A general feel of autumn in the air ahead!

Gusty winds will blow in Chicago Wednesday. Humidities and dew point are to remain elevated going into Wednesday morning, but will begin to drop off Wednesday afternoon and evening. Still, daytime heating may generate enough instability to pop a few spotty showers later in the afternoon and early Wed evening—one or two of which which may produce lightning.  But areal coverage on those will be quite limited.

It’s Wednesday night and forward through the coming weekend and into next week which temps will cool. There’s to be the general feel of autumn in the air. Daytime highs will hold to the upper 60s to low 70s Thursday through Saturday—and the coming weekend is likely to average 12.5° cooler than last.  THAT’S QUITE A CHANGE! 

Northeast winds are likely to travel down Lake Michigan into Chicago and this is likely to produce 60s on area beaches Friday into Sunday.

WHILE THERE MAY WELL BE CLOUDS Thursday into Friday amid some gusty north/northeast winds—no rain of consequence is anticipated.

We’ve moved into PRIME TIME in the 2023 Atlantic hurricane season. This is the point in the season we start seeing Cape Verde-type hurricanes spin up.

Those are tropical cyclones (the term meteorologists use to describe “tropical storms” and “hurricanes”) which spin up over the Atlantic off the west coast of Africa.

SUCH A SYSTEM appears to be a candidate for explosive development over the abnormally warm ocean waters over which it will travel in coming days—in a 2023 Atlantic hurricane season which Dr. Phil Klotzbach tweets (https://twitter.com/philklotzbach) Tuesday is already running ahead of normal (see the graphic he’s posted among the graphics below) Says Klotbach in a Tuesday post:

“So far, the 2023 Atlantic #hurricane season has tracked well above average for named storms, named storm days and major hurricane days, while other metrics are near to slightly above average.”

TWO WESTBOUND TROPICAL SYSTEMS ARE UNDER THE WATCHFUL EYE OF THE NATIONAL HURRICANE CENTER

  • Here’s a collection of model tracks produced by tropical forecast models examined by NHC forecasters
  • Here are a series of European ensemble member track forecasts

System moving over exceedingly warm water

Sea surface temp and ocean heat content analyses out of CIMSS at the University of Wisconsin-Madison have the storm poised to track over warm, high heat content Atlantic waters in a low wind shear environment—perfect for further storm intensification.

  • Ocean temps are HIGH–more than sufficient to sustain tropical cyclone development
  • It’s to remain over HIGH OCEAN HEAT CONTENT water as indicated by the CIMSS UW-Madison analysis
  • Here’s a collection of model tracks produced by tropical forecast models examined by NHC forecasters
  • Here are a series of European ensemble member track forecasts

Catastrophic Flooding in Greece

ONLY A WEEK AGO, AN OUT OF CONTROL WILDFIRE, ONE OF A SERIES WHICH CHARRED THE COUNTRY THIS SUMMER, WAS BURNING–THE MOST RECENT FIRE BEGAN AUG 19th AND GREW INTO THE EUROPEAN UNION’S LARGEST SINCE 2000

It’s just the latest example of a WHIPLASH WEATHER SHIFT. It involves a literal overnight shift from one weather extreme to another. In this case—from drought and stifling heat to torrential rains and catastrophic flooding.

YOU’VE HEARD ME TALK of ATMOSPHERIC BLOCKING PATTERNS. Such pattern involve “WAVY” jet stream configurations which slow the progression of large scale weather movement to a crawl. Blocking patterns contribute to prolonged periods of extreme weather–sieges of very dry or very wet weather and of extreme heat and cold–and often have at their core HUGE POOLS of abnormally warm air. These WARM POOLS OF AIR distort upper steering winds and jet stream patterns.

Climate researcher Dr. Rika Rantanen of the Finnish Meteorological Institute, who studies the impacts of climate change, has posted on his social media page (https://twitter.com/mikarantane) a diagram of the current “OMEGA BLOCK” in place across Europe–a graphic which lays out its impacts, from flooding in Greece but also flooding in Spain even as heat bakes other sections of western Europe. (I’ve posted some additional analyses/maps of this atmospheric blocking pattern).

“Omega” block’s derive their name from their shape—upper wind/jet stream wind patterns within such blocking patterns are shaped like the Greek alphabet letter “OMEGA” (https://en.wikipedia.org/wiki/Omega).

At the heart of many atmospheric blocking patterns are mammoth domes of hot air–in this case, a huge pool of hot air draped across Europe.

Watch this fascinating METEOSAT ANIMATION of the storm involved in the Greek flooding occurring beneath the eastern flank of the European atmospheric “block. Also evident on the METEOSAT animation are clouds and moisture spinning ashore over Spain and Portugal (the Iberian Peninsula).

NASA reports Mediterranean waters are running 2-4-deg C warmer than normal. Just as warmer than normal ocean waters helped fuel southern California’s first Tropical Storm in decades and Hurricane Idalia’s rapid intensification before slamming into Florida, the warm waters off Greece appear to have played a role in fueling the catastrophic rains and resulting flooding now in the news.

As recently as a week ago, a fleet of firefighting aircraft was involved in a desperate effort to contain an out of control fire burning in Greece. 20 had perished. Here’s how PBS and the Associated Press reported on the fires: https://www.pbs.org/…/a-massive-weeks-long-wildfire-in…

And now the reporting is on DEVASTATING FLOODING IN GREECE where more than a year’s worth of rain in 2 days: https://apnews.com/…/greece-rainstorm-flooding-traffic…

Late season heat is making news in other sections of Europe–including portions of the UK: https://www.metoffice.gov.uk/…/heat-to-last-into-the…