It’s been hot, and we will close out the week hot. But, why?
It all starts in the upper levels of the atmosphere, at least in this case.
The setup has been stagnant for days and is common when there are large undulations as the one currently set up over the U.S. First a large Low-pressure system located over the Pacific Northwest and a large high-pressure system (ridge) over the southeast. Between these two, there is a kind of tunnel where the winds are strong and lots of humidity enters causing very unstable weather, as we have seen for many days across the Central U.S. and all the severe weather they have experienced.
The problem is that when this setup occurs, it often gets stuck this way. In meteorology, we call it an Omega Block because it looks like the Greek Omega symbol, Ω, and it blocks the atmosphere flow. Some blocks, depending on the angle, are stronger and longer lasting than others.
Luckily, the atmosphere is starting to get “unstuck.” So, the pattern will start to become more variant now, in many places going back to normal, or average, conditions.
The heat will be present to close out the workweek, with temperatures still in the mid to upper 90s. The weekend will have a few more clouds knocking down the temperatures a few degrees, but it will still feel very muggy. Next week will be our “going back to average.” Temperatures will be in the low 90s, which is average for this time of the year, and still lots of humidity. The winds will shift coming from the east-southeast and this will trigger afternoon showers and an isolated storm in the afternoons.
⬆️60s dewpts. Although not summer-like, still very MUGGY.— Irene Sans (@IreneSans) May 30, 2019
This (& w/ calm winds) help fires not to propagate.Dry season almost ends & we NEED rain.Luckily all ingredients aren’t there for fires, but if 1 gets going (by human) it can burn for a while & much pic.twitter.com/QJ9i17vCOz
PEAK OF FIRE SEASON
The setup in the winds across Florida has aided the containment of fires. To have a fire (and for fire propagation) we need:
- A spark. Although it is usually caused by humans, it can also be ignited by lightning.
- Dry vegetation: fuel for a fire.
- Once the fire is going, high winds and not having much water vapor in the air (low humidity, as known as low dew points) helps the fires propagate faster.
We’ve been fortunate to still have lots of water vapor in the air. That’s why it still feels muggy out there, so the fires that have been started have not propagated. We still need rain. There is lots of dry vegetation across Central Florida. The rainy season will start in no time and we will move over to the typical afternoon thunderstorms. The heat, though, that stays until late October, early November, when cold fronts are able to reach Florida again.
Large undulations like these are becoming more (& +) common & are tied to #climatechange— Irene Sans (@IreneSans) May 30, 2019
They bring (to differente locations, depending on setup) hotter, to already hot, conditions, stronger (to already strong) storms- producing more intense/severe weather https://t.co/bIGuIYyzby https://t.co/1zEgxwFbMF
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