[simonusa3]

Originally Posted by 7 Wishes

On the overall average, yes, but what it does is usually lower the daytime highs as it lessens the heating effect of the sun but raises the nighttime lows as it acts as a blanket to keep heat from escaping.

A lot of places through the decades have had small, sometimes even not statistically significant rises in the highs but most of the "warming" is actually in the nighttime lows. Now there can be a lot of debate as to why (and why since it's part of the reason we are cloudier and get more precip in the past), be it growing UHI, greenhouse effect from CO2 etc or even just natural causes (or perhaps a combination of all 3), but just noting a fact here, no point or agenda on this one.

Agree, there’s no doubt that clouds act as a blanket at night and keep nighttime lows up.

However, I also, think when conditions are right, they can also help boost daytime highs:

A cloudy night followed by a clearing morning, can help temps start off higher than they would without a cloudy night. We often experience this right here in the Tri-State area in deep summer. Even as a kid I have vivid memories with my brothers of hot, humid, cloudy nights in July or August, (the low would never fall below say 77 - 78 F), followed by heavy thundershowers in the middle of the night, then that sun would be burning through the blinds at 7 AM and the temp was already near 80 F. By noon we were already near 90 F. lol

[jbgusa]

Originally Posted by simonusa3

Agree, there’s no doubt that clouds act as a blanket at night and keep nighttime lows up.

However, I also, think when conditions are right, they can also help boost daytime highs:

A cloudy night followed by a clearing morning, can help temps start off higher than they would without a cloudy night. We often experience this right here in the Tri-State area in deep summer. Even as a kid I have vivid memories with my brothers of hot, humid, cloudy nights in July or August, (the low would never fall below say 77 - 78 F), followed by heavy thundershowers in the middle of the night, then that sun would be burning through the blinds at 7 AM and the temp was already near 80 F. By noon we were already near 90 F. lol

I remember a spectacular example of that in July 1995. We got down to maybe 83° during the night. We had a quick shower in the morning and then it cracked 100 in the afternoon. that was followed by a semi-back door, cold front with straight line or derecho winds, pretty widespread and very destructive further upstate.

[simonusa3]

Originally Posted by jbgusa

I remember a spectacular example of that in July 1995. We got down to maybe 83° during the night. We had a quick shower in the morning and then it cracked 100 in the afternoon. that was followed by a semi-back door, cold front with straight line or derecho winds, pretty widespread and very destructive further upstate.

Interesting memory.

I think it would be interesting to research how many nights from June through mid September the three area NWS stations that have lows of 80 F or higher. My guess is most occur from late June to late August.

[simonusa3]

As of 8 am obs...most locations already in the 50's F (New Haven/Danbury 55F) under sunny skies. Should be a perfect mid April day. With the strong sun and west winds will be interesting to see how far into the 70's each location gets?

[RoundTableKnight]

I was told I was supposed to see the sun today? Nothing but grey skies where is my sun???????

[7 Wishes]

Originally Posted by simonusa3

Agree, there’s no doubt that clouds act as a blanket at night and keep nighttime lows up.

However, I also, think when conditions are right, they can also help boost daytime highs:

A cloudy night followed by a clearing morning, can help temps start off higher than they would without a cloudy night. We often experience this right here in the Tri-State area in deep summer. Even as a kid I have vivid memories with my brothers of hot, humid, cloudy nights in July or August, (the low would never fall below say 77 - 78 F), followed by heavy thundershowers in the middle of the night, then that sun would be burning through the blinds at 7 AM and the temp was already near 80 F. By noon we were already near 90 F. lol

This is a good point I didn't think of. But as indirectly pointed by jbgusa, that basically works if it clears up immediately after a cloudy night (more common in the summer). As he said, it does help to produce a 100+ degree day (more on that), but if it stays cloudy the next day, it will likely just stay in the low 80s.

Brings up a side note I forgot about regarding changes in daytime highs vs lows. In the tri-state area at least, there are significantly more 70+ lows than before 1980 (though Central Park's long record shows a weird period from the 1870s to around 1910 when such lows actually were as common as today, but unlike today had way more summer lows in the 50s as well to balance them off), but we have actually averaged less 90+ and 100+ highs since 2000 than in the 1945-1999 period.

A really good example of this is last year. Central Park shattered the record for average annual temperature at 57.9F (a full 0.6F over the previous record) but the highest temperature for the year was only 93 which actually ranks in the top 10 years for lowest annual highest temperature. It also had a below normal amount of 90+ degree days (12, average is 15), and 2 of them were in April and 4 in September! It was the low temperatures that made a big difference.

[simonusa3]

Originally Posted by 7 Wishes

This is a good point I didn't think of. But as indirectly pointed by jbgusa, that basically works if it clears up immediately after a cloudy night (more common in the summer). As he said, it does help to produce a 100+ degree day (more on that), but if it stays cloudy the next day, it will likely just stay in the low 80s.

Brings up a side note I forgot about regarding changes in daytime highs vs lows. In the tri-state area at least, there are significantly more 70+ lows than before 1980 (though Central Park's long record shows a weird period from the 1870s to around 1910 when such lows actually were as common as today, but unlike today had way more summer lows in the 50s as well to balance them off), but we have actually averaged less 90+ and 100+ highs since 2000 than in the 1945-1999 period.

It's interesting how much of the recent warming has been due to a rise in lows more so than highs.

I do think that tracking days when the high anywhere in the Tri-State area hits 100 F or higher, is really meaningless though. 100 F anywhere within 100 - 150 miles of the Atlantic/East Coast is pretty uncommon. Not only here in the Tri-State area, but even down into the subtropical lower East Coast. In fact, not sure it is still the case, but places like Charleston, Savannah, have not hit 100 F many more times than places like Trenton, Hartford, or Central Park. I think a few NWS reporting stations in Florida have never hit 100 F. I think a more interesting and perhaps telling thing would be to tack days above 70 F or maybe 80 F. NWS should research this.

[simonusa3]

As of 1:00 PM obs...temps are flying up fast. Almost everywhere into the 70's F. Central Park at 80 F. I'm not too far from Chester right now, and they are reporting 75 F

Can't mess with the power of that sun now - lol

[jbgusa]

Originally Posted by 7 Wishes

This is a good point I didn't think of. But as indirectly pointed by jbgusa, that basically works if it clears up immediately after a cloudy night (more common in the summer). As he said, it does help to produce a 100+ degree day (more on that), but if it stays cloudy the next day, it will likely just stay in the low 80s.

Brings up a side note I forgot about regarding changes in daytime highs vs lows. In the tri-state area at least, there are significantly more 70+ lows than before 1980 (though Central Park's long record shows a weird period from the 1870s to around 1910 when such lows actually were as common as today, but unlike today had way more summer lows in the 50s as well to balance them off), but we have actually averaged less 90+ and 100+ highs since 2000 than in the 1945-1999 period.

A really good example of this is last year. Central Park shattered the record for average annual temperature at 57.9F (a full 0.6F over the previous record) but the highest temperature for the year was only 93 which actually ranks in the top 10 years for lowest annual highest temperature. It also had a below normal amount of 90+ degree days (12, average is 15), and 2 of them were in April and 4 in September! It was the low temperatures that made a big difference.

It is my understanding that NYC records were taken at the Battery back in the day and Central Park may not have existed for a part of that earlier period. As far as 80+ nighttime lows I recall a series of those in 1972, a summer I believe the max was 94° for the entire summer. July 1972 was above normal but not spectacularly so. June was the first or second coolest, with 2009 in the other position. August was below normal despite one record daily high and a pretty hot period near the end of the month. As far as the post-2000 period, 2005 and 2010 had a large amount of 90+ days. 2005 had one 100+'er, and 2010 had two or three, as well as a spectacular late-season heat wave.

Originally Posted by simonusa3

Interesting memory.

I think it would be interesting to research how many nights from June through mid September the three area NWS stations that have lows of 80 F or higher. My guess is most occur from late June to late August.

That particular day was my 20th HS reunion. I remember driving in the morning to play tennis. A brief shower splattered my windshield as I drove south on the Hutch. When I got to the tennis courts in Mamaroneck you could almost see the steam coming off the pavement and tennis courts. It was excruciating.

The Reunion activities that afternoon, which were outdoors on the High School premises, were also uncomfortable. It was around or over 100°.

That is how I remember that day.

[simonusa3]

Originally Posted by jbgusa

That particular day was my 20th HS reunion. I remember driving in the morning to play tennis. A brief shower splattered my windshield as I drove south on the Hutch. When I got to the tennis courts in Mamaroneck you could almost see the steam coming off the pavement and tennis courts. It was excruciating.

The Reunion activities that afternoon, which were outdoors on the High School premises, were also uncomfortable. It was around or over 100°.

That is how I remember that day.

We often remember events by the weather on the day they occurred. It's a tough memory, but I'll always remember the morning of 911, there was not a cloud in the sky and it was as blue as the skies in the Mediterranean, and the temps were a perfect 70 F.