Month: July 2021

Not a whole lot to cover in this morning’s post, which is good news for most of us. But there are a couple things we’ll dig in on, mainly heat index values this weekend and rain chances with the cold front next week.

Today through Sunday

All of the next few days look fairly similar in nature, with sunshine, some clouds, and at least a smattering of afternoon downpours across the region. Exactly how numerous those are will likely vary from day to day, with today seeing the best odds of a downpour (still probably no worse than about 30 percent coverage) and tomorrow or Sunday probably seeing the lowest odds. Areas along and south of I-10 probably have the highest odds of seeing a shower play out, while areas north of Houston likely have the lowest odds.

The other weather issue you’ll contend with this weekend is heat. Look for highs in the mid to upper-90s today through Sunday with nighttime lows in the 70s to around 80 degrees.

It will feel more like 104° to 108° each afternoon when you factor in the humidity, with some places possibly even sneaking up close to 110° at times. It’s a good idea to take it easy outdoors this weekend and drink lots of water.

Monday

Consider Monday our transition day, albeit late. We will start off like the weekend, with ample heat and humidity. Look for 70s to near 80° in the morning again and daytime highs in the mid to upper-90s as well. The front will arrive sometime Monday night or early Tuesday it appears. As Eric has noted, August fronts don’t usually arrive with a ton of fanfare in the temperature department, so you probably won’t realize when it gets here. But, storms are possible by Monday evening.

Tuesday through Thursday

With the front overhead or just offshore, it will serve as a focal point, in concert with the sea breeze each day for showers and thunderstorms. Because we’ll have more clouds and higher rain chances, we can expect cooler temperatures. Highs will likely be in the upper-80s to low-90s with lows in the 70s. You may walk outside one morning and comment, “Hey, this isn’t all that bad.” But short of that, this looks like it will remain a fairly warm and humid period.

How much rain should we expect with all this next week? I think it depends on exactly how far offshore the front gets. Today that means probably an inch or two for some areas, a bit less in others.

Some higher amounts will be possible in isolated areas, but honestly this doesn’t look like too menacing a period, and it will probably just be mostly a nuisance couple of days for us. Rain chances should peak Tuesday and Wednesday and probably begin to tail off a little by Thursday. There is still some uncertainty on these details, so you’ll want to check back with us on Monday to see what has changed over the weekend.

Tropics

All remains quiet right now and probably for at least the next 5 to 7 days. There are some hints that activity may begin to pick up again the week of August 9th. But as of now, there is nothing specific we can hone in on anywhere in the Atlantic basin, so that’s purely speculation, albeit speculation rooted in meteorology. We shall see. But nothing to worry about for now at least!

Good morning. Overall the forecast story remains the same, with scattered afternoon rain chances this week, a hot and sunny weekend, and then better rain chances next week as a rare August front moves into Texas and approaches our area.

Thursday

It’s rather sultry outside this morning, with temperatures solidly at 80 degrees or above for most of the metro area. Our weather today will continue the pattern we’ve seen for this week, with hot and mostly sunny conditions, and high temperatures in the mid- to upper-90s. Winds today will be out of the southeast at 5 to 10 mph. The sea breeze should generate some shower activity late this morning and into the afternoon, but showers should be fairly scattered with one-third or less the metro area seeing rainfall. Lows tonight will again be warm.

Friday

See Thursday’s weather.

Saturday and Sunday

As the influence of high pressure over the plains states expands further, Houston’s temperatures should rise into the upper 90s this weekend, and rain chances will transition from “scattered” to “isolated.” This will be a classic August weekend as we head into August.

Next week

Monday looks hot and sunny again, but then an honest-to-goodness front will push into Texas and move toward the Houston region on Monday night. I want to set expectations accordingly, as this front won’t bring much cooler or drier air. Rather, it should instead drive increased shower activity on Tuesday and perhaps Wednesday of next week, and the increased cloud cover may push highs into the lower 90s. After a hot week some showers and somewhat cooler weather would not be unwelcome.

Good morning. Houston’s summertime pattern will continue for the rest of this week, with hot days and a decent chance of afternoon showers and thunderstorms. These storms will be hit or miss—a few locations in the Houston region saw one-half inch of rain on Tuesday afternoon and evening, while most people saw no rain at all.

Wednesday

If the air feels a tiny bit drier this morning you can thank some thunderstorms that developed on the east side of Houston on Tuesday evening. These ushered some slightly cooler air into the region. This may slow development of showers today, but we still expect at least scattered activity later this afternoon and evening. Probably about one third of the area will see at least some brief showers, with a few locations seeing downpours. Highs should get into the mid-90s with light easterly winds. Lows tonight may briefly drop below 80 degrees.

Thursday and Friday

Quite honestly the setup does not change much. Skies will still be partly to mostly sunny, with highs in the mid-90s, and a chance of afternoon and evening showers.

Saturday and Sunday

As high pressure becomes a little bit more dominant this weekend I think rain chances will lower a bit, but not go away entirely. Mostly, we’re going to see sunshine and hot weather, with highs likely in the upper 90s. August begins on Sunday and yeah, it will feel like it.

Monday and beyond

Monday looks hot and sunny again, but thereafter a dying front approaching Houston from the northeast may act to raise rain chances and slightly lower temperatures. We may be talking highs in the low 90s and rain chances of 50 percent or higher, but at this point it’s difficult to have too much confidence in such a forecast.

The last time we had a tropics post was back on July 13th, and since then zero storms have formed. By July 30, 2020 Isaias had formed. We’re still stuck on Elsa this year, and I hope no one is complaining. It would seem that the next week or two, broadly, will continue on this quiet trajectory. Today, we will look into perhaps why things have been so different this month compared to a year ago.

Tropical outlook in a sentence

While one can never rule out a rogue “homegrown” system this time of year from a disturbance over the Gulf or off the Southeast coast, there is no sign of any organized activity in the Atlantic over at least the next 7 to 10 days.

2021 vs. 2020

So the obvious question here is “what gives?” Why has 2021 behaved so differently from last season? Well, for one 2020 was not “the norm.” At all.

We had 30 named storms last year. The defeatist in me really did expect this season to also be very busy by now, even if it lagged 2020 by a bit. That has not yet happened thankfully, and ultimately I think it mostly comes down to a law of averages in some sense. Of course, that doesn’t explain things scientifically. Let’s look at a couple things.

First, sea surface temperature. How warm is the Atlantic Basin right now? Well, if we look at a snapshot of recent water temperature anomalies, you’ll be able to see that we’re still a bit above normal in most of the Atlantic.

Now, granted, the water temps off the Southeast coast and in the eastern Caribbean and central Atlantic aren’t impressive. And indeed, this is notable, particularly when you look at how late July compares in 2021 versus last year. The map below shows water temperatures for the week of July 18th through July 24, 2021 minus the same week in 2020.

In some cases, we’re running 1 to 2 degrees cooler than a year ago, at least for late July. So that may be one reason why this year has lacked some of last year’s firepower to date.

Let’s go into the meteorological weeds a bit. If we look at a metric called “velocity potential,” or “VP,” we can see a very interesting year over year difference in the Atlantic basin. Without getting too deep into things, think of negative velocity potential values as being favorable for tropical development and positive ones as being unfavorable. This is especially true if those values are over the eastern half of the Atlantic basin. Negative VP will promote more rising air & thunderstorm activity in the background, while positive VP will promote more sinking air and fewer robust tropical waves. It’s much more complex than this, but at a very high level, that explains some of the basics.

In a nutshell, the deep purples on the map above indicated a lot of smoke on the water in 2020, which ultimately meant a number of tropical systems. Edouard, Fay, Gonzalo, Hannah, Isaias, and a bonus tropical depression all formed in July of 2020. This July is likely to finish with just one storm, Elsa. Looking at the map labeled 2021 above, you can see the reds and oranges in western two-thirds of the Atlantic basin, Caribbean, and Gulf, along with much less blue and purple over Africa and the eastern basin. Thus, the background state this July has been less favorable than it was a year ago and subsequently, it’s been a fairly quiet month.

The obvious question is whether that will change. In general, based on most modeling I’ve seen, this is expected to change a bit in August to a pattern not as robust as 2020 but at least something more like it perhaps. So in addition to climatology favoring our typical ramp in tropical activity in August and September, we may get a subtle addition from the overall background state too. My gut feeling is that August will start quiet, but as the month wears on, we will have systems to watch closely, as we typically would in any hurricane season. I don’t think it will be quite at the frenetic levels of 2020 or even 2017, but to be sure, it won’t stay this quiet forever. My advice? Enjoy what we have left of the quieter conditions, and make sure you’ve got your plans and kits together for the August and September gauntlet.