Oh, my friends. We hear you. You’re tired of us saying, “There are a lot of uncertainties” when it comes to forecasting Tropical Depression #14 and Tropical Storm Laura. But the fact of the matter is that the latest model guidance is giving us less clarity, rather than more. I’m going to discuss the realm of possibilities, but first I want to start with this:
The overall probability of the Houston region, including Galveston, seeing significant, sustained effects from one or both of these storms remains fairly low. What do I mean by this? At present, the odds of Galveston seeing hurricane force winds in the next week is under 10 percent. The odds of the Houston region seeing 5 inches or more of rainfall, total, is probably less than 10 percent too. We’re not saying Houston will not experience severe weather in the next week. What we’re saying is that given the spread of possibilities, the overall chances are fairly low. It’s our job to let you know if that changes. And we will.
Now, onto the forecast. As the National Hurricane Center predicts, both TD 14 and Laura are likely to move into the Gulf of Mexico. The depression will come first, on Sunday, after moving across the Yucatan Peninsula. Laura will follow, likely traveling near or over Cuba. Because of these land interactions, both systems may only be weak tropical storms, or depressions, upon entering the Gulf of Mexico.
Normally we’d be scared pants-less when a low pressure system enters the Gulf, with its warm water, in August. But the combination of these land interactions, as well as less than ideal wind shear and dry air over the Gulf, suggest neither of these systems are locks to become hurricanes; and if they do, there is no signal whatsoever they will become major ones.
The big question is track, and the forecast models are all over the place. For TD 14, most of them have made significant shifts over the last 12 hours. Some, but not all, have shifted their landfall predictions from the Houston region, down the Texas coast, more toward Corpus Christi. (Update: The National Hurricane Center’s 4pm CT track forecast for TD 14 has shifted significantly south). Given this wide variability, we have very low confidence in TD 14’s track.
One thing to note is that, should TD 14 go more toward the central Texas coast rather than a more northward track, this may open up a lane for Laura to follow a more westerly track across the Gulf. Instead of moving into the Florida Panhandle, therefore, it may eventually threaten Louisiana or even Texas. The following plot of the UK model shows how this might work. If you look closely, you can see the Fujiwhara Effect at the end of the run, as TD 14 dips southwest, and TS Laura jumps north.
12z UKMET shows #Laura quite a bit south of previous runs and takes the weak system right into Hispaniola. Intensity forecast thereafter would be extremely difficult as it would rely on the organization of both #Laura and #TD14 pic.twitter.com/7EjFgSEn0y
— Steve Copertino (@TheSteveCop) August 21, 2020
We always talk about the ensemble models, so here’s the forecast for “low locations” from the European model that has just been run. The first image shows low locations on Monday night, when we can see a bunch of weak TD 14s or TS Marcos moving toward Texas. (Note, sea level pressure is 1013 millibars, so numbers from 1000 to 1005 represent very weak storms). The point here is that, even for a forecast less than four days from now, there is very little agreement on track.
Now let’s jump ahead to Wednesday morning. This is just 36 hours later in the forecast period, and we’re taking a look at the same plot. TD 14 has gone poof, and in its wake “Laura” has moved westward, toward Texas or Louisiana. Some of ensemble members have developed a slightly deeper and stronger system, but most are still tropical storms.
So yeah, it’s pretty much chaos. There are so many forecast challenges here it’s hard to know where to begin. Bottom line: We’ve got to watch out for TD 14, and potentially Laura as well. But as for specific threats, we’re a ways from saying anything intelligible. We’ll continue to track the madness, that we can promise.
So, you are basically saying to be prepared for anything, as usual?
If your not God, then you don’t know what’s going to happen. No one knew that Harvey would what it did. It was a disorganized storm when it crosses the Yucatan Peninsula. It was Cat 4 when it hit the Texas Coast. How do you know what will happen. All we can do is prepare.
Actually, if you go back, A LOT of weather scientists were keyed in early about the rainfall totals popping up for Harvey. It is the locals here that were refusing to believe that we would see 40″+ rain. I think most folks didn’t assume that it would turn into a CAT 4. In fact, I’d say that the nearly spot-on Harvey forecasting by Mr Lanza and Mr Berger is why this site is so popular today, and why they won an award for their forecasting for Harvey.
So very true! They have been accurate, even down to the massive surge from Hurricane Ike. They were spot on!
Maria, wind shear + dry air = no Harvey.
Is it too early to see what effect two Tropical Cyclones in the gulf might have on the accumulated energy? Ie is there any hope that they may take some the energy so there’s less to strengthen future cyclones in the gulf this season?
This isn’t how it works. The accumulated energy is a metric to quantify how much energy has been created by storms and is increased, not decreased, with storms. There isn’t energy floating around waiting to be used by storms and it has no impact on the development of future storms.
Thanks! Meteorology is not my forte, so thanks for clearing that up
Makes no sense less than 10%
Scratching my head on that one too. Possibly of TWO hurricanes in the same vicinity and less than 10% chance of hurricane force winds, even being conservative I would think it would be at least 25% based on the latest tracks.
I think the take is neither one, as modeled right now, will reach hurricane force. Therefore no hurricane winds.
Thank you for your honesty, and honest frustration. Y’all are very much appreciated.
Thank you for looking after us. I always feel better whatever the news is when it comes from y’all.
I want to know how big is the high over Texas
Probably need to ask Willie Nelson….
Willie has given up pot… as of last year.
You guys are the best! Thanks for the honesty!!
Anyone else watch Perfect Storm today?! 🤣 #Sooo2020
Thank you for your straightforward and non-hyped forecasts. You are greatly appreciated.
so you are saying we have less than 10% chance of any major threat. Basically we are all ok and will just get a little rain?
Today the chance is less than 0%.
I’m sorry, maybe you didn’t understand. If you read the article it talks about the 10% chance for NEXT week.
Oh ok 10% chance of rain….got it
Not quite what they said. There’s currently a small estimated chance we’ll get hit with something big. We have to be careful about averaging a larger chance of nothing and a small chance of something major as meaning something in between. And this is all subject to change considering all the uncertainty.
thank you for the not quite but almost…
Was surprised to see that in the latest GFS run that both storms go POOF. And the later in the week what looks like remnants from Laura come into SE Texas as not even a low.
So TD 14 may just dissipate before it even becomes Marco. My intuition was telling me it’s not going to be much.
Please, proto-Marco, please at least give my lawn an inch or 2 of rain!
Grateful for you analysis. Thank you!
Thanks. You provide excellent information and you are always my go to source on Houston weather.
I appreciate your recognition of uncertainty, given the weather’s vicissitudes.
Seeing that I just spent money getting a generator, both will likely miss us (not complaining) and it will be money spent for another day.
Should League City evacuate? Asking for a friend.
We fulltime RV and workcamp on the way west end of Galveston Island. We should leave right? Hanna wasn’t fun down here by the Pass.
Is there any way we can rename these storms to Marco and Polo? It may help to determine where they are headed.
Thanks guys. We really appreciate your explanations! May not like them all the time, but we do appreciate them!
So pretty much what you guys are saying, is that we are in the clear and we have nothing to worry about. Well if that’s the case I will now let my guard down and not worry. Thanks!