bluewave

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.

I had to laugh when NYC was able to drop below 0° in February 2016 but couldn’t do it in February 2015. Data for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 2016-02-01 59 44 2016-02-02 50 38 2016-02-03 59 42 2016-02-04 59 44 2016-02-05 44 31 2016-02-06 40 30 2016-02-07 47 33 2016-02-08 39 28 2016-02-09 36 27 2016-02-10 39 31 2016-02-11 31 18 2016-02-12 27 15 2016-02-13 22 6 2016-02-14 15 -1 2016-02-15 35 13 2016-02-16 54 35 2016-02-17 39 35 2016-02-18 36 27 2016-02-19 39 24 2016-02-20 61 39 2016-02-21 55 44 2016-02-22 52 38 2016-02-23 40 35 2016-02-24 60 36 2016-02-25 61 37 2016-02-26 39 27 2016-02-27 41 26 2016-02-28 60 38 Data for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. 2015-02-01 36 20 2015-02-02 34 14 2015-02-03 26 13 2015-02-04 43 24 2015-02-05 42 14 2015-02-06 27 12 2015-02-07 40 25 2015-02-08 37 29 2015-02-09 29 25 2015-02-10 40 26 2015-02-11 34 22 2015-02-12 40 16 2015-02-13 21 8 2015-02-14 32 16 2015-02-15 25 4 2015-02-16 21 3 2015-02-17 27 14 2015-02-18 33 19 2015-02-19 27 8 2015-02-20 19 2 2015-02-21 32 13 2015-02-22 43 32 2015-02-23 38 8 2015-02-24 24 4 2015-02-25 37 20 2015-02-26 32 21 2015-02-27 30 18 2015-02-28 29 13

Yeah, whenever that Aleutian ridge can become more poleward and get pushed into the West Coast the Central US has been the focus of the relatively short but potent Arctic outbreaks since 14-15. It’s ironic that my strongest Arctic outbreak since the 15-16 super El Niño was on Valentine’s Day 2016. It was the only time NYC went below 0 since 1994. But it was a brief Arctic outbreak as has been the case across the U.S. So we can still generate significant Arctic cold over North America but the lasting power is much shorter than when it occurred in the past.

Yeah, that Arctic outbreak at the end of January 2019 was very impressive in the Midwest. While the warmth has dominated US winters since 15-16, there have been a few potent Arctic outbreaks. Another was in Texas during the 20-21 winter. The common theme is that the core of several of them have remained west of the Northeast closer to the center of the Continent.

We have effectively had 7 out of the last 8 winters with La Niña conditions. The weak El Niño in 18-19 and 19-20 wasn’t able to couple due to the very strong La Niña background state with the record WPAC warm pool. So we got a very strong Niña-like Aleutian ridge and Southeast ridge both winters. Warm MJO 5 tropical SSTs near 120E and marine heatwave east of Japan has been a common theme. If we count Niña-like background elements, then all of the last 9 winters would be included. December 2015 featured the record MJO 4-6 for an El Niño that strong. Plus this recent winter featured an unusual amount of Nino 4-7 forcing for such a strong El Nino also. The piece of the Aleutian ridge hanging on NW of Hawaii pushed the typical Nino +PNA ridge further east than usual. So there was stronger ridging into the Eastern US. The typical Nino trough was also dampened across the U.S. Southern Tier.

If the WAR verifies stronger than forecast again then those totals may begin to shifter further north over time as the month continues.

Thanks very much for posting that updated picture. It shows how the growth has even become more dense in recent years. The interesting thing is that the name attached to the photo is from a lead NWS forecaster in DC that used to be an active poster in our forum years ago. Ray is a really good guy that maintains a great winter storm archive. My guess is that he had to see the site in person since it has been running so much lower than surrounding sites. https://commons.wikimedia.org/wiki/File:2024-05-24_17_49_58_View_south_across_the_Central_Park_Automated_Surface_Observing_System_(ASOS)_in_Central_Park,_Manhattan,_New_York_City,_New_York.jpg

Yeah, it has been. First July that a place like SMQ had an average max 74.7° dew point and maximum average daily heat index of 98.0° . https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=76&network=NJ_ASOS&station=SMQ&season=jul&varname=feel&agg=max&year=1893&w=bar&hours=0-23&_r=t&dpi=100&_fmt=png

This was a top 3 warmest first half of summer across the Northeast.

Both the EPS and GEFS continue the active convection pattern going forward. We finally get a break from the major 95° to 100° heat. The front that lowers the temperatures and dew points here next few days comes back north with numerous waves of low pressure riding along it into late July.

A recent paper found it had a slight cooling effect on the Southern Hemisphere which only lasted through 2023. https://d197for5662m48.cloudfront.net/documents/publicationstatus/203287/preprint_pdf/44b2ee49f72f9858308861dbd4a9f8ed.pdf

The storm that moved through between 10:30 and 11:00 pm had the most lightning flashes since moving up here. The .89 for the day brings the rainfall total here up to 14th place for July so far. It was one of the few times that the 3rd round of storms on the day was the heaviest with the most lightning. Time Series Summary for NEW HAVEN TWEED AP, CT - Month of Jul Click column heading to sort ascending, click again to sort descending. 1 1971 8.73 0 2 2009 8.60 0 3 2023 8.22 2 4 2021 6.82 0 - 1953 6.82 0 5 1960 6.08 0 6 1956 5.25 0 7 2008 4.85 0 8 2019 4.83 0 9 2004 4.78 0 10 1969 4.73 0 11 1967 4.17 0 12 2018 4.06 0 13 1959 4.04 0 14 2024 3.84 14 15 1950 3.83 0

There is at least one study that found a slight cooling effect in the Southern Hemisphere which only lasted through the end of. 2023. https://d197for5662m48.cloudfront.net/documents/publicationstatus/203287/preprint_pdf/44b2ee49f72f9858308861dbd4a9f8ed.pdf

Yeah, they were on the northern edge and got the strong outflow.

Great video. That was actually from the severe storm in the evening. I was on the beach for a storm like that about 20 years and got sandblasted heading home. Thanks for posting as it was only a few blocks away from where I used to go to the beach.

Pretty impressive heat closer to the drought areas before the heavy rains arrive.

Can’t use that site to compare since it’s at an elevation of 311 ft.

The downtown areas of Manhattan are cooler on a south wind off the Harbor. Midtown and Central Park are the warmest parts of the city since they are away from the water. The old NWS office near the Battery would always run cooler than Central Park. The Manhattan moseonet sites with in a few miles of the park were 98° yesterday. This is why Central Park was always warmer than LGA before the ASOS set up in 1995. The NJ mesonet does a great job measuring temperatures in park-like settings like New Brunswick. The sensor isn’t under the trees and the sensor with the radiation shield is out in the sun. Shift that sensor into the nearby wooded area under the trees like the newer location in Central Park and the temperature would be 3 to sometimes 5 degrees cooler. This is why temperatures were never officially measured underneath trees. In a wet pattern enhanced transpiration can have an even greater cooling effect. The issue in Central Park isn’t that it’s a park, it’s that the old site was out in the open and not underneath the trees. So on major 95°+ days before the 90s it was 3° to 5° warmer than it is now. It’s strictly a change in how they measure the temperature and not whether it’s a park or airport. Trying to compare the warm season high and data to before the change in 1995 is like comparing apples to oranges. Also the rain gauge is under the trees and errors in rainfall and rates occur. This is why they NWS tells their observers not to measure rainfall or temperature under trees at their official COOP sites. Plus the reason the highest Central Park wind gust in 1974 hasn’t been exceeded is the trees are growing around it reducing the wind measurement accuracy. So the Central Park temperature yesterday was at least 4° too low. 28th St. / Chelsea 98

It looks like the pattern will begin to weaken the drought over the Southeast. So maybe the next warm up after this relaxation of major heat will be slightly less intense. We’ll see if wetter conditions over the source region for this recent heatwave can make a difference.