bluewave

All that we know is the new default winter and summer patterns since the super El Niño in 15-16. Warmer than normal winters with above normal snowfall. The two exceptions were the below normal snowfall winters in 18-19 and 19-20. But they were still warm. The summers since 16 have been warmer than average and more humid. The only outlier was the cooler 2017 summer but it was still humid. So it’s very difficult to know ahead of time when the coming season is going to deviate from recent experience.

No problem. The Central Park sensors used to be located in direct sunlight before the trees created deep shade. My rough calculation is that this has created an artificial 2° to 3° average maximum temperature summer JJA cooling since 1971. Notice how the mean summer high temperature increase at the other local stations since 1971 has been +2.7°.The high temperature staying steady at NYC instead of increasing was a function of trees blocking the sun. 1971 to 2020 summer JJA high temperature increase NYC….82.9….82.9…..0.0 LGA…..81.0….84.9….+3.9 EWR….83.4….85.4….+2.0 JFK…..80.1…..82.3..+2.2 ISP…….78.5…..81.6..+3.1 HPN….79.0….81.6…+2.6 BDR….79.1…..81.4…+2.3

The overgrowth of vegetation blocking the sensors has been well known for a while now. They would need to move the ASOS to a clearing away from any trees. The video below shows the correct sitting of weather sensors in parks or more rural settings. 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 http://www.weather2000.com/ASOS/NYC_ASOS.html 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.

This weekend actually looks like our last dry heat for a while. The next warm up on Wednesday is forecast to be more humid. So we may get back to the familiar 70° dewpoints. It would fit with the guidance showing better rain chances coming up.

The 36° degree difference between the high and low at JFK is the 2nd greatest on record for May. Just goes to show how dry it has been. This is closer to normal for Tucson, Arizona. CLIMATE REPORT NATIONAL WEATHER SERVICE NEW YORK, NY 434 PM EDT SAT MAY 22 2021 ................................... ...THE KENNEDY NY CLIMATE SUMMARY FOR MAY 22 2021... VALID TODAY AS OF 0400 PM LOCAL TIME. CLIMATE NORMAL PERIOD 1991 TO 2020 CLIMATE RECORD PERIOD 1948 TO 2021 WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST VALUE (LST) VALUE VALUE FROM YEAR NORMAL ................................................................... TEMPERATURE (F) TODAY MAXIMUM 94R 148 PM 94 1992 70 24 73 MINIMUM 58 243 AM 43 1990 54 4 52 AVERAGE 76 62 14 63 ...THE TUCSON AZ CLIMATE SUMMARY FOR MAY 21 2021... CLIMATE NORMAL PERIOD 1991 TO 2020 CLIMATE RECORD PERIOD 1895 TO 2021 WEATHER ITEM OBSERVED TIME RECORD YEAR NORMAL DEPARTURE LAST VALUE (LST) VALUE VALUE FROM YEAR NORMAL ................................................................... TEMPERATURE (F) YESTERDAY MAXIMUM 89 325 PM 107 2005 94 -5 89 MINIMUM 68 1159 PM 42 1899 63 5 53 AVERAGE 79 78 1 71

JFK tied the record high of 94° today. 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.

The 93°at JFK is just under the 94° record high. 22 May 1:51 pm 92 52 26 WNW 16 10.00 FEW060,SCT190,BKN250 30.12 1020.4 30.13 93 67

Newark is close with a high of 94° so far today. 22 May 1:51 pm 93 54 27 NW 13 10.00 FEW140,FEW200,OVC250 30.11 1020.4 30.13 94 75

Easy to beat guidance with such dry conditions. Newark Liberty CLOUDY 92 52 25 NW13G21

91° at Newark with the warm downslope flow.

Higher population in Manhattan during those years than today. the Manhattan island population in 1900 was even larger (1.85 million persons in 1900) than today 1.54 million in 2000), due to turn-of-century immigration. So to the extent that population is an indicator of UHI strength, the relative 1900 UHI magnitude may be partial- ly understandable. http://www.theurbanclimatologist.com/uploads/4/4/2/5/44250401/gaffinetal2008nycuhiandtemptrends.pdf

Slowing AMOC and rapidly warming Gulf Of Maine have gone together with the anomalous ridging over New England and the Canadian Maritimes. So I guess that it’s no surprise that the seasonal models have a similar pattern this summer. It will be interesting to see if we can make it four summers in a row.

It’s been tough to bet against the greatest 500mb height anomalies setting up over New England since 2018. The stronger ridging to our NE has allowed for higher dewpoints and more onshore flow. If you want more westerly flow dry heat events like 2010 to 2013, then the best 500 mb anomalies need to be over the Great Lakes.

Second May in a row up at BTV with a top three warmest monthly maximum temperature. RECORD REPORT NATIONAL WEATHER SERVICE BURLINGTON VT 135 AM EDT FRI MAY 21 2021 ...RECORD HIGH TEMPERATURE SET AT BURLINGTON VT... A RECORD HIGH TEMPERATURE OF 92 WAS SET AT BURLINGTON VT YESTERDAY. THIS BREAKS THE OLD RECORD OF 91 SET IN 1975. Time Series Summary for Burlington Area, VT (ThreadEx) - Month of May Click column heading to sort ascending, click again to sort descending. Rank Year Highest Max Temperature Missing Count 1 2020 95 0 2 2017 93 0 - 1977 93 0 3 2021 92 11 - 2010 92 0 - 1987 92 0 - 1979 92 0 - 1978 92 0 - 1929 92 0 - 1911 92 0

Detroit was very close to the all-time May 500 mb height record this morning. Had we seen this anomalous a ridge during the summer, it would probably mean temperatures approaching or exceeding 100° In the Northeast. So it will be interesting to see if Newark can sneak in at least 95° max this month.

While specific rainfall forecasts past 5 days can be low skill, the Euro has a chance of rain on Memorial Day weekend. Every Memorial Day weekend for the last 5 years had measurable rainfall one out of the three days. We just missed a deluge in 2015 with 3.73 on Tuesday May 31st at Newark. Newark Memorial Day bolded 5-25-20…..5-23….0.79 5-27-19……5-26…0.20 5-28-18…..5-27….0.87 5-29-17…..5-29…..0.14 5-30-16……5-30…..1.57…….our last very dry spring Tuesday 5-31-15……3.73

If the long range guidance is correct, then the humidity will probably increase as we head into June. So this is when we could start to see better chances for rain again. The record breaking ridge just to our west is acting as a block. EPS lifts the ridge axis north to near the Canadian Maritimes to start June. This is where the ridge axis was for the last 3 summers with the warm and moist onshore flow. So it will be interesting to see if we can make it 4 in a row. EPS May 31- June 7 forecast

This was the lowest relative humidity 90° day at Newark in May since 2016. Came in with a relative humidity of 19% at 4pm. Matches up with this being the driest spring at Newark since 2016. Newark Liberty MOSUNNY 90 43 19 5-26-16…..91/43/19% 5-25-16…..90/39/17% Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Mar through May Click column heading to sort ascending, click again to sort descending. Rank Year Total Precipitation Missing Count 1 1935 4.54 0 2 2016 6.35 0 3 1941 6.50 0 4 1965 6.64 0 5 1995 6.81 0 6 2021 6.95 13 7 1985 6.99 0 8 1963 7.19 0 9 1959 7.61 0 10 1938 7.68 0 11 1981 8.13 0 12 2006 8.19 0 13 1962 8.25 0 14 1992 8.29 0 - 1971 8.29 0 15 1964 8.35 0

Highs close to 90° today with the extremely dry forecast soundings.

Looks like we will have to keep watering through at least the weekend. The record rains have been along the western side of the ridge. This is our 2nd dry spring in row.

Models have been really struggling with the timing of the backdoor cold front later this week. Looks like Wednesday could be the warmest day of the week now. We’ll have to wait for later runs to refine the timing. In general, it seems like guidance has been jumping around quite a bit beyond 3-5 days recently. The very amplified pattern has been a challenge to the models.

The ridge should be really impressive before the front arrives later in the week. 500mb heights will be close to record levels in areas just to our west. Rainfall will be much needed as the Euro has a lower dewpoint warm up.

12z Euro has something for everyone. The warm spots could see their first 90° of the season on Thursday. Then it has a backdoor for Friday. It’s a compromise between the warmer CMC and cooler GFS. Models struggling with where too place the ridge axis and offshore low.

That was the famous sensor calibration error when the temperature at Newark stopped recording. While the temperature was missing at Newark, Harrison reached 106°. But they went with the last reading at 12:38 at Newark of 103° before the outage. Central Park made it to 103° just after 3pm with all the foliage blocking the sensor. So the actual high at Newark was probably around 106°. Data for July 6 - HARRISON, NJ Click column heading to sort ascending, click again to sort descending. Date Max Temperature Min Temperature Precipitation Snowfall Snow Depth 2010-07-06 106 80 0.00 0.0 0 PUBLIC INFORMATION STATEMENT NATIONAL WEATHER SERVICE NEW YORK NY 509 PM EDT TUE JUL 6 2010 ...HIGH TEMPERATURE RECORDS FOR JULY 6TH BROKEN OR TIED AT ALL SIX WFO NEW YORK NY CLIMATE SITES. .....TEMPERATURE.....TIME (LDT).....PREVIOUS RECORD CENTRAL PARK NY........103............311 PM...........101 1999... LA GUARDIA NY..........103............342 PM...........101 1999... JFK ARPT NY............101...........1240 PM............99 1999... ISLIP NY...............101............255 PM............99 1999... BRIDGEPORT CT...........98...........1252 PM............98 1999... NEWARK NJ..............103*..........1234 PM...........102 1999... *NOTE: SENSOR CALIBRATION ERROR OCCURRED AT NEWARK NJ. OFFICIAL TEMPERATURE OF 103 WAS MEASURED BY FAA CONTRACT OBSERVER.

You can see how the more onshore flow since 2018 has allowed Harrison to pull ahead of Newark. During the previous years with less sea breeze activity, both stations were nearly equal in 90° days and summer maximum temperature. This reflects the record ridging near and east of New England last 3 summers producing more S to SSE flow. Time Series Summary for NEWARK LIBERTY INTL AP, NJ - Jan through Dec Click column heading to sort ascending, click again to sort descending. Year Number of Days Max Temperature >= 90 + Max Harrison 2020 31 96 39 98 2019 27 99 39 101 2018 36 98 47 101 2017 22 99 23 98 2016 40 99 40 100 2015 35 98 32 99 2014 15 98 16 95 2013 25 101 25 102 2012 33 104 35 103 2011 31 108 31 107 2010 54 103* 50 106 * 2010 thermometer malfunction at Newark during hottest day of year leaving high 3° too cool