La Manzanilla.info Message Board Archives

Re: Hot!!!!

Posted by Bret B on July 14, 2014, 6:41 pm, in reply to "Hot!!!!"
201.138.176.170

Wow, that's some heat wave you're having Evelyn: 25F / 14C above normal! At least you're having desert-like low humidities to keep your heat index (or "feels like" temperature) down.

According to the Weather Underground's weather data from the Kamloops airport ( http://www.wunderground.com/history/airport/CYKA/2014/7/13/DailyHistory.html? ), they had an afternoon high temp yesterday of 105F / 40.6C, sometime around 5 or 6 PM (there is an irregularity in the data.) At the same time, the relative humidity was 8% or 9% (disregarding the anomalous data point.) Combining the temp and RH gives a heat index of 99F / 37C. (It's common in dry locations to have a heat index lower than the temperature. It's very common in Phoenix, AZ where I'm from.)

You might be glad you DON'T have a warm ocean next door, at least in the summertime. The Pacific brings us copious humidity. Here at my place in La Manzanilla, yesterday's afternoon high temperature hit 96.3F / 35.7C, and at the same time the relative humidity was 55%, yielding a heat index of 113F / 45C. That's what it "feels like" here in the afternoon, in the shade, in calm air. And for those of us without air conditioning, it's about the same inside and outside.

Our afternoon highs only tell half the story. Our nighttime lows are also quite warm and muggy, making it challenging to get a good night's sleep sometimes. To blame are the powerful thermal mass of the nearby Pacific combined with the nightly (and very annoying) "debris clouds" left by the thunderstorms that usually peter out before giving us any cooling rains. This thick overcast traps the day's heat like a greenhouse, preventing the radiation of the heat out to cold space.

So a typical nightly low temperature here in my back yard this time of year is 82F / 27.8C, with a RH of 77%, for a heat index of 88F / 31C.

Contrast this with yesterday's Kamloops nighttime low temp of 61F / 16C, with a RH of 56% (heat index is not valid at this temperature.) Even in winter, the nighttime lows hardly ever get that cold in my back yard here in La Manz!

Anyway, here's hoping we all get some relief soon. It's 11 days and counting since our last cooling rains here in La Manz.
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