What's going on?
It's our nemesis..."Southern" high pressure! I make the distinction because high pressure is usually our pal.
Every year, at just about this time, high pressure will settle in over the middle of the country. Usually, the placement lasts a couple of days. Finally, what I call a "kicker", some sort of weather feature will move the high across the nation. Poof! We're back to normal; but, every once in a while, there ain't no kicker!
Specifically, when a high pressure system develops in the atmosphere, the air below it sinks and compresses. This causes temperatures closer to the ground to heat up.
This "dome of high pressure" also pushes the jet stream and its drier, cooler air, farther north. At the moment, the jet stream is well into Canada. This leaves the hot, humid air from the Gulf of Mexico circulating clockwise around the dome, traveling farther inland than normal. Now, combined with generally clear skies and the sun's higher summertime angle, you get stifling heat.
Occasionally, thunderstorms can develop around the perimeter of the dome bringing temporary relief to some areas. But, this dome is so large that the heat rebuilds quickly.
I don't see any relief in sight until next week. A cold front drops down from Canada allowing a cooler, drier air mass to sweep into the Tri-State.
COOLING SPRAYS
The Japanese have a new hip, COOL way to beat the heat. How about spray cans full of coolant? I just posted a story in our video player, right after the forecast here .
HEAT INDEX
Considering we could set a few records over the next 48 hours, I wanted to touch on the heat index. Frankly, the National Weather Service just released a well explained article on the this important topic.
THE NATIONAL WEATHER SERVICE USES THE HEAT INDEX AS A MEASURE OF THE APPARENT TEMPERATURE...OR WHAT IT FEELS LIKE...TO A HUMAN BEING OUTSIDE IN THE ELEMENTS. THE HEAT INDEX WAS DEVELOPED IN 1978 BY GEORGE WINTERLING...BASED ON WORK BY ROBERT STEADMAN. THE INDEX IS A COMPLEX MATHEMATICAL EQUATION WHICH TAKES INTO ACCOUNT THE AMBIENT
AIR TEMPERATURE...AMBIENT RELATIVE HUMIDITY...AND MAKES ASSUMPTIONS ON WHAT THE AIR FEELS LIKE TO A HUMAN OF AVERAGE WEIGHT/HEIGHT WALKING IN A LIGHT BREEZE WEARING LONG PANTS AND A SHORT SLEEVED SHIRT.
AT THE NATIONAL WEATHER SERVICE OFFICE IN WILMINGTON OHIO...THE HEAT INDEX IS USED TO TRIGGER THE ISSUANCE OF HEAT ADVISORIES...EXCESSIVE HEAT WATCHES...AND EXCESSIVE HEAT WARNINGS.
FOR A HEAT ADVISORY...HEAT INDICES MUST REACH 100 DEGREES
FAHRENHEIT. FOR AN EXCESSIVE HEAT WARNING...HEAT INDICES MUST REACH 105 DEGREES. FOR THE DAYTON AND CINCINNATI METRO AREA /MONTGOMERY AND HAMILTON COUNTIES/...TWO CONSECUTIVE DAYS OF HEAT INDICES IN EXCESS OF 100 DEGREES WILL TRIGGER THE ISSUANCE OF AN EXCESSIVE HEAT
WARNING.
CINCINNATI
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DATE/TIME TEMPERATURE DEWPOINT HEAT INDEX
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6/23/1930 - 3 PM 98 78 116
7/30/1999 - 2 PM 98 77 114
7/23/1983 - 3 PM 100 75 114
7/11/2011 - 7 PM 93 80 112
7/21/1934 - 5 PM 108 64 112
8/03/1964 - 3 PM 100 74 112
7/14/1954 - 5 PM 102 71 111
7/27/1997 - 4 PM 97 76 111
7/20/1934 - 6 PM 104 68 110
7/11/1936 - 3 PM 104 68 110
HEAT INDICES OF 100 DEGREES OR MORE HAVE BEEN RECORDED ON 1837
DIFFERENT HOURLY OBSERVATIONS IN CINCINNATI. OF NOTE...WHILE 112 DEGREES WAS THE HIGHEST INDEX MEASURED ON AN OBSERVATION ON JULY 11 2011...THE HEAT INDEX ACTUALLY MADE IT TO 114 DEGREES AT 340 PM /BETWEEN HOURLY OBSERVATIONS/ ON THE KCVG ASOS. AT THAT TIME...THE
TEMPERATURE WAS 96 AND THE DEWPOINT 79. THAT DAY FEATURED SIX CONSECUTIVE HOURS WHERE THE HEAT INDEX REACHED OR EXCEEDED 110 DEGREES...MAKING IT ONE OF THE MOST UNCOMFORTABLE DAYS IN CINCINNATI HISTORY SINCE 1930.
Oh, one other thing. Send me your "Beat the Heat" pictures! How are you staying cool? If I get a really good one, I'll send you some Channel 9 stuff!
steve.raleigh@wcpo.com
Earth Gauge: Cool Efficiently
When the temperature goes up outside, so does the demand for energy for cooling. Research shows that for every one degree Fahrenheit increase in outdoor air temperatures, demand for energy increases by 1.5 to two percent!
Rising energy use can lead to an increase in air pollutant emissions, which impact human health and contribute to the formation of ground-level ozone, or smog.
Viewer Tip: As the temperature rises, give these tips a try to save energy at home while staying cool.
· Bump the thermostat up to 78 degrees when no one is home. For each degree you raise the thermostat, you’ll save three to five percent on air conditioning costs. Close shades and curtains during the day to keep the heat out.
· Run a ceiling fan
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