Weak tropical activity persists in the West Pacific, with two depressions and a tropical storm causing disproportionate impacts:
Most of the impact is from Co-May, which just passed over the northern Philippines. The storm itself was relatively weak, but the cumulative effects of all of the recent rain has forced evacuations of 278,000 people and left 25 dead from flooding, making this a major disaster.
In the Atlantic and East/Central Pacific, there are no active storms, and only one disturbance with a significant chance of spinning up. That one is southeast of Hawai’i, but even if it develops should not be a threat to land …
Elsewhere, it is northern hemisphere summer. In a shocking pattern that seems to repeat every year, it gets hot and humid in the southeastern US. This year is no exception. In all seriousness, the next few days will be rather unpleasant in the southeast with the mix of temperatures pushing 100F and high humidity making it potentially unhealthy or even dangerous for some as the heat index values will probably top 120F in places. So be careful out there.
A quick note about the “heat index” or “feels like” values. Some are derisive of this and think it is a way for weather doomers to exaggerate and hype. Yes, it is often used that way, but it is a useful metric if properly understood. So just what is the heat index?
To understand the heat index you have to understand a bit of both physics and biology. In simple terms, whenever a substance undergoes a phase change (from solid to liquid or liquid to gas, or vice versa) the process requires an energy exchange. When water evaporates, it pulls energy out of the environment and therefore under the law of conservation of energy, the temperature of the overall system decreases. This is how “swamp coolers” work, and how your body works as well, by exuding water and letting it evaporate, what we call perspiration. It generally works well, but with a catch: the rate of evaporation (and cooling) depends on how much water vapor is already in the atmosphere (the humidity). The higher the humidity, the slower the evaporation and if it’s humid enough, it doesn’t evaporate at all. There are of course equations that let you calculate the evaporation rate, and relationships like the heat index have been developed to try to relate how hot it feels because your perspiration can’t evaporate and your body can’t get rid of excess heat.
These are general relationships, because we are all different, with different genetics and acclimation to our local environment. Something to keep in mind is that each National Weather Service office sets local caution and danger levels for heat index values, on the (correct) assumption that someone who lives in Frogmore isn’t going to care about a 95 degree heat index, but a 95 degree heat index in New York would be a crisis. So when you’re traveling, be aware of that – if you are from up north go home, but if you insist on staying here don’t complain, learn patience, how to say “please,” slow down, and be aware that even days when there isn’t a warning your body might not be able to take it. Age is a factor too – as we age we can’t handle temperature extremes as well.
Also remember the reported heat index values are usually calculated at the airports;- in cities or, suburbs they can easily be 10 or more degrees higher due to humidity, urban heat island effects, etc. Bottom line is there will be a “persistent and dangerous” heat wave across the southeast starting this weekend and running through midweek next week so be careful.
Here is a page by the WSFO/Amarillo TX with more info. One last reminder, animals don’t do well in this either, so take care of pets and ensure our feline overlords have lots of water and cool places to hang out. After all, cat’s didn’t domesticate us because of altruism 😛
The “climate change” phrase will no doubt appear. While you can’t really pin any specific event on anthropogenic (human caused) climate change, there are elements of climate change that make these kinds of events more likely. What is interesting is that for the most part the daytime temperatures aren’t a lot higher – what is higher is the humidity (due to higher evaporation rates from the oceans due to higher heat content), and night time temperatures are staying significantly higher than they have in the past. In other words, the overnight lows and average daily temperature are going up, even if the daily high’s aren’t.
If you like this commentary you can subscribe to the emails (and/or donate to keep it going) at this link. You can also follow us on X/Twitter (@EnkiResearch), Telegram, or even Facebook if that’s your preferred social media dystopia.