Heat Ridge About To Pump Temps Up

We're starting the core and prime heat days of our heat wave today, with three days of nastiness ahead where temperatures and dew points combine to make it feel like it's over 100 each afternoon...perhaps even as high as 110 in the prime heat of the day tomorrow afternoon.   Some low clouds, haze, and light fog graze the region this morning as residual less hot air from yesterday lingers while the heat ridge bubbles in from the southwest.   Temperatures are starting out on the toasty side regardless -- generally in the 70's and on the way to topping out well into the 90's by day's end.

Nationally, the main focus of the heat is shifting a bit to the east and southeast from its position of the past few days.   Minnesota and most of the Upper Midwest have seen the passage of a cool front and the introduction of some relief in the temperatures and humidity, with the heat dome shifting to the Ohio Valley and Appalachians for the next few days.  You can see the vast swath of real estate that are under some form of heat advisory, warning, or watch over the next couple of days (inland areas in a red shading) -- effectively close to 2000 miles from Massachusetts to Oklahoma.   Locally, we're under an excessive heat warning through Saturday.

Today's peak heat features heat index values between 102 and 107.   Based on an assumption that we reach high temperatures from 94-97 locally, with dew point values in the low or middle 70's, the heat index below is calculated for a number of different locations based on different combinations.   Even with a lower high temperature, a higher dew point can offset the "cooling" benefit of three degrees and give you an apparent temperature as high, if not higher, than the heat index of a locale with a higher temperature and lower dew point.   That's why it's more critical to know what the heat index is as opposed to simply knowing how high the air temperature is.    All of the air temperatures over the next three days will be hot -- perhaps record breaking in spots -- but the bigger story will be the combination of this heat with dew points that are borderline tropical.   That combination compounds air temperatures in the upper 90's or 100ish and makes it feel like it's a good 5-12 degrees warmer.

Most of us would probably feel better if we were talking about subzero wind chills this morning and not heat index values in the 100's or low 110's!   Regardless, stay cool (or as cool as possible) and drink lots of water.

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