Tropical Development Possible in the Western Caribbean or Gulf Next Week

September 29, 2024

Hi everyone. As far as I know none of you received any direct impacts from Helene last week, but I know of at least one person that had family members impacted in North Carolina. Helene made landfall near Keaton Beach, FL as a 140 mph storm. Helene was a large storm, in the top 10% of hurricanes by size. The areas near the landfall location are devastated with extensive storm surge and wind damage and recovery will take a long time. It was fortunate that the storm went a little more to the east, missing most of Tallahassee and Atlanta almost entirely. Other areas weren't so fortunate. What I think will become the more memorable aspect of the storm will be the flooding and inland wind damage in Georgia, South Carolina, North Carolina and Tennessee. I am honestly at a loss as to what to say. I don't understand the details fully (I have some reading to do), but something called a predecessor rain event (PRE) occurred ahead of the storm followed by continued rain from the interaction with the remnants of Helene and the cutoff low that steered the storm away from the more populated areas along the coast. I think we may see the total cost of damages exceed every other natural disaster in our history. I don't remember one that impacted such a large area to such a degree.

Moving on to the current weather. As I mentioned in my last update there is the possibility of tropical development again in roughly the same area where Helene developed. The cause may be the same as well. A Central American Gyre is in the beginning stages of formation and this combined with energy from a westward moving tropical wave may combine to spawn another tropical cyclone. Details are murky at this point. If it makes you feel better the models have been less consistent for this system than they were for Helene but there is enough of a signal that the NHC is forecasting a 50% chance of development over the next 7 days. You can see from the size of the orange area that development could occur anywhere from the southwest Caribbean to the southern Gulf with timing anywhere from Tuesday to as late as Thursday or Friday. Landfall, if a storm forms, could be around the weekend or early the following week. The landfall possibilities at this point are broad and range from Louisiana to the west coast of Florida.

While this sounds like a potential repeat of Helene, I'm not so sure. The models are less consistent and not as strong overall. I know I mentioned this early with Helene, but wind shear looks to be a bigger factor this time which would hopefully limit the strength of any storm that forms. While I think we will see some kind of weather system develop I am not as concerned as I was with Helene. Not to say we couldn't be looking at another strong storm, I'm just not seeing as many signals for that as with Helene. Hopefully I'm not just overly optimistic. The models were amazing with Helene and hopefully will have more clarity on this system in a day or two.

Just in case it happens, I do want to mention that there is a small chance we could see two systems try to form, one in the southwest or western Caribbean and another in the southern Gulf. This could just be the GFS model being too aggressive but there is some ensemble support for this idea. If this were to happen it is unlikely to have two strong storms located that close together, but it may complicate the forecast.

Enjoy the rest of your Sunday and have a good start to the week, I'll send out another update in a few days.

Chris

Final Update on Helene - We Will Need to Watch the Same Area Again Next Week

September 26, 2024

Below is 10 a.m. update for Helene. The storm is now a category 2 hurricane. While the intensity forecasts have back off a little bit, it is still forecast to be a category 3 and maybe a category 4 at landfall later today. The track (finally) shifted a bit to the east and I am confident that Bay and Walton Counties will only experience minor impacts, with heavy rain likely being the main threat except along the immediate coast as mentioned previously.

It's too early for any specifics, but we need to watch the same general location in the Caribbean next week as roughly the same scenario may repeat. It's too early to know for sure that a storm will develop, let alone what the track or strength may be, but several models have been consistent at indicating development in the same area that spawned Helene.

Be safe and let me know if you have any questions.

Chris

Helene Now A Hurricane - Overall Forecast is Mostly Unchanged

September 25, 2024

This will be a shorter update today, the day job is getting in the way...I'll start off by telling those along the coast that if you don't already follow Meteorologist Ross Whitley on Facebook, he is the best local resource you will find. He will also be covering this storm more or less 24/7 and will have the most up to date info. Now for the storm. As of the 10 a.m. CDT advisory today Helene has become a hurricane. The track has shifted just slightly west, but overall the forecast is unchanged. Helene is forecast to become a major hurricane and make landfall between Panama City and Keaton Beach tomorrow evening. There have been no comments in the NHC's discussion for the last few advisories regarding track shifts but they did note that track can be off by about 60 miles at a 36 hour lead time. I was thinking (and hoping) we'd see a little bit of an eastward shift but that hasn't happened, so far I've been wrong in that regard. They also noted that upward adjustments to the intensity forecast may be needed. It is certainly possible that Helene may reach category 4 strength and while it is probably a top end scenario and not very likely, category 5 strength is technically possible.

Normal Cone

Experimental Cone Showing Inland Impacts

Below is the wind threat map from the NWS Southern Region Tropical Webpage. Bay and Walton Counties are in the orange zone, which is "Potential for wind 58 to 73 mph. This is in line with what I was saying yesterday that if the storm stays on track the most severe impacts should stay to your east. The models are very tightly clustered, but it would only require a small change in the timing of the turn from the northeast to the north for the impacts to change significantly. I'm cautiously optimistic this will not happen, but be prepared in case it does.

I'm sure you're all watching this as close as I am, but I'll probably send at least one more update tomorrow.

Please be safe and let me know if you have any questions.

Chris

Tropical Storm Helene forms in the Gulf, Will Likely Make Landfall as a Major Hurricane on Thursday

September 24, 2024

Tropical Storm Helene has formed in the Caribbean as of the 11 a.m. EDT advisory from the National Hurricane Center. I didn't send an email yesterday but I think all of you have seen the first several advisories from the NHC. Since the first advisory the cone has narrowed considerably (just due to inland progression, not increased forecast confidence) and the track has shifted east a bit. Helene is currently forecast to make landfall somewhere between Panama City and Tampa on Thursday as a category 3 hurricane. If you're in or near the forecast cone you should be making preparations or at the very least have a very solid plan that you can act on quickly, more thoughts below.

In their discussion, the NHC made the following comment:

"The track guidance is very tightly clustered, which would normally imply high forecast confidence. However, depending on exactly where the center forms could end up shifting the entire guidance suite in future cycles, so it is imperative to not focus on specific landfall locations this far in the future."

A few things to note about this. First, it is interesting to hear the NHC talking about where the center may form when by definition a tropical storm has a relatively well defined center... Perhaps it is not quite well defined enough yet to consider it locked in, I don't know. Second, I would not expect any very large shifts, maybe 20-30 miles at the most. This shift would be largest at the storm's center and probably not quite that much at the landfall end of track. As it is my thinking is that any shifts due to center realignment will be to the east and not the west as the strongest convection (storminess) is off to the east of the low level center so it may pull the center more that way. This can happen in the opposite direction though and currently the low level center is moving to the south-southwest with the mid level center moving to the northwest. Also, I think we may see some more shifts to the east as the model forecasts are trending that way, with many operational models still to the east of the hurricane spaghetti models. Whatever happens, I think confidence will increase a lot later today or overnight as the center completely consolidates.

Regarding intensity, the official forecast is for Helene to be a low end category 3 hurricane at landfall. In itself that would be a very powerful storm but this may be underdone and it is possible that it could even become a category 4. To make you feel better, the stronger solutions seem to be more to the east compared to the more moderate solutions. So if it does make landfall on the western edge of the guidance envelope hopefully a category 3 storm is the strongest we will see. No guarantees.

Going out on a limb here a little bit and hopefully this isn't premature, but I think everyone from Panama City west will not see the most severe impacts from Helene as I think it will continue to adjust east a bit. The one exception to this being for immediate coastal areas as they are likely to be impacted by storm surge at least to some degree. All the same, if you're near the forecast cone stay vigilant and be prepared to adjust your plans at a moment's notice. Also, if local authorities recommend you evacuate, please heed their advice regardless of what I have said.

Maps of expected impacts are below. There will likely be a tornado threat but I expect it to be to the east and later northeast of the storm center.

Stay safe and if you have any questions please let me know.

Chris

Tropical Development Likely in the Gulf of Mexico This Week

September 22, 2024

Confidence is still high that some sort of tropical system will develop in the northwest Caribbean or Gulf of Mexico this week. The National Hurricane Center is currently forecasting a 40% chance of development through 2 days and an 80% chance through 7 days. A Central American Gyre has formed as expected and it is likely that a tropical cyclone will form out of this circulation. There is still a lot of uncertainty regarding the timeframe of development and the potential strength of the storm once it forms. As always we won't have a solid forecast until a low level center forms. However, it does seem that we have a better idea of where the storm may go. From what I've read today confidence in the upper level steering flow forecast is fairly good now and it looks like the landfall window has narrowed from the AL/FL line to Tampa (those outside this area don't let your guard down yet). While that is still very large it is smaller than the Louisiana to Tampa window we had a few days ago. This is good news in that once the storm forms I think the track confidence will increase quickly. The bad news is that whoever gets this storm will not have much time to prepare. While I think the overall intensity trend has decreased a little in that fewer ensemble members are showing stronger solutions than before, a major hurricane of category 3 strength is still a possibility. I'm hoping there isn't time over water for anything stronger than that and we could also just see a tropical storm at its strongest but the consensus at this time is that at least a category 1 hurricane is expected.

It may not be until Tuesday or Wednesday that the forecast starts to consolidate with the storm making landfall as soon as Thursday or Friday. Today several local meteorologists started to recommend that people along the eastern and central Gulf Coast start making preparations since there will be short warning time for this storm. These people are usually fairly conservative and don't say things of this nature unless the situation is serious. Most of us probably have time to keep watching but if you have preparations that take some time you may want to get started.

I'll send out the next update as soon as there is more information.

Chris

Tropical Development Possible in the Western Caribbean or Southern GOM Next Week

September 18, 2024

The tropics remain somewhat active and the National Hurricane Center is watching a new area in the western Caribbean for tropical development. It looks like a broad area of rotation called a Central American Gyre (CAG) may form near Panama and Costa Rica this weekend. CAGs can sometimes develop enough vorticity (large scale spin) to provide a seed for tropical development. Several models have been showing this scenario for a few days and it has been consistent enough for the NHC to flag this area with a 20% chance of development through 7 days. 

My opinion is that we need to watch this area closely. CAG development can be tricky to forecast but there is enough consistency that I would say there is at least a 50% chance we'll see development in this area next week, maybe as early as Monday or Tuesday or perhaps not until later in the week. If development occurs the most likely track will generally be to the north with a broad range of possibilities. There is one scenario where this system gets stuck under a ridge and goes west, but I don't think that is very likely. That said it's still early and I don't have a lot of confidence in the track forecast. It's too early also to think about intensity. I will say that it looks like a northward moving storm may be interacting with a trough as it gets into the northern Gulf and that would impart wind shear and hopefully limit intensity. We could also see another system try to develop off the East Coast around the same time that could cause unfavorable conditions in the Gulf.

There is a chance that a CAG doesn't form at all or that if it does development occurs in the Pacific instead of the Caribbean. There are a lot of variables still in play but I think there's a strong enough signal to pay close attention to this area. Hopefully confidence will increase over the weekend but as always until a storm actually forms uncertainty remains relatively high.

Have a good rest of the week.

Chris

Update on Tropical Storm Francine

September 10, 2024

With impacts expected to begin tomorrow, I think it is a good time for an update. I'm not going to go into too many details on the hurricane forecast itself as I think the forecast cone gets the point across well enough. That said, there is still a little bit of uncertainty with timing, track, and intensity but no significant changes are expected. Below is the 10 a.m. update and what you are seeing is the new experimental forecast cone. The only difference is this shows inland impacts and not just impacts right along the coast. Francine, currently a tropical storm, is expected to become a hurricane sometime tonight. It is expected to make landfall along the east-central Louisiana coast as a strong category 1 hurricane tomorrow evening. It could be a bit stronger than that, but that is the current forecast.

I am going to focus my discussion from the MS/AL state line to the east but if you have questions about other areas please let me know. With the latest update, the track shifted a little to the east and Alabama coastal areas are now under a tropical storm watch. We could see this extend to the Florida Panhandle if the track shifts more or if the wind field expands a bit. Right now, tropical storm force winds could arrive along the Alabama coast as early as 8 a.m. Wednesday, with the most likely arrival time a bit later in the day. Barring any big changes, sustained tropical strong force winds are unlikely east of AL. Storm surge could be as high as 4 feet along the Alabama coast and Mobile Bay and I expect the western most part of Florida will see a slight (1-2 ft) increase in sea level as the storm approaches. Coastal flooding will likely occur, especially for low lying areas, and rip currents and high surf will be risks as well.

Flooding from rain and tornadoes will also be threats. Most of the FL Panhandle and SW AL are in a slight risk area for excessive rainfall, potential rainfall totals through Sunday (this storm should be out of the area before then) is shown.

The tornado threat will start Wednesday and will be confined mostly to coastal areas. On Thursday it may extend inland as far north as TN but there is a lot of uncertainty how far north the threat may go. As it is, the tornado threat isn't particularly high, but folks along the immediate coast, especially in the Mobile area, should be alert for severe weather should it occur.

That should about cover things. I expect only minor impacts for anyone east of the AL/MS state line, subtle changes to the details are possible but I don't expect any major changes. This is a good time for a reminder that threats from water, either coastal flooding from storm surge or inland flooding from rain, tend to be a much higher risk to people and property than wind. Keep that in mind if you're in an area prone to these hazards.

This should be my last update unless there are significant changes.

Stay safe.

Chris

PTC 6 Designated in the Gulf of Mexico

September 8, 2024

The National Hurricane Center has started issuing advisories on PTC (potential tropical cyclone) 6 in the southwest Gulf of Mexico. The official forecast track is below and it is possible (with some uncertainty) that it could be a hurricane at landfall. I don't expect any crazy changes, but both the track and intensity forecast are a bit uncertain at this point. More details below if you're interested. 

It is important to note that this isn't a tropical cyclone yet, not even a tropical depression, as it still consists of an elongated north-south-ish trough of low pressure. The forecast track is based on a guess of where the center may consolidate but the NHC discussion notes that it could form anywhere along the trough axis (to the north or south of their guess). The general track forecast is well understood with an initial northwest motion followed by a turn to the north-northeast expected by midweek. But because of the uncertainty regarding the location and timing of the formation of a consolidated center it is of low confidence. The NHC also notes that some models have trended a bit to the east and that eastward shifts to the forecast may occur in the future. The current track could be right on, but I think an east-central Louisiana landfall is also a possibility, but I don't think we'll see it go farther to the east than that. It may take until late tomorrow or sometime Tuesday for the center to form and for confidence to improve.

The intensity ceiling is a bit higher than what I was thinking a few days ago. As shown, the official forecast calls for a hurricane at landfall but in their discussion they note that this level of intensification requires an interaction with another feature and is of low confidence at this point. Right now, a strong category 1 hurricane seems to be a reasonable ceiling. We've all seen how fast storms can intensify unexpectedly, so until we get a better picture of the forecast once the center forms, just know that a moderately stronger storm may be a possibility. We'll talk about potential impacts once we know more.

That's it for today. I'll send out another update if something changes or when the forecast confidence increases.

Chris

Tropical Weather Update - September 6th

September 6, 2024

I'm not sure if I can come up with a concise title for this update. The most recent 7-Day Outlook from the NHC is below. While the tropics look busy with 4 areas being watched (there were 5 yesterday...) I don't think any of them are major threats, probably at least, especially in the short term. To summarize, the area off of Texas, designated Invest 90L, has a 10 percent chance of developing. The area in the Bay of Campeche has a 20 percent chance of developing, but will likely combine or interact with 90L. There's an area off the East Coast (Invest 99L), no concern. Lastly, there's an area in the Atlantic with a 10 percent chance of development. Your level of concern should be about the same as those probabilities. We'll keep watching the areas in the Gulf and the one out east, but no big concerns at the moment, more below if you're interested.

Let's talk a few details. Invest 90L off the Texas coast is expected to drift to the south through the weekend and development is unlikely until early to mid next week, if at all. As it drifts south it is going to interact with a tropical wave crossing the Yucatan (yes, the same one we've been watching for a few weeks now) with the wave adding energy and moisture to 90L. By Monday or Tuesday we may see this system try to organize as it consolidates and moves back north through the end of the week. Slow development is possible, but right now it looks like a tropical depression or maybe a tropical storm impact along the Texas/Louisiana coasts will be the upper end for this system. Land interaction and wind shear from a stalled front are likely to limit development but let's watch to make sure.

The area in the Atlantic is another tropical wave that has a chance (currently low) to develop as it moves west. Models aren't too excited about it and the overall environment in the Atlantic isn't particularly favorable for tropical cyclone development right now. This is expected to remain the case until mid month or the third week of September but we should also keep an eye on it as it moves west. As it is it has a pretty good chance of going north before reaching the Gulf but that's not guaranteed.

Speaking of unfavorable conditions, the lack of activity in the tropics has been a head scratcher. Some reasons are known, but the underlying causes are not understood. Globally there are some unusual weather patterns and they are likely linked. Still, Colorado State thinks we will end up with an above average season and they expect favorable conditions to develop in the second half of September and into October. CSU also mentioned that a hyperactive season is still a possibility, but is a lower probability now. A lull like we've had followed by a big increase in activity is not unprecedented. We'll see.

It is officially fall (meteorological fall). Earth, Wind, and Fire will usher us into astronomical fall in a few weeks on the autumnal equinox, although this year it's on the 22nd and not the 21st. Northern AL and TN should see a night or two in the 50's this weekend before warming back up to near normal. Temps have been mostly cooler than normal and should remain so (especially daily high temps) through the start of the week and maybe longer from about Montgomery south thanks to some fronts stalling along the coast. It will also be pretty wet for the same area for the same reason. No cold weather on the horizon yet, but I think we're done with the excessive heat.

That's it for today.

Have a great weekend.

Chris

Labor Day Tropical Weather Update

September 2, 2024

Happy Labor Day. I know for me the three day weekend is most welcome.

TL;DR we need to keep watching the Caribbean system as it moves west. Development chances are currently on the low side (40%), but expected to improve. Lots of uncertainty still, but any tropical system in the western Caribbean in September needs to be watched closely regardless. Too many details below, I guess I felt like writing a lot today.

I've been waiting for this area in the Atlantic to get figured out before sending another update but as of this morning I don't think we're any closer to knowing what is going to happen. You can see there are three areas being watched, but the only one of any real concern is the orange X in the eastern Caribbean, that is the same system we were looking at a week ago. The area in the Gulf is bringing a lot of rain to parts of Texas and Louisiana but is not expected to develop, current chances are at 10%. Another tropical wave just coming off the African coast has a 40% chance to develop over 7 days. It is something to watch but it doesn't look to make it very far to the west based on current modeling.

Back to the Caribbean system, the NHC gives this area a 40% chance of development through 7 days. In my previous update I said that I didn't expect it to do much and regardless of what ultimately happens that statement was premature. Computer models can't seem to figure this thing out. A few days ago I was a bit worried about this one. For a few days development looked very likely, with some scary scenarios in some of the solutions, only to see that wax and wane every other model run, now tapering off a bit overall. As of this morning development chances look to be lowering in the short term but we still need to keep watching. Thankfully this system has remained broad and elongated without any consolidating areas of vorticity (spin) and hopefully this continues as this moves off to the west. It looks like some moderate wind shear and stronger winds on the north side of the wave axis may be currently inhibiting development but the NHC expects conditions to improve in a few days in the western Caribbean. If you know your history you know that a moderately healthy tropical wave in the western Caribbean in September can be bad news, so we need to keep watching.

As mentioned, models can't figure this thing out. The operational GFS is currently the most bullish on development but the others not so much. The ensembles are indicating a medium-low chance of development, so I think the NHC's assessment of 40% is right on. Either way, the off again and on again signals from run to run are enough to pay attention to. Were this to develop, the potential tracks are somewhat troubling. Earlier on (last week) there were some model tracks that took any developing system out in the Atlantic as well as into the Gulf. Now that it has made it farther west without development the solutions all end up in the Gulf with possibilities from Mexico to Florida. Southern solutions (Mexico) seem to be the most likely at this point, but I think confidence in where any system that does development may go is on the low side at this point, there are just too many unknowns. Timing is another unknown. We could see development as soon as the end of the week (unlikely) to late the following week if this gets penned up in the southern Gulf by a front (low confidence). The most likely scenario is slow development around the weekend near the Yucatan or southern Gulf, at which point we'll need to watch a little closer to see where it goes from there. There are also too many unknowns to speculate on intensity, but all possibilities are on the table.

A few more notes. Cooler(ish) and wet weather is on the way towards the end of the week, with a warm up near the middle of the month near the coast. We'll see one or two fronts push through during this period, perhaps with one or both stalling near the coast or offshore. I will welcome the rain and cooler temps, but we'll need to watch the Gulf after these push offshore in case something tries to develop along the tail end. There is some low confidence model support for this idea.

That's it for today. If you've made it this far, thanks for reading!

Have a great Labor Day.

Chris