October ended as an usually hot and dry month. Eric covered this a bit yesterday, but weather data from Houston’s Bush Intercontinental Airport shows that 25 out of 31 days were warmer than average, with a measly 0.14 inches of rain recorded for the month. By the end of October, the heat and lack of rainfall produced drought conditions in the eastern third of Texas.
The jet stream
Figuring out why our weather has been so warm starts with analyzing the jet stream. The image below is an upper-air map, showing the state of the atmosphere at 250mb (about 30,000 feet above the ground, or a just above the peak of Mount Everest).
250 mb map showing the location of the jet stream on 30 October, 2016 (courtesy of The College of Dupage)
Houston’s high temperature peaked at 85 degrees on Halloween, but our run of very warm (for late fall) weather will soon come to an end—by this weekend. And after this week I think we can look for most days to only reach the 70s as we get deeper into November.
Today through Thursday
But the warm, muggy air is not ready to go yet. With air now flowing off the Gulf of Mexico and into the Houston area today, expect the next few days to see mostly cloudy skies, with highs in the low- to mid-80s, and some scattered showers. Rain chances will be greatest today the southwest of Houston, closer to Matagorda Bay, where moisture levels should be highest. More widespread rain is possible on Thursday across the Houston area as some instability moves in along with an approaching front. But I don’t think we’re going to see significant accumulations of more than a tenth of an inch of rain, or two. Nights won’t see much cool down through Thursday, with temperatures only falling to around 70 degrees for most areas.
Friday
After a cool front limps into Houston later on Thursday, the region should being seeing some drier air on Friday, which will set us up for a pretty nice weekend. Under mostly sunny skies we should see a high of around 80 degrees, with a low of 60.
Although a cool front should arrive late Thursday, much drier air (noted by dewpoints) is unlikely to move in before Friday afternoon. (Weather Bell)
Happy Halloween! Before jumping into the forecast let’s take a look at what a trick of a month this has been for Houston and much of the southern United States. The following graphic shows the ranking of the average temperature this October compared to more than 100 years of temperature records for this month. Hint: It was warm.
(Eric Blake via Twitter)
The Houston area has had some sites with the second warmest temperatures, but Dallas, Lubbock, Brownsville, and many other sites are on pace for their warmest Octobers on record. It looks like we’ll have one more warm-ish week before the pattern really does change for good into more fall-like weather.
Today
Houston is under a dense fog advisory until about 10 am CT. With high pressure overhead, today will be another warm, mostly sunny day with high temperatures in the mid- to upper-80s, and overnight lows falling only to around 70 degrees. It won’t be chilly this evening during trick-or-treating, but it won’t be particularly unpleasant, either. Rain chances will be near zero.
Tuesday through Thursday
As high pressure moves off moisture levels will increase over Houston. This will accomplish several things—we’ll see more clouds, which should limit high temperatures to the low 80s, and after an extremely dry October we might see some rain showers to start off November.
The rain accumulation forecast for this week shows the best chances southwest of Houston. (Weather Bell)
We’re fast coming up on Halloween and I’m happy to report that we’re not going to face the kind of uncertainty we did in 2015, when Houston was in the midst of widespread rain storms that threatened to ruin Halloween. (We got soaked in my neighborhood in Clear Lake).
Rain chances aren’t zero this year, because the onshore flow will resume in force on Monday, which should further increase humidity levels for the region. This could produce some isolated showers for coastal areas, but I don’t expect any widespread issues. Right now it looks like rain chances will improve on Tuesday and Wednesday.
A Halloween scene at the Zoo Boo. (Photo by Jason Cross/Flickr)
