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Showery and windy with April-level temps Thursday; New Cat. 6 Hurricane?


WARMER WEATHER AHEAD as southerly winds take hold

Only modest cooling is likely on the immediate lakeshore Wednesday as Chicago heads into 3 days of 50-degree inland warmth—with the potential of a 60-degree reading in some warmer locations amid strong south winds Thursday.  Wind gusts by Thursday afternoon could top 40 mph as the storm system which has drenched California sweeps across the Rockies and into the Plains tightening the pressure gradient BIG TIME across the Greater Chicago area.

Only 26 of the past 153 years since 1871 have seen temps hit or exceed 60-degrees in Chicago by Feb 10th

A 60-degree high on Thursday would represent the warmest 17% of pre-Feb. 10 temps of the past 153 years. Put a bit differently, only just shy of 2 in 10 days have managed a temp that warm. Such unseasonably mild air is a product of mild oceanic air associated with the El Nino pattern which has dominated this winter taking control once again.  Current indications are Thursday may end up averaging an eye-catching 25-degrees above normal and Friday 20 degrees above normal. This week as a whole is likely to finish close to 15 degrees above normal.

This week’s temp to average +15° above normal

Whereas this week is to see an average temp 15-degree above normal, NEXT WEEK’S AVERAGE TEMP is to come in only a bit more than 3 degrees above normal. That translates to our late week 50s this week cooling to the 30s next work week. And signs of cooling will be evident as early as this weekend when Saturday’s predicted high will fall from Friday’s 56 down to 43 degrees—and Sunday’s high may struggle through the upper 30s.

A change in the pattern suggests colder days are ahead —though nothing close to the arctic chill of two weeks ago is currently indicated. 

And if there is any kind of late winter storm in our future, it’s not showing up on model projections at this point. That doesn’t necessarily mean there isn’t such a system out there—it’s just not caught the attention of our models at this point.  

Where a couple of days ago we had two of three major ensemble models with the hint of some snow or a wintry mix in our future toward Sunday night into Monday, now only one model, the Canadian ensemble model, offers a hint of snow.  

The changing pattern involves the development of a pool of abnormal warmth over Greenland in the next week and a half. This buckles the North American jet stream, which guides the movement of weather systems across the continent.  Typically upper winds blowing into the Midwest shift INTO THE REGION FROM CANADA—thus dropping temps. That’s what appears to be in the offing next week and into the week that follows. This should produce a near 10-degree drop in the average weekly temp here in Chicago next week—a noticeable change to colder air—but not the sort of arctic blast we saw two weeks ago.  We’ll keep monitoring developments, of course, and keep you updated.

Deluge in SoCal

Drenching rains have produced 3-day totals in southern California approaching or creeping past one foot in the hardest-hit locations. 

Proposed addition of ‘Cat. 6’ to Hurricane Scale due to Earth’s warming

A new paper published in the journal Proceedings of the National Academy of Sciences proposes adding a “CATEGORY 6” to the current 5-level Saffir-Simpson Hurricane Intensity Scale—The paper argues that Earth’s warming atmosphere and oceans are more frequently creating a faster-intensifying breed of tropical cyclone necessitating the change

Energy from Earth’s warming atmosphere and oceans is being tapped by tropical cyclones—storms more commonly referred to as hurricanes, typhoons, and cyclones depending on where they occur on the planet—causing them to intensify more quickly and grow stronger.

Below is a world map plotted with color blocks depicting percentiles of global average land and ocean temperatures for the full year 2023. Color blocks depict increasing warmth, from dark blue (record-coldest area) to dark red (record-warmest area) and spanning areas in between that were “much cooler than average” through “much warmer than average.” (Image credit: NOAA NCEI)

The Saffir-Simpson scale currently has an open-ended CATEGORY 5 top intensity which is applied to storms producing sustained winds of 157 mph or higher. A CATEGORY 6 would be added to cover tropical cyclones producing sustained winds of 192 mph or greater. Such storms have already occurred—among them: Super Typhoon Haiyan, which devastated the Philippines in 2013, Hurricane Patricia in 2015, and Super Typhoon Meranti.

BUT AS AXIOS ENVIRONMENTAL WRITER ANDREW FREEDMAN POINTS OUT—-there is, and has been for some time, the serious contention among some meteorologists involved in tropical cyclone tracking and forecasting, that an entirely different intensity scale should be put into use, replacing the Saffir Simpson storm rating scale, one which would—unlike Saffir Simpson— take into account a broader range of hazards produced by tropical systems—including more heavily weighing the devastating impacts of the storm surges and waves produced by these storms—something which these meteorologists contend isn’t adequately captured by Saffir-Simpson designations. Still, other tropical meteorologists suggest using central barometric pressures rather than sustained winds as the basis for ranking tropical cyclone intensity would provide a better indicator of hurricane/typhoon/cyclone intensity.

Excellent reporting on the proposal can be found here:

THE ASSOCIATED PRESS’ SETH BORENSTEIN FILED THIS REPORT ON THE “CAT 6” PROPOSAL MONDAY: https://apnews.com/…/hurricanes-stronger-climate-change…

ALSO, READ MORE ON THIS FROM AXIOS’ ANDREW FREEDMAN, INCLUDING LINKS TO THE PAPER ON WHICH THIS REPORT IS BASED, HERE: https://www.axios.com/2024/02/05/category-6-hurricanes-study

ALSO—Here’s an interesting description of the SAFFIR-SIMPSON scale which includes an animation that depicts the damage that occurs at the 5 levels of intensity that SAFFIR SIMPSON lays out: https://www.nhc.noaa.gov/aboutsshws.php



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