Bertha bringing beneficial rains to parts of northeast Caribbean

Recent radar out of San Juan, PR showing much needed rains moving across the region

Recent radar out of San Juan, PR showing much needed rains moving across the region

There is one positive about tropical cyclones – they often bring much needed rain to areas and as long as it’s not too much, too soon, it really can be a good thing.

Such is the case today with TS Bertha. Puerto Rico and surrounding islands have been very dry in recent months. Bertha is helping just a little with some much needed rain. While there is the risk of flash flooding, especially in the mountainous terrain, Bertha’s quick movement and disorganized structure will help to limit this impact. It looks like another 12 to 24 hours at the most and the rains will move on, passing over parts of the Dominican Republic and in to the extreme southeast Bahamas tomorrow and Monday.

Bertha has probably lost its well defined low level center and may not technically be a tropical cyclone – more of a strong tropical wave. This was not unexpected and while it might not ever recover, the computer models are actually in pretty good agreement that Bertha will eventually become a hurricane.

Once the storm moves out of the Caribbean, the environment in the atmosphere is forecast to be much more suited for development. Fortunately, Bertha will be well east of the United States and sufficiently west of Bermuda to avoid any direct impacts.

I do see the potential for increased swells and rip currents along parts of the East Coast later next week. I’ll have more on this once we see how strong Bertha does in fact get over the western Atlantic. Anyone with plans to head to the beach will want to just make sure you’re aware of the local surf conditions ahead of time. While it could be a nice few days for surfers, rip currents and rougher than normal breaking waves are a danger, especially to children who may think big waves are exciting while not understanding the risk.

Latest GFS model showing two potential impacts for Hawaii in the coming days

Latest GFS model showing two potential impacts for Hawaii in the coming days

Meanwhile, in the Pacific, we will need to watch hurricane Iselle closely in the coming days. It is likely to track far enough west as a tropical storm that it may bring rain and wind to Hawaii later next week.

As if this were not enough, global models are indicating the formation of another tropical cyclone to the east of Iselle which could also track west enough to impact Hawaii. The next 10 days are going to be quite interesting for the region as the Pacific has really come to life with a lot of tropical activity.

I will post more on all of these systems tomorrow morning.

M. Sudduth 12:38 PM ET Aug 2

Bertha closing in on Lesser Antilles

Visible satellite photo of Bertha showing the deeper thunderstorm activity displaced to the east of the center

Visible satellite photo of Bertha showing the deeper thunderstorm activity displaced to the east of the center

Tropical storm Bertha has more convection with it this morning but it is displaced to the east of the low level center as seen in early morning satellite imagery. This is due to the fact that upper level winds are running in to the storm instead of going with it – thus the deep thunderstorms are pushed off to the east while the storm travels westward.

Top winds are still 45 mph and the pressure is not falling much at all. Unless Bertha can wrap the deep thunderstorms around the center and develop a more organized core, it will not strengthen much. There is a chance this could happen as forecast by many of the intensity models. In fact, the statistical SHIPS model makes Bertha a hurricane but well after it passes through the Caribbean Sea.

Today, the main issue will be heavy rain and brief squally weather for portions of the eastern Caribbean as Bertha closes in from the east. The worst of the weather will be felt where the deep convection is located. It is impossible to tell with such a poorly organized system how this will play out in the coming hours. Local radar from the Caribbean will help but people in the region need to be ready for the potential of tropical storm force winds, rough seas and very heavy rain – again, mainly where the deep convection is located. Outside of that, the lighter rain bands will not have much impact other than an increase in wind and rain.

For Puerto Rico and the Dominican Republic, again, a lot has to do with how well organized Bertha becomes. Water temps are only going to rise along its path but if the shear and dry do not relent much, then Bertha could remain more of a rain maker than anything else. This is still a problem, especially for mountainous terrain but the rain itself is much needed for the region – hopefully just not too much at one time.

Once Bertha tracks out of the Caribbean, it should remain just to the east of the Bahamas as it nears the western edge of the Bermuda High and begins to turn northward. At this point, it could begin to strengthen and may have a shot at becoming a hurricane before turning out to sea. This could bring a couple of days of increased swells and coastal rip currents to parts of the Southeast coast. Surfers will love this but swimmers, especially children and those who are not used to such conditions, may be at risk from the rougher than normal surf. Check your local NWS site for more details on this potential hazard next week.

Elsewhere in the Atlantic, all is quiet on this first day of August.

As I mentioned yesterday, the east Pacific remains quite busy overall but everything is remaining well away from land and will remain that way for the time being.

I’ll post more on Bertha early this evening.

M. Sudduth 9:02 AM ET Aug 1

Not the best looking tropical storm but there it is – NHC upgrades 93L to TS Bertha

NHC 5-day track map showing Bertha moving thorugh the Caribbean and then off the Southeast coast

NHC 5-day track map showing Bertha moving thorugh the Caribbean and then off the Southeast coast

The NHC has begun issuing advisories on TS Bertha as of 11pm ET tonight. While deep thunderstorms are very limited, the circulation is well defined and an Air Force plane confirmed winds to tropical storm force earlier today.

While some may wonder why on earth something so weak looking would get an upgrade, consider this: a tropical cyclone is a large and unusual weather phenomenon when compared to everyday weather. The Lesser Antilles are a series of islands and there are many people who live or otherwise use boats and other water craft in the region. A tropical storm, no matter how ragged, can impact an area with strong winds, rough seas and heavy rain. Just because it is rather poorly organized from a convection stand point, doesn’t mean it lacks the potential to cause issues for the area that it will pass through.

Speaking of that – the forecast track takes Bertha through the eastern Caribbean before turning northward and across the Dominican Republic and in to the Bahamas. Here too, rain and related issues are a concern, especially in the mountainous areas of Puerto Rico and of course Hispaniola. Hopefully the circulation will remain rather bare of deep convection but as I have said many times, hope is not a planning tool, knowing the hazards that could affect you is. We can hope that Bertha remains weak but this only pertains to the wind speeds. It could still dump copious amounts of rain, even if in a limited area, and that could cause issues for people.

After passing through the Caribbean Sea, Bertha is expected to turn northward just off the Southeast coast. How close it tracks to, say, the Carolinas or points north, remains to be seen. Let’s see how the storm fares over the next day or two before worrying too much about the longer term outcome. Needless to say, we will be watching this closely as we move through the weekend but for now, it looks to be a wave maker perhaps for parts of the East Coast and that’s it as far as impacts. Things can change so stay tuned.

I will have more here tomorrow morning.

M. Sudduth 11:52 PM ET July 31

Tropical depression forming from 93L this morning?

Intensity graph showing considerable spread between the regional hurricane models and the larger scale global models

Intensity graph showing considerable spread between the regional hurricane models and the larger scale global models

There is not a lot of it, but deep convection is finally developing around at least part of the circulation of 93L. It is limited to the southern half of the low pressure area and any additional increase, especially on the northern side, would easily bring the system to tropical depression status – maybe even to tropical storm strength as well.

It is remarkable how well the low pressure area has held together amid such dry conditions in the deep tropics. This pattern has been in play for the past few years and, in this case for sure, has kept hurricane activity in this region to a minimum.

Taking a look at the latest intensity guidance, there are mixed signals this morning. Some of the model data suggests that this could become a hurricane while other data maintains a weak system that actually stays weak throughout the coming days. Breaking it down a bit, the regional hurricane models, developed just for predicting the intensity of tropical cyclones, are more bullish on development than the larger scale global models. The GFS, for example, shows the system basically dissipating as it moves across the northern Caribbean Sea. I think that there is a small window of opportunity for 93L to become a tropical storm before more negative conditions hinder additional strengthening. We’ll see – as I have said all along, I am skeptical of deep tropical development right now due to the fact that nothing much has come from this region in quite some time.

The track forecast seems a little more straight forward and indicates a general west to west-northwest movement towards the Lesser Antilles. As such, interests in the area should be watching the progress of 93L closely. While it looks like the impacts would be limited due to the low intensity, it is possible that tropical storm conditions will arrive in the region over the next few days. We’ll see what the NHC has to say about all of this around 11am ET when the first advisory could be issued on what could be tropical depression three or even tropical storm Bertha.

Elsewhere in the Atlantic Basin, all is quiet as we end the month of July.

In the east Pacific, there is plenty of activity to watch but nothing close to land and I see nothing in the computer guidance to suggest a change to that anytime soon.

I’ll have more here later today with additional updates on our Twitter and Facebook feeds.

M. Sudduth 8:07 AM ET July 31