bluewave

This has been the case for a while now as we have been seeing new positive 500 mb height anomaly records regularly these days. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL066669 Apart from global scale surface warming, anthropogenic forcings also lead to warming and thermal expansion of the lower atmosphere. Here we investigate these effects using the geopotential height at 500 hPa, an indicator of the combined thermodynamic and dynamic climatic response to external forcings. We employ optimal fingerprinting, which uses information from reanalysis data sets and experiments with seven state-of-the-art climate models, to assess the role of anthropogenic and natural influences on changes in the geopotential height during the satellite era. A significant global increase in the annual and seasonal mean geopotential height due to human influence is detected, a result confirmed with four different reanalysis data sets. A more moderate increase in the annual mean associated with natural forcings is also detected. Our findings, consistent with previous detection and attribution studies of changes in temperature and sea level pressure, indicate the prominent role of human influence on some recent climatic changes. Key Points New independent evidence of human contribution to recent climatic changes in the lower atmosphere Human influence is detected in global increases in the 500 hPa geopotential height since 1979 A smaller natural signal is also detected in changes of the annual mean geopotential height

The interesting thing is that the fall to winter MJO relationship only seems to apply with La Niña winters since 10-11.

The only ENSO neutral we have had since the 15-16 super El Niño was 19-20. That season got overpowered by the IOD with the strong IO forcing in the fall leading to the very strong SPV in the winter. It also allowed the WPAC warm pool to lead to the record MJO 4-6. So the weaker ENSO input permitted other factors to dominate. 2016 2.5 2.1 1.6 0.9 0.4 -0.1 -0.4 -0.5 -0.6 -0.7 -0.7 -0.6 2017 -0.3 -0.2 0.1 0.2 0.3 0.3 0.1 -0.1 -0.4 -0.7 -0.8 -1.0 2018 -0.9 -0.9 -0.7 -0.5 -0.2 0.0 0.1 0.2 0.5 0.8 0.9 0.8 2019 0.7 0.7 0.7 0.7 0.5 0.5 0.3 0.1 0.2 0.3 0.5 0.5 Year DJF JFM FMA MAM AMJ MJJ JJA JAS ASO SON OND NDJ 2020 0.5 0.5 0.4 0.2 -0.1 -0.3 -0.4 -0.6 -0.9 -1.2 -1.3 -1.2 2021 -1.0 -0.9 -0.8 -0.7 -0.5 -0.4 -0.4 -0.5 -0.7 -0.8 -1.0 -1.0 2022 -1.0 -0.9 -1.0 -1.1 -1.0 -0.9 -0.8 -0.9 -1.0 -1.0 -0.9 -0.8 2023 -0.7 -0.4 -0.1 0.2 0.5 0.8 1.1 1.3 1.6 1.8 1.9 2.0 2024 1.8 1.5 1.1 0.7 0.4

The models did a great job forecasting the new daily global high temperature record.

While the record highs across the U.S. are vastly outnumbering the record lows, Springfield, Illinois was one of the few spots in the U.S. to have 2 record lows this month. The record low on July 1st of 49° was actually the 2nd coldest temperature recorded in July since 1879. Springfield Area, ILPeriod of record: 1879-07-01 through 2024-07-22DateLowest minimum temperatures (degrees F) 7/1 49 in 2024 51 in 1984 52 in 1976+ 7/19 54 in 2024 54 in 2009 54 in 1909 Time Series Summary for Springfield Area, IL (ThreadEx) - Month of Jul Click column heading to sort ascending, click again to sort descending. 1 2013 48 0 - 1975 48 0 - 1972 48 0 - 1971 48 0 - 1967 48 0 2 2024 49 9 - 1996 49 0 - 1891 49 0

Over an inch in spots with the heavy downpours. Daily Precipitation Report Station Number: NJ-BG-60 Station Name: Montvale 1.8 ESE Observation Date 7/23/2024 8:00 AM Submitted 7/23/2024 7:28 AM Gauge Catch 1.32 in. Notes -- Daily Precipitation Report Station Number: NJ-MS-102 Station Name: Chatham 0.6 NE Observation Date 7/23/2024 7:00 AM Submitted 7/23/2024 7:09 AM Gauge Catch 1.22 in. Notes --

This is due to the WPAC warm pool taking on the primary role in our La Niña background pattern. So we can get a very strong La Niña atmospheric response with only weekly cool ONIs. In the old days before the WPAC was so warm, weak La Ninas were cold and snowy like in 95-96, 00-01, and 08-09. Our weaker La Nina’s since then have been much warmer like in 11-12, 16-17, and 22-23.

Yes. The summer pattern started over the top with the warmest departures up in Canada June 1st to 15th. Then our area got the stronger heat later in the month as the warmth eventually worked down into our area. July reverted back to the recent multiyear pattern of cool in the Midwest and warmth along both coasts.

Looks like another over the top warm up day 8-14 on the EPS. So the West and Canada will warm up first. So it may take a few days after for the warmest temperatures to work down into our area.

JFK has only been able to make it to 91° which is the 6th coolest max by July 21st. Time Series Summary for JFK INTERNATIONAL AIRPORT, NY Click column heading to sort ascending, click again to sort descending. 1 1948-07-21 85 198 2 2009-07-21 86 0 3 1951-07-21 87 2 4 1967-07-21 89 0 5 2023-07-21 90 0 - 2007-07-21 90 0 - 1979-07-21 90 0 - 1972-07-21 90 0 - 1960-07-21 90 1 6 2024-07-21 91 0 - 2014-07-21 91 0 - 2004-07-21 91 0 - 1985-07-21 91 0 - 1976-07-21 91 0 - 1975-07-21 91 0 - 1973-07-21 91 0

The main takeaway from those forecast maps is that the marine heatwave east of Japan maintains or even slightly becomes stronger heading into the winter. So regardless of the La Niña intensity we will need a mismatch along the lines of Jan 22 or elements of 21-22. Otherwise we will get another winter similar to the last 2 which were warm and relatively snowless. So hoping to get some more clues as we head into the fall as to whether we can see some improvement over the last few winters.

Yeah, parts of the Northeast can make a run on 100” of precipitation since last July as we approach the peak of the hurricane in September. Data for July 1, 2023 through July 21, 2024 Click column heading to sort ascending, click again to sort descending. CT PROSPECT 1.9 ENE CoCoRaHS 88.40 CT MIDDLEFIELD 1.4 W CoCoRaHS 87.54 CT OAKDALE 2.6 WNW CoCoRaHS 86.61 NY WEST POINT COOP 85.89 CT NORTHFORD 0.8 SW CoCoRaHS 85.18 CT BROOKFIELD 3.3 SSE CoCoRaHS 85.02 CT EAST LYME 0.5 SW CoCoRaHS 84.90 CT NORWICH 2.5 NNE CoCoRaHS 84.89 NY STONY POINT 0.7 NW CoCoRaHS 84.77 CT COLCHESTER 0.6 ENE CoCoRaHS 83.62

The one difference is that the PDO started positive and went to neutral in 16-17. This time we have a very strong -PDO. So not sure if the combo this time around would support some of the better snowstorms we had that winter despite the warmth. But even just a little better than the last few winters in the snowfall department would be nice.

The removal of the natural grasslands and poor farming practices were actually able to influence the circulation pattern of the entire Northern Hemisphere during that summer. https://news.ucar.edu/132872/1930s-dust-bowl-affected-extreme-heat-around-northern-hemisphere The 1930s Dust Bowl, fueled by overplowing across the Great Plains and associated with record heat and drought, appears to have affected heat extremes far beyond the United States. New research finds that the hot, exposed land in the central U.S. during the Dust Bowl drought influenced temperatures across much of North America and as far away as Europe and East Asia. That’s because the extreme heating of the Great Plains triggered motions of air around the Northern Hemisphere in ways that suppressed cloud formation in some regions and, in combination with the influence of tropical oceanic conditions, led to record heat thousands of miles away. “The hot and dry conditions over the Great Plains during the Dust Bowl spread extreme heat to other areas of the Northern Hemisphere,” said Gerald Meehl, a scientist with the National Center of Atmospheric Research (NCAR) and lead author of the new study. “If you look at daily record high temperatures, some of these areas are just now breaking the records that were set in the 1930s.” To determine the climatic impact of the Dust Bowl, the research team drew on observed high and low daily temperatures, as well as advanced computer models of the global climate system. They focused on the role of a teleconnection pattern, known as wave-5, that can regulate the meandering of jet streams and link far-flung weather patterns around the Northern Hemisphere during summer. The study was published in Scientific Reports. It was funded by the U.S. National Science Foundation, which is NCAR’s sponsor, as well as by the U.S. Department of Energy. TEASING OUT THE DUST BOWL’S INFLUENCE The Dust Bowl is widely viewed as one of the nation’s worst environmental disasters. Farmers in the early part of the 20th century plowed up millions of acres of native grassland across much of the Great Plains to plant wheat and other crops. When a multiyear drought struck in the 1930s, the exposed land became exceptionally hot and topsoil blew away, causing devastating dust storms as well as a health and economic catastrophe. The new research points out that extreme weather conditions extended far beyond the immediate vicinity of the Dust Bowl. Much of North America, northern Europe, and eastern and northeastern Asia experienced such heat that some record high temperatures of the 1930s are only now being exceeded as temperatures rise with climate change. Previous research pointed to patterns of warm and cool surface temperatures in the tropical oceans as triggering the drought in the Great Plains. These conditions were associated with a pair of multidecadal phenomena known as the Interdecadal Pacific Oscillation (IPO) and Atlantic Multidecadal Oscillation (AMO). The question addressed by Meehl and his co-authors was whether such oceanic conditions could also explain the hot and dry weather around so much of the Northern Hemisphere, or if the Dust Bowl itself played a role. To tease out the influence of the Dust Bowl, the scientists first used an NCAR-based model of global climate, known as the Community Earth System Model (CESM). They ran a series of simulations on the Cheyenne supercomputer at the NCAR-Wyoming Supercomputing Center to see whether the IPO and AMO could fully account for the distribution of extreme daily high temperatures across three continents. But even though they set the model to capture the likely oceanic conditions of the time, they could not reproduce the high daily temperatures of the 1930s. They then turned to a version of the CESM atmospheric model that is a component of the DOE Energy Exascale Earth System Model, and set the model to isolate the influence of the extreme heat over the Great Plains during the 1930s. This time the results closely matched actual climate records, indicating that the Dust Bowl generated an atmospheric reaction that, in combination with conditions in the tropical Pacific and Atlantic, triggered extreme heat across vast areas of the Northern Hemisphere. “When you put the influence of the Great Plains Dust Bowl drought in the model, you get record-breaking heat in the areas where we saw them in the Northern Hemisphere during the 1930s,” Meehl said. INFLUENCE OF WAVE-5 Additional analysis of the simulations revealed the reason the Dust Bowl had such a pronounced effect on other regions: it generated a series of far-reaching vertical motions in the atmosphere. Such movements are known as a wavenumber-5 or wave-5 teleconnection — so named because it consists of five pairs of alternating high- and low-pressure features that encircle the globe along jet streams. In this case, the intense surface heating of the Great Plains created an upward motion of warm air, which then moved downward in surrounding areas, suppressing the formation of clouds over much of the northern U.S. and Canada. It also produced sinking air that suppressed clouds in other regions around the Northern Hemisphere, allowing more sunlight to reach the surface and resulting in soaring temperatures. At the same time, the pattern enabled warm, southerly winds to reach as far north as Scandinavia and eastern Asia. These winds contributed to the extreme heat over much of northern Europe and parts of eastern Asia. Meehl said the study helps illuminate how conditions on one part of the planet can affect the atmosphere thousands of miles away. Scientists have long known about the climatic influence of the vast tropical oceans, which pump out enormous amounts of relatively moist, warm air affecting weather patterns worldwide, as with El Niño. But it has proven more difficult to tease out linkages that arise from conditions over smaller areas of land in the midlatitudes, especially during summer. “This is a mechanism that arose in a unique way from human influence — not by burning fossil fuels but from plowing up the middle third of the U.S.,” Meehl said. “It’s possible that intense regional droughts in the future could also influence heat extremes in the Northern Hemisphere.” ABOUT THE ARTICLE Title: How the Great Plains Dust Bowl drought spread heat extremes around the Northern Hemisphere Authors: Gerald A. Meehl, Haiyan Teng, Nan Rosenbloom, Aixue Hu, Claudia Tebaldi, and Guy Walton Journal: Scientific Reports SEE ALL NEWS CONTACT David Hosansky Media Relations Manager 303-497-8611 TOPICS Climate, Weather TAGS News Release RELATED NEWS Dampening the “seeds” of hurricanes MON, 07/01/2024 - 12:00 Artificial climate control might become ineffective THU, 06/27/2024 - 12:00 Climate models underestimate carbon cycling through plants TUE, 06/25/2024 - 12:00

With a break in the 95° to 100° heat in the forecast, Hightstown in Mercer County only needs 2 more 95° days for the new all time record for a year. The previous record was set in 2002. The sea breeze influence has been so strong that places like Newark on the bay have been lagging behind. Harrison a little further from the bay made it to 101° during this most recent heatwave while Newark maxed out at 99°. Time Series Summary for HIGHTSTOWN 2 W, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. 1 2002 17 0 2 2024 16 168 - 1955 16 8 3 1953 14 0 4 2021 13 0 - 2018 13 1 - 2016 13 2 - 2010 13 4 - 1988 13 0 - 1949 13 0 5 2022 12 2 - 1999 12 0 - 1944 12 1 Data for January 1, 2024 through July 20, 2024 Click column heading to sort ascending, click again to sort descending. HIGHTSTOWN 2 W COOP 16 PENNSAUKEN 1N COOP 13 PHILADELPHIA/MT. HOLLY WFO COOP 12 EWING 3 WNW COOP 11 CALDWELL ESSEX COUNTY AP WBAN 11 TRENTON-MERCER AIRPORT WBAN 10 Trenton Area ThreadEx 10 SEABROOK FARMS COOP 9 HARRISON COOP 9 SOMERSET AIRPORT WBAN 8 MOORESTOWN 4 E COOP 7 NEW BRUNSWICK 3 SE COOP 7 NEWARK LIBERTY INTL AP WBAN 7 ESTELL MANOR COOP 7 SOUTH JERSEY REGIONAL AIRPORT WBAN 7 Newark Area ThreadEx 7 New Brunswick Area ThreadEx 7 Data for July 1, 2024 through July 20, 2024 Click column heading to sort ascending, click again to sort descending. TETERBORO AIRPORT WBAN 101 HARRISON COOP 101 TETERBORO AIRPORT COOP 101 HIGHTSTOWN 2 W COOP 100 NEWARK LIBERTY INTL AP WBAN 99 CALDWELL ESSEX COUNTY AP WBAN 99 SOUTH JERSEY REGIONAL AIRPORT WBAN 99 Newark Area ThreadEx 99 PENNSAUKEN 1N COOP 99

Will be interesting to see if we can get a new global high temperature record next week.

Just in terms of ONI, this reminds me of the transition from our last strong to super El Niño in 16-17. There was so much SST warmth leftover from that event in 2016, that the La Niña only achieved weak ONI for the 16-17 La Niña winter. It was a very warm winter since there was so much global heat left over from the previous winter being a super El Niño. The stronger La Niña didn’t arrive until 17-18. 2016 2.5 2.1 1.6 0.9 0.4 -0.1 -0.4 -0.5 -0.6 -0.7 -0.7 -0.6 2017 -0.3 -0.2 0.1 0.2 0.3 0.3 Super El Niño To weak La Nina Weak La Niña surrounded by residual super El Niño warmth

Yeah, human-induced land degradation was one of the leading causes of the Dust Bowl. https://www.pnas.org/doi/abs/10.1073/pnas.0810200106 The “Dust Bowl” drought of the 1930s was highly unusual for North America, deviating from the typical pattern forced by “La Nina” with the maximum drying in the central and northern Plains, warm temperature anomalies across almost the entire continent, and widespread dust storms. General circulation models (GCMs), forced by sea surface temperatures (SSTs) from the 1930s, produce a drought, but one that is centered in southwestern North America and without the warming centered in the middle of the continent. Here, we show that the inclusion of forcing from human land degradation during the period, in addition to the anomalous SSTs, is necessary to reproduce the anomalous features of the Dust Bowl drought. The degradation over the Great Plains is represented in the GCM as a reduction in vegetation cover and the addition of a soil dust aerosol source, both consequences of crop failure. As a result of land surface feedbacks, the simulation of the drought is much improved when the new dust aerosol and vegetation boundary conditions are included. Vegetation reductions explain the high temperature anomaly over the northern U.S., and the dust aerosols intensify the drought and move it northward of the purely ocean-forced drought pattern. When both factors are included in the model simulations, the precipitation and temperature anomalies are of similar magnitude and in a similar location compared with the observations. Human-induced land degradation is likely to have not only contributed to the dust storms of the 1930s but also amplified the drought, and these together turned a modest SST-forced drought into one of the worst environmental disasters the U.S. has experienced.

Since the 500 mb heights continue to rise as we warm, they get updated to the most recent 30 year normals which are the highest. If we could go back to a 1961-1990 period, then the current 500 mb height anomalies south of the Aleutians would look even more impressive with that older climo. They allow you to adjust the temperatures for the older climate normals. So the current winter temperatures look much more impressive since 15-16 using the colder 1961-1990 normals.

Models seeing the stronger Southeast ridge next week than in earlier runs. So this means that the stalled front to the south will come back north. This is when the chances for more widespread heavy convection will return. 70s dew points and 2.00”+ PWATS have been the norm this summer. New run Old run

This is the 1st time we have had such a strong and persistent Aleutian ridge over a 9 year period going back to the 1950s. Previous -PDO eras never had such a strong Aleutian ridge. So this is something new over the last 9 winters. The old -PDOs were more defined by their stronger -PNA troughs over Western North America. Since the -PDO from 1950s into 1970s didn’t have the strong Aleutian ridge, they also didn’t have a Southeast ridge. This is why the old -PDO winters were much colder in the East. We can remember cold -PNA patterns back then for the East. This new Aleutian ridge teleconnection has been an important driver of the Southeast ridge and record 9 warm winters in a row in parts of the East. Both ridges are function of the marine heatwaves in the MJO 4-7 regions generating this winter standing wave pattern through the stronger MJO 4-7 forcing. Plus the marine heatwaves east of Japan are also linked into this process. This process has also been warming the NW Atlantic leading to even stronger ridges in the East.

Only in the Great Plains as we regularly get much warmer summers than those were here in the Northeast. Time Series Summary for Allentown Area, PA (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 1949 75.3 0 2 2018 74.9 0 - 2016 74.9 0 3 2005 74.6 0 - 1980 74.6 0 4 2019 74.4 0 5 2020 74.3 0 - 1943 74.3 0 - 1937 74.3 3 6 1994 74.1 0 7 2010 74.0 0 - 1983 74.0 0 - 1973 74.0 0 - 1966 74.0 0 - 1939 74.0 0 8 1995 73.9 0 - 1993 73.9 0 - 1988 73.9 0 - 1955 73.9 0 9 2011 73.8 0 10 2022 73.6 0 11 2021 73.5 0 - 2012 73.5 0 - 1944 73.5 0 - 1936 73.5 5 Time Series Summary for Burlington Area, VT (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 2020 72.3 0 2 1949 72.2 0 3 2018 72.1 0 4 2021 71.9 0 5 2005 71.5 0 6 2016 71.4 0 - 1995 71.4 0 7 1901 71.2 0 8 2022 71.0 0 - 1899 71.0 0 9 2012 70.9 0 - 1999 70.9 0 - 1895 70.9 0 10 1900 70.8 0 11 1955 70.6 0 12 2019 70.4 0 13 1896 70.3 0 - 1893 70.3 1 14 2023 70.1 0 15 1975 70.0 0 16 2013 69.9 0 17 2011 69.8 0 - 1994 69.8 0 - 1973 69.8 0 - 1959 69.8 0 - 1947 69.8 0 - 1944 69.8 0 18 1898 69.7 0 19 2015 69.6 0 - 2014 69.6 0 - 2010 69.6 0 - 1892 69.6 0 20 2003 69.5 0 21 2001 69.3 0 22 1993 69.2 0 - 1952 69.2 0 - 1937 69.2 0 23 2017 69.1 0 - 1988 69.1 0 - 1984 69.1 0 - 1894 69.1 0 24 2006 69.0 0 25 1991 68.9 0 - 1989 68.9 0 - 1938 68.9 0 Time Series Summary for Caribou Area, ME (ThreadEx) Click column heading to sort ascending, click again to sort descending. 1 2020 66.9 0 2 2021 66.2 0 - 2018 66.2 0 3 1973 66.0 0 4 1970 65.8 0 5 2014 65.7 0 - 2012 65.7 0 - 1995 65.7 0 6 2010 65.4 0 7 2023 65.2 0 - 1990 65.2 0 8 2016 64.9 0 9 2005 64.8 0 - 1975 64.8 0 - 1967 64.8 0 10 2019 64.7 0 11 2022 64.6 0 - 1999 64.6 0 - 1952 64.6 0 12 1979 64.5 0 13 1994 64.4 0 14 2011 64.3 0 - 1949 64.3 0 15 2006 64.2 0 16 1991 64.1 0 17 2001 64.0 0 - 1981 64.0 0 18 2017 63.9 0 - 1978 63.9 0 - 1974 63.9 0 - 1947 63.9 1 19 2008 63.8 0 - 1998 63.8 0 - 1955 63.8 0 20 2003 63.7 0 - 1944 63.7 0 21 1983 63.6 0 - 1939 63.6 0

NYC was able to get a decent 4.4” event on 2-17-18. This was a few days before parts of the area had their first winter and February 80° day on record. It was also the warmest February on record in NYC at 42.0°. Even with no cold air to speak of we got a nice BM track and decent high positioning for the event. The last time NYC had a 4” daily snowfall was on 1-29-22. So the last two winters have been a combination of record warmth and unfavorable storm tracks. We can get by with warm to record warm patterns. But when unfavorable seasonal storm tracks gets added to the mix there is very little we can do.

Yeah, I agree. Especially for the mid areas of the continent since the 15-16 super El Niño. We haven’t even needed severe cold around NYC metro for the great snowfall outcomes. Our area has seen a big uptick in 50°+ and 60°+ days in close proximity to our snowstorms. So while we have had numerous snowfall records since then, the overall snow cover days have been shrinking due to rapid melts. It really comes down to getting the Niña background to relax enough so we can get some decent BM storm tracks. The ridge that keeps pumping near the East Coast in recent years has forced the storm tracks too far west for areas other than the interior and high elevations to cash in. All we need is just cold enough with a good storm track.