Meteorologist Paul Gross looks back at our historic heat wave

Historical perspective and lessons learned

By Paul Gross - Meteorologist
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DETROIT -  I received a number of questions during our recent heat wave, and I thought I'd share these answers with all of you:

1.  The heat wave lasted from June 27th to July 7th, and we set four records during that span:  a record high of 102 on July 4th, a record average temperature for the day of 87 degrees on July 4th, a daily rainfall record of 1.76" on July 5th (obliterating the old record of 1.08" set back in of our oldest records), and a record average temperature for the day of 88 degrees on July 7th.  By the way, the last time we hit 100 degrees was July 21, 2011.  And with all of these record highs we've had this year, I was wondering when our last record low was, and that occurred way back on January 16, 2009 (-15 degrees).

2.  One record we didn't set but almost did was for consecutive 90-degree days.  Had thunderstorms and their accompanying cloud cover NOT hit Metro Airport (where Detroit's official stats are recorded) on July 3rd and 5th, we easily would have exceeded 90 degrees on those two days.  Had that happened, we would have tied our all-time record of eleven consecutive 90 degree days, set back in 1953.  Other parts of the area got into the 90s on those days, but it needed to happen at Metro.

3.  The numerous, but seemingly random batches of very severe storms during the week just reinforced the importance of having a weather radio.  You can still get our Local 4 weather radio at all ABC Warehouse stores for the special price of $29.99 (normal retail price is $39.99).  It's well worth the investment...and especially for those severe weather events that occur when you are sleeping, such as last Thursday morning.  And don't forget that you can program these radios to only warn you for the county you are in, and that they have a battery backup that keeps them working if your power goes out.

4.  Speaking of last Thursday morning's storms, several people have asked me why they were so severe at night, when it seems that most of our severe storms happen in the afternoon.  Those storms were a special severe thunderstorm complex called a Mesoscale Convective System.  These storms actually  blow up at night when the nocturnal low-level jet stream directs copious amounts of heat and moisture northward.  The resulting storms are heavy rain producers and can be particularly destructive, and they start to die after sunrise when temperature begins to rise and the low-level jet weakens.

5.  We had extremely large hail on several days this week.  A number of people have asked how hail that large forms.  What happens is raindrops are carried upward by violent  thunderstorm updrafts, where they freeze near the top of the storm where temperatures fall below freezing.  The resulting little ice balls then start falling, but are carried aloft again by the updraft.  On the way up, they accumulate more moisture, which then freezes into another layer.  If the storm is very severe and has a super violent updraft, the hailstone can make a number of trips up and down...accumulating more layers of ice and growing in size.  Thus, the larger the hailstone, the more severe the storm is. 

6.  If you ever want to see something REALLY cool, the next time you see large hail (please wait until after the storm passes), grab some and put them in the freezer.  Get a very sharp knife, and slice a hailstone in half.  You'll see the various layers...they look almost like tree rings!

7.  By the way, terminal velocity of a hailstone when it reaches the ground is 125 mph.  Ouch!

8.  My air conditioning was out all week (great timing, eh?), so I had to practice what I preach to keep my house as cool as possible.  You have no idea how much it helped to close the blinds on the sun sides of the house...keeping that sun out really made a difference.  Also, regular light bulbs give off heat, so using those lights sparingly also helped.  A fan really helped me sleep...until my power went out, of course.  At that point, I slept downstairs on the really is cooler the lower in your house you go.

9.  One great lesson I remembered when my power went out was to NOT open my freezer for any reason.  If you leave it closed, most frozen food in the freezer will keep for about twenty-four hours.  My power (fortunately) was out for only nineteen hours, and all of my frozen food was fine.  However, I did have to throw out some of the food in my refrigerator.

10.  Something else to remember when the power goes out is to shut off anything that was turned on at the time (and unplug appliances and your computer).  I was sleeping on my couch Thursday night when the power came back on, and all of the lights in the room suddenly came on, which scared the dickens out of me!

11.  I'm a person who charges my cell phone every night, whether it needs it or not, because I always want a full charge in the event an emergency occurs.  I'm SO glad I had that full charge, because a regular house phone that receives power from an outlet becomes useless when the power goes out.  It even allowed me to report live over the phone on Local 4 News Morning that Thursday morning.

12.  If you have a basic cordless phone / answering machine set-up at home, and it became useless when the power went out, I suggest getting one of those old-fashioned phones that only had a phone cord that plugged into the phone jack in the wall.  My wife and I saved her grandmother's old phone, and it worked like a charm when the power failed and my cordless phones all went silent.

13.  PLEASE check on any elderly friends or relatives during a long-duration power failure.  I was talking to my elderly neighbor, and found out that they were unable to reach their daughter and son-in-law because none of their phones were working (even their cell phones weren't working, for some reason...perhaps the power outage affected some cell towers).  Don't assume that people are okay...check on them.

14.  Several people have asked me if this heat wave was caused by global warming.  The answer is no, global warming did not cause the heat wave.  Heat waves are part of our history:  they happened in the past, and will happen in the future.  HOWEVER, our planet's sharply warming climate likely made it worse (same thing with our March heat wave).  Global warming is clearly increasing the number of severe heat waves:  The European heat wave in 2003 was the hottest summer on record there since at least the year 1540, and it killed 35,000 people.  The Russian heat wave of 2010 was their hottest one since 1880.  We had extraordinary heat waves here in the U.S. both last year and this year.  And who can forgot the heat wave of in Detroit, we had four days of 100 degrees or above, and thirty-nine 90 degree days.

15.  Finally, I did some research using Detroit weather records.  I counted the number of heat records and cold records set in the 1990s, and the first decade of the 2000s.  Record heat outnumbered record cold by a three-to-one ratio in the 1990s, and by a six-to-one ratio in the 2000s.  This is proof of a strong warm forcing on Detroit's climate because, with our long climate record, at this point we would see a much more equal distribution of cold and warm records.

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