Another Intense Heat Wave May Team Up with Drought in Europe Next Week

July 16, 2019, 8:10 PM EDT

Above: A woman walks in the center of Lyon, central France, Tuesday, June 25, 2019, as a severe heat wave affected much of Europe. AP Photo/Laurent Cipriani.

Severe midsummer dryness is paving the way for a new episode of heat in Europe next week, less than a month after the continent endured its hottest June on record. Models indicate a strong ridge of upper-level high pressure developing over Europe, which may lead to a multiday stretch of temperatures in the 35-40°C (95-104°F) range in many areas. The heat will spread from Spain this coming weekend northeastward into France by early next week and across western and central Europe as the week unfolds. Even London may see temperatures above 30°C (86°F) by late next week.

The heat wave of late June set dozens of all-time high temperatures across Europe, a feat all the more amazing for having occurred so early in the summer. Next week’s heat is unlikely to be as seasonally impressive, given that Europe is normally at its hottest from late July into early August. It's still too soon to know where the worst heat will occur and how long the heat wave will last, and this could end up being more of a “normal” midsummer heat wave than a record-smasher. Regardless, the heat will intensify drought conditions that are already causing serious impacts.

The parched soil could allow surface temperatures to rise even further than models are projecting. Most of the incoming solar energy will go to heating up the surface rather than evaporating moisture, and computer models do not always fully capture this shift in energy balance.

A month without rain in Paris

Some of the worst drought conditions in Europe are plaguing central and western France. The Paris area has not received significant rain since June 21, which makes this the city's driest astronomical summer to date in records going back to 1873, Meteo-France tweeted on Monday. Ominously, the next-driest period from June 21 to July 15 occurred just last year (2018). As of Wednesday night, the Weather Underground forecast for Paris showed no rain for at least the next ten days, except for a small chance of thunderstorms on Saturday, so it's quite possible Paris will extend its dry streak beyond a 30-day span.

Water restrictions now extend to almost two-thirds of France's 96 water districts, the nation's environment minister said on Tuesday as reported by The Wall Street Journal.

Also on Tuesday, the Facebook page Severe Weather Europe noted: “A number of fires are reported to be ongoing in department Pyrénées-Orientales (66), south France today, July 16th.” The embedded video below, from the regional meteorological agency for the Pyrenees, shows one of five water bombers reloading while fighting fires in this region.

The upcoming heat wave will likely intensify the fire threat in parts of Europe, especially France and the Iberian Peninsula. "We believe we're seeing the start of this phenomenon rather than the middle," said Cedric Ficht, a local chief of the French national forests office (ONF), as reported in phys.org.

Climate change made France’s June heat wave many times more likely

A rapid-attribution study released on July 2 found that the June heat wave in France was at least 5 times more likely to occur as a result of human-produced greenhouse gases, and perhaps 100 or more times more likely. The study was released by the World Weather Attribution project, an international effort by leading climate scientists to analyze and report on climate-change-related aspects of major weather events on a time scale of weeks to months, while the events are still fresh in mind. By design, such reports are preliminary, but they are conducted by the same scientists who carry out more comprehensive studies, using many of the same tools.

Most of the authors of the new report happened to be in Toulouse, France, for a conference on extreme events and climate change when the heat wave struck, so they decided to focus their analysis on France as a whole and on Toulouse in particular. They found that a June heat wave in France of this magnitude can now be expected about every 30 years in our current climate, but it would most likely happen only every few hundred years in the period before industrialization. The analysis focused on three-day average temperatures, because these are more robust in observations and they convey the accumulated health impact of a heat wave more than would a single day of extreme heat.

The difference between the highest three-day average temperature in June 2019 and the highest such values observed during June in the period 1981-2010
Figure 1. The difference (in degrees C) between the highest three-day average temperature in June 2019 and the highest such values observed during June in the period 1981-2010. In some locations, the highest three-day average in 2019 was 7-10°C (13-18°F) warmer than any three-day June heat wave between 1981 and 2010, which itself was warmer than the early and mid-20th century. Image credit: World Weather Attribution.

The global models consulted by the team varied widely on how much of an increase in June heat-wave risk they depicted for France, in part because models tend to underestimate the trends already being observed in extreme highs during heat waves. However, the authors note, “All models and observations qualitatively agree on a strong human influence in increasing heatwave risk. There is thus high confidence in the sign (increase) of the human contribution to the heatwave risk.”

The June heat wave occurred during an extremely unusual mid-level pattern, with a hot upper high over western Europe and a cold upper low just to the west. This pattern is so unusual that the authors could find no trend in its occurrence, and they concluded climate change probably did not play a strong role in this particular aspect of the heat wave.

The U.S. is in store for a heat wave too

Thus far this summer, the United States has avoided any large-scale heat waves, but that’s about to change. Temperatures over most  of the nation will be rising above normal from late this week into next week, coupled with high humidity from the Plains eastward. As a result, heat indices will be entering dangerous territory in many areas, already prompting a patchwork of heat advisories and excessive heat warnings from southern California to New Jersey.

Chicago may hit its first 100°F high since 2012, and Washington, D.C., its first 100°F since 2006. Even readings like this will mostly fall short of the torrid records that are common in late July, though. With this heat wave, the perennial saying "it's not the heat, it's the humidity" may ring especially true for millions. All of that moisture will help keep nights especially warm, boosting the risk of heat impacts over time.

See the weather.com article for more on the late-July U.S. heat wave.

The Weather Company’s primary journalistic mission is to report on breaking weather news, the environment and the importance of science to our lives. This story does not necessarily represent the position of our parent company, IBM.

author image

Bob Henson

WU meteorologist Bob Henson, co-editor of Category 6, is the author of "Meteorology Today" and "The Thinking Person's Guide to Climate Change." Before joining WU, he was a longtime writer and editor at the University Corporation for Atmospheric Research in Boulder, CO.

bob.henson@weather.com

@bhensonweather

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