TheClimateChanger

Looking more closely at the data, there are 69 days of 95+ in 71 years, which is an average of just under 1 per year. However, those 69 days were spread across only 21 years, meaning the actual incidence of a 95 or better reading is only roughly 2 out of each 7 years. It is much more common not to reach 95 than it is to reach that value. Using historical averages, approximately 5 out of every 7 years would be expected to reach no more than 94 degrees. In years in which it reaches at least 95 degrees, it is much more likely than not to reach that value multiple times. Of the 21 years in which 95 or better was reached, 13 of them reached that figure on multiple occasions. Further, 8 years failed to even reach 90 - meaning it is 4x more likely that the temperature will not exceed 89 than it is to reach 100. Historically, about 1 in every 9 years at PIT fails to reach 90. There were no years between 1953 and 1975, inclusive, in which it failed to reach at least 90. The longest stretch since 1975 with no years topping out at 89 or below is 9 years, set three times - 1983 to 1991; 2005 to 2013; and 2015 to 2023. If it reaches 90 or better next year, we will be in the longest consecutive stretch with no years topping out below 90 since 1976.

That's because extreme heat is exceptionally rare. There have only been 21 years since records began at Pittsburgh International Airport in September 1952, in which the mercury reached 95 or better. There have only been 2 years since records began there, in which the mercury reached or exceeded 100 degrees. Honestly, the 95+ readings in the late 1980s through mid 1990s were very likely inflated by the use of the HO-83 hygrothermometer in that era, which has a known, significant warm bias - particularly on sunny days with light winds in the warm season. So it's not suprising to find 30 of the 69 days of 95+ occurred between 1988 and 1995, in a period of about a decade or so in which that hygrothermometer model was in use. All 3 100+ readings at PIT also occurred in that era. From 1956 through 1987, a period of 32 years, there were 16 days in which the temperature reached or exceeded 95 degrees, spread across 8 years.

Fake news.

No reason to expect this to continue for the rest of this century or beyond. I would expect to eventually reach a level of warming where it is no longer feasible to grow most crops in that region, which would lead to crop failures and extremely rapid warming. In such a scenario, the cooling effect would not only be reversed, but replaced by an articifial warming effect of a desert-like landscape devoid of crops. If this were to occur, parts of the midwest could see temperatures approach or exceed the all-time world record. Temperatures of 120+ have already been observed in the Dakotas, including at CO2 levels not much above 300 ppm. I don't think it's out of the question to see 130+, maybe even 140 degrees, were that same weather pattern to recur at CO2 levels of say 450-500 ppm. Even if high temperatures stay in the 110s to around 120, low temperatures may struggle to drop below 95 or 100 in the high CO2 environment. This type of warmth would dessicate and destroy all plant life in the region, leading to flash desertification. I don't know if this is an effect the models produce. But this is just thinking logically and using past weather as a guide to project what could happen in a worst-case scenario. Unfortunately, most people seem unwilling to even consider the possibility of a worst-case scenario. And instead point to the 1934 and 1936 drought and heat wave as evidence of past periods of climate tumult and assume (incorrectly) that our improved farming and soil conservation techniques will prevent that from recurring. However, it is certainly possible that the weather, in the near future, could become so harsh that there is a season where widespread crop failures occur despite our agricultural advances. If this were to occur, then you could see a recurrence of Dust Bowl conditions in a high CO2, enhanced greenhouse effect environment.

One of only two years (out of 136) at Harrisburg, where the minimum temperature has not dropped below 65F.

Appears to be a good chance that this month will be the first to not have at least one low temperature below 55 at DuBois-Jefferson County Airport (dating to 1963), and one low temperature below 50 at Bradford Regional Airport (dating to 1957). While it hasn't been a super hot month, it has been consistently warm - particularly at night - leading to elevated minima. DuBois [days with minimum <55F] Bradford [days with minimum <50F]

I am working, so I didn't have time to respond. 1) I did not intend to cherrypick a date. I ran the analysis after seeing well-known Alaskan climatologist Brian Brettschneider's map earlier today on Twitter. I wasn't even aware there was a negative trend in snowfall. 2) Brian's map ran from 1973 - a period of 50 years. I selected 1950 to integrate more data, and specifically chose that date because (1) that's around the time most observations moved to airports from city centers; and (2) observations prior to that timeframe include a lot of missing data and generally seem less reliable to me. I did not realize the 1960s were an unusually snowy period in eastern Pennsylvania. It was one of the least snowy decades at Pittsburgh. 3) Yes, the linear trend line is not a good fit. But that is, indeed, the best fit linear trend line calculated by Excel for each of those datasets. The r-squared value is very low, because the data is so noisy. You are not going to generate a strong fit with such noisy data.

The trend at Williamsport is even worse. A loss of about 26" per century. Wow - I had no idea the situation was so bleak on that side of the state.

Wow! I redid this trend for Harrisburg, PA, and snowfall has plummeted at a rate of 20" per century since 1950 for Harrisburg. That is wild.

For context, here is the graph for Pittsburgh since 1950. The first few years are from AGC, the rest at PIT. I used 1950, as I feel that's the start of reasonably reliable snowfall records. Not to mention, the early years were all downtown.

So far, we have been fairly lucky, although snowfall has trended downwards over the past several decades. Since 1950, I calculate the trend as a loss of 7" per century, so a fairly slow decline. But looking at the map posted by Brian Brettschneider, it looks like the oranges and reds aren't looming too far to our south. Do you guys think we will eventually reach a level of warming where snowfall in Pittsburgh plummets on the order of 25 or 50 percent?

I had responded earlier, noting the daily high shift from the actual observations. This site reported a 7 am observation time - which was pretty rare in the 1930s. Most sites observed temperatures between 5 and 8 pm, which resulted in "double counting" of high temperatures, relative to a midnight-to-midnight day. Also missed the occasional midnight daily lows that occur. What appears to happen is the algorithm used to clean these records up assumed the high temperature was being assigned to the day on which it was measured, and so it shifted them all back since the high actually would have occurred the prior day. However, it appears that this observer was already making that shift, ascribing the max temperature at 7 am to the prior day and the low to the day on which it was observed. So the algorithmic shift incorrectly bumped all the highs to the day prior to when they occurred.

The next few days will likely drop those figures a bit, but modeling shows hotter weather moving in by middle of next month and perhaps through the end of the month. Therefore, I felt pretty comfortable that the final figures should be fairly similar to the current ones (and possibly, a bit higher depending on how the heat performs later this month). The fact that upper 40s in northern Pennsylvania is a big deal now just shows how these changes have been normalized. There have been years where the mean minimum at Bradford for the entire month of July was in the 40s, including as low as 47.3 in 1971.

Has the NWS shared the 2022-2023 snowfall map yet?

Records are from Jefferson County Airport.

Runaway "urban heat island effect" leading to record or near record high minimum temperatures this month, even in some of the most remote places in the Commonwealth, such as Jefferson and McKean Counties. Just not sure how we are going to be able to stop all of this urban waste heat from polluting our forests, streams and oceans. DuBois Bradford Mount Pocono Williamsport Comment: I have my doubt about the validity of the 71.1 from 1901. LOL. Scranton/Wilkes-Barre Harrisburg Reading

It's crazy to see how this urban heat island effect keeps growing and even affecting places hundreds of miles from any city, such as McKean County, Pennsylvania.

Made at a surprise run at the 50s this morning, but fell just short with a low of 60.

If the 1936 heat wave occurred this year, Bastardi would be downplaying it by saying its not that hot on a per capita basis. Looking at the actual data, July 1936, as a whole, was actually around or slightly below current July normals in most places where people actually lived. And outside of a one week intense heat wave, downright chilly (especially at night) compared to recent Julys. Funny how it was only hot in places where no one lived. I suspect this temperature pattern would not score highly on Bastardi's population density metric. Toronto (downtown), Canada Excluding 7-days from 7/8 to 7/14: 79.6/58.6 Mean: 69.1F Boston, Massachusetts No heat wave to knock out, only a few discrete hot days scattered early-mid month. New York, New York Excluding 7-days from 7/8 to 7/14: 83.4/64.8 Mean: 74.1F Buffalo, New York Excluding 7-days from 7/8 to 7/14: 76.5/61.3 Mean: 68.9F Rochester, New York Excluding 7-days from 7/8 to 7/14: 78.9/59.0 Mean: 68.9F Hartford, Connecticut Excluding 7-days from 7/8 to 7/14: 81.0/60.4 Mean: 70.7F Harrisburg, Pennsylvania Excluding 8 days from 7/8 to 7/15: 83.8/63.9 Mean: 73.8F Philadelphia, Pennsylvania Excluding 7 days from 7/9 to 7/15: 83.4/66.9 Mean: 75.1F Scranton/Wilkes-Barre, Pennsylvania Excluding 7 days from 7/8 to 7/14: 82.7/59.0 Mean: 70.3F Williamsport, Pennsylvania Excluding 7 days from 7/8 to 7/14: 85.9/56.9 Mean: 71.4F Erie, Pennsylvania Excluding 7 days from 7/8 to 7/14: 78.8/61.8 Mean: 70.3F Washington, District of Columbia Excluding 8 days from 7/8 to 7/15: 85.3/67.3 Mean: 76.3F Hagerstown, Maryland Excluding 7-days from 7/9 to 7/15: 83.4/59.3 Mean: 71.4F Baltimore, Maryland Excluding 7-days from 7/9 to 7/15: 85.0/67.9 Mean: 76.4F Detroit, Michigan Excluding 7-days from 7/8 to 7/14: 82.6/58.9 Mean: 71.4F Lansing, Michigan Excluding 7-days from 7/8 to 7/14: 81.2/56.2 Mean: 68.7F Alpena, Michigan Excluding 7-days from 7/8 to 7/14: 80.9/48.0 Mean: 64.5F Akron, Ohio Excluding 7-days from 7/8 to 7/14: 84.0/58.0 Mean: 70.9F Toledo, Ohio Excluding 7-days from 7/8 to 7/14: 82.2/61.9 Mean: 72.1F Morgantown, West Virginia Excluding 7-days from 7/9 to 7/15: 85.9/56.5 Mean: 71.2F Elkins, West Virginia Excluding 7-days from 7/9 to 7/15: 80.7/57.3 Mean: 69.0F Clarksburg, West Virginia Excluding 7-days from 7/9 to 7/15: 84.9/59.3 Mean: 72.1F Milwaukee, Wisconsin Excluding 8-days from 7/8 to 7/15: 77.0/63.7 Mean: 70.3F Chicago, Illinois Excluding 8-days from 7/8 to 7/15: 80.9/66.2 Mean: 73.5F

It's kind of funny. Ryan Maue, on Twitter, was comparing low temperatures at Phoenix to those observed at Tuscon to illustrate the supposed UHI effect. However, he did not mention that Tuscon is 1500' higher in elevation. Wonder why he didn't compare the lows at Sky Harbor Airport to those at Furnace Creek? After all, nobody lives in Death Valley. Sky Harbor Airport is actually closer in elevation to Death Valley than to Tucson. Rather unsurprisingly, the low temperatures in Death Valley are significantly higher than those observed at PHX. Not because of more urbanization at the former than the latter, but rather the difference in elevation!

Wow - those lows! Clearly, it must be the urban heat island effect!

I did a little comparison between PHX and Grand Canyon Airport (GCN) - the latter of which is quite literally in the middle of nowhere when it comes to human population density. Unfortunately, records for GCN were only available back to 1997 for GCN, but that still allowed for about a quarter century of data. From 1997-2022, I calculated a warming trend of 7.3F/century for daily maxima at GCN, 4.3F/century for daily minima, and 5.7F/century for daily mean temperature. For the same period at PHX, I calculated a warming trend of 10.0F/century for daily maxima, 7.8F/century for daily minima, and 8.8F/century for daily mean temperature. While the relatively short period of analysis makes drawing definitive conclusions a bit challenging, a couple of observations. It is warming at an alarming rate at both sites; however, PHX does show a residual warming trend of about 3.0F/century compared to GCN. This residual may be related to a growing urban heat island effect. However, Dr. Spencer's research would suggest that, at some point, the UHI effect will essentially "max out" and stop being a significant contributor to the trend. Second, maximum temperatures have climbed more than minimum temperatures at both sites over this interval. This is inconsistent with UHI effect. Mr. Maue has some graphics showing a collapse in the diurnal temperature range (DTR) at Phoenix since the mid 20th century. This data suggests that trend has reversed somewhat since the late 1990s, and DTR has increased by a small bit since that time. Lastly, I feel it is disingenuous to compare the PHX trend to the globally averaged trend and suggest all of the excess is due to UHI. It should be clear that the regional climate around PHX is warming considerably faster than the global average.