Beyond the Sun
An excessive heat watch for temperatures 110 degrees or higher as well as an extended ozone advisory have been issued for the Las Vegas Valley today.
When asked why the National Weather Service issued an excessive heat watch for Las Vegas, meteorologist Jon Adair said Thursday's high was 109 degrees and conditions aren't expected to change much -- except to get hotter. The record high for Thursday was 111 degrees, set in 2002 and 1962.
Average temperatures for this time of year range between 101 and 103 degrees.
Normally at this point, summer thunderstorms rumble into the valley from Arizona. But a dome of high pressure is sitting over Nevada at the moment, keeping lightning, thunder, rain and hail east and south of us, Adair said.
The annual rainfall this year is 0.98 of an inch, measured at McCarran International Airport, the area's official weather station. That's 2.08 inches below the average normal total, Adair said. January, February and March were dry, adding to the lack of rain.
Today's high could reach 110 or higher, Adair said. The record of 111 was set in 2002 and 1994.
Things have been hot and dry recently. While July had seven days below 100 degrees -- July 11 through the 15, 20 and 26 -- Aug. 5 is the only day this month when temperatures didn't reached the triple digits, Adair said. Even with seven days below 100 degrees, this July was sixth hottest on record.
Over the past eight to 10 years, summer days and nights produce higher temperatures due to the urban island heating effect, Adair said. More homes, offices, asphalt parking lots and roads keep nighttime lows in the low to mid 80s.
Along with the extra heat, Clark County's Department of Air Quality and Environmental Management has extended an ozone advisory through today.
Although ground-level ozone is not a problem at the moment, the extra heat today could increase the levels that are a key ingredient of urban smog. Strong sunlight, hot temperatures and pollutants from automobiles and other sources are the ingredients for the smog stew.
Exposure to ozone also can prompt coughing, wheezing and shortness of breath, even in healthy people, which is why the county issues an advisory.
If unhealthful levels of ozone occur in the valley, people can find out by accessing the air quality Web site at www.accessclarkcounty.com/depts/daqem/Pages/index.aspx.
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