HOUSTON – I’ve had two questions coming from viewers that I’m going to address here. First, what brought on this week’s amazing cooldown and, second, does it mean anything to the coming winter?
WHAT CAUSED IT?
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The Southwest Monsoon. Every year (and it’s been late this year) an Upper Level High builds east, usually over us, making it terribly hot and oppressive, while a Low builds to the southwest of Arizona. This is the typical year:
Monsoon is technically WIND and those winds transport Pacific and Gulf moisture into the desert Southwest bringing heavy rain. They count on it.
The monsoon High is strongest this year to our northwest and that has allowed cooler air from the north to sneak in here. We often get a weak front in July that never really does much but this one has been nice and strong:
A 594mb High is not that much to write home about, but it’s the strongest around and that makes it kingpin. So, thank the monsoon for the marvelous weather.
DOES IT MEAN ANYTHING TO OUR WINTER?
Well, maybe. I really enjoy climate data, but take it as guidance, not gospel. I looked at June/July/August record lows: when they occurred and their relationship to the year in general.
Here’s what stands out to me: in 1972 and 1974 we had a plethora of June and July records (listed below) and in 1973 it snowed 3 times in January and February. Coincidence? No. The globe was actually in "cool down" mode back then and that’s when the famous TIME magazine article suggesting another ICE AGE was published—June 24, 1974 (the 1977 cover, btw, is a fake).
So, not to cherry-pick, there is then 1989: two record lows in June, one in July (two in 1990), and 4 in August (another in 1990). A couple of cold years? Yes…December of 1989 was BRUTAL with our lows of 7F, 11F and 13F degrees from Dec 22-24! And, snow to go with it. Thus, another ‘cold snap’ lingered from summer to winter.
We also had two July record lows in 1994 and, behold, we had snow and ice in 1994 and 1995 (meaning BEFORE those record lows and AFTER).
And don’t forget 2004—that August we had a run of record lows from August 13th to the 16th and then on Christmas Eve it snowed 8” to the south of Houston (remember the snowmen on the Galveston Beach??).
So, does this July cold snap mean we will have a colder than usual winter? Let’s just say it wouldn’t surprise me. Climate tends to be just that—what we come to expect (weather is what you get) and the reason is because of tendency. When the climate is cool or warm or normal, it tends to last a bit (like when we couldn't shake that 2011 drought for months which really began after our 2008 Hurricane Ike). That suggests a colder than normal climate in place now would last into fall and winter. It will be interesting to see what August brings as another cool snap is certainly possible.
Caution! Southeast Texas had a very active tropical season here in 1989 and unforgettable flooding in October 1994. The tropical season of 2005 brought Dennis, Katrina, Rita and Wilma. With these cold snaps comes a weakness in our atmosphere and Low-Pressure systems follow that weakness. And Mother Earth is always trying to balance, especially when it comes to balancing cold winter weather with tropical heat. So, while the cool weather is certainly enjoyable it can come with a price.
Frank
Record July Lows 1972 and 1974:
1972:
7/7 62F
7/24 68F
7/26 68F
1974:
6/17 62F
6/25 60F
6/26 59F
6/27 57F
6/28 59F
6/29 59F
7/17 67F
7/18 67F
7/19 68F