Wednesday Morning Update on PTC 9

July 29, 2020

There's bad news and good news for residents along the Gulf this morning. The bad news is that the track of PTC 9 has shifted to the west with the center of the forecast track now showing the storm entering the Gulf on Sunday. Note that the cone is still fairly broad out to Sunday and that a more eastern track is still possible. The good news is that it looks like conditions in the Gulf may be hostile enough to limit intensification or cause the storm to dissipate altogether but it'll be a few more days before we're confident in this.

Add caption

PTC 9 has the wind strength to be a named tropical storm but I think there must not be enough of a well defined and closed off low pressure center for it to be officially considered as such. PTC 9 has been really big for a tropical wave with a broad circulation spread out over a large area. Generally if a wave develops it is favored that the circulation will consolidate on the north or northeast side of the circulation. With this wave most of the convection (storminess) has been on the southern or southwestern side and this has caused the circulation to consolidate more to the south. The initial NHC forecast tracks were based on the storm forming more to the north but now that it looks like it is trying to develop a tighter circulation on the southern side of the wave the track has been shifted to the southwest to compensate. This is one of the issues with forecasting tropical cyclone development. The storm track is based on the location of the low pressure center and until there's a defined center to feed into the models they're doing their best trying to estimate where the center may form. Because of this we have the bad news that this storm could enter the Gulf.  

So now back to the good news. First, the track of the storm is likely to be one that causes at least some if not a lot of land interaction through Hispaniola and the rest of the Greater Antilles which have mountainous terrain. The storm will also have to fight off some dry air so conditions for strengthening don't look that great overall. The best scenario for strengthening would be for the storm to thread the needle between the islands and the Florida Keys and form a bubble of moisture around itself to fight off dry air. I don't see this as being very likely. Additionally, both the Euro and GFS show a fairly strong trough moving in and stalling over the lower Mississippi Valley on Sunday. This trough will bring with it strong mid and upper level southwesterly winds that will impart a lot of wind shear on PTC 9 as it enters the southeastern Gulf, if that is its track. Both models currently show a weak storm surviving the trek into the Gulf through the islands that then struggles to maintain a circulation as it fights wind shear off the west coast of Florida. With both major global models showing this occurring 4 days from now we can have a fair amount of confidence in it but to really ease my mind I'd like to see this trend hold through Friday morning.

That's it for today, we just need to keep watching what happens. I probably won't send out another update until Friday unless things change significantly before then. Have a great rest of the week.

Chris

Quick Update on the Tropics

July 28, 2020

The NHC has designed the tropical wave that was Invest 92L as Potential Tropical Cyclone 9. I was going to wait another day before sending an update because there's still not a lot of confidence that models are seeing this system correctly. Even so there has been a trend towards a more northeast track as you can see from the cone and one that shows only slow intensification.

That's it for today, we'll have to keep watching how this evolves. Have a great week.

Chris

Saturday Morning Tropical Weather Update

July 25, 2020

This is a long one and I'm going to share a lot of images today, starting with the Atlantic 5-Day outlook. For a synopsis Hannah is the big story at the moment but I think we'll have something even more concerning next week. Gonzalo and Hannah flip-flopped with Hannah becoming the first 2020 hurricane and Gonzalo falling apart a bit earlier than expected.

Not to minimize the impact of Hannah on Texas, but the big story continues to be the new tropical wave now in the Eastern Atlantic off of the African coast. This product below is called day cloud phase with low clouds colored blue and high clouds pink. You can easily see the wave off of the African coast as well as Hannah in the Western Gulf and what's left of Gonzalo.

The NHC has designated this wave as Invest 92L which is helpful because we'll start seeing some of the specialized hurricane models take a look at this. Looking at the models the Euro was almost an outlier initially with the GFS showing no development and the other models in between, that is no longer the case. Over the last few days every major model has jumped on board with developing this system. Below I'm going to share several model products but I want to emphasize that none of these are a forecast. For one thing most of these are out seven days from now, which is a few days beyond what is considered to be reliable. Also, until a storm develops models have trouble getting a handle on exactly what is going on. What we can do is get an idea what the trend is if we sort of lump these together. It's not exactly scientific but it can give us some confidence looking at the longer term. I'm also showing a few different model products based on what is available and depending on what I think best shows the situation.

With that said, let's start with the Euro (ECMWF) and its 51-member ensemble (EPS). These are for the same time frame. You can see that the operational model (ECMWF) has a weak system in the Central Caribbean where the ensembles show some stronger possibilities to the northeast. It is subtle, but there are several weaker systems showing up in the Central Caribbean in agreement with the operational model. You can see this better on the spaghetti map which shows weaker tracks through the Caribbean and stronger tracks to the northeast, with maybe a few more southern tracks than northeast.

Now for the operational GFS and its 21 member ensemble (GEFS). This may be showing the opposite with the operational GFS showing a northeast track and the GEFS maybe weighted more to the south. I'm not sure that the GEFS spaghetti map is showing all 21 members so the MSLP heat map may better represent the GEFS in showing a majority of the members to the northeast. It could be that these northeast members are just stronger, washing out the weaker solutions.

Now let's look at the UKMET, Canadian operational model (CMC), and Canadian ensemble (GEPS). I only have access to UKMET products out to 144 hours but both Canadian products are at the same time frame as the Euro and GFS maps above. Both the UK and CMC are favoring the northeast track, but there's quite a bit of spread on the GEPS, maybe slightly favoring a more southern track. Not shown are the German ICON and Australian ACCESS models, which favor northeast and southern tracks respectively.

I think we can be fairly certain that we'll see some sort of development as 92L approaches the Lesser Antilles next week. To hazard a guess on a consensus, a track through the Northeast Caribbean right across the Greater Antilles looks favored at this time. This could end up being a good thing for the US as this may take the storm across some large mountainous land masses depending on the exact track. I think we can also say that a track more to the northeast favors a stronger storm, where a more southern track favors a weaker storm, at least out to about 1 week. One thing to note is that tracks through the Caribbean can favor weaker storms due to the general environment that exists there. A southern track would be more concerning for us on the Gulf Coast but a northeast track does not mean that 92L would not enter the Gulf. It could very well run up the east coast or it continue an east-northeast track north of Cuba right into the Gulf. I also don't want to discount the more southern track from the ECMWF just yet. It was the first to really pick up on 92L so it may be handling this the best even though it is a bit to the south of most of the other models. A possibility could be that we see a weaker storm move through the Caribbean that strengthens as it curves into the Gulf.

I wasn't expecting to send another update until early next week but with all the models jumping on board I decided to send one a little earlier. As we move into next week we will hopefully get a better idea on what 92L is going to do.

Have a great weekend and go stock up your hurricane kit if you haven't done so.

Chris

Update on the Tropics - July 23, 2020

July 23, 2020

Over the past few days the tropics have evolved more or less like we thought they would with the one exception being the intensity of both systems. On Tuesday I mentioned the possibility that both could become stronger than what was forecast and this looks to be the case.

It looks very likely that TD 8 will become tropical storm Hanna by Friday morning and slowly strengthen prior to landfall on the mid-Texas coast on Saturday. If TD 8 becomes Hanna this will be the earliest 'H' storm on record, behind Gonzalo which was the earliest 'G' storm.

Tropical Storm Gonzalo will most likely become the first hurricane of the 2020 season tonight or tomorrow. It is still expected to weaken after it passes the Lesser Antilles, however there have been a few model runs suggesting that the storm could hang on enough to cause trouble next week farther to the west-northwest. This isn't expected at this time but it's something to watch.

We've got plenty of time but the yellow x on the African coast will be the next area to watch as it moves west. The European operational and ensemble models have been very bullish on developing this wave into a tropical cyclone somewhere near the Lesser Antilles around the end of next week. Curiously, the American GFS and it's ensembles do not develop this at all so there isn't a consensus on what might happen. There are some interesting conversations going on as meteorologists try to figure out which model, if any, is handling the environment correctly. The lack of model consensus has been a frustrating issue lately and it looks like that may continue. We'll have to keep watching the model trends as this wave moves west over open water this weekend and early next week to get a better idea what might happen.

There continue to be serious concerns that the approaching peak of the hurricane season could be very, very active. It's a good time to think about your plan and finish any preparations you've been putting off.

I'll probably send out another update around the start of next week. Have a great weekend.

Chris

Tropical Weather Update - July 21, 2020

July 21, 2020

I wanted to provide a quick update on the tropics. The area that was near the Bahamas has made steady progress west and now is located right along the northern coast of Cuba. The NHC now gives this system a 30% chance of development over the next 2 days and 40% over the next 5 days. The consensus still seems to be that we will not see any major development, with a tropical depression or maybe a tropical storm expected at landfall on the Texas coast on Friday. Based on some recent trends with other systems there are a few hints that models may be underestimating development a little, but intensification beyond a tropical storm doesn't seem likely at this time.

The other orange area out in the Atlantic is one of the tropical waves I mentioned last time. This may develop a bit over the next several days but beyond that it will likely encounter hostile conditions that will limit development and cause the system to dissipate as it continues west.

Beyond what is shown above there are some early signals that a tropical wave that will come off of Africa towards the end of the week may really need to be watched for development. Not all models agree but several are showing that this wave could make a run at development around the end of the month.

I'll send out another update in a day or so if it looks like the Gulf system may develop more than what is expected now.

Have a good week.

Chris

Tropical Weather Update July 19, 2020

July 19, 2020

The NHC is watching an area southeast of the Bahamas. They give this system a 20% chance of development over the next 5 days as it moves west-northwest towards the Gulf. The consensus seems to be that chances for development will remain low, but it is something to watch.

Elsewhere and in the longer term, we may see a few tropical waves try to develop over the next few weeks as they move west across the Atlantic. There are no really strong signals yet but some ensemble model members show a couple of these waves trying to spin up.

That's it for today, have a great week.

Chris

Quick Severe Weather Update for Central Alabama

July 12, 2020

A severe thunderstorm watch has been issued for Central Alabama from 12:10 p.m. to 7: p.m ahead of a line of strong storms moving to the south-southeast.
   

The severe weather threat has increased a little for Central Alabama today.Just a few minutes ago the SPC updated the Day 1 Outlook to include a slight (yellow) risk area. Coinciding with this is a 2% tornado risk and a wind risk that has increased from 5 to 15%. 

Stay safe and have a great Sunday.

Chris

Marginal Chance of Severe Weather Tomorrow for AL and TN, Tropics Look Mostly Quiet

July 11, 2020

There is marginal risk (level 1 out of 5) for severe weather for most of Alabama and all of Tennessee tomorrow. There have been some other marginal severe weather days lately that I haven't mentioned but I'm mentioning this because the risk area covers a fairly large area and includes all three modes of severe weather. There is a 2% tornado risk that is confined to extreme northern Alabama and most of Tennessee with a 5% wind and hail risk covering the rest of the area. It sounds like the potential for severe storms will be to the west Sunday morning moving east throughout the day and leaving the area by evening. There is a possibility that the risk could be upgraded to slight (yellow) as the event gets closer.

The tropics look to remain mostly quiet over the next week or so if not longer. This time of year there is always a chance for a quick spin up system like we saw with Fay but none of the model guidance is showing any major activity. There were a few hints that something might try to develop in the gulf in 7-8 days from a tropical wave but that idea has been dropped for now. The season has been interesting in that we have set several records regarding the earliest named storm starting with a given letter, most recently with Fay, and also with how far north some of the storms have been. Even though we've had six named storms none of them have been very strong so the ACE (Accumulated Cyclone Energy), another way of comparing one hurricane season to another, has been low. That being said from all indications it is just a matter of time before we start seeing a few really serious storms develop.

Have a great weekend.

Chris

Quick Tropical Weather Update

July 5th, 2020

Yesterday the National Hurricane Center designated an area in the northern Gulf as a place to watch for tropical development over the next 2 to 5 days. As of this afternoon the 2-Day outlook gives this area a 20% chance of development and the 5-Day outlook gives it a 40% chance. Over the next day or so this area will move ashore somewhere along the northern or northeast Gulf so it doesn't have a long time to develop. With that in mind there isn't a lot to limit its development other than time and some wind shear to its southeast. Models aren't showing any Gulf development but they haven't done a good job with this system so far. Instead it looks like development somewhere off of the southeast coast is more likely as it moves up that way in a few days. This is basically what the 5-Day outlook is showing, but it's something to watch for in the Gulf just in case. I don't think this is anything to get excited about but I want you to know that it is there.

Have a great week.

Chris