bluewave

Top 10 driest November as the fast Pacific flow didn’t let many storms amplify. Time Series Summary for LAGUARDIA AIRPORT, NY - Month of Nov Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 1976 0.31 0 2 2021 0.81 1 3 2001 0.91 0 4 1974 1.01 0 5 1949 1.03 0 6 1965 1.29 0 7 2012 1.35 0 8 1993 1.37 0 9 2009 1.40 0 10 1998 1.48 0 Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Month of Nov Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 1931 0.37 0 2 1976 0.51 0 3 1933 0.70 0 4 1974 0.80 0 5 2001 0.81 0 6 1998 0.86 0 7 2021 0.88 1 8 1936 0.94 0 9 1934 1.12 0 10 1949 1.15 0 Time Series Summary for WESTCHESTER CO AP, NY - Month of Nov Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 1976 0.26 0 2 2009 0.61 0 3 1949 0.84 0 4 2012 1.01 0 5 2021 1.11 1 6 2001 1.23 0 7 2017 1.44 2 8 1964 1.69 0 9 2019 1.96 0 - 1993 1.96 0 10 2008 2.01 0 Time Series Summary for JFK INTERNATIONAL AIRPORT, NY - Month of Nov Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 1976 0.32 0 2 2001 0.61 0 3 2021 0.67 1 4 1993 0.88 0 5 1974 1.10 0 6 1998 1.13 0 7 2015 1.20 0 8 1949 1.30 0 9 1965 1.36 0 10 2009 1.41 0 - 1973 1.41 0 Time Series Summary for ISLIP-LI MACARTHUR AP, NY - Month of Nov Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 1976 0.39 0 2 2001 0.63 0 3 2021 0.71 1 4 1965 1.08 0 5 1991 1.27 0 6 1990 1.57 0 7 1998 1.64 0 - 1974 1.64 0 - 1964 1.64 0 8 1984 1.69 0 9 2019 1.81 0 10 2012 1.91 0

We have seen high temperatures reach 55+ every year since 2011 between the 18th and 25th. This warm up approaching the holidays has happened in every ENSO state from La Niña to El Niño. Time Series Summary for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Ending Date Highest Max Temperature Dec 18 to Dec 25 Missing Count 2020-12-25 62 0 2019-12-25 57 0 2018-12-25 61 0 2017-12-25 57 0 2016-12-25 59 0 2015-12-25 71 0 2014-12-25 64 0 2013-12-25 71 0 2012-12-25 57 0 2011-12-25 62 0

They made the decision in the 90s when the office moved to OKX to accept the less accurate readings from Central Park. But National Weather Service meteorologists say they knew the weather readings in the park would never be as keenly accurate as the ones at the airports where guidelines prevent foliage from being within 100 feet of the station.

It was regularly getting stolen in the 1970s. Also notice how they mention that Central Park was warmer than LGA during the summer in the 1970s when the equipment was out in the open. Now it’s hidden underneath the trees and people can’t see it. So while it’s bad for accuracy, at least they don’t have to worry about it getting stolen or vandalized anymore. https://www.nytimes.com/1977/07/22/archives/vandals-in-central-park-forcing-weather-service-to-seek-new-site.html Besides taking New York City's temperature and trying to predict when it will go up or down. National Weather Service forecasters are searching for a new place in Central Park to keep the sensitive instruments they use to prepare their hourly reports. “It's really a sh‐me, but we have to move,” said Harold Gibson, the meteorologist in charge of the New York bureau, as he stepped carefully through the debris at the crumbling Belvedere Castle, where weather data is collected and transmitted electronically to Weather Service headquarters in Rockefeller Center. Mr. Gibson said he decided to leave the hilltop castle, which is the highest point in the park, because he cannot predict the frequency of break‐ins that interrupt the monitoring of temperature, humidity, sunlight and wind at the unmanned station in the unguarded, city‐owned castle, which is south of the Delacorte Theater at 79th Street on the west side of the park. Vandalism Disrupts Work “Mostly we suffer from malicious destruction,” Mr. Gibson said. “The problem up here can be as little as somebody pulling a circuit‐breaker switch that stops the current and halts the measurements. But from our standpoint, that's almost as bad as stealing all the equipment—it disrupts our work.” The last break‐in occurred two weeks ago. The thermometer was not damaged, but the anemometer, which meastures wind speeds, was stolen, and other equipment has not functioned properly since. Some of the forecasters work in windowless rooms and cannot tell whether the sun is shining without the Central Park equipment. As a result, visitors to the Weather Service office at Rockefeller Center are sometimes asked what the weather outside is like. When the devices at the castle are not functioning, the Weather Service substitutes readings from La Guardia Airport. But Mr. Gibson said those readings do not really reflect conditions in the city, because they may be several degrees cooler in summer or warmer in winter than those in Central Park. During the current hot spell, the Weather Service has used wind and humidity readings from La Guardia in its forecasts. Replacing the Central Park equipment is fairly expensive—an anemometer costs about $2.500, Mr. Gibson said—but the forecasers arc reluctant to install replacements because they fear another break‐in. “Whoever does this to us is speedy,” Mr. Gibson said, recalling_ one break‐in that had occurred in the morning. By 2:30 P.M. the repairs were completed. No sooner was the 4 P.M. forecast released than the new equipment was stolen. The police have increased the number of patrols passing the castle, and that has deterred some vandals, Mr. Gibson said. And the Parks Department put steel gratings over the windows after vandals smashed through the concrete blocks that had been installed in place of the semicircular windows. “Clearly, that's not enough,” said Joseph P. Bresnan, director of historic parks, monuments and restoration. “That building should be used.” Meanwhile, the stonework at the castle, which was designed by Calvert Vaux, a collaborator wtih Frederick Law Olmsted on the design of Central Park, has been frescoed with graffiti. A $557,000 project to restore the castle, the top priority item in a 1973 study of Central Park, has been put off indefinitely because of the city's economic problems. One possible site for housing the sensitive instruments is the roof of the Central Park Precinct station house, which the police have offered. It is only a short distance from the castle, and meteorologists think the climate conditions there are almost identical to those at Belvedere, where weather data have been gathered for 109 years. “It would be almost criminal to destroy the century‐old data base we have accumulated here at Central Pork.” Mr. Gibson said. “It is one of the best in the United States, or, for that matter, in the world.”

Before the Central Park thermometer was located under the trees, it used to have similar high temperatures to EWR and LGA during heatwaves. This shows open areas of the park outside of deep shade are much closer to LGA and EWR than people realize. The big 1970s heatwaves are a great example of this. 1970s heatwaves in NYC before the trees were similar or warmer at times than EWR and LGA Data for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature 1973-08-28 98 77 1973-08-29 95 76 1973-08-30 98 78 1973-08-31 94 74 1973-09-01 95 72 1973-09-02 94 74 1973-09-03 96 75 1973-09-04 93 74 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature 1973-08-28 100 79 1973-08-29 96 79 1973-08-30 98 79 1973-08-31 97 78 1973-09-01 95 75 1973-09-02 95 77 1973-09-03 94 79 1973-09-04 95 75 Data for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature 1973-08-28 97 78 1973-08-29 94 77 1973-08-30 96 81 1973-08-31 94 75 1973-09-01 91 73 1973-09-02 92 75 1973-09-03 93 75 1973-09-04 93 75 Data for NY CITY CENTRAL PARK, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature 1977-07-13 93 73 1977-07-14 92 73 1977-07-15 96 72 1977-07-16 98 75 1977-07-17 97 78 1977-07-18 100 78 1977-07-19 102 78 1977-07-20 92 75 1977-07-21 104 78 Data for NEWARK LIBERTY INTL AP, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature 1977-07-13 92 73 1977-07-14 91 73 1977-07-15 93 71 1977-07-16 97 72 1977-07-17 99 77 1977-07-18 98 75 1977-07-19 100 78 1977-07-20 90 75 1977-07-21 102 78 Data for LAGUARDIA AIRPORT, NY Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature 1977-07-13 92 72 1977-07-14 89 72 1977-07-15 90 69 1977-07-16 96 72 1977-07-17 95 74 1977-07-18 95 76 1977-07-19 99 75 1977-07-20 90 74 1977-07-21 99 78

It’s exactly the type of fast Pacific Jet pattern across the US that we get this time of year with no blocking and a strong -PDO.

The thermometer needs to be in a fan aspirated radiation shield which all ASOS, NCDC, and mesonet weather stations have. But the sensor itself can’t be located under a dense canopy of trees which will keep it several degrees cooler than surrounding open grassy fields. The NY mesonet site has a great video on the proper sitting of weather sensors near heavily wooded areas away from tall trees. NYC ASOS violates official sitting rules http://www.weather2000.com/ASOS/NYC_ASOS.html You can imagine how much denser the canopy has become since the 2013 photo and 2003 story. Central Park Weather: Vegetative Overgrowth Affecting Weather Readings - WABC-TV (New York-WABC, August 22, 2003) - Forecasting the weather is not easy. Government equipment can often be blamed for giving faulty weather information. As Bill Evans explains, a big culprit may be some of the equipment buried in Central Park. Rainfall, snowfall, and the temperature are all vital information recorded 24 hours a day at the weather station located in the heart of Central Park. But meteorologists like Michael Schlacter have serious concerns about the accuracy of the stations data. It sits amid overgrown vegetation and he says thats the problem. The leaves can trigger snow gauges and trees can warp rain and wind measurements. On this hot day, a temperature gauge is in the shade instead of direct sunlight. Michael Schlacter, Weather 2000: "Its kind of like driving a car without a speedometer, odometer, and gas gauge. You are running with false information." The weather instruments at Belvedere Castle have long adorned the top. There used to be a government meteorologist here in the city to keep an eye on them. But now the nearest meteorologist is 60 miles that way. But National Weather Service meteorologists say they knew the weather readings in the park would never be as keenly accurate as the ones at the airports where guidelines prevent foliage from being within 100 feet of the station. Schlacter: "We knew that at times we would have flaky readings, that leaves would fall in gauges, that we would have problems with visibility sensors." [NWS Meteorologist-in-Charge Michael] Wyllie says the weather station is there because it was historically significant to maintain its presence in the park. He says theres been a lot of growth because of the wet spring at so much in fact that temperatures have routinely been recorded lower in the park than at the airports. Wyllie: "We are actually having a micro climate system there because of the vegetation." Imperfect perhaps but nonetheless the system provides the official record of weather for the country's largest city. And Michael Schlacter says its a city that deserves better. Schlacter: "I think New Yorkers deserve a lot better, and I think they deserve the best weather station money can buy." Copyright 2003 ABC Inc., WABC-TV Inc.

The MJO 6 is building the ridge over the West while the fast Pacific Jet tries to flatten it out. So the trough can’t dig into the Southeast. We end up with the gradient favoring New England. There is a parade of storms crossing the Northern Tier. This results in warm ups for us ahead of the Great Lakes lows and cool downs behind.

Changing the NYC temperature measurements to underneath a dense tree canopy in the 1990s has had a big impact on the high temperatures while the trees still have leaves on them. The older NYC thermometer out in the open like the other official stations prior to the 1990s was more in line with EWR and LGA. Once the leaves drop over the next week or so, the highs will be similar to LGA and EWR again. NYC has experienced an artificial reduction in annual 90° days since the 1990s due to the foliage blocking the sensor. But winter 50° days have increased at similar rate to EWR and LGA. Those bare trees during the winter don’t block nearly as much sun as the fully leafed out trees do. So open areas of Central Park probably have closer to 23 to 25 days reaching 90° as opposed the 17 located in the deep shade. That’s how big a difference it makes when you take temperatures under a dense tree canopy instead of an open field. EWR 90° days 1961-1990…..23……1991-2020…..28……+5 NYC 1961-1990…..18……1991-2020…..17………-1 LGA 1961-1990….14…….1991-2020….22……..+8 EWR winter 50° days 1961-1990….16……1991-2020…..23…….+7 NYC 1961-1990….16…..1991-2020…..22……..+6 LGA 1961-1990….14……1991-2020…22………+8

I posted the recent photos of the delayed Manhattan leaf drop a few days ago. You probably don’t remember when the Central Park high temperatures were on par with EWR and LGA. They installed the new ASOS under a stand of trees in the 1990s that grew into a dense canopy over the last 30 years. The old thermometer used to be in the open area near the castle with no trees shading the sensor. So when you take high temperature readings under a dense canopy of trees, it can be several degrees cooler than in a nearby open field depending on the weather conditions. That’s why you can’t take official temperature measurements directly underneath trees. Even rural weather stations like at the NWS in Upton are located in a clearing away from trees. They would never place their equipment out there underneath the dense natural pine barrens in that area. All part of the standardization process of how official weather measurements are taken.

First flakes of the season here in SW Suffolk. Light dusting earlier on the rooftops and cars. Temperature at 37° now.

You can see the gradient favoring New England at least in early December.

Yeah, the day 11-15 EPS looks like a classic 0z to 12z run windshield wiper effect. One run tries to pump the Western ridge with more of a MJO 6 influence. The next run leans more on the fast Pacific Jet and tries to flatten the ridge. But the storm track should be similar either way with lows passing through the Great Lakes every several days. Brief warm ups ahead of the lows followed by cool downs behind.

That’s an error caused by the delayed leaf drop keeping thr ASOS in the shade. Even HPN made it to 40°. The temperatures won’t become reliable until the dense canopy finally drops all its leaves. EWR 43 NYC 39 JFK 41 LGA 42 HPN 40

An open field in Central Park would be a great place to measure temperatures in NYC. Before the new ASOS was installed in the mid 90s, the old sensor was in the open. That’s why the NYC high temperatures were more in line with LGA and EWR up through the 1980s. They let the trees grow over the ASOS and put it in deep shade. That’s why there is a continuity break in the NYC observations from the days when the sensor wasn’t in the shade. So the highs became cooler relative to EWR and LGA since the 1990s. Central Park was warmer at times than EWR and LGA like during the July 1977 heatwave. So the lower 90 degree counts at the park since the 90s is just an artifact of the ASOS being in deep shade. If they would allow the ASOS to be moved to one of the open fields in Central Park, then you would immediately see an increasing 90 day count closer to EWR and LGA like the old days.

Another top 5 warmest fall across the Northeast.

Yeah, I think the PNA trying to go positive again is a result of the MJO slowing in phase 6. MJO812 posted the composite for a La Niña a few posts back. The link that has the ENSO specific MJO phases is below. The phase 6 during a La Niña in December has more of a +PNA and trough near the Northeast. But since we have such a fast Pacific flow with a +EPO, it may end up favoring New England more while we still remain in phase 6. The big question is how long the MJO lingers in phase 6? At the very least, it may slow down any transition to a more zonal flow during the 2nd week of December. https://www.frenchscotpilotweather.com/mjo

The stations that I posted are closest to the core of the heat island. Places like JFK and TEB are more on the periphery. My comparison was about the low temperatures within the central areas of the heat island. Not a comparison of low temperatures between the heat island and more suburban or rural areas.

Plants developed their own version of the internet long before we did.

It’s amazing how intelligent and interconnected nature is.

That’s not what the raw data says. The minimums and maximum departures have been running lower than the surrounding ASOS sites. NYC has also been running colder than many of the micronet sites. The first freeze in NYC was much closer to the recent average date than areas away from the heat Island. POU had one of their latest first freezes on record. While NYC wasn’t even close to its latest first freeze. NYC had the lowest temperature on the coldest morning this week for surrounding urban sites 11-24 low temperatures EWR…32 NYC…30 LGA….33 Corona….32 Queensbridge….32 East 40th Manhattan….33

Some of the rooftop gardens around Central Park are gorgeous.

Urban environments can cool at night with enough of a tree canopy when it’s very dry like November has been in NYC with only 1.00”. https://www.sciencedirect.com/science/article/abs/pii/S1618866716303776 Highlights • Urban trees are incorporated into an advanced single-layer urban canopy model. • Shading effect of trees is enabled by a Monte Carlo ray-tracing algorithm. • The fully-integrated WRF-urban modeling system with trees was applied to simulate. • Urban hydroclimate in an arid city. • The cooling effect of urban shade trees is found to be more prominent in nighttime.

With the unusually calm winds this month, it almost looks like all the foliage near the sensor is creating a very localized radiational cooling effect. We can see how much cooler the highs are than the other stations that are in open sunlight. But the cold departure is much lower than any of the other urban sites. EWR…max….+2.4….min….-0.5 NYC…max….-0.1…..min…..-1.8 LGA….max…..+1.1….min….+0.3 JFK….max…..+1.6….min….-1.2 ISP…..max…..+1.9…..min….-2.2

Looks like the delayed leaf drop keeping the NYC ASOS in deep shade has allowed it to have a colder departure this month so far of the major ASOS sites. The other stations are -0.2 to +0.9. While the departures will decline with colder temperatures to close out the month, NYC will be artificially low. EWR…+0.9 NYC….-0.9 LGA…..+0.7 JFK….+0.2 ISP…..-0.2