Why weren’t the storms last week considered tropical systems?

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

Now that we’ve enjoyed a few sunny days after an extremely wet May and early June, we wanted to tackle a few ‘weather whys’ questions people have asked, either on Facebook, Twitter, or in the blog comments. One reader asked why the weather system last week, which dumped so much rain on the region, was not considered a ‘tropical system.’ After all the system spun counter-clockwise, and had the satellite appearance of a tropical cyclone.

A satellite image from last Friday show a large circulation over Texas. (NCAR)
A satellite image from last Friday show a large circulation over Texas. (NCAR)

 

The answer has to do with how and where different low pressure cyclones form. Pressure, and how it influences weather systems, is vexing. Often, it was the most challenging concept for my students to grasp in my introduction to meteorology classes. We could probably do a 50-part series on the science behind it, called cyclogenesis.  For now, we’ll spare you that and only focus on the large, synoptic scale cyclones that influence our weather.

EXTRATROPICAL VS. TROPICAL CYCLONES

Extratropical cyclone over Pacific Ocean, December 2014 (NOAA)

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Houston likely to record its first 90-degree day today

Well, the party probably ends today. We’ve made it five months and six days into the year 2016, but Houston will likely finally reach 90 degrees today.

Latest dates in the year when Houston has recorded its first 90-degree day. (Matt Lanza)
Latest dates in the year when Houston has recorded its first 90-degree day. (Matt Lanza)

 

The forecast beyond this data point is pretty straight forward.

TODAY through THURSDAY

Partly to mostly sunny skies. Drier air should allow highs to reach around 90 degrees. Lows in the low- to mid-70s. A slight chance of afternoon and early evening showers and thunderstorms along the sea breeze. There’s not much more to say than that.

FRIDAY through SUNDAY

We’re going to see more moisture returning from the Gulf of Mexico by this weekend, which should allow for a greater possibility of rain during the afternoon and evening hours. The European model suggests accumulations of a few tenths of an inch of rain for the weekend, which seems about right. I would not expect any kind of a washout.

After the rains, summer comes to Houston this week

Well, it’s been quite the start to the year 2016. We’ve had floods west of Houston, northwest of Houston, north of Houston southwest of Houston, east of Houston—pretty much all over the city. This most recent rain event, during the second half of last week, was enough to push the city above 1992 for the wettest year to date, through June 5.

The city has officially recorded 39.67 inch of rain at Bush Intercontinental Airport (blue line below). This is all the more remarkable because, only about six weeks ago, the city was actually below normal for total rainfall for this year:

(Victor Murphy/National Weather Service)
(Victor Murphy/National Weather Service)

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Finally, clearing skies, goodbye to monster rain storms

Good morning. How pleasant it is to wake up to a clear radar and partly sunny skies!

Low pressure is moving away from the upper Texas coast, and as a result so the likelihood of organized storm activity is fading. And thank goodness. I’ll have a more comprehensive wrap-up on Monday, but even yesterday, when most areas saw less rain, parts of the eastern Houston metro area near Mont Belvieu saw in excess of 10 inches of rain in six hours. This was a nasty system and I’m glad to see it go.

Rain totals from early Saturday morning to early Sunday morning. (NOAA)
Rain totals from early Saturday morning to early Sunday morning. (NOAA)

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