Delightful Wednesday, Thursday; heat, humidity build on Friday
The cold front that was triggering showers and thunderstorms across Minnesota on Tuesday has kindly plowed all the muggy air well off to our east. Behind it we have much drier air with lower dew points in the 50s to some low 60s.
Wednesday will be a very comfortable day across Minnesota. Seasonal high temperatures will be in the upper 70s to mid-80s. Very pleasant dew points will remain down mainly in the 50s.
Sunshine will come our way, through broken high clouds at times. Isolated non-severe afternoon showers or thunderstorms might dampen the southeastern corner and parts of the far north.
The Twin Cities should see a high in the low 80s with afternoon dew points in the 50s and a light southwest breeze.
Create a More Connected Minnesota
MPR News is your trusted resource for the news you need. With your support, MPR News brings accessible, courageous journalism and authentic conversation to everyone - free of paywalls and barriers. Your gift makes a difference.
Warmer but mostly storm-free again on Thursday
Thursday will be a few degrees warmer than Wednesday but still not very muggy. High temperatures will be in the mainly in the 80s with the Twin Cities heating to about 86. Isolated non-severe thunderstorms are likely to break out in the northwest half of the state.
Back to the tropics Friday; thunderstorms at times
Heat will build again on Friday and stay with us through the weekend. Ample humidity will return with that southerly flow as well.
Strong thunderstorms are likely to develop in North Dakota on Friday and spread across northern Minnesota Friday night, maybe reaching the northwestern corner of Wisconsin by Saturday morning. Severe storms are possible during those nighttime hours.
Saturday is likely to be the hottest, muggiest day of at least the next week with highs into the 90s across the southern half of the state where dew points will climb into the sultry low to mid-70s.
The Twin Cities should reach a high temperature of about 94 degrees, with a dew point of around 74 on Saturday.
Why is dew point so important?
You will notice that all above mentions about mugginess refer to dew point rather than relative humidity.
Dew point is the temperature at which the air would reach 100 percent relative humidity if it were cooled without changing its moisture content. A dew point increase of 20 degrees Fahrenheit, such as from 50 to 70, represents approximately a doubling of the moisture content of the air.
Humans are much more sensitive to the actual moisture content of the air, measured and reported as the dew point, than they are to relative humidity.
For example, using my forecast for Saturday afternoon in the Twin Cities, a temperature of 94 with a dew point of 74 (often referred to as “94 over 74”) would represent a relative humidity of just 53 percent. That 53 percent relative humidity might not sound very uncomfortable, but I will guarantee you that 94 over 74 is well into the sultry category.
Relative humidity is important in some meteorological applications such as forecasting fog, but that’s another story.