On Monday the state climatologist, John Nielsen-Gammon, called my attention to the visible satellite image page for the upper Texas coast. I’ve attached a snippet below, showing the period roughly from 8am to 1pm on Monday. If you look just northwest of Galveston Bay you can see the cooling stack plumes show up from some of the largest refineries in the Ship Channel. These facilities are leaving bow wakes in the low-stratus cloud layer.

So what is causing this? The cause is weather-related, John speculates it is likely a combination of the following factors:

• A well-defined temperature inversion at the top of the low cloud deck.
• Weak stability and strong wind shear above the inversion that would enable waves to be trapped horizontally on the inversion rather than propagating upward and away.
• A sufficiently shallow stratus layer that a bit of downward motion would be enough to temporarily clear out the clouds.
• A sufficiently large volume of heated air rising from the plants to produce strong enough wakes to be seen.

In any case, the weather on the Texas coast is rarely dull! Now, on to the forecast.

Tuesday

A diffuse mass of mostly light to moderate rain showers will move slowly from west to east across the Houston area today. The showers, with possibly a few embedded, stronger thunderstorms, will probably persist through most of the daytime hours. Most parts of the region should see between 0.25 and 0.5 inches of rain throughout the day. The combination of clouds and rain will likely limit daytime highs to the upper 60s for most of the region. After sunset, a cold front will sweep through Houston to help dry the region out. Conditions tonight will be breezy and colder, dropping into the 40s.

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Good morning. Some areas of dense fog have developed north and west of Houston this morning, but it should burn off entirely within a few hours of sunrise. For this week the region will fall into a pattern of a day of rain chances, followed by one to two sunny days, and then more clouds and rain. Fortunately, right now, it appears as though sunshine will align with Saturday and Sunday. This will probably make for a fine weekend.

Monday

Low temperatures this morning in the upper 50s should rise to around 70 degrees this afternoon under mostly sunny skies. With calm winds slowly turning to the southwest this afternoon, it’s going to be a gorgeous day for whatever you need to do outside. Lows tonight will generally fall into the mid-50s again tonight with the likely redevelopment of some fog for the southern half of the Houston region.

Tuesday

This will be a gray day. Likely beginning some time during the mid-morning hours, light to moderate rainfall will begin to spread over most of the Houston area. A slightly more organized band of showers may work its way through during the afternoon or evening hours, but for the most part we expect accumulations on the order of a few tenths of an inch of rain. A cold front will sweep through during the evening, likely between 6pm and 10pm, bringing stronger winds (likely gusting above 20mph) and drier air. Skies should clear out Tuesday night, with lows dropping into the 40s.

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Wednesday’s rainfall provided a good soaking for the region, with generally 0.75 to 2.0 inches of rain falling across Houston, and slightly more along the coast. It made for a rather dreary day and night, but at least the mostly light- to moderate nature of the rainfall posed no problems. Looking ahead, the weather pattern holds nothing too extraordinary for us, with the return of sunshine, and a stretch of mild days.

Thursday

In the wake of Wednesday night’s rainfall, it is a fairly warm morning, with temperatures generally in the upper 50s to 60 degrees across the region. Partly to mostly clouds this morning will give way to sunshine, allowing temperatures to warm up to around 70 degrees this afternoon. A cool front will push through Houston around noon, and off the coast this afternoon, bringing drier air this evening. The front will subtly shift the winds from the west to the north, and temperatures tonight will be cooler, dropping into the upper 40s for most of the region under clear skies.

Friday

This should be an exceptional day, with sunny skies, light winds, and highs in the upper 60s. Overnight lows will be similar to Thursday night.

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The combination of increasing atmospheric moisture levels and rising air will create healthy conditions for rainfall today, and the potential for a bit of heavy rainfall later Wednesday evening and during the overnight hours. After this, a front will push through to return sunny conditions for awhile, but alas not through the entire weekend.

Wednesday

Light rain has begun moving into the Houston area from west to east, and a pattern of intermittent mostly light rain should hold for the daytime hours. Due to persistent cloud cover, high temperatures today will likely remain in the upper 50s. The potential for heavier rainfall will increase after sunset tonight, through about 3 or 4am CT on Thursday. Most of the region will likely see about 1 to 1.5 inches of rain, cumulatively, but there could be some areas with 2 inches or more of rainfall. We’re not expecting any real problems from this, just a soggy day and night. Lows Wednesday night won’t fall more than a degree or two most likely due to thick, insulating clouds.

Thursday

As the rains move out, sunshine will move in on Thursday morning, followed by a front reaching the area by around noon. The afternoon should be nice and sunny, with highs in the upper 60s. Low temperatures on Thursday night should fall into the 40s, under clear skies, for most of the region except for the immediate coast.

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