Temperatures are soaring from the Plains to Great Lakes this afternoon with 100s over Iowa and lower 90s up into Minneapolis and Chicago.

Thank a trough over the Rockies, dry ground southwest winds, sunshine and a ridge. The mid-summer level heat is not only breaking daily but monthly records with Des Moines currently simmering at 101 degrees. That’s in fact a 3 pronged record as it breaks the old record for latest 100, for the date and also ties the all-time record for Sept.

Chicago is already at 93 degrees and tomorrow looks set to surpass the record of 95 with possible high near 98.

Here are the current readings across the country.

Here’s the 500mb chart for tomorrow off the ECMWF.

Below are the highs for tomorrow and notice the much cooler temps back over Minneapolis while it’s significantly warmer over the Northeast.

Philadelphia will go from low to mid 70s today with sunshine and low humidity to the upper 80s to perhaps 90 while Minneapolis goes from mid 90s to low 80s with storms.

By Wednesday the trough sinks a little further south over the Midwest, dropping temperatures some 8-10 degrees in Chicago while heights continue rising over the Northeast along with the temperatures. I wouldn’t be surprised if we see 96 in Washington, 94 in Philadelphia and New York while Boston up to perhaps Portland, Maine reaches 92 with a strong southwest wind.

Here’s the 500mb chart for Wednesday.

Note the 588 height line reaches central Vermont, New Hampshire and Maine.

Here’s the 850 temps.

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Below are the forecasted highs according to weather.com on Wednesday.

Note the upper 90s to perhaps near 100 still over Kansas City and St Louis but the cooling over Chicago as the jet begins to drop south. This marks the start of a significant 48 to 72 hour temperature drop. As the jet takes a southward drip here, so heights are forced to rise over the Northeast, strengthening the SW wind at all levels of the atmosphere and this drives readings up 2 to 5 degrees on the previous day.

So while Tuesday should see 90 in DC tomorrow, it could hit 95 Wednesday and while Philly reaches 88 or 89 Tuesday, we could see 93 or 94 Wednesday, likewise for New York City.

What’s interesting is the fact that we’re seeing temperatures rise potentially 20 degrees in Chicago from Sunday’s 77 to Wednesday’s potential 97 and by Friday, it may fail top hit 70. Saturday morning may start in the upper 40s believe it or not. Perhaps one of the bigger rise and falls of temperature in many a year in Sept?

The same goes for the Northeast with today’s low and mid 70s in New York. While it soars to 93 or 94 Wednesday, ity may stay in the low 60s Saturday, perhaps 50s Sunday and Monday with the first 40s of the season by night.

Check out the 500mb chart by Friday.

Here’s the 850 temps Saturday morning and what a different compared with Wednesday.

GFS surface temps Wednesday afternoon.

Saturday morning!

These numbers are conservative as ECMWF has stronger heat pump Wednesday and also a deeper trough, lower heights and colder air by Saturday.

500mb chart off ECMWF at 132 hr or late Saturday over the Northeast.

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