Hot weather continues, and a few words about a tropical system

Good morning. Summer has clearly arrived in Houston when the morning low is about 80 degrees, and relative humidity is above 90 percent. Another feature of summer is possible tropical activity, and you may hear some talk of a tropical storm in the Gulf of Mexico later this week, or during the weekend. But it’s not something I’d be too concerned about as a resident of Texas.

TODAY-SATURDAY

Summer-like conditions continue, with about four more days of highs in the mid-90s, mostly sunny skies, and rain chances near zero. Don’t really need to say more when we’re under this kind of influence from high pressure. Beware of afternoon heat indices near 105 degrees.

SUNDAY-TUESDAY

By Saturday or so the high pressure over Texas should move back west, anchored more over Colorado and the southwestern United States.

A very strong ridge of high pressure over the southwestern United States will bring anomalously high temperatures to parts of the country this weekend. (Weather Bell)
A very strong ridge of high pressure over the southwestern United States will bring anomalously high temperatures to parts of the country this weekend. This is the GFS forecast for temperature anomaly on Sunday evening. (Weather Bell)

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It’s that time of year—so what exactly is the Heat Index?

Here’s the latest edition of Weather whys, a series of posts by Braniff Davis explaining the science behind weather phenomenon affecting Texas.

A reader asked us a great question on Eric’s post this morning about the meaning of a heat index. In a place as hot and humid as Houston, we see meteorologists refer to the heat index all the time, saying things like, “The air temperature is 97 degrees, but the humidity makes it feel like 107 degrees outside.” But what does this actually mean?

With heat indices, there’s a little bit of meteorology—and a little bit of perception. The heat index is an ‘apparent temperature,’ or a measure of how hot air actually feels against your skin. When our bodies sweat, that sweat evaporates off of our skin into the atmosphere. This evaporation of moisture releases latent heat away from the body and, in turn, cools you down. However, when there is already a lot of moisture in the air, the sweat doesn’t evaporate as easily. This makes it harder for our bodies to cool, and therefore, the temperature you feel on your skin is much hotter than the actual air temperature.

HOW DO WE KNOW HOW HOT IT FEELS?

NOAA Heat Index Table
NOAA Heat Index Table

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And so it well and truly now begins … summer

Did you miss the heat?

Houston has had a long, slow slide into summer this year, only reaching the 90s this week, and with wet soils helping to keep a lid on temperatures. That all changes. Now.

High pressure will begin building over the region today, and while we can’t entirely rule out a few isolated thunderstorms, I wouldn’t expect to see much rain over the metro area. Instead we’re going to see partly to mostly sunny skies and lots of heat. With highs likely climbing into the mid-90s today through Saturday, the National Weather Service has issued a special statement warning of elevated heat indices, from 100 to 107 degrees when factoring in humidity. Lows will only fall into the upper 70s to around 80 degrees. This is absolutely typical summertime weather in Houston.

Rain accumulation forecast for now through Saturday. (Weather Bell)
Rain accumulation forecast for now through Saturday. (Weather Bell)

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Houston just had its wettest 60-day period on record

It has been one hell of a spring storm season. Pretty much every part of the Houston region has flooded to one extent or another, with some rivers and bayous reaching historical flood levels. And now, courtesy of Brian Brettschneider, here’s another amazing data point about this spring’s rain—the period of April 14 through June 12 is the wettest 60 days in Houston’s recorded history. Any year, any time.

(Brian Brettschneider)
(Brian Brettschneider)

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