Matt Lanza

Splendid Friday gives way to a slightly murky weekend

The weather pattern over Houston is making up for months and months of wet, dreary weather since last fall. As Eric alluded to yesterday, we’re going to end up below normal on rainfall for the month of March. I’ll take it one step further: Since late January, we have been exceedingly dry.

Rainfall since late January has been no better than 70 percent of what is normal over most of the area. (High Plains Regional Climate Center)

For Harris County, we have only averaged about 70 percent of what is normal over the last 60 days. Go a bit west of Houston, and parts of Central Texas from San Antonio through Austin are averaging about 50 percent or less of normal. Thanks to weeks and months of wet weather prior to the last 45-60 days, we are not in drought, nor are we even abnormally dry according to the latest Drought Monitor report. With an El Niño event ongoing and likely to continue, it would be surprising for this drier weather to continue (El Niño springs are usually fairly wet in Texas). But this will be a story to watch over the next few weeks.

Today

Unfortunately, our nicest week of the year so far has been marred by varying and unrelated forms of air quality issues. It has either been the situation in Deer Park with the ITC Terminal fire (which at least this morning seems under control), obscenely high levels of pollen, smoke from numerous agricultural fires across the Southeast leading to increased particulate matter, or as in today, high levels of ozone.

Visible satellite imagery from late Thursday shows numerous agricultural fires in the Southeast. The red dots represent clearly visible ones; there are likely others. (College of DuPage)

The Texas Commission on Environmental Quality has declared today an ozone action day, meaning we should see high levels of ozone and generally poor air quality. These types of days aren’t necessarily infrequent in Houston, but it’s just compounding our issues here of late. But, hey, other than that, it should be great today! Expect wall to wall sunshine with some passing high clouds today. We should manage upper-70s to around 80° in some spots.

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Finally, an extended stretch of mostly quiet weather for Houston

We will get to the forecast in just a second. First, we’ve received a number of questions, asking about the recent “bomb cyclone” and what the heck it means. If you’re an NPR listener, you may catch me discussing exactly that today on Texas Standard.

What is it? A “bomb cyclone” by definition is an area of low pressure (or an “extratropical cyclone”) whose minimum central pressure drops by an average of 1 mb per hour for 24 hours. In other words, it has to drop at least 24 mb over the course of a day or less.

Was this recent storm actually a “bomb cyclone?” Yes. Here are the official surface analysis maps every three hours between 10 PM CT on Wednesday (0300Z) and 1 PM CT on Thursday (1800Z).

Official NWS surface maps from 10 PM Tuesday through 1 PM Wednesday show the storm in the Rockies deepening from about 995 mb to 968 mb, qualifying it as a meteorological “bomb,” or “bomb cyclone.” (National Weather Service)

The storm went from about 995 mb at 10 PM on Tuesday to 968 mb at 1 PM on Wednesday. That’s a 27 mb drop over 15 hours, which allowed this storm to meet the technical definition of a bomb cyclone.

Is bomb cyclone just some fancy new term the media made up to hype weather? Not at all. The term has informally been around since at least the 1940s in Norway (where a lot of modern meteorology has its roots). The technical definition came from a 1980 journal article by MIT meteorology professor Fred Sanders.

So why are we only hearing about it recently? Are these becoming more common? If you catch me on “Texas Standard” today, you’ll hear me say that I believe social media has taken what used to be conversations that only occurred between scientists or super hardcore weather geeks and thrust them into the public square. In other words, instead of these conversations with cool terms like “bomb” or “polar vortex” or “derecho” only occurring in sciencey circles, they’re now occurring in forums where journalists or the public can eavesdrop. I don’t know that these types of storms are necessarily more common in 2019, though that may change in the future. It’s mostly that these terms just accidentally end up out in the wild for everyone to use, rather than only among a select few.

I hope you found this informative! Let’s move on to our forecast.

Today

In the wake of yesterday’s front, look for a mix of clouds and some sunshine early today, though those clouds should thicken up as the day progresses, especially south of I-10. It will be cooler and breezy today, with temperatures likely peaking around 60 degrees or so this afternoon. Some locations will likely struggle to get out of the upper-50s with enough clouds.

Rodeo weather

A light jacket will be a good accessory tonight, as temperatures will drop back into the middle or upper-50s this evening before the show. Heading home, you’ll see temperatures down into the low- to mid-50s under mostly cloudy skies. A few sprinkles or some drizzle can’t be entirely ruled out.

Weekend

It won’t be beautiful, but at least a fairly quiet weekend is expected. On Saturday we should see plentiful clouds unfortunately, meaning it will be rather cool. We also can’t entirely rule out some showers or a period of light rain, especially along the coast and south of Houston on Saturday. Sunday’s rain chances should shift even further south toward Matagorda Bay, mostly. I don’t really think rain this weekend will be a big issue if you have outdoor plans, but it’s just something to know may happen.

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Late winter whiplash continues into this weekend

I’m going to start today’s post with a bit of controversy: February of this year wasn’t that bad of a month when you compare it to February 2018. Believe it or not, 74.3% of all hourly observations in February 2019 had some form of overcast reported. That could be fog, low clouds, high clouds, or even thin clouds with a little sunshine still getting through. But it’s a nice barometer of how cloudy the month was. Guess what? In February 2018, we managed to do 81.9% of all hourly observations in some form of overcast. So as bad as this past month was, it wasn’t quite as cloudy as last year.

February 2019 had some form of overcast almost 75% of the time, which was somehow not as bad as February 2018, which managed that over 80% of the time. (Iowa State University)

February 2019 also ended up with only 1.73″ of rain officially at IAH Airport (Hobby had 3.29″). Last February saw 5.73″ of rain officially. So despite our many days of rain this year, it was actually wetter last year. But last February averaged 62.5°, while this February averaged 59.7°. So I’m giving the edge to this February for being the worse of the two months on the colder weather alone.

Today

Whatever the case, February is in the rear view mirror, and it is now onto March, which will come in….as February ended. Expect a lot of low, dreary cloud cover today. Showers are possible, but not likely. More likely will be patches of drizzle at times.

Temperatures will be the challenging part of the forecast today. That cold front from yesterday was supposed to return back north today as a warm front. That appears to not be the case, so expect a mostly chilly start to the month today. Model guidance says we will get into the low- to mid-60s later today. Given our starting point this morning in the mid-40s, I would not be shocked to see us struggle to get into the upper-50s by evening and then continue a slow rise to near 60° tonight. Either way, we’ll get there. It’s just a matter of whether it’s today, tonight, or Saturday morning.

Rodeo weather


I think we are in good shape for the rodeo tonight in terms of rain chances. Yes, I cannot entirely promise there will not be a shower, but I think that would be rather unlikely. Temperatures are another matter. Expect mostly cloudy and cool, damp conditions. Temperatures will probably be about 56-59° in the early evening and post-show temperatures should be, well, in the 56-59° range. Temps won’t move much during the evening. Watch for areas of patchy fog on your drive home, especially if you’re heading southeast of town.

Saturday

I don’t expect much serious weather Saturday, aside from areas of dense sea fog developing once again. Coastal and Bay Area communities will likely be plagued by fog once again late tomorrow and tomorrow night. The rest of us should see mostly clouds, again, though a few scattered showers will be possible through the day, especially along or north of I-10. Temperatures will continue to be difficult. South of I-10 stands the best chance at being quite warm tomorrow with highs near 75° or so. Those chances of warmth get smaller as you go north. Some places north of I-10 tomorrow may not get above the low- to mid-60s. It’s possible that at some point tomorrow Conroe is around 60°, while Pearland is sitting at 76°. It will be that kind of day.

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Clearing up through the weekend

The good news is that the worst of the weather the next couple days will likely miss the Houston area well to the northeast. The bad news is that we will still have multiple rain chances to contend with through tomorrow before we get on to the good stuff.

Today

While today should not be a washout, there will be plenty of shower activity around. Initially, showers are west of Houston near Katy and north up through Conroe.

Radar this morning shows most shower activity from about Katy north through Tomball and into Conroe. (RadarScope)

As we go into this afternoon, I think we’ll see the focus of these showers shift east of I-45 and north of I-10. Thunderstorms will also be possible, but with the area likely to see some degree of atmospheric capping (“the cap,” as it’s often referred to, which is basically an atmospheric temperature inversion that inhibits thunderstorm growth) I don’t think we will see too much in the way of significant storms. That will be reserved for areas well north of Houston, up toward the ArkLaTex.

Yesterday was cold and drizzly. Today will begin similarly. We should see temps warm a bit further today though and manage at least the upper-60s in Houston, mid-60s in The Woodlands, and low-60s in the Brazos Valley. That being said, sometimes temperatures behave very stubbornly in these types of patterns, so there’s a definite slight chance we don’t get out of the 50s until later tonight. Keep the jacket handy.

For at least the 500th* time this month, fog is pestering the coast this morning once again.
*approximate

Dense fog is an issue along the coast and in the bays, so give yourself extra time if you are traveling to or from those areas today. (NWS Houston)

Dense fog is likely to hang along the coast and in the bays most of the day today. Exercise caution if you’ll be driving to or from those areas today.

Tonight

We will carry a continued chance of showers through the night, but no heavy activity is expected. It may be more mist or drizzle than anything, with a gradual transition toward showers. Fog will continue in the bays and along the coast, though it could begin to become a little more dispersed at times overnight as winds pick up a bit. Look for temperatures to hold steady or finally rise into the mid- to upper-60s if they haven’t gotten there this afternoon.

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