Four things to watch this week in the Tropics

As we begin the first week of fall, the National Hurricane Center (NHC) is tracking two named systems and two others trying to organize. 

This satellite image shows a couple of swirls in the Atlantic Ocean, and a blob of rain near the Lesser Antilles. They are:

1. Tropical Depression Kirk, in the Eastern Atlantic
2. Sub Tropical Storm Leslie, in the Mid Atlantic
3. What was Depression #11 near the islands

The First thing to watch is Kirk. 

It is not a good looking system with most of the rain found on the western side of the storm. NHC says this is probably due to drier air impacting the spin in the mid to upper levels of the atmosphere. 

Kirk will be traveling through warm waters over the next few days with little in the form of shear to weaken it. Shear is very strong upper level winds that can cut down the tops of developing thunderstorms, thus keeping it in check. Without it, Kirk is expected to get a little stronger (or at least keep it from reaching hurricane strength).

In the long run, the shear flowing from southwest to northeast, catches up with Kirk near the Lesser Antilles, and just like it took care of depression 11, here too it should take a toll on Kirk.

For the time being, the Bermuda high will steer Kirk west rather quickly, with a slow down expected in about 3 days, as the high weakens.

Spaghetti Models

The models have a consensus for the first few days that Kirk will travel mostly west but around days 3 - 4, they start to fan out. This is the time when the shear should move in. Some models think it will get tossed north into the middle of the Atlantic, while others suggest it may sneak underneath the shear and stay in the Caribbean.

The Cone

The official forecast track from NHC, bumps Kirk back up to a Tropical Storm through the Lesser Antilles and into the Caribbean Sea. From Trinidad and Tobago North through Guadeloupe, you need to monitor the progress of Kirk. Some gusty winds and rain may start to show up by midweek.

Once Kirk enters the Caribbean Sea, all interests there and even South Florida should keep an eye on it in case the models start turning it towards land. We'll keep you posted. Worry meter for So. FL is zero at the moment.

The second area to watch

Subtropical Storm Leslie will just be a nuisance for the Shipping Lanes.

A Subtropical Storm is a hybrid system, half tropical, half like an average low pressure you may find attached to a cold front.  It has a cold center instead of a warm one like regular hurricanes.

It has a nice spin to it, but notice the line of clouds moving into the picture in the upper left, that is a front and it is forecast to absorb Leslie in a few days. It may do a few loop de loops before being completely taken in by the front.

The third and fourth areas to watch

There are two other areas trying to organize in the Atlantic.

The one next to Subtropical Storm Leslie, has a medium chance for development in the area highlighted orange over 5 days. Even if something does develop it should end up just like Leslie, meandering in the Northern Atlantic.

Then there's another area just South of Bermuda with a medium chance to develop. If it does, it should organize in the orange area. This one is worth watching because even if it doesn't organize it could drop more rain across the Carolinas.  If it does develop, it would be an awful mess to have the Mid Atlantic states hit by another tropical system. Hoping for the best there.

Fierce Florence

There's nothing left to say to folks living along the coast of South & North Carolina... "Get out of the way!"

Hurricane Florence remains a ferocious category 4 system with winds of 140 mph.

It 's well organized, good feeder banding, a well developed eye and nothing in its way to debilitate it.

The National Hurricane Center is using words in their storm advisories like, dangerous, life threatening, and catastrophic. This in not code and they are not sugar coasting it. This will be a killer storm.

You need to get out of the way.

The cone of concern shows the system making landfall on Thursday and then weakening inland. It will slowly weaken across the area dumping a lot of rain.

This is the reason why it will stall over the region. A cold front with a dome of high pressure moves in trapping Florence for a few days. Eventually the front will push it out over the Northeast.

Rain forecasts indicate anywhere from 1 to 2 feet of rain widespread, with a few spots seeing as much as 4 feet through next Tuesday. This will lead to catastrophic flash flooding.

Our impacts from Florence will be in the form of rough surf mostly for Palm Beach and Broward Counties with up to 5 foot waves.

Tropical Storm Isaac is also on pace to make landfall across the Lesser Antilles, but it's looking more and more disorganized. The winds came down at the 11 pm advisory from 70 mph, to 65. 

 

 

Having said the, the National Hurricane Center keeps it as a storm through much of the Caribbean Sea. Coastal Haiti, Dominican Republic and Jamaica should monitor closely.

These are just two of the five areas NHC is watching.

There's also Helene. It should weaken across the Northern Atlantic in the days ahead. It may brush the Azores towards the end of its life cycle.

Then a vigorous tropical wave near the Yucatan Peninsula has a high chance for development. A 70% chance it could develop into a depression or a storm in the area highlighted. 

 

These very early model runs are just giving an educated guess since nothing has developed yet. But if it does, they are trending the track towards Southern Texas. Mexico and Louisiana should monitor as well.

 

 Then an area in the middle of the Atlantic with nothing there now, has a 50% chance for a system to develop over a period of 5 days.

We'll be monitoring.

Monster Florence aiming for the East Coast

Hurricane Florence is a major system with winds of  140 mph, as of the Monday night advisory.

Everyone along the Mid Atlantic States should be getting ready.

Major Hurricane Florence

Earlier Monday afternoon, the eye of Florence measured roughly 10 miles wide. A category 4 system churning in the Western Atlantic. You can see the tube heading down into the surface. That is the eye wall, where you find the strongest winds and heaviest of the rain. It's a ring of destruction that will pummel whichever area it runs into.

Florence's Vital Statistics

The area where you will find tropical storm force winds from 39 to 73 mph, extends out from the center 150 miles.

 The area where you will find hurricane force winds from 74 to 140 mph, extends out from the center 40 miles.

 The system itself is 450 miles around.

Where is Florence Headed?

The system will aim for the Carolinas as a category 4 with the potential to get a little stronger before landfall. Notice the bulge at the end of the cone. That suggests it may stall across the region dumping plenty of rain.

Spaghetti Models

They actually show the system doing loop de loops along the coast, blocked by a dome of high pressure and cold front. This will keep the threat of torrential rains in place for days.

 

Some areas could see as much as two feet of rain which will lead to flooding, land and mudslides.

More Activity in the Tropics

 We are also following:

• Isaac downgraded to a Tropical Storm
• Hurricane Helene
• A tropical wave in the Caribbean
• And a potential are of low pressure in the Northern Atlantic

Isaac will steer toward the Lesser Antilles. The small size of this system is making it difficult to forecast its intensity. It could get a little stronger and just as easy weaken. The Lesser Antilles need to monitor.

Hurricane Helene will move north and may eventually impact the Azores with gusty winds and squally weather.

In the Western Caribbean a tropical wave is meandering. It should move into the Gulf of Mexico where it will have a 60% chance for development in the area highlighted.

Then in the Northern Atlantic, nothing is there now, but NHC says that an area of low pressure may form over 5 days. That has a 50% chance for development.

We'll be monitoring.

Stronger Florence moving faster. Isaac on a steady pace for the Lesser Antilles.

"Life threatening impacts from Florence" Remains the message the National Hurricane Center (NHC) wants everyone to hear as the hurricane aims for the U.S. East Coast.

Florence's Vital Statistics as of Monday morning:

• Winds: 105 mph - Category 2. It's forecast to get even stronger. Hurricane force winds extend out from the center 25 miles. Tropical storm force winds reach out 125 miles from center.
• Pressure: 969 mb. It was 984 mb Sunday afternoon. That's a drop of 15 mbs. The lower the pressure, the stronger the system.
• Storms: Plenty of thunderstorm activity around the center. 
• Any shear?: Very little 
• Outflow: Firmly in n place. Hurricanes take in moisture at the base in a counterclockwise fashion. That air is then released in the upper levels of the atmosphere in a clockwise motion. When this happens, you have a fine tuned tropical engine at work. Notice the satellite loop as the spin moves inward at the center, but at the top of the image, the spin is opposite. This is your outflow at work. Impressive.

Where is it headed?

Spaghetti Models:

The main grouping is now showing a more unified consensus that Florence will aim for the Carolinas. There are outliers on both sides, but NHC's cone of concern is following the clustered grouping. NHC is also warning that the models are suggesting a larger wind field that could impact the coast many miles away from the center.

Models are also indicating a faster forward speed in days 3 - 4 of the forecast which unfortunately "increases the risk of a destructive hurricane landfall"' according to NHC.

NHC says, "the major impacts from Florence will be wind, storm surge at the coast, heavy rain leading to flooding from the beaches to far inland locations. Everyone from the Carolinas northward should pay attention and prepare.

More NOAA and Air Force Hurricane hunter missions are scheduled .

The other system capable of landfall is Isaac.

As of 11pm Sunday night, here are the vitals:

• Winds: 75 mph. Isaac is now a hurricane.
• Size: This a small and compact storm. This can play both in its favor and against its overall health.
• Storms: While there isn't impressive feeder banding, it does have plenty of thunderstorm activity around the center. Drier air is keeping it in check for the time being.

Where is it going?

Spaghetti Models:

NHC warns that the models do not have a good handle on this system. The GFS and European models keep Isaac on a steady westward course increasing in forward speed, while the UKMET and HWRF suggest a slower moving storm with a possible jog to the north. This is evident on the fanning out of models in the spaghetti chart.

Official Cone of Concern

The cone keeps Isaac heading west.  The size of the system may play a big factor in how strong it may be once there.

Low shear at the moment will allow it to gain strength, specially as it moves over warmer waters. It will take full advantage of this situation to intensify. But as it gets close to the islands, strong shear will show up and because of its small size, it should weaken rather quickly. The GFS model weakens it the most, down to a lowly wave. We hope that is the case.

A change in the intensity forecast. NHC says it may be a category as it nears the Lesser Antilles instead of Category 2.  The strength outlook will fluctuate in the days ahead due to its small size.    Still too many variables with Isaac. Please monitor and prepare now.

The National Hurricane Center is watching:

1. Hurricane Florence
2. Hurricane Isaac
3. Hurricane Helene
4. An area of concern in the Gulf of Mexico
5. An area of concern in the Mid Atlantic

Quick Tropical Scan

• Helene should stay in the open waters of the Atlantic 
• An area of concern in the Gulf has a 30% chance for development in the area highlighted in yellow over 5 days.
• An area of concern in the Mid Atlantic has a 40% chance for organization in the zone highlighted in orange over a 5 day window. This will be interesting because it promises to move southwest in the long run.

With all these system to watch, NHC is extremely busy.

We have to go back to last year to find three hurricanes in the Atlantic Basin. On September 6th, we had Katia in the Gulf of Mexico, Irma northeast of the Leeward Islands, and Jose in the mid Atlantic Ocean.  We are at the peak of hurricane season, today September 10th.

We'll be monitoring

Hurricane Florence forecast to be a Monster

Florence is a hurricane again, and likely to be a very POWERFUL system as it moves over the western Atlantic toward the southeastern United States.

That's the message Sunday morning from the National Hurricane Center (NHC).

The satellite loop from today shows a more symmetrical Florence, better organized, with increased thunderstorm activity around its center. It even appears to have an eye with an eyewall already in place. 

A NOAA recon mission reported that Florence had hurricane force winds and the pressure was at 984 mb. 

Its only weakness at the moment are the frail feeder bands. These are the outer bands of clouds that feed moisture to the center. They need to be unbroken to provide a steady stream of fuel. They are looking patchy. Once they turn into good uninterrupted banding, then we'll have a monster.

Status Report on Florence

• Good Outflow: While the spin at the surface is counterclockwise, a healthy system needs the opposite motion in the upper levels of the atmosphere.  Florence has it which means it's starting to fire on all cylinders. Notice the satellite loop, the center is spinning inwards. Now look at the upper left hand corner, here the clouds are moving in the opposite direction. This is not happening near the surface like the lower level spin, but way high up in the atmosphere. This is the outflow. It helps carry warm moist air from the surface up into the system turning it into thunderstorms. It then gets spit out similar to your car's exhaust pipe.
• Sea Surface temps: Check. Here too it will be traversing some of the warmest waters of the Atlantic. Plenty of tropical fuel for it to grow.

Where's it headed?

A look at the models:

Most of the model runs are all in agreement the system will move Northwest over the next few days but around Wednesday, they start to fan out.

• The GFS model, (The Global Forecast System provided by the National Weather Service (NWS) is among those predicting a more northwesterly track.
• The HWRF, (Hurricane Weather Research and Forecasting Model-used to forecast track and intensity) and the ECMWF, (European Center for Medium-Range Weather Forecasts) both keep Florence on a more southwesterly route.

The official forecast cone from NHC is in the middle of the above extremes.

This is why NHC is telling residents along the U.S. East Coast from Northern Florida to the Carolinas, to review their hurricane supplies, action plan, and if told to evacuate, do so. Florence can have life threatening impacts!

The cone just shows where the eye of the storm might be located. Florence's feeder bands extend outward hundreds of miles so its impacts will be felt far away from the center.

Even large ocean swells could make it across the Bahamas and parts of South Florida.

Florence's influence go far beyond the East Coast, it may also impact the future of Isaac.

Tropical Storm Isaac looks much healthier Sunday morning

It has plenty of thunderstorm activity with good feeder banding, except for the northwestern sector. A little shear and dry air is impacting it. Regardless, it's getting stronger and winds are up to 65 mph as of 11 am Sunday morning.

The question is "How strong will it be as it nears the Lesser Antilles?"

Most of the solutions maintain Isaac on a steady westerly course. Only a handful turn it north in a couple of days.  The reason why it is expected to stay on a westerly track is high pressure sitting to its north.

Notice on the map the lines with the number 14,18, 20. They represent the leading edge of a huge dome of high pressure. The winds here rotate clockwise and will continue to push Isaac west through September 12. After that it appears the high weakens just a bit, but how much is uncertain.

The official forecast cone from NHC keeps it due west as a hurricane. By the time it reaches the islands it could be as strong as a category 2 with 100 mph winds.  This intensity could fluctuate over the next few days as the outflow from Florence could actually impact it.   The outflow could provide some shear helping to weaken Isaac. We are hoping that it does.

Everyone from Trinidad and Tobago to Puerto Rico should keep an eye on Isaac and start preparing now.

We'll be monitoring

Two storms to watch for landfall threat

We continue to monitor the progress of Florence and Isaac, two systems that threaten landfall by the middle or late part of next week.

It is a crowded Atlantic Ocean with many features to analyze. We will start with Florence, which could be a major hurricane making landfall somewhere along the U.S. Eastern Seaboard.

Florence

The color satellite is showing a classic swirl developing again, recouping after a few days of being battered by shear. 

These are very strong upper level winds that tend to weaken storms. It's now free of it, and will begin a steady climb in overall strength.  It may be a hurricane by 11pm Saturday night.

The colors represent where you can find the heaviest rainfall within the system. The blues and greens are light rain, while the yellows, oranges, browns represent heavy downpours.

A NOAA recon aircraft performed a mission Saturday afternoon. It detected a stronger wind field and lower pressure readings. 

Those are clear indications that Florence is on the comeback.

It may reach major hurricane status of winds of 111 mph in the upcoming days.

Residents in its path should start taking this threat seriously and begin reviewing their supplies and action plan. 

Where is Florence Now?

The map above shows what is happening over the Atlantic Ocean. Find Florida and move right until you find the red swirl (tropical storm icon). Notice there is a big blue "H",  to its north. This is high pressure and this is responsible for pushing it west.  There is another blue "H" over Canada. It is forecast to move into the Atlantic.  Florence is looking for the gap between the two so it can travel north.  What the models are trying to figure out is the timing of those two highs and where the gap will set up. To the East, and the system stays over water, to the west and it makes landfall .

Where is Florence Headed?

The Spaghetti Models

Most of the models are calling for a gradual turn northwest over 5 days. 

They are all looking for the gap, but have yet to reach a good solution on where and when. 

Some take it as far south as Central Florida and others into New England.  

This is a nail biter and will remain so for a few more days until the atmosphere decides on where the highs will move to.

 

There's plenty of warm water ahead of Florence. Tropical systems need sea surface temperatures of 80 degrees and above to grow.                            There is plenty ahead in its path. It will be going over the Gulf Stream Current which is some of the warmest water in the Atlantic. This is one of the reasons why Florence will intensify.

The forecast cone will change over the next few days, as it aims for the U.S. The National Hurricane Center is advising the following:

• Florence is forecast to become a dangerous major hurricane near the southeast coast by late next week
• Where exactly it will make landfall, at what time and strength, is still unknown
• Residents from North Florida thru the Carolinas should be watching the forecasts closely
• Large ocean swells will impact Bermuda and parts of the East Coast next week

The following tweet was made public at 8:33 pm. It gives you an idea of how serious a threat, Florence will be. Hampton Roads is a body of water in Virginia.

UPDATE: @USFleetForces orders all #USNavy ships in Hampton Roads area to set Sortie Condition Bravo ahead of #Florence. Condition Bravo is set when onset of destructive weather conditions to the port are within approximately 48 hours - https://www.navy.mil/submit/display.asp?story_id=106990&utm_source=twitter&utm_medium=social&utm_content=100000320273031&utm_campaign=Misc … #NavyReadiness

The next system to threaten land is Tropical Storm Isaac

Isaac is over 1600 miles east of the Lesser Antilles. It's encountering some shear and should remain as a storm for a few days. In the long run that shear will weaken, giving it the opportunity to reach Category 1 status with winds over 74 mph.

Where is it Headed?

It's being steered west by high pressure and should remain on a westerly path for 48 hours.

After that, a handful of models veer the system north and away from any land, but the majority insist on keeping it west. There is some shear forecast to move in just as it nears the islands. It's still unclear if it will weaken Isaac.

Detailed models

The NAVGEM model is one of those that intensifies the system, but turns it north at the last minute in about 150 hours or roughly 6 days. Notice the tight green swirls. It shows Isaac to the north of the Leeward Islands. (You can also see Florence impacting the Carolinas in this solution).

The GFS model on the other hand, places a weaker system right over the island chain in about 117 hours or around 5 days. Keep in mind that while it may not be a hurricane, it is still capable of gusty winds, storm surge, and heavy downpours, that could lead to flash flooding, land and mudslides.

The European Model has the same thinking of a weaker system across the islands also in 5 days. Please be alert and get your supplies and action plan ready now. Keeping fingers crossed it does weaken before reaching shore. 

It is curious to note that on all of these model runs, the path of Florence shows either a direct hit or a glancing blow to the Carolinas.  

Lastly, Tropical Storm Helene

This storm may intensify as it moves away from the Cape Verde Islands, but the best news is that it will stay over open waters.