IT WAS A GORGEOUS WEDNESDAY with 100% of the day’s possible sunshine and winds a fraction of the 25 to 40 mph gusts (highest at the lakeshore and out over Lake Michigan) which blew across Chicago Tuesday stirring waves and rip currents along Lake Michigan and on Chicago’s beaches.  

Wednesday Chicago weather couldn’t have been more different with flocks of weekday beachgoers enjoying a quiet lake, free of the 4 to 6 ft. waves which crashed on Chicago shores Tuesday. The day’s SOUTHWEST winds overcame lake cooling—so it was warm right up to the lakeshore! Peak wind wind gusts Wednesday reached 17 mph at O’Hare and 18 mph at Midway Airport.

Chicago’s August 2023 Temperatures

Temps on 9 of the past 12 days were AT or BELOW NORMAL—but only marginally so.  August is currently a veritable statistical “wash”—in other words, virtually normal with month to date temps, when today’s temps factored,  averaging 0.4° BELOW NORMAL—just a fraction of a degree from the most recent  smoothed 30 year average! And the month’s opening 16 days will go into the books running just 0.5° cooler than the same period a year ago.

Here’s What’s Ahead Weather-wise For Chicago

Southeast-bound cool front reaches the area with showers and some thunderstorms Thursday morning. The bulk of these could be passing across the city a portion of the morning rush hour—with rain likely to impact 50 to 60% of the area.

Spotty lead showers could be in parts of the area as early as 4 to 6 am.  But the bulk of the showers will sweep through between 6 and 10 am. Clearing, breezy and less humid weather follows with some wind gusts to 30 mph delivering the drier air which will have mostly sunny skies taking over in the afternoon and a cloudy, rain start to the day.

By later Saturday, an increase in humidities will begin to be felt—and the hotter temps which take hold Sunday, Monday and Tuesday should be accompanied by MARKEDLY MORE HUMID AIR. Dew point, a measure of atmospheric moisture, with rise from the mid 50s Saturday morning to the mid 60s by Saturday evening then surge into the low to mid 70s Sunday afternoon through Tuesday.

The DOME OF HOT AIR predicted to develop continues to be featured by virtually all computer forecast models available to us.  The one twist which is interesting and still not completely resolved is the insistence by several models that a Canadian high pressure will force a cold front to sweep across the area Sunday night and Monday. If that were to occur, it could interrupt or even derail heating.  But these same models building the most expanded HOT AIR DOME of the summer over the region. 

My experience has been that an atmosphere forecast to warm dramatically aloft is likely to do the same thing down here at ground level.

WHAT MAY HAPPEN Monday is that winds may shift off Lake Michigan—probably not as vigorously as some models are predicting. This could temper the heat on area beaches while inland areas would broil in the 90s—and with muggy low and mid 70-deg dew point to boot. The combination of heat and that level of moisture would send PEAK AFTERNOON HEAT INDICES  into the 98 to 106 degree range Sunday—and each afternoon from Monday through Tuesday

This a situation which will have to monitored. If the front forecast by some models verifies, that could impact the heating early next week. But for now, it appears A PERIOD OF LATE SUMMER HEAT is on the way. We’ll keep you posted.

A cool front will settle through the area Tuesday night and Wednesday, stalling south of Chicago with the potential for t-storm generating wave to move along it. With a jet stream overhead, any storm clusters may warrant observation as potential active t-storm producers.

Could weather across the Atlantic Basin be “coming alive” in the coming week? The Saharan dust noted by the CIRA/RAMBB satellite folks notwithstanding—the NOAA/NWS National Hurricane Center is following a series of tropical disturbance and is writing in that agency’s Wednesday morning release:

Tropical Weather Outlook NWS National Hurricane Center Miami FL 800 AM EDT Wednesday August 16 2023

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

1. Central Tropical Atlantic:

Disorganized showers and thunderstorms located over the central

tropical Atlantic are associated with an elongated trough of low pressure centered about 750 miles west-southwest of the Cabo Verde Islands. Environmental conditions appear conducive for gradual development of this system, and a tropical depression could form during the next several days while moving toward the west or west-northwest at about 10 mph across the central tropical Atlantic.

* Formation chance through 48 hours…low…30 percent.

* Formation chance through 7 days…medium…50 percent.

2. Eastern Tropical Atlantic:

A tropical wave moving off the west coast of Africa is producing a large area of disorganized showers and thunderstorms. This system is forecast to move toward the west-northwest at about 15 mph, with an area of low pressure expected to form in a day or so near or just to the west of the Cabo Verde Islands. Further development of the low is possible, and a tropical depression could form over the weekend before environmental conditions become unfavorable early next week.

* Formation chance through 48 hours…low…20 percent.

* Formation chance through 7 days…medium…40 percent.

3. Western Gulf of Mexico:

A broad area of low pressure could form in the central or western

Gulf of Mexico by the beginning of next week. Some slow development of this system is possible thereafter as it moves westward and approaches the western Gulf of Mexico coastline by the middle of next week.

* Formation chance through 48 hours…low…near 0 percent.

* Formation chance through 7 days…low…20 percent.

(Forecaster Bucci)

WATCH A GOES EAST WEATHER SATELLITE ANIMATION OF WEATHER OVER THE ATLANTIC BASIN AND NORTH AMERICA

The prediction has caught the eye of seasonal hurricane forecaster and tropical researcher Dr. Phil Burdick (https://twitter.com/philklotzbach) who posted Wednesday morning the National Hurricane Center (NHC) 7-day graphic, labeling each of the areas being monitored with NHC’s assessment of the potential for further development over that period of time.

Development of a mammoth hot air dome later this weekend into next week over the central U.S

We here in Chicago and the Midwest are monitoring the predicted development of a mammoth hot air dome later this weekend into next week over the central U.S. There have continued overnight and Wed morning to be some interesting overnight model runs suggesting a Canadian high pressure and cold front could swing southward into the Midwest delaying heat’s arrival in the region Sunday or Monday. Yet–the majority of upper air projections, including a number from these model’s ENSEMBLE FORECAST RUNS–continue to project a huge, expanded dome of heat is likely to develop. We’re anticipating the potential onset of late season heat beginning later this week. But chance for a derailment of the heat–or a disruption in its intensity—aren’t ZERO. Makes for interesting forecast possibilities which I’m monitoring with great interest.

My sidebar note is this:

A huge HEAT DOME of the type being predicted would simultaneously produce powerful “EASTERLIES” on its southern flank. Those would blow from the Atlantic westward across the Gulf of Mexico and Mexico—the sweep northward into the Southwest U.S.

Any tropical systems which might evolve in the Atlantic Basin would be influenced/guided by such winds.

Of interest are medium range (i.e. 4 to 10 day) indications of a tropical system making its way northward from the Pacific waters off western Mexico into the Southwest U.S.–including the deserts there and potentially sections of California.

This potential has been picked up by the MODEL BLEND FORECAST of precipitation generated by the National Weather Service’s WEATHER PREDICTION CENTER (WPC)–the agency’s central analysis and forecast facility on the University of Maryland campus which sends out forecast guidance to NWS office and other meteorologists across the country and elsewhere.

The DOME OF HOT AIR which is predicted to take shape is a real eye-catcher—more expanded than any air mass to date this summer if model forecasts verify.

The unanimity among models from range of meteorological centers is stunning. I’m posting a number of those upper air model forecast for you to see–including predictions generated by supercomputers operated by our National Weather Service, the UK Met Office, Environment Canada, the European Centre for Medium Range Forecasts, the German meteorological service and the Japanese Meteorological Agency. All agree on expanding the atmosphere more than with any hot spell to arrive thus far this summer.

There’s an interesting twist in machine projections of the developing warm spell which we continue to follow—and likely will be monitoring the next several days. While there’s strong agreement on the development of HUGE DOME OF HEAT, several models are bringing a Canadian high pressure system into the Midwest—at least for a time—early next week. This is the sort of development which could impact the incoming heat—in the most extreme case, derailing the heat. Frankly, these predictions seem odd given the expansion of the atmosphere being predicted by the models. And ensemble versions of these model downplay the high pressure development being predicted my some models. So we’ve chosen to lay those forecasts aside as “outliers” and more aggressively heat the Sunday through Tuesday and possibly Wednesday period–at least FOR NOW. We’ll continue to monitor updated model scenarios and keep you posted.

It’s monsoon season in the Southwest and western U.S.

It’s been my experience that the onset of active thundery monsoonal rains in the Southwest has, on occasion in the past, helped prod the shift in the core of hot air domes eastward from the West into the Plains and Midwest. That is what many model projections are suggesting and could help drive heat’s movement into the Midwest later this weekend into next week. Whether this shift will be impacted by a Canadian high pressure and cold front on its southern flank is an interesting twist which warrants the scrutiny it will receive in coming days.

All in all, there are some fascinating forecast developments which appear to be coming together and worth following in the coming week! There’s more to say on ALL of this–and more to come in future posts here.

Smoke’s on the way, this time from fires flaring in record heat in the Pacific Northwest—smokier Chicago skies ahead in coming days

It’s happening again—MORE SMOKE’s on the way to the skies above Chicago. We’ve been tracking its advance on the area on weather satellite imagery. We’ve been here before this summer. The incoming SMOKE will turn Chicago skies hazy over coming days–smoke which is to ride gusty NW winds into the Chicago areas—much of it aloft.

(Watch this National Weather Service RAP MODEL smoke forecast for the coming 2 days here)

Before the smoke gets here, there’s to be a period of cold frontal showers and t-storms Thursday morning—the heaviest concentration of them in the 6 to 10am CDT Thursday time frame

First, cold frontal showers & possible t-storms Thursday morning, mainly 6 to 10 am—a period of pleasant weather with cooler but comfortable temps and lower humidities Thursday afternoon, Friday and into Saturday morning—but models build dome of hot humid air which is to be draped across a good portions of the lower 48 and centered on the Midwest—heat and humidity to build in Chicago Sunday into Wednesday

Gusty NW winds are to follow the showers, lowering Thursday highs to the 70s from the 82-degree max recorded Wednesday. The weather remains comfortable under sunny skies Friday into Saturday–but by late Sunday, careful observers will note the air in Chicago is growing a bit more humid.

Dew points—a measure of atmospheric moisture—are to rise from the mid 50s as Saturday gets underway to the mid 60s by evening.

THEN, NOTICEABLY MORE HUMID AIR—WITH GULF COAST LEVEL 70-DEG DEW POINTS–IS TO SWEEP INTO THE AREA ACCOMPANYING THE ARRIVAL OF 90-DEG HIGH TEMPS SUNDAY INTO WEDNESDAY NEXT WEEK.

When the atmosphere heats, its expands. We can see this expansion on upper air charts which track the height at which certain barometric pressure readings occur.

READ THE FULL NOAA RELEASE ON JULY 2023 TEMPS HERE: https://www.noaa.gov/…/record-shattering-earth-had-its…

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I traveled last fall with my WGN-TV colleagues, producer Katharin Czink and video journalist Steve Scheuer, to Lake Mead in southern Nevada. What we saw was striking. Drought had reduced water levels In Lake Mead by 178 feet—a decline equivalent to an 18 story building. The reservoir’s high water mark, achieved decades earlier, had left a so-called “bathtub ring”-which offered stunning evidence of decline of the reservoir’s water level.

Lake Mead is the country’s largest reservoir—a water body created with the construction of Hoover Dam in the 1930s. It is the source of water for more than 40-million across the Southwest U.S.—including the city of Las Vegas.

Lake Mead’s water are critical in irrigating farm fields in the region, including across southern California, which generates a huge percentage of our country’s fresh vegetables and fruits.

The reservoir was in the news at the time (last autumn)— its waters having fallen to just 26% capacity—the lowest since the Lake Mead was created in the ’30s. Then came a temporary break in a 20 year drought—this past WET WINTER in the West brought heavy mountain snows. Their meltwater feeds Lake Mead.

Water levels have risen, much as has occurred upstream in Lake Powell–another mammoth reservoir on the Colorado River. The reservoirs have risen to 33% and 39% capacity in Lakes Mead and Powell respectably. This is allowing an easing of water restrictions on the usage of these reservoir’s water—but hardly means ALL issues with water there have been resolved.

CLICK HERE to read how the Associated Press (AP) is reporting the story

And CLIMATE NEXUS writes the following in their Wednesday newsletter:

“COLORADO RIVER IS SLIGHTLY LESS DEPLETED: The state of the Colorado River is less dire than a year ago, federal officials said Tuesday, but substantial climate- and over-consumption-driven challenges remain. The Bureau of Reclamation — a division of DOI that implements agreements made by states, tribes, and other stakeholders — said heavy rain and snow over the winter have eased the crisis slightly, meaning that cuts to state water usage will be eased somewhat. But the river, and the overall hydrological system, are still stressed by climate change-fueled heat and drought, as well as fundamentally unsustainable assumptions of water availability. Between 70% and 80% of all water in the Colorado River basin is used for large-scale agriculture. Lake Powell and Lake Mead, the two biggest Colorado River reservoirs, are still only about 39% and 33% full, respectively. “If we want to keep the reservoirs functioning – which is a very wise thing to do – you need to reduce consumption by 15 to 20%,” Jonathan Overpeck, dean of the University of Michigan’s School for Environment and Sustainability, told CNN. “But you’ve got to acknowledge that climate change is going to make the situation worse, and in the future, we’re going to have to reduce consumption even more.”