / Low 28

some of those are truly mindblowing I didn't know it was possible in our area to have temps near 90 during the day and in the 20s at night....anything like this from Westhampton (FOK) or Marthas Vineyard (MVY)..... those are the other two places I know of that radiate really well.

I don't see Toms River in here (MJX) either, which I thought they would be

 

[LibertyBell]

12 hours ago, Stormlover74 said:

Up to 9

 

8.... that last one says straight line winds

Breaks the record of 7 in one day for NJ from the notorious and lethal outbreak from November 16, 1989 that I remember so well (the one that killed 10 kids at East Coldenham High School in Orange County.)

also there was an EF3 in Delaware, wow?!  I think that's the one that ended up being lethal?

 

[LibertyBell]

14 hours ago, bluewave said:

It’s a good observation. -PNA and +AO patterns of the 1950s and 1960s didn’t have the SE Ridge. So those patterns were colder and snowier than what we have been getting recently. The Gulf Stream is much warmer and pumps the SE Ridge.

 

 

 

One thing I am puzzled about, with the Gulf Stream warming so much how come we haven't seen a hurricane like Hugo hit us (not that I want that of course, but that was a hurricane that warmed up rapidly because of the Gulf Stream.)  Hurricanes still seem to rapidly weaken before they get to our region.

[bluewave]

1 hour ago, SnowGoose69 said:

Its hard to say if the NATL SSTs are solely responsible for that change though, there may be some other factor we just are not aware of which is leading to it.  I know many in the meteorology world argue that SSTs really do not impact atmospheric heights and that its an overblown theory...we see this in the GOA every year when the argument breaks out whether its the chicken or the egg

The GOA SSTs are mostly a function of Rossby waves being driven from the subtropical and tropical parts of the Pacific. So record SSTs to the south of that area are probably driving that process. Same goes for the increasing SE Ridge or WAR in our region. A 7° increase in the Gulf Stream off the Mid-Atlantic subtropics can cause an expansion of the subtropical ridge into our area. Notice how the models consistently underestimate the SE Ridge in the day 11-15 forecast. Also look back at winter forecasts for the US from all the private and public forecasters. The seasonal maps have underestimated the warmth in area. So we have to look into changes with the Gulf Stream we see a very anomalous 8 warmer than average winters in a row for the Northeast.
 

[forkyfork]

14 hours ago, bluewave said:

It’s a good observation. -PNA and +AO patterns of the 1950s and 1960s didn’t have the SE Ridge. So those patterns were colder and snowier than what we have been getting recently. The Gulf Stream is much warmer and pumps the SE Ridge.

 

 

 

when you look at the actual values of the anomalies the past western troughs were actually deeper than this year's

[bluewave]

50 minutes ago, forkyfork said:

when you look at the actual values of the anomalies the past western troughs were actually deeper than this year's

Same goes for the PNA. We used to get much more negative values back in the 1950s to the 1970s. March was the deepest the trough got this year. 

 

[SACRUS]

 

Records:

 

Highs:

 

EWR:  82 (1950)
NYC: 80 (1892)
LGA: 76 (2010)


Lows:

EWR: 23 (1954)
NYC: 21 (1874)
LGA: 24 (1954)

 

Historical:

 

1804 - A large tornado crossed six Georgia counties killing at least eleven persons near Augusta. (David Ludlum)

 

1923: An estimated F4 tornado killed 15 people and injured 150 at Alexandria and Pineville, LA. 142 homes and businesses in Pineville were destroyed.

1933 - Pigeon River Bridge, MN, reported 28 inches of snow, which established the state 24 hour snowfall record. (4th-5th) (The Weather Channel)

 

1966: One of the strongest tornadoes in Florida's history moved in from the Gulf of Mexico and ripped through Pinellas, Hillsborough, Polk, and Osceola County. Damage was very severe in the towns of Gibsonia and Galloway in Polk County. 11 people were killed, and 350 were injured. The tornado was classified as F4.

1973 - Sandia Crest, NM, reported a snow depth of 95 inches, a record for the state of New Mexico. (The Weather Channel)

1983 - Colorado was in the midst of a three day winter storm. Buckhorn Mountain, located west of Fort Collins, received 64 inches of snow. (Storm Data)

1987 - Rains of five to eight inches drenched eastern New York State, and ten persons were killed in a bridge collapse over Schoharie Creek. (The National Weather Summary) (Storm Data)

1988 - Sunny and warm weather prevailed across the nation. Fort Smith AR reported a record high of 90 degrees. (The National Weather Summary)

1989 - Thunderstorms produced severe weather from the Lower Mississippi Valley to the Southern Appalachians. The thunderstorms spawned seventeen tornadoes, including one which caused two million dollars damage at Baldwin AL. Thunderstorm winds gusted to 90 mph at Bremen GA. (The National Weather Summary) (Storm Data)

1990 - A deep low pressure system in northern New York State brought heavy snow to parts of western and central New York during the day. The snowfall total of 5.8 inches at Buffalo was a record for the date, and 9.5 inches was reported at Rochester. Snowfall totals ranged up to 11 inches at Warsaw. (The National Weather Summary) (Storm Data)

[SnowGoose69]

1 hour ago, LibertyBell said:

One thing I am puzzled about, with the Gulf Stream warming so much how come we haven't seen a hurricane like Hugo hit us (not that I want that of course, but that was a hurricane that warmed up rapidly because of the Gulf Stream.)  Hurricanes still seem to rapidly weaken before they get to our region.

You need a stupidly odd pattern to really get a Cat 3 or 4 up here and even then its probably likely to be a warm seclusion type thing which many now think 1938 was.  It has to be a case of a trof over the lakes interacting with a strong ridge where the system is pulled N or NNW because anything else will want to bend NNE naturally as it comes north and any storm which is near or touches the NC coast will usually weaken and be west of the warmest Gulf stream waters.

[MANDA]

14 minutes ago, SnowGoose69 said:

You need a stupidly odd pattern to really get a Cat 3 or 4 up here and even then its probably likely to be a warm seclusion type thing which many now think 1938 was.  It has to be a case of a trof over the lakes interacting with a strong ridge where the system is pulled N or NNW because anything else will want to bend NNE naturally as it comes north and any storm which is near or touches the NC coast will usually weaken and be west of the warmest Gulf stream waters.

Add to all of this it needs to be moving rapidly.  Warm seclusion can be a slower mover (they can do plenty of damage) but to get a Cat 3 pure hurricane up here it has to be moving fast.  Very much agree with a NNW movement as well, anything west of north in terms of track would be more favorable to get pure tropical system up here from an east of Hatteras location.  Having said all this those western Atlantic waters are quite warm so I would think that ups the ante of a possible strong tropical hit if the right steering is in place.

[Volcanic Winter]

Wasn’t there a supposed high end hurricane that landfalled on south NJ in 1821? And then I thought I read something about finding sedimentary evidence for a potentially Cat 4 hitting in the 15th century, though this would seem  a bit more speculative depending on how they determined its intensity  

Probably had to be extremely fast moving storms with not much chance to weaken. 

[LibertyBell]

1 hour ago, SnowGoose69 said:

You need a stupidly odd pattern to really get a Cat 3 or 4 up here and even then its probably likely to be a warm seclusion type thing which many now think 1938 was.  It has to be a case of a trof over the lakes interacting with a strong ridge where the system is pulled N or NNW because anything else will want to bend NNE naturally as it comes north and any storm which is near or touches the NC coast will usually weaken and be west of the warmest Gulf stream waters.

It seems to be easier to get a Cat 1 to do that, looking over the 20th century, the only hurricanes that have bent back into the coast were all Cat 1s.

[LibertyBell]

36 minutes ago, Volcanic Winter said:

Wasn’t there a supposed high end hurricane that landfalled on south NJ in 1821? And then I thought I read something about finding sedimentary evidence for a potentially Cat 4 hitting in the 15th century, though this would seem  a bit more speculative depending on how they determined its intensity  

Probably had to be extremely fast moving storms with not much chance to weaken. 

Yes to both, the 1821 hurricane was known as the Norfolk and Long Island Hurricane, though how it maintained Cat 4 intensity to Cape May and Cat 3 intensity when it hit Manhattan, I have NO idea.  If you look at the track, it looks a lot like Irene's (except slightly farther to the west-- which should mean even more land interaction!)

PreColumbine era yes-- there's also evidence of a high end supertsunami resulting from an asteroid impact (maybe the same one that formed Chesapeake Bay....which may have broken into two parts, the second of which landed just east of Toms River!)

 

[Brian5671]

1 hour ago, MANDA said:

Add to all of this it needs to be moving rapidly.  Warm seclusion can be a slower mover (they can do plenty of damage) but to get a Cat 3 pure hurricane up here it has to be moving fast.  Very much agree with a NNW movement as well, anything west of north in terms of track would be more favorable to get pure tropical system up here from an east of Hatteras location.  Having said all this those western Atlantic waters are quite warm so I would think that ups the ante of a possible strong tropical hit if the right steering is in place.

Think of Sandy 2 months earlier...would stay mostly over the gulf stream

[MANDA]

26 minutes ago, Brian5671 said:

Think of Sandy 2 months earlier...would stay mostly over the gulf stream

Agree but the odds of getting that upper air setup in August are much less likely I would think.

[bluewave]

4 hours ago, LibertyBell said:

One thing I am puzzled about, with the Gulf Stream warming so much how come we haven't seen a hurricane like Hugo hit us (not that I want that of course, but that was a hurricane that warmed up rapidly because of the Gulf Stream.)  Hurricanes still seem to rapidly weaken before they get to our region.

I believe it comes down to the steering currents during the hurricane season. Bob was the last New England hurricane back in 1991. All the high impact events like Sandy had the eye come ashore south of 40N. From what I can see, the much warmer SSTs have allowed the subtropical ridge to push up into New England and Eastern Canada. So the high impact hurricanes have all come in further down the coast. Like the hurricanes have been squeezing under. The Gulf has been the main focus for most of the landfalling major hurricanes in the last 30 years. During the previous 40, it was more evenly divided between Gulf and East Coast. 
 

https://www.aoml.noaa.gov/hrd/hurdat/All_U.S._Hurricanes.html

 

1991	Aug	RI, 2; MA, 2; NY, 2; CT, 2	2	962	90	Bob
1992	Aug	FL, SE5, SW4; LA, 3	5	922	145	Andrew
1993	Aug	* NC, 3	3	961	100	Emily
1994	None
1995	Aug	FL, NW2, SE1	2	973	85	Erin
1995	Oct	FL, NW3, I-AL 1	3	942	100	Opal
1996	Jul	NC, 2	2	974	90	Bertha
1996	Sep	NC, 3	3	954	100	Fran
1997	Jul	LA, 1; AL, 1	1	984	70	Danny
1998	Aug	NC, 2	2	964	95	Bonnie
1998	Sep	FL, NW1	1	987	70	Earl
1998	Sep	FL, SW2; MS, 2	2	964	90	Georges
1999	Aug	TX, S3	3	951	100	Bret
1999	Sep	NC, 2	2	956	90	Floyd
1999	Oct	* FL, SW1; NC, 2	2	964	95	Irene
2000s
2000	None
2001	None
2002	Oct	LA, 1	1	963	80	Lili
2003	Jul	TX, C1	1	979	80	Claudette
2003	Sep	NC, 2; VA, 1	2	957	90	Isabel
2004	Aug	* NC, 1	1	972	70	Alex
2004	Aug	FL, SW4, SE1, NE1; SC, 1; NC, 1	4	941	130	Charley
2004	Aug	SC, 1	1	985	65	Gaston
2004	Sep	FL, SE2, SW1	2	960	90	Frances
2004	Sep	AL, 3; FL, NW3	3	946	105	Ivan
2004	Sep	FL, SE3, SW1, NW1	3	950	105	Jeanne
2005	Jul	LA, 1	1	991	65	Cindy
2005	Jul	FL, NW3; I-AL 1	3	946	105	Dennis
2005	Aug	FL, SE1, SW1; LA, 3; MS, 3; AL, 1	3	920	110	Katrina
2005	Sep	* NC, 1	1	982	65	Ophelia
2005	Sep	FL, SW1; LA, 3; TX, N2	3	937	100	Rita
2005	Oct	FL, SW3; FL, SE2	3	950	105	Wilma
2006	None
2007	Sep	TX, N1; LA, 1	1	985	80	Humberto
2008	Jul	TX, S1	1	967	75	Dolly
2008	Sep	LA, 2	2	954	90	Gustav
2008	Sep	TX, N2; LA, 1	2	950	95	Ike
2009	None
2010s
2010	None
2011	Aug	NC, 1	1	952	75	Irene
2012	Aug	LA, 1	1	966	70	Isaac
2012	Oct	* NY, 1	1	942	65	Sandy
2013	None
2014	Jul	NC, 2	2	973	85	Arthur
2015	None
2016	Sep	FL, NW1	1	981	70	Hermine
2016	Oct	* FL, NE2; GA, 1; SC, 1; NC, 1	2	963	85	Matthew
2017	Aug	TX,C4	4	937	115	Harvey
2017	Sep	FL, SW4,SE 1	4	931	115	Irma
2017	Oct	LA 1, MS 1	1	983	65	Nate
2018	Sep	NC, 1	1	956	80	Florence
2018	Oct	FL, NW5; I-GA, 2	5	919	140	Michael
2019	Jul	LA, 1	1	993	65	Barry
2019	Sep	NC, 2	2	956	85	Dorian
2020s
2020	Jul	TX, S1	1	973	80	Hanna
2020	Aug	NC, 1; SC, 1	1	986	80	Isaias
2020	Aug	LA, 4; TX, N1	4	939	130	Laura
2020	Sep	AL, 2; FL, NW2	2	965	95	Sally
2020	Oct	LA,2	2	970	85	Delta
2020	Oct	LA,3; MS, 2; I-AL, 1	3	970	100	Zeta
2021	Aug	LA,4	4	931	130	Ida
2021	Sep	TX,N1	1	991	65	Nicholas

[LibertyBell]

5 minutes ago, bluewave said:

I believe it comes down to the steering currents during the hurricane season. Bob was the last New England hurricane back in 1991. All the high impact events like Sandy had the eye come ashore south of 40N. From what I can see, the much warmer SSTs have allowed the subtropical ridge to push up into New England and Eastern Canada. So the high impact hurricanes have all come in further down the coast. Like the hurricanes have been squeezing under. The Gulf has been the main focus for most of the landfalling major hurricanes in the last 30 years. During the previous 40, it was more evenly divided between Gulf and East Coast. 
 

https://www.aoml.noaa.gov/hrd/hurdat/All_U.S._Hurricanes.html

 

1991	Aug	RI, 2; MA, 2; NY, 2; CT, 2	2	962	90	Bob
1992	Aug	FL, SE5, SW4; LA, 3	5	922	145	Andrew
1993	Aug	* NC, 3	3	961	100	Emily
1994	None
1995	Aug	FL, NW2, SE1	2	973	85	Erin
1995	Oct	FL, NW3, I-AL 1	3	942	100	Opal
1996	Jul	NC, 2	2	974	90	Bertha
1996	Sep	NC, 3	3	954	100	Fran
1997	Jul	LA, 1; AL, 1	1	984	70	Danny
1998	Aug	NC, 2	2	964	95	Bonnie
1998	Sep	FL, NW1	1	987	70	Earl
1998	Sep	FL, SW2; MS, 2	2	964	90	Georges
1999	Aug	TX, S3	3	951	100	Bret
1999	Sep	NC, 2	2	956	90	Floyd
1999	Oct	* FL, SW1; NC, 2	2	964	95	Irene
2000s
2000	None
2001	None
2002	Oct	LA, 1	1	963	80	Lili
2003	Jul	TX, C1	1	979	80	Claudette
2003	Sep	NC, 2; VA, 1	2	957	90	Isabel
2004	Aug	* NC, 1	1	972	70	Alex
2004	Aug	FL, SW4, SE1, NE1; SC, 1; NC, 1	4	941	130	Charley
2004	Aug	SC, 1	1	985	65	Gaston
2004	Sep	FL, SE2, SW1	2	960	90	Frances
2004	Sep	AL, 3; FL, NW3	3	946	105	Ivan
2004	Sep	FL, SE3, SW1, NW1	3	950	105	Jeanne
2005	Jul	LA, 1	1	991	65	Cindy
2005	Jul	FL, NW3; I-AL 1	3	946	105	Dennis
2005	Aug	FL, SE1, SW1; LA, 3; MS, 3; AL, 1	3	920	110	Katrina
2005	Sep	* NC, 1	1	982	65	Ophelia
2005	Sep	FL, SW1; LA, 3; TX, N2	3	937	100	Rita
2005	Oct	FL, SW3; FL, SE2	3	950	105	Wilma
2006	None
2007	Sep	TX, N1; LA, 1	1	985	80	Humberto
2008	Jul	TX, S1	1	967	75	Dolly
2008	Sep	LA, 2	2	954	90	Gustav
2008	Sep	TX, N2; LA, 1	2	950	95	Ike
2009	None
2010s
2010	None
2011	Aug	NC, 1	1	952	75	Irene
2012	Aug	LA, 1	1	966	70	Isaac
2012	Oct	* NY, 1	1	942	65	Sandy
2013	None
2014	Jul	NC, 2	2	973	85	Arthur
2015	None
2016	Sep	FL, NW1	1	981	70	Hermine
2016	Oct	* FL, NE2; GA, 1; SC, 1; NC, 1	2	963	85	Matthew
2017	Aug	TX,C4	4	937	115	Harvey
2017	Sep	FL, SW4,SE 1	4	931	115	Irma
2017	Oct	LA 1, MS 1	1	983	65	Nate
2018	Sep	NC, 1	1	956	80	Florence
2018	Oct	FL, NW5; I-GA, 2	5	919	140	Michael
2019	Jul	LA, 1	1	993	65	Barry
2019	Sep	NC, 2	2	956	85	Dorian
2020s
2020	Jul	TX, S1	1	973	80	Hanna
2020	Aug	NC, 1; SC, 1	1	986	80	Isaias
2020	Aug	LA, 4; TX, N1	4	939	130	Laura
2020	Sep	AL, 2; FL, NW2	2	965	95	Sally
2020	Oct	LA,2	2	970	85	Delta
2020	Oct	LA,3; MS, 2; I-AL, 1	3	970	100	Zeta
2021	Aug	LA,4	4	931	130	Ida
2021	Sep	TX,N1	1	991	65	Nicholas

Thanks for this!  It also seems that although hurricanes maintain intensity further north, a lot of them get closer to Eastern Canada than they do to us.

in the above chart does * stand for post tropical?

 

[LibertyBell]

41 minutes ago, MANDA said:

Agree but the odds of getting that upper air setup in August are much less likely I would think.

possibly but one hit ACY early in the 1900s I think that was an August hurricane (not sure). But still only Cat 1

 

[Dark Star]

19 hours ago, bluewave said:

It’s a good observation. -PNA and +AO patterns of the 1950s and 1960s didn’t have the SE Ridge. So those patterns were colder and snowier than what we have been getting recently. The Gulf Stream is much warmer and pumps the SE Ridge.

 

 

 

Interesting.  This conveys warm water north.  One of the theories is that the rapid warming of the ice fields could cool down the northern oceans as the ice melted and be conveyed south, possibly cooling other currents headed south?  Or even possibly touching off an ice age?

[bluewave]

42 minutes ago, LibertyBell said:

Thanks for this!  It also seems that although hurricanes maintain intensity further north, a lot of them get closer to Eastern Canada than they do to us.

in the above chart does * stand for post tropical?

 

Yeah, Canada sticks out further to the East. So they can catch many recurving systems that miss the US. 
 

 

[winterwx21]

77 here right now. It hit 79 earlier. No surprise that temps are overperforming today. 

[CIK62]

Three months from now, a forecast like this will mean EMS would be scraping people off the sidewalks.

Oh.    It is also Dry.      JB has April as BN, vis-a-vie the JMA.       The last 10 days of the month better be real cool, man.

[bluewave]

1 hour ago, Dark Star said:

Interesting.  This conveys warm water north.  One of the theories is that the rapid warming of the ice fields could cool down the northern oceans as the ice melted and be conveyed south, possibly cooling other currents headed south?  Or even possibly touching off an ice age?

The AMOC slowdown pulls the Gulf Stream in closer to the Northeast and only cools a small part of the North Atlantic south of Greenland.

In the North Atlantic, the measured values differ markedly from the average global warming: the subpolar Atlantic (an area about half the size of the USA, south of Greenland) has hardly warmed up and in some cases even cooled down, contrary to the global warming trend. In contrast, a wide area along the American east coast has warmed up at an excessive rate. Both can be attributed to a weakening of the AMOC in the model simulation. The cooling is simply due to the reduced heat input from the AMOC. The excessive warming, on the other hand, is based on a somewhat more nerdy mechanism that has been known to experts for some time: if the AMOC weakens, the Gulf Stream shifts closer to the coast. (This has to do with conservation of angular momentum on the rotating globe.)

 

study by Duchez et al. (2016) shows that cold in the North Atlantic correlates with summer heat in Europe. This is due to the fact that the heat transport in the Atlantic has not yet decreased strongly enough to cause cooling also over the adjacent land areas – but the cold of the sea surface is sufficient to influence the air pressure distribution. It does that in such a way that an influx of warm air from the south into Europe is encouraged. In summer 2015, the subpolar Atlantic was colder than ever since records began in the 19th century – associated with a heat wave in Europe. Haarsma et al (2015) argue on the basis of model calculations that the weakening of the AMOC will be the main cause of changes in the summer circulation of the atmosphere over Europe in the future. Jackson et al (2015) found that the slowdown could lead to increased storm activity in Central Europe. And a number of studies suggest that if the AMOC weakens, sea levels on the US coast will rise more sharply (e.g. Yin et al. 2009). The impacts are currently being further researched, but a further AMOC slowdown cannot be considered good news. Yet, although the oscillations seen in Fig. 2 suggest the AMOC may well swing up again for a while, a long-term further weakening is what we have to expect if we let global warming continue for much longer.

 

[Volcanic Winter]

2 hours ago, Dark Star said:

Interesting.  This conveys warm water north.  One of the theories is that the rapid warming of the ice fields could cool down the northern oceans as the ice melted and be conveyed south, possibly cooling other currents headed south?  Or even possibly touching off an ice age?

Younger Dryas. 

Discounting the theories about a large airburst meteor strike causing the sharp return to near stadial conditions, the traditional thinking is that it was caused by the melting of the Laurentide ice sheet shutting down the AMOC (snapping it into its “slow” state, apparently the AMOC has two stable configurations, the one we’re in now and and “off” or “slow” state). When the forcing of the meltwater dissipated, temperatures sharply rebounded. 

We’re seeing something similar now with the melting of Greenland slowing the AMOC and the melting of Antarctica slowing the SMOC (new papers came out in 2023 about this, highly suggest reading). Will it be enough to terminate the overall thermohaline circulation into its other configuration? Continued slowing is a guarantee, which already implies destabilization.  
 

Edit:

This is one of the newer studies:

Paper

It’s believed the slowing SMOC by 2050 will cause something like an additional ~20% slowdown in the AMOC.