Drivers of Exceptional Coastal Warming in the Northeastern United States

[bluewave]

 

 

 

https://www.nature.com/articles/s41558-021-01159-7.epdf?sharing_token=_FVaOVyABkcD2Hudkuy4HdRgN0jAjWel9jnR3ZoTv0O_gxR6rgaJtPXjMaI-B_Efht4SyFms8mqqnoqmB-1adVBLGM5Ox8NTZgYnk58C8f_MqmRXlgMUKAvhPoz3ntaVpIMcZZ9PrSyXcXowWePIeqVtKWaAjhHN6qpaUvjsKJPMu2-ItgHqBkpP-ekBm2TbTkyKT4Ld921Svm7C1wJQmod5-Am_0W6rnLf3GjdTJ9U%3D&tracking_referrer=www.theguardian.com

Abstract

The northeastern United States (NEUS) and the adjacent Northwest Atlantic Shelf (NWS) have emerged as warming hotspots, but the connection between them remains unexplored. Here we use gridded observational and reanalysis datasets to show that the twentieth-century surface air temperature increase along the coastal NEUS is exceptional on the continental and hemispheric scale and is induced by a combination of two factors: the sea surface temperature (SST) increase in the NWS associated with a weakening Atlantic Meridional Overturning Circulation (AMOC), and atmospheric circulation changes associated with a more persistent positive North Atlantic Oscillation. These connections are important because AMOC slowdown and NWS warming are projected to continue. A survey of climate model simulations indicates that realistic SST representation at high spatial resolution might be a minimum requirement to capture the observed pattern of coastal warming, suggesting that prior projection-based assessments may not have captured key features in this populous region.

[so_whats_happening]

It is interesting of course because living in the area that has experienced warming I can say easily night time lows are the biggest change we have seen around here. Makes sense with it correlating to ocean heat flux increasing. Basically we are getting more low level moisture to stick around longer/ be replaced more frequently thus locking in higher temps especially at night versus daytime which don't get me wrong has increased but not on the level of nighttime temps in all seasons. I would love to see a study showing the differences to confirm that most of the warming has occurred via nighttime vs daytime or whether it truly is a balance of both and at what times of the year it is most likely to occur (my guess would be fall showing higher daytime peaks and warmer nights in all seasons but winter being the largest change).

So for those that didn't watch:

Increase in atmospheric CO2 --> higher SST (globally and locally) --> slowing of AMOC/ building up of NW Atlantic warmer waters --> changing jet pattern enhances this mode change and compounds the situation more for warming

We have seen the change of more interspersed snowfalls across the Mid Atlantic, higher snowfall totals when we do get those big systems to occur, and overall snow-water equivalent levels well above average over the region as well as the NHEM as a whole.

 

Having more ridging potential further in the NW Atlantic is a blessing sometimes and can be a big curse. In winter it is beautiful as it would allow for a further west trough allowing us to be near that baroclinic zone for these monster storms to occur. Of course the caveat is the issues that come in the summer time with tropical activity. This further NW Atlantic ridging promotes steering currents into the eastern US more so than the Gulf States, not to say these regions won't get hit, but the frequency of east coast hits may very well go up in the future do to this.

I distinctly remember growing up in the 90's (in SEPA) we had some pretty decent drought years and during the summer we would be rather warm during the day and had many years with some really dead grass in the yards because of the lack of rain and heat that occurred. It seems around 2000-2005 area things flipped a bit we started to introduce more wet summers with less intense heat. Pretty difficult for us to push 100 outside of what the heat island metro areas produce. Flora has been going crazy in the region over the last 10 years it seems, we seem to have ripe conditions for a subtropical feel come late spring early summer, my backyard specifically is constantly on jungle watch with how quickly everything grows. Interesting stuff!

[LibertyBell]

6 hours ago, so_whats_happening said:

It is interesting of course because living in the area that has experienced warming I can say easily night time lows are the biggest change we have seen around here. Makes sense with it correlating to ocean heat flux increasing. Basically we are getting more low level moisture to stick around longer/ be replaced more frequently thus locking in higher temps especially at night versus daytime which don't get me wrong has increased but not on the level of nighttime temps in all seasons. I would love to see a study showing the differences to confirm that most of the warming has occurred via nighttime vs daytime or whether it truly is a balance of both and at what times of the year it is most likely to occur (my guess would be fall showing higher daytime peaks and warmer nights in all seasons but winter being the largest change).

So for those that didn't watch:

Increase in atmospheric CO2 --> higher SST (globally and locally) --> slowing of AMOC/ building up of NW Atlantic warmer waters --> changing jet pattern enhances this mode change and compounds the situation more for warming

We have seen the change of more interspersed snowfalls across the Mid Atlantic, higher snowfall totals when we do get those big systems to occur, and overall snow-water equivalent levels well above average over the region as well as the NHEM as a whole.

 

Having more ridging potential further in the NW Atlantic is a blessing sometimes and can be a big curse. In winter it is beautiful as it would allow for a further west trough allowing us to be near that baroclinic zone for these monster storms to occur. Of course the caveat is the issues that come in the summer time with tropical activity. This further NW Atlantic ridging promotes steering currents into the eastern US more so than the Gulf States, not to say these regions won't get hit, but the frequency of east coast hits may very well go up in the future do to this.

I distinctly remember growing up in the 90's (in SEPA) we had some pretty decent drought years and during the summer we would be rather warm during the day and had many years with some really dead grass in the yards because of the lack of rain and heat that occurred. It seems around 2000-2005 area things flipped a bit we started to introduce more wet summers with less intense heat. Pretty difficult for us to push 100 outside of what the heat island metro areas produce. Flora has been going crazy in the region over the last 10 years it seems, we seem to have ripe conditions for a subtropical feel come late spring early summer, my backyard specifically is constantly on jungle watch with how quickly everything grows. Interesting stuff!

thats extremely unfortunate I really loved and enjoyed those dry summers, the last two that I remember were like that were 2002 and 2010.  I loved those summers!  Nice dry heat.  Since the early 2010s peak heating our highs have gotten less and the lows have gotten higher like you said, especially for coastal areas.

[etudiant]

7 hours ago, so_whats_happening said:

It is interesting of course because living in the area that has experienced warming I can say easily night time lows are the biggest change we have seen around here. Makes sense with it correlating to ocean heat flux increasing. Basically we are getting more low level moisture to stick around longer/ be replaced more frequently thus locking in higher temps especially at night versus daytime which don't get me wrong has increased but not on the level of nighttime temps in all seasons. I would love to see a study showing the differences to confirm that most of the warming has occurred via nighttime vs daytime or whether it truly is a balance of both and at what times of the year it is most likely to occur (my guess would be fall showing higher daytime peaks and warmer nights in all seasons but winter being the largest change).

So for those that didn't watch:

Increase in atmospheric CO2 --> higher SST (globally and locally) --> slowing of AMOC/ building up of NW Atlantic warmer waters --> changing jet pattern enhances this mode change and compounds the situation more for warming

We have seen the change of more interspersed snowfalls across the Mid Atlantic, higher snowfall totals when we do get those big systems to occur, and overall snow-water equivalent levels well above average over the region as well as the NHEM as a whole.

 

Having more ridging potential further in the NW Atlantic is a blessing sometimes and can be a big curse. In winter it is beautiful as it would allow for a further west trough allowing us to be near that baroclinic zone for these monster storms to occur. Of course the caveat is the issues that come in the summer time with tropical activity. This further NW Atlantic ridging promotes steering currents into the eastern US more so than the Gulf States, not to say these regions won't get hit, but the frequency of east coast hits may very well go up in the future do to this.

I distinctly remember growing up in the 90's (in SEPA) we had some pretty decent drought years and during the summer we would be rather warm during the day and had many years with some really dead grass in the yards because of the lack of rain and heat that occurred. It seems around 2000-2005 area things flipped a bit we started to introduce more wet summers with less intense heat. Pretty difficult for us to push 100 outside of what the heat island metro areas produce. Flora has been going crazy in the region over the last 10 years it seems, we seem to have ripe conditions for a subtropical feel come late spring early summer, my backyard specifically is constantly on jungle watch with how quickly everything grows. Interesting stuff!

It might be worth checking what the pattern is for the west coast to tease out the differential impact.

California is in a prolonged drought, despite the increase in SST. Are they also getting mostly increases in their night time lows?

[LibertyBell]

22 hours ago, etudiant said:

It might be worth checking what the pattern is for the west coast to tease out the differential impact.

California is in a prolonged drought, despite the increase in SST. Are they also getting mostly increases in their night time lows?

there has to be a way to make the pattern flip

 

[so_whats_happening]

On 3/18/2022 at 6:55 AM, etudiant said:

It might be worth checking what the pattern is for the west coast to tease out the differential impact.

California is in a prolonged drought, despite the increase in SST. Are they also getting mostly increases in their night time lows?

Would have to do a little digging around to find out. Might be a thing where temps are being accentuated due to the drought conditions prevailing as deserts while dry do still have some moisture availability so it would help keep the nighttime highs a little warmer while highs a little cooler. Now maybe it is allowing warming to go beyond what it was for daytime highs and not allowing the cool off to occur nearly as much at night? Small changes in moisture out that way probably play large differences in temps.

It is also a cold current versus a warm current so flux is probably not nearly on the level of the east coast. I would assume maybe legit right along the coast may experience a similar setup to the east but further inland I feel would struggle with the net moisture flux especially considering the topography out that way. Feel more often then not winds are blowing from land to sea except along the immediate coast. May totally be wrong in that assumption having never lived out there and experiencing a few days of weather when visiting. 

[Typhoon Tip]

It's interesting ...

- this study really quite exquisitely corroborates my own observations regarding the 'pattern behavior' of the continental circulation mode, of particularly mid to late spring into early summer, over the Ohio Valley, ...through southern/southeastern Canada and the northeast U.S. - as well as the upper Mid Atlantic.   These regions, ...usually between late April and the beginning of Junes ( over the last decade ), have experience unusual episodic heat departures, those with higher non-hydrostatic 500 mb geopotential heights associted.  However, rather atypical relative to day time temperature extremes, the hydrostatic heights ( referred to commonly as 'thickness' ) are lower.  This is reflected in lower DPs, with lower night time lows, ... giving rise to unusually vast diurnal changes due to radiative forcing ( sun ).  

They don't have to be heat waves, per se?   Just lows of 48 with highs of 87 will make the point.   41 to 80 ...etc.  Extreme diurnal changes where the atmosphere is kinetically charged, but lacks the moisture input to store latency, ...such that nighttime lows would remain elevated.  

We don't see that near the coast, because the SE flow tendency is loading theta-e proficiently into these latter regions.  I've been noticing this, and suspecting that is the cause, and so... quite refreshing to see this study's presentation corroborate that.   What is interesting also... I have posted material, replete with annotations, showing how there appears to be an increasing tendency for ridging nodes to set up near Quebec, as a year -to- year repeating spring theme ( roughly in that date range above).  This creates a W wind at locations such as Watertown NY to Burlington VT to Montreal, QUE and further out through the lower/SW Martime, while there was that SE flow coming into the mid Atlantic underneath this nodal circulation mode, keeping those regions from experience higher afternoon temperatures.  There were a few years in the last decade, where in one or two events ... Burlington VT was as high as the middle or upper 90s, while it was only 82 to 84 between DCA and Philly...  

I have a hypothesis on what is driving these circulation oddities... and it relates also to why the NAO domain quadrature of the Annular Mode has been dominating the positive phase state... but that's extends this into another area having to do with the expansion(ing) Hadley Cell. 

[LibertyBell]

1 hour ago, Typhoon Tip said:

It's interesting ...

- this study really quite exquisitely corroborates my own observations regarding the 'pattern behavior' of the continental circulation mode, of particularly mid to late spring into early summer, over the Ohio Valley, ...through southern/southeastern Canada and the northeast U.S. - as well as the upper Mid Atlantic.   These regions, ...usually between late April and the beginning of Junes ( over the last decade ), have experience unusual episodic heat departures, those with higher non-hydrostatic 500 mb geopotential heights associted.  However, rather atypical relative to day time temperature extremes, the hydrostatic heights ( referred to commonly as 'thickness' ) are lower.  This is reflected in lower DPs, with lower night time lows, ... giving rise to unusually vast diurnal changes due to radiative forcing ( sun ).  

They don't have to be heat waves, per se?   Just lows of 48 with highs of 87 will make the point.   41 to 80 ...etc.  Extreme diurnal changes where the atmosphere is kinetically charged, but lacks the moisture input to store latency, ...such that nighttime lows would remain elevated.  

We don't see that near the coast, because the SE flow tendency is loading theta-e proficiently into these latter regions.  I've been noticing this, and suspecting that is the cause, and so... quite refreshing to see this study's presentation corroborate that.   What is interesting also... I have posted material, replete with annotations, showing how there appears to be an increasing tendency for ridging nodes to set up near Quebec, as a year -to- year repeating spring theme ( roughly in that date range above).  This creates a W wind at locations such as Watertown NY to Burlington VT to Montreal, QUE and further out through the lower/SW Martime, while there was that SE flow coming into the mid Atlantic underneath this nodal circulation mode, keeping those regions from experience higher afternoon temperatures.  There were a few years in the last decade, where in one or two events ... Burlington VT was as high as the middle or upper 90s, while it was only 82 to 84 between DCA and Philly...  

I have a hypothesis on what is driving these circulation oddities... and it relates also to why the NAO domain quadrature of the Annular Mode has been dominating the positive phase state... but that's extends this into another area having to do with the expansion(ing) Hadley Cell. 

That would explain why the departures further north are much higher than they are in our region.  I've been wondering why VT seems to be so much hotter than NYC the last few summers.  It's also conducive to more TC making landfall nearby.

 

[bluewave]

10 minutes ago, LibertyBell said:

That would explain why the departures further north are much higher than they are in our region.  I've been wondering why VT seems to be so much hotter than NYC the last few summers.  It's also conducive to more TC making landfall nearby.

 

As the subtropical ridge expanded northward to the Canadian Maritimes, the flow became more S to SSE. So this has allowed the record high dew points to move into the region during recent summers. At times the result was higher actual temperatures into New England than around NYC Metro. This was due to a more SW flow into those areas. But both our area and New England have experienced the warmest and most humid summers on record summers since 2010. 

 

[HailMan06]

2 minutes ago, bluewave said:

As the subtropical ridge expanded northward to the Canadian Maritimes, the flow became more S to SSE. So this has allowed the record high dew points to move into the region during recent summers. At times the result was higher actual temperatures into New England than around NYC Metro. This was due to a more SW flow into those areas. But both our area and New England have experienced the warmest and most humid summers on record summers since 2010. 

 

So we basically experience a northern extension of the trade winds?

[bluewave]

21 minutes ago, HailMan06 said:

So we basically experience a northern extension of the trade winds?

During recent summers, the high has set up east of New England instead of near Bermuda like in the old days. So this allowed Hartford to record more 90° days than around NYC in 2020.  Burlington, Vermont was also able to record their first 80° minimum temperature in 2018. 

Time Series Summary for Hartford Area, CT (ThreadEx) - Jan through Dec
Click column heading to sort ascending, click again to sort descending.

Rank	Year	Number of Days Max Temperature >= 90	Missing Count
1	2020	39	0
2	1983	38	0
3	2002	35	0
4	2010	34	0
-	1965	34	0
5	2018	32	0
-	1966	32	0
6	2016	31	0
-	1991	31	0
7	1988	30	0
-	1973	30	0

 

Time Series Summary for LAGUARDIA AIRPORT, NY - Jan through Dec
Click column heading to sort ascending, click again to sort descending.

Rank	Year	Number of Days Max Temperature >= 90	Missing Count
1	2010	48	0
2	2018	38	0
3	2002	35	0
4	2020	34	0
-	1991	34	0
5	2016	32	0
6	1983	31	0
7	2005	30	0
-	1953	30	0

 

Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec
Click column heading to sort ascending, click again to sort descending.

Rank	Year	Number of Days Max Temperature >= 90	Missing Count
1	2010	54	0
2	1993	49	0
3	1988	43	0
4	2021	41	0
-	2002	41	0
-	1991	41	0
5	2016	40	0
-	1983	40	0
-	1959	40	0
6	1994	39	0
-	1944	39	0
7	2005	37	0
-	1987	37	0
8	2018	36	0
-	1949	36	0
9	2015	35	0

 

 

[LibertyBell]

47 minutes ago, bluewave said:

As the subtropical ridge expanded northward to the Canadian Maritimes, the flow became more S to SSE. So this has allowed the record high dew points to move into the region during recent summers. At times the result was higher actual temperatures into New England than around NYC Metro. This was due to a more SW flow into those areas. But both our area and New England have experienced the warmest and most humid summers on record summers since 2010. 

 

when will it get to the point where places like NYC and JFK will regularly hit 100 each summer, Chris?  It has to get to that point by 2050 right-- all the climate projections say so.  We should be averaging 3 100 degree days every summer by 2050 even at JFK

 

[LibertyBell]

45 minutes ago, HailMan06 said:

So we basically experience a northern extension of the trade winds?

if thats the case we should eventually see a TC moving NW from near Bermuda to hit us....oh wait that almost happened last year lol

 

[bluewave]

1 hour ago, LibertyBell said:

when will it get to the point where places like NYC and JFK will regularly hit 100 each summer, Chris?  It has to get to that point by 2050 right-- all the climate projections say so.  We should be averaging 3 100 degree days every summer by 2050 even at JFK

 

We need a SW to W flow for our local area to reach 100°. This usually requires the ridge axis to build westward toward the Great Lakes. But the ridge axis during recent summers has been elongated to the east of New England. So we get more onshore flow and higher humidity instead of more 100° days. 

Our most extreme daily heat record in recent years occurred during February 2018. The SE Ridge built to record heights over the region for the entire cold season. This was associated with the 500 mb heights increase as outlined in the presentation at the start of the thread. It was the first time that our area experienced 80° record heat in February. 
 

 

https://www.wunderground.com/cat6/summer-february-80-massachusetts-78-nyc

Astonishing summer-like heat cooked the Eastern U.S. on Wednesday, smashing all-time records for February warmth in cities in at least ten states, from Georgia to Maine. At least 24 cities recorded their hottest February temperature on record on Wednesday, including New York City (78°), Hartford, CT (74°) and Concord, NH (74°). According to Weather Underground weather historian Christopher C. Burt, February 20 - 21 marked the most extraordinary heat event to ever affect the Northeastern quadrant of the U.S. during the month of February, since official records began in the late 1800s. He catalogued the following eight states that tied or beat all-time February state heat records over the past two days, noting that in the case of Maine and Vermont, “It is simply amazing to beat a state temperature record by some 8°F!”:

Pennsylvania: 83° at Capitol City (ties old record for the state)
New York: 79° at La Guardia Airport (old state record 78°)
Vermont: 77° at Bennington (old state record 68°)
New Hampshire: 77° at Manchester and Danbury (old state record 72°)
Maine: 77° at Wells (old state record 69°)
New Jersey: 83° at Teterboro (old state record 80°)
Massachusetts: 80° at Fitchburg (old state record 73°)
Ohio: 80° at Cincinnati Lunken Airport (ties old record for the state)

[Typhoon Tip]

6 hours ago, bluewave said:

During recent summers, the high has set up east of New England instead of near Bermuda like in the old days. So this allowed Hartford to record more 90° days than around NYC in 2020.  Burlington, Vermont was also able to record their first 80° minimum temperature in 2018. 

 

[Typhoon Tip]

That‘s that gust of it yup. 

[LibertyBell]

6 hours ago, bluewave said:

We need a SW to W flow for our local area to reach 100°. This usually requires the ridge axis to build westward toward the Great Lakes. But the ridge axis during recent summers has been elongated to the east of New England. So we get more onshore flow and higher humidity instead of more 100° days. 

Our most extreme daily heat record in recent years occurred during February 2018. The SE Ridge built to record heights over the region for the entire cold season. This was associated with the 500 mb heights increase as outlined in the presentation at the start of the thread. It was the first time that our area experienced 80° record heat in February. 
 

 

https://www.wunderground.com/cat6/summer-february-80-massachusetts-78-nyc

Astonishing summer-like heat cooked the Eastern U.S. on Wednesday, smashing all-time records for February warmth in cities in at least ten states, from Georgia to Maine. At least 24 cities recorded their hottest February temperature on record on Wednesday, including New York City (78°), Hartford, CT (74°) and Concord, NH (74°). According to Weather Underground weather historian Christopher C. Burt, February 20 - 21 marked the most extraordinary heat event to ever affect the Northeastern quadrant of the U.S. during the month of February, since official records began in the late 1800s. He catalogued the following eight states that tied or beat all-time February state heat records over the past two days, noting that in the case of Maine and Vermont, “It is simply amazing to beat a state temperature record by some 8°F!”:

Pennsylvania: 83° at Capitol City (ties old record for the state)
New York: 79° at La Guardia Airport (old state record 78°)
Vermont: 77° at Bennington (old state record 68°)
New Hampshire: 77° at Manchester and Danbury (old state record 72°)
Maine: 77° at Wells (old state record 69°)
New Jersey: 83° at Teterboro (old state record 80°)
Massachusetts: 80° at Fitchburg (old state record 73°)
Ohio: 80° at Cincinnati Lunken Airport (ties old record for the state)

These records are amazing but I checked through the records and where you and I live, it only stayed in the 60s....we've had hotter days in February.

[LibertyBell]

1 hour ago, Typhoon Tip said:

That‘s that gust of it yup. 

do either of you see this changing? could this be cyclical and the high will just reposition east of or on top of Hatteras where it should be and give us that hotter westerly flow?

 

[bluewave]

Large increase in Northeast rainfall and snowfall extremes as the SSTs rapidly warm and water vapor rises. 
 

 

https://phys.org/news/2018-07-extreme-precipitation-northeast.html

 

From Maine to West Virginia, the Northeast has seen a larger increase in extreme precipitation than anywhere else in the U.S. Prior research found that these heavy rain and snow events, defined as a day with about two inches of precipitation or more, have been 53 percent higher in the Northeast since 1996. A Dartmouth study finds that hurricanes and tropical storms are the primary cause of this increase, followed by thunderstorms along fronts and extratropical cyclones like Nor'easters. The findings are published in the Journal of Geophysical Research.

 

Our study provides insight into what types of extreme storms are changing and why. We found that hurricanes were responsible for nearly half of the increase in extreme rainfall across the Northeast. A warmer Atlantic Ocean and more water vapor in the atmosphere are fueling these storms, causing them to drop more rain over the Northeast," explains Jonathan M. Winter, an assistant professor of geography at Dartmouth and co-author of the study. "Other research has demonstrated that these two conditions have been enhanced in our warmer world," added Huanping Huang, a graduate student in earth sciences at Dartmouth and the study's lead author.

The findings demonstrate that 88 percent of the extreme precipitation increase after 1996 was caused by large storms in Feb., March, June, July, Sept. and Oct.

• Hurricanes and tropical storms, also known as "tropical cyclones," accounted for nearly half, or 48 percent, of the increase in extreme rainfall. After 1996, the Northeast experienced almost four times more extreme rainfall events from hurricanes and tropical storms than from 1979-1995.
• Severe thunderstorms along "fronts," especially intense downpours along cold fronts, accounted for 25 percent of the increase in extreme precipitation. 
• Nor'easters and other "extratropical cyclones," which are storms that form outside of the tropics, accounted for 15 percent of the increase in extreme precipitation. 
• Other research has found that the causes of more frequent extreme precipitation events in this study—increased ocean temperatures, more water vapor in the atmosphere, and a wavier jet stream—are associated with a warmer world.

These results build on the team's earlier research by examining what caused the increase in heavier or extreme precipitation beginning in 1996. The researchers analyzed precipitationdata from 1979 to 2016 across the Northeast— Maine, New Hampshire, Vermont, Mass., Conn., R.I., N.J., N.Y., Pa., Md., DC, Del., and W.Va. in conjunction with data pertaining to daily weather maps and oceanic and atmospheric fields.

 

https://journals.ametsoc.org/view/journals/wefo/29/6/waf-d-14-00056_1.xml

Abstract

On 8–9 February 2013, the northeastern United States experienced a historic winter weather event ranking among the top five worst blizzards in the region. Heavy snowfall and blizzard conditions occurred from northern New Jersey, inland to New York, and northward through Maine. Storm-total snow accumulations of 30–61 cm were common, with maximum accumulations up to 102 cm and snowfall rates exceeding 15 cm h⁻¹. Dual-polarization radar measurements collected for this winter event provide valuable insights into storm microphysical processes. In this study, polarimetric data from the Weather Surveillance Radar-1988 Doppler (WSR-88D) in Upton, New York (KOKX), are investigated alongside thermodynamic analyses from the 13-km Rapid Refresh model and surface precipitation type observations from both Meteorological Phenomena Identification Near the Ground (mPING) and the National Weather Service (NWS) Forecast Office in Upton, New York, for interpretation of polarimetric signatures. The storm exhibited unique polarimetric signatures, some of which have never before been documented for a winter system. Reflectivity values were unusually large, reaching magnitudes >50 dBZ in shallow regions of heavy wet snow near the surface. The 0°C transition line was exceptionally distinct in the polarimetric imagery, providing detail that was often unmatched by the numerical model output. Other features include differential attenuation of magnitudes typical of melting hail, depolarization streaks that provide evidence of electrification, nonuniform beamfilling, a “snow flare” signature, and localized downward excursions of the melting-layer bright band collocated with observed transitions in surface precipitation types. In agreement with previous studies, widespread elevated depositional growth layers, located at temperatures near the model-predicted −15°C isotherm, appear to be correlated with increased snowfall and large reflectivity factors Z_H near the surface.

 

[rclab]

1 hour ago, bluewave said:

Large increase in Northeast rainfall and snowfall extremes as the SSTs rapidly warm and water vapor rises. 
 

 

https://phys.org/news/2018-07-extreme-precipitation-northeast.html

 

From Maine to West Virginia, the Northeast has seen a larger increase in extreme precipitation than anywhere else in the U.S. Prior research found that these heavy rain and snow events, defined as a day with about two inches of precipitation or more, have been 53 percent higher in the Northeast since 1996. A Dartmouth study finds that hurricanes and tropical storms are the primary cause of this increase, followed by thunderstorms along fronts and extratropical cyclones like Nor'easters. The findings are published in the Journal of Geophysical Research.

 

Our study provides insight into what types of extreme storms are changing and why. We found that hurricanes were responsible for nearly half of the increase in extreme rainfall across the Northeast. A warmer Atlantic Ocean and more water vapor in the atmosphere are fueling these storms, causing them to drop more rain over the Northeast," explains Jonathan M. Winter, an assistant professor of geography at Dartmouth and co-author of the study. "Other research has demonstrated that these two conditions have been enhanced in our warmer world," added Huanping Huang, a graduate student in earth sciences at Dartmouth and the study's lead author.

The findings demonstrate that 88 percent of the extreme precipitation increase after 1996 was caused by large storms in Feb., March, June, July, Sept. and Oct.

• Hurricanes and tropical storms, also known as "tropical cyclones," accounted for nearly half, or 48 percent, of the increase in extreme rainfall. After 1996, the Northeast experienced almost four times more extreme rainfall events from hurricanes and tropical storms than from 1979-1995.
• Severe thunderstorms along "fronts," especially intense downpours along cold fronts, accounted for 25 percent of the increase in extreme precipitation. 
• Nor'easters and other "extratropical cyclones," which are storms that form outside of the tropics, accounted for 15 percent of the increase in extreme precipitation. 
• Other research has found that the causes of more frequent extreme precipitation events in this study—increased ocean temperatures, more water vapor in the atmosphere, and a wavier jet stream—are associated with a warmer world.

These results build on the team's earlier research by examining what caused the increase in heavier or extreme precipitation beginning in 1996. The researchers analyzed precipitationdata from 1979 to 2016 across the Northeast— Maine, New Hampshire, Vermont, Mass., Conn., R.I., N.J., N.Y., Pa., Md., DC, Del., and W.Va. in conjunction with data pertaining to daily weather maps and oceanic and atmospheric fields.

 

https://journals.ametsoc.org/view/journals/wefo/29/6/waf-d-14-00056_1.xml

Abstract

On 8–9 February 2013, the northeastern United States experienced a historic winter weather event ranking among the top five worst blizzards in the region. Heavy snowfall and blizzard conditions occurred from northern New Jersey, inland to New York, and northward through Maine. Storm-total snow accumulations of 30–61 cm were common, with maximum accumulations up to 102 cm and snowfall rates exceeding 15 cm h⁻¹. Dual-polarization radar measurements collected for this winter event provide valuable insights into storm microphysical processes. In this study, polarimetric data from the Weather Surveillance Radar-1988 Doppler (WSR-88D) in Upton, New York (KOKX), are investigated alongside thermodynamic analyses from the 13-km Rapid Refresh model and surface precipitation type observations from both Meteorological Phenomena Identification Near the Ground (mPING) and the National Weather Service (NWS) Forecast Office in Upton, New York, for interpretation of polarimetric signatures. The storm exhibited unique polarimetric signatures, some of which have never before been documented for a winter system. Reflectivity values were unusually large, reaching magnitudes >50 dBZ in shallow regions of heavy wet snow near the surface. The 0°C transition line was exceptionally distinct in the polarimetric imagery, providing detail that was often unmatched by the numerical model output. Other features include differential attenuation of magnitudes typical of melting hail, depolarization streaks that provide evidence of electrification, nonuniform beamfilling, a “snow flare” signature, and localized downward excursions of the melting-layer bright band collocated with observed transitions in surface precipitation types. In agreement with previous studies, widespread elevated depositional growth layers, located at temperatures near the model-predicted −15°C isotherm, appear to be correlated with increased snowfall and large reflectivity factors Z_H near the surface.

 

I know a concern of mine is on the wrong side of naivety. I am always wondering the effect on the atmosphere if the north polar ice cap melted completely and what affect the prolonged sunshine would have on the now completely ice free ocean. If, even in such a scenario, the skirting continental land masses could still support snow …  extended periods of 20+ hour sun drawing ocean moisture into the atmosphere when how where (?) does it get released. Just a concern. As always ….

[Roger Smith]

The discussion of extreme warmth in March does not include any reference to the consecutive record breaking Marches of 1945 and 1946 which were just before the era of reliable upper air measurements. It is quite plausible from the surface temperatures that 500 mb heights in late March 1945 were similar to the records set recently. Also, what about late March 1998, there were some very high surface temperatures recorded then.

For NYC, March 1945 remains top monthly average (51.1) ahead of 2012 (50.9) with 1946 in third place (49.8). Daily records of 84F and 86F were set on March 28-29, 1945, matched by 86F on March 31, 1998. I think there were some places in the northeastern US that came very close to 90F in late March 1945. The notable warmth was repeated in many places in late March 1946 (Toronto actually had a higher reading that year and set its monthly record of 80F). At Toronto the order of the three months was 2012, 1945 and 1946. 

Any attempt to separate out natural and anthropogenic factors involved should include these two very warm months as well as the rest of the recent data. 

[LibertyBell]

3 hours ago, Roger Smith said:

The discussion of extreme warmth in March does not include any reference to the consecutive record breaking Marches of 1945 and 1946 which were just before the era of reliable upper air measurements. It is quite plausible from the surface temperatures that 500 mb heights in late March 1945 were similar to the records set recently. Also, what about late March 1998, there were some very high surface temperatures recorded then.

For NYC, March 1945 remains top monthly average (51.1) ahead of 2012 (50.9) with 1946 in third place (49.8). Daily records of 84F and 86F were set on March 28-29, 1945, matched by 86F on March 31, 1998. I think there were some places in the northeastern US that came very close to 90F in late March 1945. The notable warmth was repeated in many places in late March 1946 (Toronto actually had a higher reading that year and set its monthly record of 80F). At Toronto the order of the three months was 2012, 1945 and 1946. 

Any attempt to separate out natural and anthropogenic factors involved should include these two very warm months as well as the rest of the recent data. 

I dont use avg monthly temps as good indicators of extreme heat, it's better to use extreme heatwaves.

March 1990 stands out to me as the hottest weather I've ever seen in March with 3 consecutive days of 85+ getting close to 90 during the middle of the month.  Ditto for April 2002 when we hit 90+ three straight days and almost 4, and topped out at 96, matching a similar heatwave in April 1976 (but in 2002 the heat lasted all throughout the spring and summer and even into early fall.)

 

[LibertyBell]

On 3/20/2022 at 10:01 AM, rclab said:

I know a concern of mine is on the wrong side of naivety. I am always wondering the effect on the atmosphere if the north polar ice cap melted completely and what affect the prolonged sunshine would have on the now completely ice free ocean. If, even in such a scenario, the skirting continental land masses could still support snow …  extended periods of 20+ hour sun drawing ocean moisture into the atmosphere when how where (?) does it get released. Just a concern. As always ….

Looks like we should also be worrying about Antarctica melting.

 

[chubbs]

Made an attempt to check how the recent past has tracked the paper findings. Below is 2011-2021 against a 1981-2010 normal, i.e the last ten years vs the previous 30.  The AMOC signal can be seen but the cooling center is SE of Greenland and S of Iceland and heights have tended to rise recently near Greenland. Also visible is broad global warming, and a nina signal in the Pacific. The nina signal is not surprising considering enso decade trends since 1980. Guess one message is be careful analyzing regional circulation trends.

[LibertyBell]

On 3/24/2022 at 9:48 AM, chubbs said:

Made an attempt to check how the recent past has tracked the paper findings. Below is 2011-2021 against a 1981-2010 normal, i.e the last ten years vs the previous 30.  The AMOC signal can be seen but the cooling center is SE of Greenland and S of Iceland and heights have tended to rise recently near Greenland. Also visible is broad global warming, and a nina signal in the Pacific. The nina signal is not surprising considering enso decade trends since 1980. Guess one message is be careful analyzing regional circulation trends.

Cooling around Greenland waters is because of ice melt right-- and the la nina standing wave in the Pacific is because of rapid warming of the West Pac heating up?

 

[Typhoon Tip]

On 3/19/2022 at 9:43 AM, Typhoon Tip said:

It's interesting ...

- this study really quite exquisitely corroborates my own observations regarding the 'pattern behavior' of the continental circulation mode, of particularly mid to late spring into early summer, over the Ohio Valley, ...through southern/southeastern Canada and the northeast U.S. - as well as the upper Mid Atlantic.   These regions, ...usually between late April and the beginning of Junes ( over the last decade ), have experience unusual episodic heat departures, those with higher non-hydrostatic 500 mb geopotential heights associted.  However, rather atypical relative to day time temperature extremes, the hydrostatic heights ( referred to commonly as 'thickness' ) are lower.  This is reflected in lower DPs, with lower night time lows, ... giving rise to unusually vast diurnal changes due to radiative forcing ( sun ).  

They don't have to be heat waves, per se?   Just lows of 48 with highs of 87 will make the point.   41 to 80 ...etc.  Extreme diurnal changes where the atmosphere is kinetically charged, but lacks the moisture input to store latency, ...such that nighttime lows would remain elevated.  

We don't see that near the coast, because the SE flow tendency is loading theta-e proficiently into these latter regions.  I've been noticing this, and suspecting that is the cause, and so... quite refreshing to see this study's presentation corroborate that.   What is interesting also... I have posted material, replete with annotations, showing how there appears to be an increasing tendency for ridging nodes to set up near Quebec, as a year -to- year repeating spring theme ( roughly in that date range above).  This creates a W wind at locations such as Watertown NY to Burlington VT to Montreal, QUE and further out through the lower/SW Martime, while there was that SE flow coming into the mid Atlantic underneath this nodal circulation mode, keeping those regions from experience higher afternoon temperatures.  There were a few years in the last decade, where in one or two events ... Burlington VT was as high as the middle or upper 90s, while it was only 82 to 84 between DCA and Philly...  

I have a hypothesis on what is driving these circulation oddities... and it relates also to why the NAO domain quadrature of the Annular Mode has been dominating the positive phase state... but that's extends this into another area having to do with the expansion(ing) Hadley Cell. 

Bump for bearing current relevancy - ... here we are again, in May, with clockwise circulation node emerging (modeling) between NS/Cape Cod.  

This delivers 'over-the-top' early heat signal ... targeting SE Canada/ perhaps NNE ... maybe as far S as NYC...etc, with anomalies that push those region above areas from TV-MA ( possibly).   

[StormchaserChuck!]

We are also superdue for a NE Hurricane hit

[LibertyBell]

1 hour ago, StormchaserChuck! said:

We are also superdue for a NE Hurricane hit

They are actually becoming less common.  Not only that major hurricane hits north of NC are also less common than they used to be.  Most of those go into the Gulf or Florida.  When we do get hurricanes at our latitude now they are Cat 1 or just TS.

[StormchaserChuck!]

0-5 year 0-10 year normal hit's, that's for sure

[Vice-Regent]

22 hours ago, StormchaserChuck! said:

We are also superdue for a NE Hurricane hit

Did we not have one last year? Also as LibertyBell mentions the Northeastern strike frequency is ticking down and Mid-Atlantic/Gulf-Coast is ticking up. I imagine as a result of some changes in the Rosby Wave depth.