Another chance for 90° today, then an unsettled weekend

Unsettled weather is going to be the main story this weekend, as we continue to bounce around in a weather pattern that resembles something more like a roller coaster ride than anything. Here are the details.

Friday

A change is afoot this morning. Overnight, winds shifted solidly onshore, and as you step outside this morning, you may not like how it feels.

Dewpoints that were in the 40s just 24 hours ago are now around 70°. It feels like summer. (NWS)

 

Onshore winds mean higher dewpoints which means more humidity. It’s back, and it’s staying through tomorrow. Outside of the high humidity and temperatures, expect an otherwise nice day today. We’ll see a mix of clouds and some sun. We have a good shot at making another run at 90° this afternoon if we can get enough sunshine. Combined with humidity, it will feel like closer to 100° outside. Unpleasant. With strengthening southerly winds, there is also the potential for some minor coastal flooding starting late tonight and continuing into tomorrow night.

(Space City Weather is sponsored this month by The Mole, a Jonathon Price novel.)

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After hitting 90 degrees, storms likely this weekend in parts of Houston

As we predicted might happen, Houston reached 91 degrees on Wednesday, the city’s first day reaching the 90-degree plateau of calendar year 2017—but certainly not the last. Since 1981 the city has averaged its first 90-degree day on April 30th, so it’s not all surprising that we reached that mark this week.

Today

Wednesday’s sizzling temperatures were enabled by drier air arriving along with a cool front during the afternoon hours, which allowed the mercury to briefly jump up about three or four degrees. This drier air also allowed us to cool off quickly last night, and temperatures have fallen into the 50s across most of the region today. Highs will rebound into the low- to mid-80s as the front washes out this afternoon. A warm flow from the Gulf will prevent lows tonight from falling much below 70 degrees.

Texas is enjoying a cool start to this late April morning. (Weather Bell)

Friday

A warm, sunny day with high temperatures likely reaching 90 degrees again. Or getting very close.

(Space City Weather is sponsored this month by The Mole, a Jonathon Price novel.)

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Hot today—maybe 90°—and storms are possible this weekend in Houston

We’ve got a dynamic forecast ahead, with potential record highs today, more warm weather to end the week, and a chance of storms Saturday night and Sunday morning. Let’s get to it.

Today

It’s going to be quite warm today—ironically because a cold front will be moving through Houston. Matt explained all the details in a special post Tuesday evening, but essentially the combination of a warm air mass already in place and drier air moving in with a cool front this afternoon could be enough to push high temperatures to 90 degrees this afternoon for parts of Houston. We think it will get close—whether we get that warm is dependent upon when the front and drier air arrives (earlier in the afternoon means we’ll be warmer)—and the entire region will be hot regardless.

It’s going to be warm today, with highs possibly reaching 90 degrees in parts of Houston. (National Weather Service)

The other question with today’s forecast is whether any rain showers are likely to break through the capping inversion. Looking at some different variables this morning, I think it’s going to be difficult for most areas to see much, if any rain. A few thunderstorms are possible if the cap breaks, but that would most likely be well north of the metro Houston area.

Thursday and Friday

A cool breeze by Wednesday evening should bring much more seasonable weather to the region by Thursday morning, with lows in the mid- to upper-50s across most of Houston except for the coast. But high temperatures will bounce back quickly into the mid-80s, and a warmer, moist flow will resume off the Gulf of Mexico by Thursday afternoon, or so.

This will set the stage for a very warm day on Friday, with high temperatures possibly reaching 90 degrees, again, under mostly sunny skies.

(Space City Weather is sponsored this month by The Mole, a Jonathon Price novel.)

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How Houston could hit 90° Wednesday

We’ve been talking since last week about how the end of this week and/or the weekend look like hot days in Houston, giving us our first shot at 90° in 2017. However, after looking at weather data today, I think there’s a legitimate chance Houston could officially touch 90° for the first time tomorrow. Not a guarantee by any means, but there’s a chance. And the meteorology around it is sort of interesting, so let’s lay it out for you.

Step 1: Have a warm air mass in place

The recipe for Houston to hit 90° in late April involves a few factors. And this may seem like a “duh” statement, but it’s important to touch on. You need to have a warm enough air mass overhead.

The GFS forecast for 850 mb temperatures tomorrow afternoon is for them to be around +18°C. (Weather Bell)

 

The GFS forecast for tomorrow afternoon has temperatures borderline, but close enough to historically be capable of producing a 90 degree day in Houston. The map of 850mb temperatures above shows how warm it is about 5,000 feet up in the atmosphere. There’s an old school meteorology trick you can use to forecast high temperatures using the 850 mb temperature in the morning. It involves using a sounding (as explained here) and taking the 850 mb temperature down what we call the dry adiabat to the surface. One of the problems tomorrow is that with a front coming through, it creates volatility, which makes using that method difficult. But if you look at forecast soundings for 4 PM tomorrow afternoon, they look healthy for at least an 87-89° sort of day.

The forecasted sounding tomorrow afternoon over Houston is favorable for at least the upper 80s. (BUFKIT, NWS)

 

So on Wednesday, we have just a barely warm enough atmosphere to work with.

(Space City Weather is sponsored this month by The Mole, a Jonathon Price novel.)

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