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Milwaukee's Daily Magazine for Wednesday, Oct. 22, 2014

Wed
Hi: 53
Lo: 37
Thu
Hi: 55
Lo: 47
Fri
Hi: 59
Lo: 46
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Week-long heat wave starts Saturday

A full-fledged heatwave, complete with blistering temperatures and tropical humidity, is set to start this weekend. Most indications are that it isn’t going to break until next weekend.

It all starts Saturday when temperatures soar into the middle to upper 80s. It gets hotter on Sunday, with highs in the upper 80s to low 90s. Monday will be in the low 90s.

Slight relief appears to be in the cards on Tuesday, when highs will be in the mid to upper 80s. Then, it’s right back into the 90s for Wednesday, Thursday and Friday.

The humidity will be at persistently stifling levels during the entire stretch. Dewpoints will climb to around 70 on Saturday, then into the low to mid 70s Sunday, Monday and Tuesday. Middle to upper 70s aren’t out of the question for Wednesday, Thursday and Friday.

The heat index, which is the temperature our bodies perceive it to be when relative humidity is considered along with the reading on the thermometer, will be over 100 degrees many afternoons during the heat wave. In fact, it will likely exceed 105 degrees at times.

On top of the heat, it appears it will remain very dry. During the week-long heat wave, it’s likely that parts of the area will receive no rain at all. Scattered thunderstorms seem to be most possible on Saturday, Monday night, Thursday and Friday.

Still, even if these do develop, it’s reasonable to expect that they will only affect parts of the area.

Here’s my detailed forecast:

Saturday
Partly sunny with a 30 percent chance of thunderstorms.
Highs in the middle to upper 80s.
Dewpoints around 70.
Afternoon heat index in the low 90s.

Sunday
Mostly sunny.
Highs in the upper 80s to low 90s.
Dewpoints in the low to mid 70s.
Afternoon heat index near 100.

Monday
Partly sunny.
Highs in the low 90s.
Dewpoints in the mid 70s.
Afternoon heat index 102-104.

Tuesday
Mostly sunny.
Highs in the mid 80s to near 90.
Dewpoints in the low to mid 70s.
Afternoon heat index in the mid to upper 90s.

Wednesday
Mostly sunny.
Highs in the low …

Read more...

Heat lightning is a lot of hot air

It flickers in the distance on warm summer nights; a silent light show on the dark horizon.

Like me, you probably learned at an early age that this is "heat lightning," a special type of weather phenomenon.

Like me, you learned wrong.

There is no such thing as heat lightning, at least not to the extent that it's some different or special type of lightning.

What we were taught was heat lightning is actually just ordinary lightning. We don't hear the thunder associated with it because the storm generating it is so far away.

The tops of powerful thunderstorms can extend over 50,000 feet (around 10 miles) into the sky. Lightning occurring in clouds at this height can be seen over 125 miles away. Meanwhile, thunder usually isn't heard more than 15-25 miles away. (Not only does light travel faster than sound, it travels farther, too.)

The term 'heat lightning' probably developed because the only time this distant, silent phenomenon is observed is on warm summer nights when people are outside long after the sun goes down.

The outlook is hot, hot, hot - and then more comfortable

Weather for 4th of July weekend:

Friday
The holiday weekend will have a sizzling start as Friday may be the hottest day of the year so far. Afternoon highs will be in the mid 90s … and that includes areas near Lake Michigan, like Summerfest. The humidity will be very high leading the heat index to peak near 108 in the afternoon. (Heat index is a measure of how hot it really feels when relative humidity is considered along with the reading on the thermometer.)

It will be partly to mostly sunny on Friday, with no threat for rain. There is a small threat for thunderstorms after Midnight on Friday night.

Saturday
Temperatures will be down a touch on Saturday, but it will still be very warm and humid. Highs will be in the upper 80s with the heat index peaking in the low to mid 90s.

It may start rather overcast early on Saturday, and there is a small threat for early morning thunderstorms. If those occur, and it’s a big if, they should depart by mid-morning, giving way to mostly sunny skies the rest of the day.

Sunday
Sunday will be the most comfortable day of the weekend as the humidity will be down considerably. Highs will be in the low to mid 80s.

Skies look to be mostly sunny all day with no threat for rain. That goes for Sunday night as well, good news for communities who have fireworks displays scheduled for the eve of the 4th.

Monday
The 4th of July won’t be much different than Sunday, although the humidity will sneak back up a little. Still, it will be reasonable, and high temperatures will again be in the low to mid 80s.

Another mostly sunny day is expected. Plus the outlook is again positive for fireworks displays. No threat of rain until Tuesday.

Have a great weekend!