Wednesday was another GORGEOUS DAY—and temps away from Lake Michigan responded big time, reaching the upper 70s and low 80s. While temps hit 82 at Joliet and Peotone and 83 at Tinley Park, mid-afternoon lakeshore air temps held to 58 at Lake Forest and 59 at Waukegan Harbor and Zion.

It was 100% Sunny Wednesday with a 25° lakeshore to inland temp spread (58° in Lake Forest and Waukegan to 83° in Tinley Park—May’s opening 10 days among the driest 25% since 1871—but more clouds and showers in our future later this week; flow off Lake Michigan plus clouds suggest cool weekend ahead…

Coming days will see increased clouds—though Thursday should see temps surge broadly to the low 80s inland with mixed sun making for another beautiful day—rain chances surge Friday and could include scattered t-storms as winds off Lake Michigan cut into daytime warming

A broad and persistent northward flow of Gulf moisture is predicted to increase clouds–particularly Thursday night and through the weekend. Dew points will be surging to the 60s Friday and into the weekend. Rain chances are to take off–but currently modeling suggest the widest coverage rainfall looks likely to occur Friday, thinning out in frequency and coverage Saturday–only to increase Sat night, Sunday and Sunday night.

Models offer rainfall estimates of 0.6″ to as much as 1.50″ by Monday morning–though rainfall is to arrive in waves.

I wouldn’t be surprised to see cool winds off Lake Michigan interact with all the moisture in the air to produce lakeside foggy spells over the coming weekend. And strengthening northeast winds with a tightening pressure gradient over the weekend is likely to take a toll temps–particularly along Lake Michigan–where weekend highs could struggle to make the upper 50s and may stay in the low 50s Sunday.

View Slideshow of the Current Weather Situation:

  • Check out this plot of May, 2023 rainfall for the opening 10 days of the month as analyzed by the Midwestern Regional Climate Center at Purdue University.
  • This is a Midwestern Regional Climate Center analysis of the per cent of normal rainfall since May 1. Areas shaded in green have had near or above normal precip. Other areas have May 2023 rain tallies running BELOW NORMAL
  • The highlighted area is a storm system which, as it clears the mountains, will sweep out onto the Plains States and draws Gulf moisture northward into the Midwest
  • Wednesday afternoon observed temps
  • Wednesday afternoon surface winds
  • 24 hour temp change through early afternoon Wednesday highlighting the warming which is taking place
  • Dew points offer a measure of atmosphere moisture. Areas reporting dew points in excess of 50-deg are shaded in green. Dew points higher than 60-deg indicated levels of atmosphere moisture which take on a “humid” feel
  • ESTIMATED TOTAL RAINFALL through 7am CDT Monday morning
  • TRACK THE NORTHWARD SPREAD OF MOIST AIR from the Gulf of Mexico as predicted by the NWS GFS model. This panel verifies at 7pm CDT Wed
  • 7am CDT Thu forecast
  • 7pm CDT Thu forecast
  • 7am CDT Friday
  • 7pm CDT Fri forecast
  • 7am CDT Saturday
  • 7pm CDT Saturday
  • 7am CDT Sunday
  • 7pm CDT Sunday forecast
  • 7am CDT Monday
  • DAY #2 SEVERE WEATHER RISK Thu & Thu night covering the 24 hour period from 7am Thu through 7am CDT Fri per the NWS Storm Prediction Center (SPC)
  • Day #3 SEVERE WEATHER RISK FORECAST covering Friday & Fri night
  • CLOUD FORECAST 7pm CDT Fri
  • Cloud forecast 7pm CDT Saturday
  • 7am CDT Sunday morning forecast
  • 7pm CDT Sunday evening
  • Watch as deep atmospheric moisture sweeping northward in the Midwest as predicted by the NWS GFS model–This panel for 7am CDT Saturday
  • 7pm CDT Sat
  • 7am CDT Sunday
  • 7pm CDT Sunday
  • WATCH AS THE PRESSURE GRADIENT TIGHTENS BETWEEN A PLAINS STORM AND CANADIAN HIGH PRESSURE TO THE NORTH. The tighter gradient is to produce strengthening east/northeast winds into Chicago and off Lake Michigan over the coming weekend. This panel is fhe forecast surface map off the GFS ensemble 7am CDT Friday morning
  • 7pm CDT Friday evening
  • 7am CDT Sat
  • 7pm CDT Sat evening
  • 7am CDT Sunday
  • 7pm CDT Sunday
  • PRECIP PROBABILITIES for Thursday night
  • PRECIP PROBS Friday
  • PRECIP PROBS Fri night
  • PRECIP PROBS Sat
  • PRECIP PROBS Sat night
  • TEMP DEPARTURE FORECAST for Days 1-5 indicating ABOVE NORMAL TEMPS off NWS GFS ensemble model
  • DAY 6 to 10 TEMP DEPARTURE FORECAST
  • DAY 11 TO 15 TEMP DEPARTURE FORECAST
This AURORA FORECAST out of the University of Alaska Geophysics Dept. for Thursday night.

NORTHERN LIGHTS potential over an expanded area of North America in coming nights

NOAA’s Space Weather Prediction Center runs the OVATION AURORA FORECAST MODEL—which predicts the potential for Northern Lights displays. Also posted is the Space Weather Prediction Center’s GEOMAGNETIC STORM FORECAST. Geomagnetic storms can impact radio transmissions and have impacts on power grids and pipelines https://www.swpc.noaa.gov/impacts

Coronal Mass Ejections—so called “CME’s”—send clouds of charged particles—PLASMA—which excite Earth’s upper atmosphere into giving off light when contact is made by this “plasma” cloud and produce geomagnetic storms.

A G3 (Strong) geomagnetic storm watch is now in effect for 11 May with a partial halo CME that erupted from the Sun on 9 May.

Thursday night Northern Lights potential from the University of Alaska: