bluewave

Record high mid 70s dew points for June in portions of the area. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=153&network=NJ_ASOS&zstation=SMQ&month=jun&var=max_dwpf&dpi=100&_fmt=png

EWR and LGA have been spot on with this heatwave. The new micronet stations show how accurate those airport readings are. The only station in this part of the country that has flawed temperature data is Central Park due to the improper sitting in the deep shade. High temperatures 6-7….6-6….6-5 LGA………………………..93…..95……94 Astoria…………………..93……94…..93 Corona…………………..94……98…..95 Brownsville……………88……95……93 Fresh Kills……………..95……96……93 EWR……………………….95……97……95 NYC……………………….91…….92……89

The most impressive heat this month could be during the first and last week of June. The heat ridge backs up to the West where the extreme drought is located during mid-June. Long range EPS hints at the ridge rebuilding near New England by the last week of June. But can the 97° at Newark this past weekend be challenged then? Stay tuned….

The ridge has been getting stronger in recent years. So the warmest 850 mb temperatures get pushed up to our north. This process also allows the winds to become more onshore here. We need more of a westerly flow to reach 100° since we are right on the Atlantic Ocean. This weekend featured the warmest temperatures relative to the records going from the Dakotas to Northern New England. The early June 2011 record heat when Newark reached 102° had a flatter ridge. So the maximum 850 mb temperatures went right through our area. Notice how Burlington had the 3rd warmest June high temperature of all time vs 6th warmest at Newark. Time Series Summary for Burlington Area, VT (ThreadEx) - Month of Jun Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 1995 100 0 2 2012 97 0 - 1994 97 0 - 1988 97 0 3 2021 96 23 - 2020 96 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Jun Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 2011 102 0 - 1994 102 0 - 1993 102 0 - 1952 102 0 - 1943 102 0 2 1988 101 0 - 1966 101 0 3 1959 100 0 - 1953 100 0 - 1934 100 0 4 2017 99 0 - 2012 99 0 - 2008 99 0 - 1999 99 0 - 1964 99 0 - 1963 99 0 - 1956 99 0 - 1949 99 0 - 1945 99 0 - 1933 99 0 5 2010 98 0 - 1981 98 0 - 1974 98 0 - 1961 98 0 - 1950 98 0 6 2021 97 23

My guess is that the actual high for this heatwave in Central Park away from the trees was 95°or 96° instead of 92°. The tree growth around the sensor became pronounced by the early 1990s. So it’s possible the sensor began to get blocked by the trees during the 1980s. The June monthly max prior to the 1980s had Central Park 1° cooler than EWR and 2° warmer than LGA. So I compared the average June monthly maximum temperatures from 1961-1980 before the tree growth to 2001-2020 with the sensor in deep shade. Current heatwave maximum temperature NYC….92 EWR….97 LGA……95 1961-1980 June average maximum monthly high temperature NYC…..94 EWR….95 LGA…..92 2001-2020 NYC…..92……..-2 EWR…..96…….+1 LGA……94……..+2 NYC bias corrected to match a 1° rise at EWR….95° NYC bias corrected to match a 2° rise at LGA….96° NYC has only reached 95° in 2 Junes from 2001-2020 with the trees shading the sensor Monthly Highest Max Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Jun Season 2008 96 96 2011 95 95 No trees blocking the sensor allowed 9 Junes to reach 95° or greater from 1961-1980 The 101° June max from 1961-1980 was 5° warmer than the 96° from 2001-2020 Monthly Highest Max Temperature for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Year Jun Season 1966 101 101 1964 99 99 1969 96 96 1967 96 96 1963 96 96 1961 96 96 1974 95 95 1973 95 95 1965 95 95

NYC is much more than slightly distorted on the high temperatures. The Central Park station used to have high temperatures comparable to EWR and LGA before the trees began to block the sensor in the early 90s. Go back and look at the comparisons from the 1950s to the 1980s. As for LGA and EWR, they are right in line with the neighborhood stations in Brooklyn, Queens, and Staten Island. The high temperatures from the new NYC micronet stations were in the same range as EWR and LGA. This makes Central Park stand out more like a sore thumb. Sunday high temperatures with ground level new micronet stations Brownsville…….95 Corona…….……..98 Fresh Kills………96 Queensbridge..96 LGA………………….95 EWR………….……..97

The Park Conservancy cut their budget back in 2017. Now their share of funding from NYC was also reduced So they are running a deficit. As you know, tree maintenance is expensive. My area has spent quite a bit of money on tree trimming and removal with all the wind damage in recent years. Probably the most damaging decade on record for trees around our area. The tree crews are true professionals. Removing damaged trees close to houses is a real art form. https://ilovetheupperwestside.com/central-park-conservancy-faces-10-million-deficit-launches-fundraiser/ https://www.bloomberg.com/news/articles/2017-05-23/nyc-s-central-park-conservancy-cuts-30-jobs-as-it-trims-spending

Second earliest 95° for Burlington, VT behind last year. And just like that, another record has fallen. Burlington just hit 95 degrees breaking the previous record of 94 degrees set in 1925. First/Last Summary for Burlington Area, VT (ThreadEx) Each section contains date and year of occurrence, value on that date. Click column heading to sort ascending, click again to sort descending. Year First Value Last Value Difference 2020 05-27 (2020) 95 07-19 (2020) 95 52 2017 06-11 (2017) 95 06-11 (2017) 95 0 1988 06-15 (1988) 97 08-03 (1988) 97 48 1994 06-17 (1994) 96 06-18 (1994) 97 0 1995 06-19 (1995) 100 07-14 (1995) 100 24

Tree pruning is a low priority for NYC. Maybe the NWS knew this all along. So they never really pushed the issue of trimming around the Central Park ASOS. https://www.thecity.nyc/2020/7/13/21323732/budget-cuts-raise-fears-of-falling-tree-branches Tree Pruning Budget Cuts Raise Fears of Falling Branches BY CARSON KESSLER JUL 13, 2020, 11:42PM EDT The city’s canopy of more than 2.6 million street and park trees will have to wait for scheduled prunings due to new budget cuts — a move slammed by a former Parks Department commissioner as “foolish” and dangerous. The Fiscal 2021 Executive Plan includes a budget reduction of $7.2 million for tree pruning contracts, leaving about $1.5 million for the job. City trees are generally trimmed every seven to 10 years. Park advocates and government officials, pointing to past incidents where people were severely injured — or worse — by plummeting branches, sounded the alarm over the cuts. “The problem with not pruning is if a limb falls from a tall tree, it can cause tremendous damage. It can kill people,” said Adrian Benepe, who served as Parks commissioner from 2002 to 2012. “It’s a meaningless cut that could cause damage both to the trees and to people.” After the city slashed tree-pruning funding in 2010, tree-related injury claims soared. By delaying pruning contracts, the city saved $1 million — but settlement costs neared $15 million, records show. “One bad tree limb fall wipes out all your savings,” said Benepe. “This saving is pennywise and pound foolish.” During 2010, the city pruned less than 30,000 street trees — 50,000 fewer trees than the year before. Full funding for the Parks pruning program wasn’t restored until FY2013 when the 10-year pruning cycle was reinstated. Claims for injuries caused by trees increased by 92% — from just under 400 claims to over 700 — during the period of reduced pruning and maintenance. In some community districts outside Manhattan claims increased by 590%, according to a 2015 ClaimStat report by City Comptroller Scott Stringer. In 2015, Stringer told the City Council that there is a direct correlation between million-dollar legal claims and the amount of money the city allocates for tree pruning each year.

It may take the NWS getting directly involved in the case. I am not sure why they took a hands off approach as far back as 2003. It was as if they were resigned to not getting accurate temperature measurements from the site. Before the trees began to block the sensors in the early 90s, Central Park was much more in line with the LGA and EWR high temperatures. It wasn’t surprising to see Central Park warmer than the other stations at times like the famous 1977 July heatwave. So that’s telling us that it’s just a maintenance issue near the castle. Go a short walk to a nearby open lawn or softball field and the temperatures will be several degrees warmer than under the trees. July 1977 heatwave Data for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature 1977-07-13 93 1977-07-14 92 1977-07-15 96 1977-07-16 98 1977-07-17 97 1977-07-18 100 1977-07-19 102 1977-07-20 92 1977-07-21 104 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature 1977-07-13 92 1977-07-14 91 1977-07-15 93 1977-07-16 97 1977-07-17 99 1977-07-18 98 1977-07-19 100 1977-07-20 90 1977-07-21 102 Data for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature 1977-07-13 92 1977-07-14 89 1977-07-15 90 1977-07-16 96 1977-07-17 95 1977-07-18 95 1977-07-19 99 1977-07-20 90 1977-07-21 99

The new NYC micronet stations show how representative the EWR and LGA temperatures are of local NYC neighborhoods. https://www2.nysmesonet.org/networks/nyc EWR and LGA high temperatures vs ground level NYC micronet stations EWR…95 LGA….94 Astoria….93 Bensonhurst…94 Brownsville….93 Corona….95 Ozone Park….94 Queensbridge….94 Fresh Kills….93

https://www.weather.gov/coop/sitingpolicy2 Proper Siting The Coop network has provided climate and weather data for over 100 years. Consistency of the measurements is an attribute of the network, and it has been maintained by rare and/or gradual change, and established standards for exposure, of instruments over the life of the network. In order to preserve the integrity of the network, NWS has established standards for equipment, siting, and exposure. Temperature sensor siting: Do not install the sensor on a steep slope or in a sheltered hollow unless it is typical of the area or unless data from that type of site are desired. When possible, the shelter should be no closer than four times the height of any obstruction (tree, fence, building, etc.). 4 Air temperature Air temperature is temperature of the free air conditions surrounding the station at a height between 4 and 6 feet above ground level. The air should be freely exposed to sunshine and wind and not close to or shielded by trees, buildings, or other obstructions. http://www.weather2000.com/ASOS/NYC_ASOS.html Most recent photo of the NYC ASOS taken in 2013 showing the trees shielding the temperature sensor https://www.ncdc.noaa.gov/cdo-web/datasets/GHCND/stations/GHCND:USW00094728/detail Obstruction Descriptions OBSTRUCTIONS BEGIN DATE¹ END DATE¹ TREES 2021-04-06 Present TREES 2017-08-01 2021-04-06 TREE 020-340 deg 25-25 ft 20-54 deg 2016-06-15 2017-08-01 HYGR 090/4 TREES ENCIRLCE/25/20-54 IN FENCED ENCOLSURE 50 FT X 25 TH 1995-06-27 2016-06-15 UNIV 050/4 CRS 180/9 H083 SENSOR 200/8 TB 220/20 TREES ENCIRCLE/25/20-54 EQUIPMENT IN FENCED ENCLOSURE 50 FEET X 25 FEET 1992-01-01 1995-06-27

Epic weather swings pattern continues. Third consecutive weekend with a high or low temperature record. We need another cold record next weekend to complete the grand slam. RECORD EVENT REPORT NATIONAL WEATHER SERVICE NEW YORK, NY 300 PM EDT SAT JUNE 5 2021 ...RECORD MAXIMUM TEMPERATURE SET AT NEWARK NJ... A RECORD MAXIMUM TEMPERATURE OF 94 WAS SET AT NEWARK NJ TODAY. THIS BREAKS THE OLD RECORD OF 92 SET IN 1966. RECORD EVENT REPORT NATIONAL WEATHER SERVICE NEW YORK, NY 301 AM EDT MON MAY 31 2021 ...RECORD LOW MAXIMUM TEMPERATURE SET AT NEWARK NJ... A RECORD LOW MAXIMUM TEMPERATURE (COLDEST HIGH TEMPERATURE) OF 53 WAS SET AT NEWARK NJ YESTERDAY. THIS TIES THE OLD RECORD OF 53 SET IN 1953. RECORD EVENT REPORT NATIONAL WEATHER SERVICE NEW YORK, NY 248 AM SUN MAY 30 2021 ...RECORD LOW MAXIMUM TEMPERATURE SET AT NEWARK NJ... A RECORD LOW MAXIMUM TEMPERATURE (COLDEST HIGH TEMPERATURE) OF 52 WAS SET AT NEWARK NJ YESTERDAY. THIS BREAKS THE OLD RECORD OF 60 SET IN 1950. RECORD EVENT REPORT NATIONAL WEATHER SERVICE NEW YORK, NY 437 PM EDT SUN MAY 23 2021 ...RECORD HIGH TEMPERATURE SET AT KENNEDY NY... A RECORD HIGH TEMPERATURE OF 92 WAS SET AT KENNEDY NY TODAY. THIS BREAKS THE OLD RECORD OF 89 SET IN 1964. RECORD EVENT REPORT NATIONAL WEATHER SERVICE NEW YORK, NY 0434 PM EDT SAT MAY 22 2021 ...RECORD HIGH TEMPERATURE SET AT KENNEDY NY... A RECORD HIGH TEMPERATURE OF 94 WAS SET AT KENNEDY NY TODAY. THIS TIES THE OLD RECORD OF 94 SET IN 1992.

August 2014 was the most extreme rainfall event for our area with 13.25 at ISP. 2nd place would be the mid-August 2011 when Long Beach picked up 10 to 11. There may have been other events which were also close to 10 that fell between the major recording stations.

This tool has hourly records. But you need to do more research to find fastest 1”. Notice all the top ten records in our wetter climate over the last 20 years. https://mesonet.agron.iastate.edu/plotting/auto/?_wait=no&q=155&network=NY_ASOS&zstation=ISP&var=max_p01i&threshold=100&hour=12&sdate=2000%2F01%2F01&edate=2000%2F12%2F31&month=all&dpi=100&_fmt=png https://www.weather.gov/okx/HistoricFlooding_081314

You can see the big Central Park temperature jump from 10 to 11 as the vegetation dried out a bit and the sun angle increased. New York City Metropolitan Area Weather Roundup National Weather Service New York NY 1100 AM EDT SAT JUN 05 2021 CITY SKY/WX TMP DP RH WIND PRES REMARKS Central Park SUNNY 79 63 57 CALM 29.96F LaGuardia Arpt MOSUNNY 82 60 47 VRB7 29.92F Kennedy Intl MOSUNNY 79 65 62 SW15 29.95S Newark Liberty MOSUNNY 84 63 49 W13 29.93F Teterboro Arpt SUNNY 82 65 56 W9 29.91F Bronx Lehman C N/A 81 63 54 SW6 N/A Queens College N/A 79 63 57 SW7 N/A Breezy Point N/A 73 N/A N/A SW7G14 N/A Brooklyn Coll N/A 79 64 61 SW8 N/A Staten Island N/A 79 64 61 W9 N/A

Central Park is the new Montauk. You know that sensor is under deep vegetation that is very wet. It’s now 10° cooler than LGA and 12° lower than EWR. Even JFK with the sea breeze off of Jamaica Bay is 5° warmer. Regional Weather Roundup National Weather Service New York NY 1000 AM EDT SAT JUN 05 2021 Note: "FAIR" indicates few or no clouds below 12,000 feet with no significant weather and/or obstructions to visibility. NYZ071-072-176-178-NJZ106-104-051500- New York City Metro Area CITY SKY/WX TMP DP RH WIND PRES REMARKS Central Park SUNNY 70 63 78 SW7 29.97S Bronx Lehman C N/A 77 64 65 W6 N/A LaGuardia Arpt MOSUNNY 80 61 52 SW9 29.93F Queens College N/A 77 63 61 W12 N/A Kennedy Intl MOSUNNY 75 64 68 SW16 29.95F Breezy Point N/A 72 N/A N/A SW9 N/A Brooklyn Coll N/A 75 64 69 SW8 N/A Staten Island N/A 77 64 65 SW12 N/A Newark/Liberty MOSUNNY 82 64 54 W9 29.94S Teterboro SUNNY 79 65 62 W8 29.92F $$ NYZ177-179-078>081-051500- Long Island New York CITY SKY/WX TMP DP RH WIND PRES REMARKS Jones Beach N/A 66 N/A N/A SW6 N/A Wantagh N/A 73 66 78 SW7 N/A Hempstead NOT AVBL Matinecock Pt N/A 72 N/A N/A SW13 N/A Farmingdale SUNNY 77 67 71 S7 29.95S MacArthur/ISP PTSUNNY 76 67 73 SW7 29.94S Shirley SUNNY 75 66 73 S7 29.94F Mt Sinai Harb N/A 79 N/A N/A SW3G9 N/A Westhampton SUNNY 72 65 78 SW7 29.96S East Hampton FAIR 74 67 78 SW6 29.94S Southold N/A 75 68 78 S5 N/A Montauk N/A 69 63 81 SE3 29.95R

The soaking wet foliage in Central Park that is blocking the sensor with the lower morning sun angle is really obvious. We seldom see the 9am temperature 10° cooler than EWR and LGA. I guess this is to be expected with such poor maintenance of the site. OSOOKX New York City Metropolitan Area Weather Roundup National Weather Service New York NY 900 AM EDT SAT JUN 05 2021 CITY SKY/WX TMP DP RH WIND PRES REMARKS Central Park MOSUNNY 68 62 81 VRB6 29.97R LaGuardia Arpt MOSUNNY 78 60 53 SW7 Newark Liberty MOSUNNY 77 64 64 SW9

It will be interesting to see if a big rainy cutoff pattern verifies in mid-June.

Yeah, we were talking about 100° and snow a few days apart in the Rockies last September. This type of extreme wavelength behavior is becoming more common. So it makes past analogs less effective in our newer climate. This was the warmest June temperature at Bismarck since 6-27-88 when they reached 107°. Newark reached 101° during that record heat at Bismarck. This coming warm up is following a much wetter pattern than June 1988 when Newark only had around 1.00” total for the month. Models have Newark toping out in the low possibly mid 90s next several days before we get backdoored again on Thursday. So a continuation of the up and down pattern for us. Climatological Data for Bismarck Area, ND 1988-06-21 105 73 1988-06-27 107 70 2021-06-04 106 57 Climatological Data for NEWARK LIBERTY INTL AP, NJ - June 1988 1988-06-22 101 74 87.5

The big weather swings just keep coming. RECORD EVENT REPORT NATIONAL WEATHER SERVICE BISMARCK, ND 0728 PM CDT THU MAY 27 2021 ...RECORD DAILY MAXIMUM SNOWFALL SET AT BISMARCK ND... A TRACE OF SNOW WAS REPORTED AT BISMARCK, ND TODAY. SNOW HAS NEVER BEEN REPORTED AT BISMARCK ON THIS DATE. RECORD EVENT REPORT NATIONAL WEATHER SERVICE BISMARCK, ND 0721 PM CDT FRI JUN 04 2021 ...RECORD HIGH TEMPERATURE SET AT BISMARCK ND... A RECORD HIGH TEMPERATURE OF 106 WAS SET AT BISMARCK ND TODAY. THIS BREAKS THE OLD RECORD OF 95 SET IN 1988. RECORD EVENT REPORT NATIONAL WEATHER SERVICE DULUTH MN 0123 AM CDT SAT MAY 29 2021 ...RECORD LOW TEMPERATURE SET AT INTERNATIONAL FALLS MN... A RECORD LOW TEMPERATURE OF 24 WAS SET AT INTERNATIONAL FALLS MN YESTERDAY. THIS BREAKS THE OLD RECORD OF 27 SET IN 1947 RECORD EVENT REPORT NATIONAL WEATHER SERVICE DULUTH MN 0145 AM CDT THU MAY 27 2021 ...RECORD DAILY MAXIMUM SNOWFALL SET AT INTERNATIONAL FALLS MN... A RECORD SNOWFALL OF A TRACE WAS SET AT INTERNATIONAL FALLS MN YESTERDAY. THIS TIES THE OLD RECORD OF A TRACE SET IN 1970. RECORD EVENT REPORT NATIONAL WEATHER SERVICE DULUTH MN 0421 PM CDT FRI JUN 04 2021 ...RECORD HIGH TEMPERATURE SET AT INTERNATIONAL FALLS... A RECORD HIGH TEMPERATURE OF 98 WAS SET AT INTERNATIONAL FALLS TODAY. THIS BREAKS THE OLD RECORD OF 92 SET IN 1988.

The highest temperature departures with the coming warm up will be from the Dakotas to Maine.

Looks like the highest temperature departures with coming ridge amplification will be focused over the drought areas to our north and west. We are are on track for a higher dew point warm up that has been common in recent years. During week 2, the models pull the ridge back to the strongest drought conditions over the Western US. So we should see a step down in temperatures then.

Two theories have emerged as to why the September 2012 record minimum has held on for so long. There is probably a piece of truth to both of them. But it’s interesting how every other time of the year has set new minimum records since 2012. So one of these years we’ll eventually surpass the record. Last year came the closest. https://climate.nasa.gov/news/2817/with-thick-ice-gone-arctic-sea-ice-changes-more-slowly/ With thick ice gone, Arctic sea ice changes more slowly Kwok's research, published today in the journal Environmental Research Letters, combined decades of declassified U.S. Navy submarine measurements with more recent data from four satellites to create the 60-year record of changes in Arctic sea ice thickness. He found that since 1958, Arctic ice cover has lost about two-thirds of its thickness, as averaged across the Arctic at the end of summer. Older ice has shrunk in area by almost 800,000 square miles (more than 2 million square kilometers). Today, 70 percent of the ice cover consists of ice that forms and melts within a single year, which scientists call seasonal ice. Sea ice of any age is frozen ocean water. However, as sea ice survives through several melt seasons, its characteristics change. Multiyear ice is thicker, stronger and rougher than seasonal ice. It is much less salty than seasonal ice; Arctic explorers used it as drinking water. Satellite sensors observe enough of these differences that scientists can use spaceborne data to distinguish between the two types of ice. Thinner, weaker seasonal ice is innately more vulnerable to weather than thick, multiyear ice. It can be pushed around more easily by wind, as happened in the summer of 2013. During that time, prevailing winds piled up the ice cover against coastlines, which made the ice cover thicker for months. The ice's vulnerability may also be demonstrated by the increased variation in Arctic sea ice thickness and extent from year to year over the last decade. In the past, sea ice rarely melted in the Arctic Ocean. Each year, some multiyear ice flowed out of the ocean into the East Greenland Sea and melted there, and some ice grew thick enough to survive the melt season and become multiyear ice. As air temperatures in the polar regions have warmed in recent decades, however, large amounts of multiyear ice now melt within the Arctic Ocean itself. Far less seasonal ice now thickens enough over the winter to survive the summer. As a result, not only is there less ice overall, but the proportions of multiyear ice to seasonal ice have also changed in favor of the young ice. Seasonal ice now grows to a depth of about six feet (two meters) in winter, and most of it melts in summer. That basic pattern is likely to continue, Kwok said. "The thickness and coverage in the Arctic are now dominated by the growth, melting and deformation of seasonal ice." The increase in seasonal ice also means record-breaking changes in ice cover such as those of the 1990s and 2000s are likely to be less common, Kwok noted. In fact, there has not been a new record sea ice minimum since 2012, despite years of warm weather in the Arctic. "We've lost so much of the thick ice that changes in thickness are going to be slower due to the different behavior of this ice type," Kwok said. Kwok used data from U.S. Navy submarine sonars from 1958 to 2000; satellite altimeters on NASA's ICESat and the European CryoSat-2, which span from 2003 to 2018; and scatterometer measurements from NASA's QuikSCAT and the European ASCAT from 1999 to 2017. https://iopscience.iop.org/article/10.1088/1748-9326/abc047 Why has no new record-minimum Arctic sea-ice extent occurred since September 2012? 4. Discussion and conclusions The behavior of Arctic sea ice during recent years has perplexed the scientific community. The ice extent has attained or flirted with new record lows during winter and spring months every year since 2012, raising the specter of hitting a new minimum in September. Instead, however, the ice-loss trajectory took a sharp turn in August or early September (except in 2020), averting a broken record. Responsible for the cessation was the formation of low pressure over the region, which brings clouds, reduced insolation, and winds conducive for expanding the ice cover. The consistency of this occurrence begs the question: why is it happening? Here we offer evidence that the dramatic negative trend in spring snow cover over high-latitude land areas—one of the most conspicuous indications of anthropogenic climate change—may be an important contributor to this behavior. The early loss of snow cover creates a belt of positive temperature anomalies that distorts the typically monotonic poleward temperature gradient by creating an additional peak. Through the thermal wind relationship, a split jet is more likely to form, favoring conditions that trap and amplify Rossby waves that have been implicated in causing extreme summer weather events over northern hemisphere continents. The second most prominent atmospheric state (PC2) during summer is associated with similar split-jet conditions, along with continental heatwaves in Asia, Scandinavia, northern North America, and ocean heatwaves in the North Atlantic and Pacific Oceans. This pattern is also significantly correlated with strong westerly winds over the Arctic during summer, creating cyclonic conditions that favor cloudiness and reduced transport of sea ice southward through the Fram Strait into the Greenland Sea. Moreover, since 2012, this second PC has exhibited several of its highest values in the record back to 1979, while a stretch of 6 yr (2007–2012) with its lowest values was accompanied by rapid declines in sea-ice extent. We hypothesize that these observations are connected, and while we cannot establish cause-and-effect and not every year will follow this chain of linkages, a negative feedback on the decline in sea-ice extent initiated by early spring snow-melt may provide a plausible explanation for the recent puzzling behavior of the late-summer sea-ice behavior. We note that the summers of 2019 and 2020, characterized by high values of PC1 and low values of PC2 (in contrast to most years since 2012), recorded near-record-low minimum sea-ice extent during September (Richter-Menge et al 2019; http://nsidc.org/arcticseaicenews/), suggesting that these atmospheric patterns during JJA may provide some predictive information for the annual sea-ice minimum. It should be noted that this application of EOF analysis reveals statistical relationships only, and future research will require targeted modeling experiments to verify causal mechanisms. These experiments might include comparisons of atmospheric patterns under conditions of climatological snow cover and soil moisture versus those projected for the late 21st century under continued greenhouse gas forcing. A further research opportunity could apply these atmospheric patterns to test the ability of climate models to simulate observed relationships between rates of sea-ice loss, large-scale circulation regimes, and extreme summer weather in mid-latitudes.