donsutherland1

This was a very important paper--perhaps one of the most important weather/climate papers that will be published this year. It describes the mechanism by which climate change is driving Southwest aridification via marine heatwave-induced changes to the PDO.

Central Park and Islip had identical high and low temperatures for the first time since May 16th. During the 1991-2020 period, they had identical high and low temperatures on an average of 6.6 days per year.

Yes. That’s true. I don’t have a sufficient base of daily dewpoint data to add it into the mix.

Denver reached 90° for the 40th time this year. Its warming climate has seen an explosion of years with a high number of 90° or above highs. The new regime of far more frequent 90° or above highs commenced in 2000. 2025 is on track for 50 or more such days. An Ed Hawkins-style warming stripes visualization of annual 90° days is below. Note: Both charts are for 1872-2024, as the 2025 total is not final. The outcome is consistent with Colorado's warming summers (0.2°F per decade over the historic climate period and 0.3°F/decade since 2000).

Here's a statistical ranking for JFK. The description is at the bottom of the chart. 1966 was 11th (pulled down by its relatively cool mean temperature and cool highest minimum temperature). Summer 1948 isn't listed, because about half the days (46) had no data. 2025 is currently battling for the third spot, but it will likely fade lower given the forecast for the second half of August.

Summer 1944 was somewhat cooler at Central Park (0.4°) and LaGuardia Airport (0.5°) than summer 1949.

Here it is. Since the dataset goes back to 1948, I pegged the summer temperatures to the 1951-1980 mean (as in the NASA GISS record).

I thought it would be useful to provide greater context to how things are evolving. Some of the most extreme heatwaves occurred during summers that are relatively cool by recent standards i.e., 1966 and 1977. Even as some of the extreme heat has not occurred, the tradeoff has been summer warmth that is greater and more persistent. Of course, there have been some hot summers that fit both criteria e.g., 2010.

Tomorrow should be partly sunny. Clouds could become more numerous during the afternoon into the evening. We'll see how Saturday evolves.

Temperatures will likely top out in the middle and upper 80s across the region. Saturday will likely be somewhat cooler before it turns briefly warmer on Sunday. Noticeably cooler air will likely overspread the region early next week. High temperatures will likely reach the upper 70s and lower 80s during the first half of next week. The extended range guidance increasingly suggests that the closing week of August could feature below normal temperatures. Precipitation could be near normal. The synoptic pattern should limit direct tropical cyclone threats for the foreseeable future. Impacts from elevated tides, surf, and rip currents would be the most likely effects produced by Erin as it tracks well offshore between the U.S. East Coast and Bermuda. The ENSO Region 1+2 anomaly was +0.8°C and the Region 3.4 anomaly was -0.3°C for the week centered around August 6. For the past six weeks, the ENSO Region 1+2 anomaly has averaged +0.50°C and the ENSO Region 3.4 anomaly has averaged -0.15°C. Neutral ENSO conditions will likely continue into early autumn. The SOI was +0.18 today. The preliminary Arctic Oscillation (AO) was -0.342 today. Based on sensitivity analysis applied to the latest guidance, there is an implied 58% probability that New York City will have a cooler than normal August (1991-2020 normal). August will likely finish with a mean temperature near 75.6° (0.5° below normal). Supplemental Information: The projected mean would be 0.4° above the 1981-2010 normal monthly value.

This outcome is consistent with the warming summers that the region has been experiencing. Warming is measured by summer mean temperature. I constructed a chart for seven regional sites for the last 60 years and pegged the shading to the median value for each site.

Phoenix's annual monsoon is changing in a warming climate. The most pronounced changes are fewer rainy days (days with measurable precipitation), reduced monsoon season precipitation, and a hotter monsoon season. The dramatic warming of the Monsoon Season shows up prominently in the Ed Hawkins-styled warming stripes: These developments are consistent with some of the literature concerning climate change and its impact on North America's monsoon season. Two examples: "It is found that the monsoon response to CO2 doubling is sensitive to sea-surface temperature biases. When minimizing these biases, the model projects a robust reduction in monsoonal precipitation over the southwestern United States, contrasting with previous multi-model assessments." Source: Pascale, S., Boos, W., Bordoni, S. et al. Weakening of the North American monsoon with global warming. Nature Clim Change 7, 806–812 (2017). https://doi.org/10.1038/nclimate3412 "Within climate science... focus has begun to include the growing role warming temperatures are playing as a potent driver of greater aridity: hotter climate extremes; drier soil conditions; more severe drought; and the impacts of hydrologic stress on rivers, forests, agriculture, and other systems. This shift in the hydrologic paradigm is most clear in the American Southwest..." Source: Overpeck, Jonathan T. and Udall, Bradley. Climate change and the aridification of North America. PNAS, Vol. 117, No. 22 (2020). https://www.pnas.org/doi/pdf/10.1073/pnas.2006323117

Yesterday was the first time since July 2, 2021 that saw Newark and White Plains pick up 1" or more of rain, while JFK Airport, LaGuardia Airport, and Central Park had less than 1" of rain. It was the first time where Bridgeport received no precipitation when Newark and White Plains picked up 1" or more of rain, while JFK Airport, LaGuardia Airport, and Central Park had less than 1" of rain.

White Plains picked up 1.12" of rain in the past hour.

Most of the time, JFK has a higher daily high temperature than Bridgeport during the summer. During summers 2000-2024, JFK had a higher maximum temperature on 58.7% of days; Bridgeport had a higher maximum temperature on 27.4% of days; both locations had equal high temperatures on 13.9% of days. In addition, there were 61 days where Bridgeport reached 90° or above when JFK Airport didn't (about 2.4 days each summer). The distribution of those days was: June: 19.7%; July: 47.5%; August: 32.8%. Last summer, there were three. Today was the first day this summer.