TheClimateChanger

A couple of thoughts for today:

You'd think we'd be lighting up those PDSI maps with numbers like this: BDR down 5.55" for the summer to date. BUF has had only 0.77" since June 30! Plus, it's a top 5-10 hottest summer in most places.

While I think this is mostly the result of general climate warming, I think the sudden explosion of heat was aided by the significant reduction in sulfur emissions. Similar to some of the discussion surrounding the impact of recent shipping regulations of sulfur emissions, and its role in ocean warming. The funny thing is you ask certain people on here and they would insist the 1980s, 1990s and early 2000s were scorching hot, even though nationally recent summers easily blow them out of the water.

You can really see the impacts of the enhanced sulfur regulations, coupled with continued warming trends. In the last 15 years, 6 years were hotter than any summer in the preceding 25 years. Only one (2014) was cooler than the median summer for that 25-year timeframe. In fact, every year since 2010, except for 2014, was hotter than at least 17 of 25 summers in the 1985-2009 period. 2025 will almost certainly finish hotter than any summer in 1985-2009, so that would be 7 of 16 years where that was the case. 2 other years (2016 & 2018) were hotter than every summer in the 1985-2009 period, except for 2006. CONUS Summer rankings of each year since 2010, versus the 25-year period 1985-2009 2010: 4th hottest of 25 (behind 1988, 2002, and 2006) 2011: Hotter than any summer for 1985-2009 period 2012: Hotter than any summer for 1985-2009 period 2013: 9th hottest of 25 (behind 1988, 2002, 2006, 2007, 2003, 2001, 2005 and 1998) 2014: 8th coldest of 25 (behind 1992, 2004, 1993, 2009, 1985, 1997 and 1989) 2015: 5th hottest of 25 (behind 1988, 2002, 2006 and 2007) 2016: 2nd hottest of 25 (behind 2006) 2017: 6th hottest of 25 (behind 1988, 2002, 2006, 2007, and 2003) 2018: 2nd hottest of 25 (behind 2006) 2019: 9th hottest of 25 (behind 1988, 2002, 2006, 2007, 2003, 2001, 2005 and 1998) 2020: Hotter than any summer for 1985-2009 period 2021: Hotter than any summer for 1985-2009 period 2022: Hotter than any summer for 1985-2009 period 2023: 5th hottest of 25 (behind 1988, 2002, 2006 and 2007) 2024: Hotter than any summer for 1985-2009 period

BTW, NCEI data release is set for tomorrow morning at 11 am. July should come in among the top ten hottest, IMO. Looks like a number of eastern states had should finish around or in top five hottest. I didn't see any record-breaking values, but I didn't check every state. I think the June/July pairing will be somewhere in the top 8 or so... within striking distance of the record hot summers (JJA) of 1936 & 2021. August, however, has gotten off to a cool start nationally. Given where I suspect we are at for June & July, August would need to be record or near record warm for a new record high summer (JJA) for the CONUS (the current record holders of 2021 & 1936 both had hot Augusts). With the first week coming in decidedly below the 1991-2020 mean, it looks unlikely at this point. While heat is building now and the next couple of weeks look generally hot, it would take a pretty big inferno to completely wipe out the first week AND propel us to near record heat for the month as a whole. Still, August should come in above (perhaps well above) normal when all is said and done, with a top 5 hot summer probable.

True, but a very impressive heat wave is ongoing now. Phoenix has set two record highs already this month, including 116F yesterday, which was just 1F shy of the all-time monthly record. The low of 94F this morning was also one shy of the monthly record high minimum. Today is forecast to reach 117F which would match the August monthly record high.

Interesting. Wonder if there is any chance for a late Beaufort melt to gain some ground? Delayed, but not denied, as JB would say.

Evening notes:

It looks like your analysis suffers from some unfounded assumptions. I don't see any evidence that "the land masses in the NH ... likely had a negative greenhouse effect" during the LGM. Looks like this phenomenon is quite rare - limited to the Antarctic Plateau - and seasonal (no negative GHE in austral summer). Much of Antarctica does not have a Negative GHE, as per Figure 1 in the paper cited. And that appears to be the case for Greenland as well. They do surmise that perhaps such conditions occurred in past ice ages, but only specifically identify Greenland as a possibility. I think it's unlikely the continental ice sheets (e.g., Laurentide) would have been sufficiently devoid of water vapor and subject to the same intensity of inversion as the Antarctica Plateau. But even if they did, I don't see how this calls into question the role of CO2? CO2 would only be a negative feedback if a true negative GHE existed; even with a weaker positive GHE, it would still be a positive feedback. Moreover, it would be a positive feedback everywhere not covered by ice even assuming a negative effect over ice. As you, yourself, have previously pointed out, warming in one location does not exist in a vacuum. Ocean and atmospheric currents would eventually move warmer air across the globe. Over time, warming of the unglaciated regions would increase water vapor and erode the surface temperature inversions over the glaciated regions, shifting any negative GHE to a positive one. The cited paper suggests the same could occur over Antarctica:

See, I've got pretty good company here. Hansen is more than a little skeptical of what the IPCC says, suggesting a climate sensitivity much higher than supposed (4.5C v. 3C).

Today will be the 9th consecutive day without measurable rainfall at the airport, assuming nothing pops up (there were a few scattered showers earlier north). Only 0.39" over the past 21 days.

Interesting temperature pattern yesterday in the northeast. Map below shows yesterday's high temperature percentile. Much of the interior decidedly above the median high temperature - generally 70 to 85 percentile. Buffalo was only a few degrees shy of a record, topping out at 89F as an odd easterly flow brought some downsloping sending the warmest temperatures to the lakeshore (typically cooler locations). The coastal Plain was pretty close to the median - generally from about the 33rd to 67th percentile, except for Boston, which didn't make it out of the low 70s. The ASOS at Logan is very close to the water. Big divergence from BOS to Blue Hill Observatory (Milton, Mass.) just to the south. Cooler high temperatures in West Virginia from clouds and showers.

Summer ain't over yet!

Today's thread:

In a stunning departure from the conditions of the summer to date, August has started off on a very cool note nationwide. The PRISM data below is only for the first two days of the month, but yesterday saw similarly impressive cold with a number of record low max temperatures in the south and a few isolated record lows in the eastern US. While I still expect August to finish out above normal for CONUS, this is going to make a new summer national record quite difficult. Will probably take a few days just to return to 1991-2020 means nationally, which means we are likely looking at one of the coolest first weeks of August in a long while. Probably would need an epic heat wave to keep pace with 2021 & 1936, at this point.

Beautiful stretch. At PIT, we've doubled our July tally of low temperatures below 60F in the first four days of the month. Happy I've been able to give the A/C a rest for a change.

Wow, I don't agree with this statement at all. Recent Julys have had mean minimum temperatures that are warmer than the mean 24-hour averages from past "cold" Julys. Probably after 2050, we will begin to see Julys where the mean minimum temperatures exceed the mean maximum temperatures from old-school cold Julys. For some reason, you only ever look and compare to the hottest years? For example, JFK's mean minimum last month was 72.7F. That exceeds the mean 24-hour average of 71.8F in 1956, 72.2F in 1996, 72.2F in 1965, 72.3F in 2000, 72.4F in 2001, and falls just shy of the 72.8F observed in 1976. It's probably just a handful of decades before JFK starts seeing low temperatures in July that exceed the mean maximum temperatures observed in cold Julys (e.g., 1956, 77.9F; 1996, 78.6F; 2000, 79.5F; and 1967, 79.7F). I don't think its too hard to imagine a future in 2060 where NYC looks more like Washington, DC of 2000-2020, where such low temperatures are common. I think it's significant when low temperatures are exceeding the mean of high and low from many past years. In the first 6 years after installation of the ASOS at JFK, there were 3 years in which the month of July had a colder mean temperature than this year's mean low temperature (1996, 2000, and 2001).

"It's only summer." Just kidding. Actually, the weather today and this weekend is closer to "only summer" weather than the past 6 weeks. The mean minimum temperature of 68.2F at PIT last month was 0.8F higher than the mean average (avg. of max & min) temperature from 1976, and pretty comparable to the mean average temperature observed in 1960, 1984 & 2000.

You can even see the point where atmospheric changes start to swamp out the UHI signal. From 1970-2000, both sites show a small cooling trend, with NYC lows dropping 0.2F, while the Charlotteburg site saw lows drop by 0.7F during that timeframe. Hard to tell if the late 20th century cooling is a real trend or just an artifact from changing equipment/observation practices and site location. I'm not sure if that cooling trend is real or just manufactured by those non-climatic factors.

Wow, since 1970, July nighttime low temperatures at NYC have risen 3.1F, while lows at Charlotteburg Reservoir have risen 7.1F, per linear regression.

I mean not every month is just going to continue being cooler than the corresponding month in 2024. Eventually that trend has to stop, no? Maybe in time for December, which was about a degree cooler than normal in 2024.

Last year was record warm only for the period 1869-2024. For the period 2025+, it will be considered a cool year.

2007 also had crazy heat in the south and Ohio Valley. I don't think summer is over yet.

Analogs seem good for some big heat. I see 1953, a couple from 1988, 2001 (big heat in early August), 2002.

That rubber band is going to snap in a BIG way soon, I would imagine.