May 2021

[donsutherland1]

The temperature rose to 90° or above in numerous locations for a second consecutive day. Areas reporting 90° temperatures included:

Allentown: 90°
Atlantic City: 94° (tied record set in 1964)
Baltimore: 95°
Bridgeport: 90° (old record: 89°, 1992)
Boston: 90°
Georgetown: 93° (tied record set in 1964)
Harrisburg: 93°
New York City-JFK: 92° (old record: 89°, 1964 and 1980)
Newark: 94°
Philadelphia: 92°
Providence: 90°
Sterling, VA: 92° (tied record set in 1964)
Trenton: 90°
Washington, DC: 94°
Wilmington, DE: 94° (tied record set in 1925)

Yesterday was the first day on record in May when Islip reached 90° or above while New York City's Central Park did not reach 90°. Today became the first day on record when Bridgeport reached 90° or above, but Central Park did not reach 90°.

90° Days for Select Cities (through May 23):

Albany: 0 (2020: 13 days; 5-Year Average: 13.6 days)
Allentown: 1 (2020: 24 days; 5-Year Average: 27.6 days)
Baltimore: 2 (2020: 46 days; 5-Year Average: 44.6 days)
Boston: 1 (2020: 14 days; 5-Year Average: 17.2 days)
Bridgeport: 1 (2020: 11 days; 5-Year Average: 13.4 days)
Burlington: 2 (2020: 20 days; 5-Year Average: 13.0 days)
Harrisburg: 1 (2020: 35 days; 5-Year Average: 30.6 days)
Hartford: 1 (2020: 39 days; 5-Year Average: 29.0 days)
Islip: 1 (2020: 8 days; 5-Year Average: 9.4 days)
New York City-JFK: 2 (2020: 12 days; 5-Year Average: 10.2 days)
New York City-LGA: 0 (2020: 34 days; 5-Year Average: 29.4 days)
New York City-NYC: 0 (2020: 20 days; 5-Year Average: 18.2 days)
Newark: 3 (2020: 31 days; 5-Year Average: 31.2 days)
Philadelphia: 2 (2020: 36 days; 5-Year Average: 34.6 days)
Scranton: 1 (2020: 25 days; 5-Year Average: 16.4 days)
Washington, DC: 3 (2020: 46 days; 5-Year Average: 50.8 days)

New York City-Newark Average: 1 (2020: 22 days)
...Expected: 2 (based on regression equation tied to JFK-LGA-EWR data)

To date, JFK Airport has recorded more 90° temperatures than both Central Park and LaGuardia Airport. Only 1978 and 1984 saw JFK report more 90° than both Central Park and LaGuardia Airport.

Tomorrow and Tuesday will see a return of noticeably cooler air before another big push of warm air takes place.

The dominant weather story into the closing week of May will be the synoptic impact of a strongly to occasionally severely negative PNA. That development will lead to a warmer to perhaps much warmer than normal second half of May. There will likely be at least one more day on which the temperature will make a run at 90° in parts of the region this week.

Today, the preliminary value of the PNA was -1.121. The PNA will likely rise above -1.000 tomorrow. During the May 16-31, 1991-2020 period, the mean temperature was 65.2° in New York City and 67.0° in Philadelphia. When the PNA was -1.000 or below, the average temperature was 67.7° in New York City and 69.3° in Philadelphia. During the May 16-23 period, the likely mean temperatures will be 71.3° at New York City and Philadelphia 70.6° at Philadelphia.

During the 1991-2020 period, 30% of days in New York City and 41% of days in Philadelphia had high temperatures of 80° or above. During the 1991-2020 period, 15% of days in New York City and 23% of days in Philadelphia had high temperatures of 85° or above. When the PNA was -1.000 or below during that period, 41% of days in New York City and 50% of days in Philadelphia had high temperatures of 80° or above. When the PNA was -1.000 or below during that period, 24% of days in New York City and 35% of days in Philadelphia had high temperatures of 85° or above. During the May 16-23 period, the temperature reached 80° or above on 50% of days and 85° or above on 38% of days in New York City. The temperature reached 80° or above on 75% of days and 85° or above on 38% of days in Philadelphia. In both cities, the warmth overperformed somewhat.

As had been the case with April, the closing week of May could wind up warmer to much warmer than normal. In the four cases where the MJO reached Phase 1 at an amplitude of 2.000 or above in combination with a cool ENSO Region 3.4 anomaly during the May 1-10 period, as occurred this year, three wound up with warmer to much warmer than normal conditions. At New York City, the mean temperature during the closing 7 days of May was 72.7° during those three cases while it was 72.0° at Philadelphia. The 1991-2020 means were 67.9° and 69.7° respectively. Only May 25-31, 2013 (monthly ENSO Region 1+2 anomaly of -1.38°C) was cooler than normal. However, 90° heat arrived on May 29 in Philadelphia and May 30 in New York City during 2013.

Nevertheless, the Memorial Day weekend will likely be unsettled and cooler. Periods of rain are possible, though there is large uncertainty about the amount of precipitation. A light to perhaps moderate rainfall appears more likely than a heavy rainfall based on the ensembles.

The first 7-10 days of June could also start off warmer than normal. The MJO's passage through Phase 4 at an amplitude of 1.500 or above during the May 15-25 period coupled with ENSO Region 1+2 temperature anomalies above -1.0°C and below +1.0°C, as has been the case this year, has typically seen warmth in the East during the first 10 days of June. Cooler conditions typically prevailed when the ENSO Region 1+2 anomalies were outside that range.

Neutral ENSO conditions have now developed. The ENSO Region 1+2 anomaly was -0.6°C and the Region 3.4 anomaly was -0.3°C for the week centered around May 12. For the past six weeks, the ENSO Region 1+2 anomaly has averaged -0.75°C and the ENSO Region 3.4 anomaly has averaged -0.38°C. Neutral ENSO conditions will likely prevail into at least mid-summer.

The SOI was +6.68 today.

The preliminary Arctic Oscillation (AO) figure was +1.261 today.

On May 21 the MJO was in Phase 4 at an amplitude of 1.644 (RMM). The May 20-adjusted amplitude was 1.863 (RMM).

In late April, the MJO moved through Phase 8 at an extreme amplitude (+3.000 or above). Only February 25, 1988 and March 18-19, 2015 had a higher amplitude at Phase 8. Both 1988 and 2015 went on to have an exceptionally warm July-August period. July-August 1988 had a mean temperature of 79.1°, which ranked 4th highest for that two-month period. July-August 2015 had a mean temperature of 78.9°, which ranked 5th highest for that two-month period. September 2015 was also the warmest September on record. The MJO's extreme passage through Phase 8 could provide the first hint of a hot summer.

Based on sensitivity analysis applied to the latest guidance, there is an implied 80% probability that New York City will have a warmer than normal May (1991-2020 normal). May will likely finish with a mean temperature near 64.5° (1.3° above normal).

 

[crossbowftw3]

Temperatures tumbling. 73/61

[psv88]

Beautiful evening! 80 and light breeze

[SACRUS]

5/23

ACY: 94
EWR: 94
JFK: 92
PHL: 92
BLM: 92
TTN: 90
New Brnswck: 90
TEB: 89
ISP: 89
LGA: 88
NYC: 88

[psv88]

3 minutes ago, SACRUS said:

5/23

ACY: 94
EWR: 94
PHL: 92
BLM: 92
TTN: 90
New Brnswck: 90
TEB: 89
ISP: 89
LGA: 88
NYC: 88

BLM replaced JFK? I think NJ plenty well represented on that list already with 7 lol, spread the wealth

[SACRUS]

9 minutes ago, psv88 said:

BLM replaced JFK? I think NJ plenty well represented on that list already with 7 lol, spread the wealth

JFK: 92

missed the paste.

[tmagan]

Central Park has not been above 96 degrees since September 8, 2015. That is tied for the second longest streak of all time with January 1, 1869 [beginning of record] to June 29, 1874. The all time record is ten years and one day from July 2, 1901 to July 3, 1911.

[psv88]

6 minutes ago, tmagan said:

Central Park has not been above 96 degrees since September 8, 2015. That is tied for the second longest streak of all time with January 1, 1869 [beginning of record] to June 29, 1874. The all time record is ten years and one day from July 2, 1901 to July 3, 1911.

More accurately stated, the Central Park thermometer has not recorded a reading above 96 degrees since that date...

[donsutherland1]

16 minutes ago, psv88 said:

More accurately stated, the Central Park thermometer has not recorded a reading above 96 degrees since that date...

IMO, the statistical evidence (slight cooling in summer high temperatures at Central Park while the remainder of the region has warmed approximately one degree F) demonstrates that the summer records are inaccurate. One of three measures should be taken to preserve or restore data integrity:

1. Trees should be trimmed so that the ASOS is in compliance with customary practice

2. The ASOS should be moved to an alternative location in the Park that would be in compliance and also have limited risk of falling out of compliance anytime soon

3. Homogenization of the Central Park temperatures to bring them into line where they should be (some degree of error would exist)

All three of these approaches are preferable to increasingly flawed summer data. I'd prefer the first two, but the third would be a useful resort were the first two not pursued.

[lee59]

If Central Park temperatures are a little to low in the day, it doesn't make up for the heat island affect at night. Another thing is the temperature readings at airports are in many cases surrounded by those hot tarmacs. I wonder if the open space of the airport lets the wind pick up that hot tarmac temperature and just make the entire airport temperature higher on those very hot sunny days.

[Intensewind002]

Disgustingly hot in my house, me and my dad haven't put the air conditioners in yet 

[lee59]

89 degree high here for the second day in a row. 65 degrees for tomorrow and still not a drop of rain.

[LibertyBell]

2 hours ago, lee59 said:

If Central Park temperatures are a little to low in the day, it doesn't make up for the heat island affect at night. Another thing is the temperature readings at airports are in many cases surrounded by those hot tarmacs. I wonder if the open space of the airport lets the wind pick up that hot tarmac temperature and just make the entire airport temperature higher on those very hot sunny days.

JFK temps are matched here in SW Nassau

[LibertyBell]

2 hours ago, donsutherland1 said:

IMO, the statistical evidence (slight cooling in summer high temperatures at Central Park while the remainder of the region has warmed approximately one degree F) demonstrates that the summer records are inaccurate. One of three measures should be taken to preserve or restore data integrity:

1. Trees should be trimmed so that the ASOS is in compliance with customary practice

2. The ASOS should be moved to an alternative location in the Park that would be in compliance and also have limited risk of falling out of compliance anytime soon

3. Homogenization of the Central Park temperatures to bring them into line where they should be (some degree of error would exist)

All three of these approaches are preferable to increasingly flawed summer data. I'd prefer the first two, but the third would be a useful resort were the first two not pursued.

we've repeatedly changed snowfall measurements after the fact, I dont get the hesitation here.

 

[Intensewind002]

15 minutes ago, LibertyBell said:

we've repeatedly changed snowfall measurements after the fact, I dont get the hesitation here.

 

There is no reason not to really, me on the south shore of suffolk county should not be getting readings equal or higher than NYC (except maybe in winter)

[CIK62]

The last 8 days of May are averaging 65degs.(56/73), or -1.0.

Month to date is  63.3[+1.2].       May should end near 63.8[+0.6].

Only part of Holiday Weekend looks like it can be salvaged.[Latest GFS looks wet at anytime you pick during Holiday now.]      GFS continues with May 26th.  at 90 degrees.      Other models now under 90.

Next hot period should kick in June 04 and may last awhile.

Made it to 90 here by 4:30pm yesterday.     Was still 89 at 6pm.

{Was 73* at Midnight}     64*(51%RH), at 6am. scattered thin overcast .        62*/63* at 9am.            58* at 10pm.

[tek1972]

The last 8 days of May are averaging 65degs.(56/73), or -1.0.
Month to date is  63.3[+1.2].       May should end near 63.8[+0.6].
Only part of Holiday Weekend looks like it can be salvaged.      GFS continues with May 26th.  at 90 degrees.      Other models now under 90.
Made it to 90 here by 4:30pm yesterday.     Was still 89 at 6pm.
64*(51%RH), scattered thin overcast.

What part of the weekend?

Sent from my SM-N986U using Tapatalk

[bluewave]

17 minutes ago, tek1972 said:

What part of the weekend?

Sent from my SM-N986U using Tapatalk
 

The higher scoring Euro and CMC are dry for the Memorial Day weekend. They bring in the rain for Friday and Friday night. But it looks like a cool Sat to Mon with plenty of easterly flow. The big high east of New England is back again as we start June.

[donsutherland1]

Morning thoughts...

The morning will feature plenty of clouds. However, it will become partly sunny this afternoon. It will be noticeably cooler than yesterday. Temperatures will likely top out in the 60s and perhaps some lower 70s in most of the region. Likely high temperatures around the region include:

New York City (Central Park): 67°

Newark: 70°

Philadelphia: 71°

Tomorrow will be partly sunny and pleasant.

Yesterday saw some record high minimum temperatures tied or broken at: Islip: 65° (old record: 63°, 2013); New York City-JFK: 68° (old record: 63°, 1980 and 2010); and, Newark: 68° (tied record set in 2013).

[the_other_guy]

11 hours ago, psv88 said:

More accurately stated, the Central Park thermometer has not recorded a reading above 96 degrees since that date...

There is more a play here though. Our minimums have been increasingly warm,  but haven’t had the extreme upper 90s/low 100s that we used to have. The obvious answer is that moist air cools and heats slower.

 

People on here like to pick on the Central Park reading three months of the year for temps, 3 months a year for snow, and ignore the problems for the other 6 months...But I would be curious to know if a densely forested park in the middle of an urban heat Island is experiencing this phenomenon to a greater degree.

The airports are easy; particularly LaGuardia and Newark...They are slabs of cement in densely populated areas. JFK is much larger, has much more open space with grass, is in a national park, and is abeam the Atlantic Ocean.

But I wonder if there is more to this than ASOS placement. Has anyone actually visited the ASOS recently and seen the conditions around it?

 

 

 

 

[psv88]

29 minutes ago, jfklganyc said:

There is more a play here though. Our minimums have been increasingly warm,  but haven’t had the extreme upper 90s/low 100s that we used to have. The obvious answer is that moist air cools and heats slower.

 

People on here like to pick on the Central Park reading three months of the year for temps, 3 months a year for snow, and ignore the problems for the other 6 months...But I would be curious to know if a densely forested park in the middle of an urban heat Island is experiencing this phenomenon to a greater degree.

The airports are easy; particularly LaGuardia and Newark...They are slabs of cement in densely populated areas. JFK is much larger, has much more open space with grass, is in a national park, and is abeam the Atlantic Ocean.

But I wonder if there is more to this than ASOS placement. Has anyone actually visited the ASOS recently and seen the conditions around it?

 

 

 

 

Break it down...why would an already densely forested park get more moist at a faster rate than non forested areas? If anything the opposite should be true. For example, which area gets more humid (from a relative standpoint) from a moist flow, a tropical rain forest or a desert? The desert clearly, because it was already dry....so the park shouldn’t see moderating temps more than any other areas. Rather, because it is more moist already, the rate of change should be slower, not faster, in other areas...

[psv88]

I can’t remember the last time it rained 

[Brian5671]

4 minutes ago, psv88 said:

I can’t remember the last time it rained 

Mother's day here-15 days ago....

[SnoSki14]

1 hour ago, bluewave said:

The higher scoring Euro and CMC are dry for the Memorial Day weekend. They bring in the rain for Friday and Friday night. But it looks like a cool Sat to Mon with plenty of easterly flow. The big high east of New England is back again as we start June.

Yeah bad timing for the upcoming holiday. Monday itself could be salvaged but a good chunk of the weekend looks cool, damp. 

Even worse if you're heading down the shore.

[nycwinter]

what lovely day it is feels like fall nice cool breeze..

[nycwinter]

2 hours ago, psv88 said:

I can’t remember the last time it rained 

it feels like rain every time  i take a shower...

[Juliancolton]

49 minutes ago, nycwinter said:

it feels like rain every time  i take a shower...

So 15 days ago, same as @Brian5671

[bluewave]

3 hours ago, jfklganyc said:

There is more a play here though. Our minimums have been increasingly warm,  but haven’t had the extreme upper 90s/low 100s that we used to have. The obvious answer is that moist air cools and heats slower.

 

People on here like to pick on the Central Park reading three months of the year for temps, 3 months a year for snow, and ignore the problems for the other 6 months...But I would be curious to know if a densely forested park in the middle of an urban heat Island is experiencing this phenomenon to a greater degree.

The airports are easy; particularly LaGuardia and Newark...They are slabs of cement in densely populated areas. JFK is much larger, has much more open space with grass, is in a national park, and is abeam the Atlantic Ocean.

But I wonder if there is more to this than ASOS placement. Has anyone actually visited the ASOS recently and seen the conditions around it?

 

 

 

 

Central Park is a great place for weather observations provided that the ASOS is placed in an open area away from trees. The problem with the Central Park site is that it was no longer maintained after the early 90s. Since the early 90s, is has been tucked in the deep shade under the trees. So the lack of direct sunlight results in afternoon highs that are 2° to 3° cooler than they used to be prior to the 90s. So this created a break in continuity from earlier observations. As for the airports, the ASOS units are placed on grassy surfaces. While there is plenty of concrete at the airports, there really isn’t any more or less than the surrounding neighborhoods where the people live. But since the airports are located on the water, they are prone to sea breezes. So there are neighborhoods around NYC metro that can be hotter depending on wind direction. 
 

Central Park before the sensor was blocked by trees

 

Most recent photo as of 2013 under trees and violating the ASOS handbook sitting rules

 

[dWave]

4 hours ago, jfklganyc said:

There is more a play here though. Our minimums have been increasingly warm,  but haven’t had the extreme upper 90s/low 100s that we used to have. The obvious answer is that moist air cools and heats slower.

 

People on here like to pick on the Central Park reading three months of the year for temps, 3 months a year for snow, and ignore the problems for the other 6 months...But I would be curious to know if a densely forested park in the middle of an urban heat Island is experiencing this phenomenon to a greater degree.

The airports are easy; particularly LaGuardia and Newark...They are slabs of cement in densely populated areas. JFK is much larger, has much more open space with grass, is in a national park, and is abeam the Atlantic Ocean.

But I wonder if there is more to this than ASOS placement. Has anyone actually visited the ASOS recently and seen the conditions around it?

 

 

 

 

For a good chunk of spring CPK isnt fully leafed out yet, so the temp disparity doesn't show as much yet compared to nearby urban stations. Also in spring the Park is a little more protected from the frequent cool E/NE  flow, keeping LGA cooler on some days. As that influence gets weaker later on, back door fronts less common, and the vegetation gets lush the Park's cool bias starts on cue.

I wish I could find the article, but the NWS has already acknowledged this phenomenon is legitimate 10 yrs ago or so. They basically just accept it as is for a few reasons...

1. Technically KNYC is accurate for what it is, a dense semi forested park, and its readings accuratly reflect that. (Kinda putting the onus on the consumer to recognize a park for what it is vs an urbanized street and analyze accordingly.)

2. Its historical significance. Its one of the longest running climate stations, and in America's biggest city. They dont want to mess with it. So its just grandfathered in to the climate data despite falling short of their own offical standards.

3. There are plenty of offical weather stations around it to reflect the local urban climate. (Kind of putting it at the medias feet to use all available data to portray an accurate picture to the public.) In fact the closest offical reporting station for many/most NYC residents isnt KNYC, but LGA or JFK...all of Queens, the BX and portions of BK would fall into that.

The ASOS is not that far from Museum of Natural History. Its fenced in, surrounded by trees, last I saw some now hang over the top as well. In wetter patterns weeds and shrubs will be overgrown near-by too. The trees do help shield it from the public which the NWS probably likes.

[lee59]

As long as were on a discussion involving  the NWS,  does anyone know why the NHC now includes subtropical storms as named tropical storms?