All is quiet this morning across Texas and while we will see popup thunderstorms this afternoon, the main story for the next two days will be summer heat and humidity. Heat index values over 105 degrees are expected this afternoon and again tomorrow afternoon. Normally I would spend some time talking about the chance of storms today along with the heat, but we have something potentially more serious to deal with.
Sorry, no raw weather model plots this morning.
I want to start off by saying that I will not be sharing raw weather model graphics in this post. You may see some of those model graphics on social media or on television. However, since we don’t even have a ‘defined’ system yet, I find it irresponsible to share those model graphics at this time. I do anticipate we will start getting regular forecast graphics from the National Hurricane Center later today or tonight – and those are graphics we’ll be sharing in earnest.
It’s still a mess, but that should change by tonight
What will likely become Tropical Storm Barry within 24 hours is a disorganized area of thunderstorms this morning. Those thunderstorms are located over the northeastern Gulf of Mexico. They’re occurring within a fairly large, but broad area of low pressure (spin). There are multiple small areas of spin ongoing in that larger gyro. Over the next 12 to 24 hours we anticipate one of those ‘spins’ to dominate and become our primary and well-defined circulation. That’s when we’ll be able to put a pin on a map and say ‘here’s where the system is now’. That data would go into weather models which would then (hopefully) spit out a more concise set of data.
Until we actually get aa defined low-level circulation models are not only guessing where the system is going to go, but they’re also trying to guess where it is located at this present moment. That’s a big deal when you consider a 30-mile shift south at the present could result in a 200+ mile shift in a forecast track in 4 days. Other important forecast factors include various upper-level features – any one of which could result in a forecast shift farther east or west if that one feature ended up being stronger or weaker. Okay, you get a general idea. There are a lot of factors that go into forecasting these things, and the fact this one will be quickly developing right off the coast is another complicating factor. I know that these forecasts are a pain in the behind and that everyone wants to know where the darn thing is going – right down to the city, but no one can tell you that. We’re probably going to multiple shifts west and multiple shifts east in weather model guidance over the coming three days. Those wobbles are normal and are also influenced by storm-scale dynamics, which are difficult to forecast when the darn storm hasn’t even formed yet!
So what is going to happen over the next 12 to 24 hours that should help improve forecast confidence?
- We’ll start having weather balloons launch from numerous cities across the southern United States every six hours instead of every twelve. That started this morning at 6 AM. Those ballons help measure the strength of various upper-level features (the strength or a certain weakness in the high pressure aloft responsible for our summer heat). That matters because that area of high pressure will help ‘steer’ Barry farther west or farther north.
- Aircraft reconnaissance (hurricane hunters) will start flying regular missions beginning this afternoon. That’ll give us real-time information on the organization of the system.
- While Invest 92L is disorganized this morning, we should start to see those thunderstorms organize an area of low pressure by this afternoon and evening. Once that occurs I anticipate that we’ll see a tropical depression or a tropical storm develop fairly quickly. That’s actually good from a forecaster standpoint – because once the thing gets going, we can actually start getting more precise data into weather models.
- The additional data mentioned above plus the initial development of ‘Barry’ should allow for weather models to start coming together on a probable track and intensity plot. Should being the key word there – there will still be some uncertainty, but hopefully less than what we’re dealing with this morning.
One reason we’re expecting intensification with ‘Barry’ is the sea surface temperatures in the Gulf of Mexico. Water temperatures are running a bit above average for July, which in themselves are usually plenty warm. An NOAA satellite was able to collect data overnight and confirms water temperatures of 87F to almost 90F across the northern and northwestern Gulf of Mexico. Generally speaking, you want water temperatures above about 80 degrees Fahrenheit support tropical cyclone intensification. 85 degrees and above? That’s like throwing jet fuel on a raging fire – tropical cyclones will eat that up all day long. There’s more to forecasting tropical cyclone intensity than just water temperatures alone, but that’s one ingredient we won’t be lacking.
Unlike our spring-time thunderstorms that love wind shear, the opposite is true for tropical cyclones. They thrive on latent heat release. Wind shear is typically detrimental to the development and maintenance of a tropical system. Some can handle wind shear better than others. Current wind shear analysis shows very weak shear in place across the central Gulf of Mexico. However, the system looks to move into some slightly higher wind shear in the next 48 hours. That factor *could* help at least slow the intensification rate. However, this graphic shows the current wind shear. It looks like it may weaken by Thursday into Thursday night. I’m not saying the ongoing wind shear will prevent organization or intensification. It certainly didn’t stop Micheal last year.
At this time, and I emphasise that strongly since we could be talking about a completely different ballgame by tonight, the upper Texas coast (High Island to Sabine Pass to Beaumont to Port Arthur) and east to mouth of the Mississippi River (New Orleans in southeastern Lousiana) have the highest probability of being impacted by a tropical storm or hurricane beginning Friday afternoon, but perhaps not until Saturday morning. Those in the Rio Grande Valley and the Coastal Bend of Texas (South Padre Island up to Corpus Christi) only have a very low chance of being impacted by this system based on current data. Those from the Coastal Plains to Galveston should continue monitoring the forecast in case this shifts west, and those from High Island east to Lousiana should be starting to at least prepare for the threat of a tropical cyclone impacting as soon as Friday night. This could be completely different later tonight for reasons I explained above.
Those along and east of the track of this system, the dirty side of a tropical cyclone, have the highest potential of being impacted by high wind, storm surge, coastal flooding, major inland flooding from heavy rains, and tornadoes. If that track is in Lousiana we in Texas might get a few showers, but otherwise would be relatively unaffected on the ‘dry’ side. If those tracks shift west into Texas we’re going to have a big problem this weekend. It’s way too close to call right now.
Inland flooding will probably become the biggest story and the highest impact of this system. The eventual track will dictate who stays hot/mostly dry, and who could end up with one to two feet of rain. Right now, that major flooding threat looks to be in Lousiana.
National Weather Service & National Hurricane Center outlooks
Here’s the forecast discussion from the National Weather Service in Houston:
Best Case: If the system moves into the LA/MS coast, then the
bulk of the storm`s rainfall activity and strongest wind field
would remain outside of SE Texas. Thus, a warmer and drier trend
would be expected. Main impacts with this scenario would be
possible high heat index values (maybe reaching Heat Advisory
criteria) along with some convective activity over the local area.
Worst Case: If the system tracks further west and moves into the
vicinity of the TX coast, then the bulk of the storm`s rainfall
activity and strongest wind field would move in or near SE Texas,
or at least portions of it. Thus, a wetter forecast pattern would
be expected over our local area. However, due to the uncertainty
of the storm`s intensity, specific wind and rainfall values are
unknown at this time.
The General Message: Uncertainty in regards of the development
and track of the system continues. Regardless of development, now
is the time to verify your hurricane preparedness plan with your
family and neighbors. Continue to monitor your local NWS and NHC
forecasts for the latest information regarding this system.
Meanwhile, this is the latest from the National Hurricane Center:
Tropical Weather Outlook
NWS National Hurricane Center Miami FL
800 AM EDT Wed Jul 10 2019
For the North Atlantic…Caribbean Sea and the Gulf of Mexico:
A broad low pressure area located over the northeastern Gulf of
Mexico about 100 miles south-southwest of Apalachicola, Florida,
is producing widespread cloudiness and disorganized showers and
thunderstorms. Environmental conditions are conducive for
development of this system, and a tropical depression is expected
to form late today or Thursday while the low moves slowly westward
across the northern Gulf of Mexico. An Air Force Reserve Unit
reconnaissance aircraft is scheduled to investigate the disturbance
this afternoon. This system could produce storm surge and tropical-
storm- or hurricane-force winds across portions of the Louisiana,
Mississippi, and Upper Texas coasts later this week, and interests
there should closely monitor its progress. In addition, this
disturbance has the potential to produce very heavy rainfall from
the Upper Texas Coast to the Florida Panhandle. For more
information, please see products issued by your local weather
forecast office and the NOAA Weather Prediction Center.
* Formation chance through 48 hours…high…90 percent.
* Formation chance through 5 days…high…90 percent.
What should you be doing?
So what should you be doing if you live on the Upper Texas Coast or in Lousiana? Well, now is a great time to ensure your hurricane supply kit is up to date. That’s a great idea for everyone on the Gulf Coast, regardless of what this system does. We’re well into hurricane season and it’s good to be prepared well before a potential storm. We’re still in the ‘ready’ phase versus the ‘set’ phase. I do expect we will have a tropical storm, hurricane, and storm surge watches issued later today. Will those include any portion of the Texas Coast? Well, that’ll depend on what data shows later on this morning. I hope it shifts east and we can keep this system east of Texas (although I don’t wish ill-will to our eastern neighbors). At this point, it is way too close to call. We’ll have updates later today and you can bet your morning cup of coffee that we’ll be staying well on top of this system. I encourage you to do the same. There will be a significant inland flooding threat wherever this thing ends up.