Invest 96L Attempts to Organize; Will Bring Heavy Rain/Squalls to Caribbean Through the Weekend

Invest 96L tries to reorganize Friday and the odds remain high tropical depression/Tropical Storm Cristobal will form by the weekend. Friday’s Hurricane Reconnaisance mission is crucial in helping computer models initialize better.  Enhanced satellite imagery shows the deepest convection near Puerto Rico. The center is likely just northeast of the island. The area of low pressure battles moderate shear and interaction with mountainous Hispaniola, but will have a better opportunity to strengthen near the southeast Bahamas Saturday or Sunday.

Floater IR Enhanced 2

Regardless of tropical cyclone classification Invest 96L will dump heavy rainfall and bring gusty winds to Puerto Rico, the Dominican Republic, Haiti and the Bahamas (especially the southeast Bahamas). The graphic below shows rainfall totals per the GFS model through Friday morning. 5+” is possible in spots. Much of this is welcomed rain after a dry summer but brief flooding is possible.

GFS-Precip Acc

The short-term 12Z model consensus is a west-northwest track towards the southeast Bahamas though Sunday morning. A few outliers suggests the center of Invest 96L is south of Puerto Rico hence a more southerly track. Interaction with Hispaniola could also throw the track off over the weekend. Beyond Sunday morning a trough of low pressure will likely steer possible Tropical Storm Cristobal away from Florida.

Invest 96L Models

There is less model agreement in the long-range forecast and U.S. impacts are not off the table just yet. Models struggle with the intensity of the east coast trough and strength of high pressure building in. A few more 12Z models suggest a track closer to the U.S. than previous runs. This is a trend needs to be monitored. The majority of models shows a track paralleling the southeast Bahamas Sunday followed by a north-northwest track between the U.S. and Bermuda Monday-Thursday. Stay tuned.

Invest 96L Models 2



Watching Invest 96L Closely into the Weekend

Invest 96L looks a little better defined on Thursday afternoon. However, it still remains fairly disorganized and lacks ample deep convection. The enhanced satellite imagery shows a broad, elongated area of low pressure with scattered storms surrounding it. The National Hurricane Center puts the chances of development at 50% by Saturday afternoon, and 70% by Tuesday afternoon.

Floater IR Enhanced 2

Invest 96L still has to contend with some dry air on it western and northern fringes. However, the atmosphere has moistened up quite a bit since Wednesday afternoon, and should continue doing so over the coming days as the disturbance moves briskly to the WNW at 20mph.


Nonetheless, water temperatures are quite warm in the vicinity of 96L. Most areas are well into the 80s, and as the system moves to the NW, water temperatures should warm as well in its path. This should aid in any future development.

Western Atlantic Water Temperatures

As far as the track goes, the thinking has changed quite a bit in the last couple of days, as happens so often this far out from a storm. It now looks like a trough along the east coast early next week will help to pick up and curve Invest 96L (or whatever tropical system it may become) out to sea. Most of the spaghetti plots below show the storm moving over the Bahamas and then curving NE. However, there are still a few models that take the storm back west into the Mainland so we’ll have to continue to watch this system.

Invest 96L Models

Even after curving to the north, we’ll still have to watch Invest 96L, as it still may turn back westward and impact the US. The ECMWF (Euro) below shows the storm making a closer approach to the Carolina coastline before heading back out to sea. This is another reason why we have to watch this system closely.

ECMWF MSLP and Precip Rate

Meanwhile, the eastern Pacific continues to heat up. Tropical Storm Karina continues to chug along and we now have Hurricane Lowell, the 7th hurricane of the East Pacific season. These systems are expected to become entangled with one another over the next few days. Meanwhile, just off to the southeast, another disturbance is looking to make a run at becoming Marie over the next few days. There is a 90% chance that it will become at least a tropical depression over the next 5 days.

Tropical Track Pacific 2

Watching Invest 96L-Could Move Into Caribbean Late Week

Models hint that the Atlantic Basin may heat up later this week. We’re watching two tropical waves in the south central Atlantic Tuesday. In the short term both tropical waves struggle with dry African air and enhanced upper level winds as they move westward. Further organization will be a gradual process. The tropical wave circled in yellow has minimal deep convection with plenty of dry air in the vicinity. It heads west-northwest over the next five days and officially per the NHC (as of Tuesday afternoon) has a 10% chance of becoming a tropical depression by Thursday and a 20% chance by Sunday. The tropical wave circled in orange, now Invest 96L, is a little more impressive, but disorganized for now. Convection is deeper due to less dry air but it is widely scattered. Wind shear is also moderate at 10-20 kts. Invest 96L has a greater chance of organizing Thursday or Friday near the Lesser Antilles. There is more moisture in this region and water temperatures are also warmer. The odds of tropical depression/tropical storm development are a little higher. As of Tuesday afternoon there is a 30% chance of development by Thursday and 40% chance by Sunday. This feature bears watching. Hurricane Reconnaissance Aircraft is on deck to investigate Invest 96L Thursday, if necessary.

atlatnci sat

Water temperatures near the Lesser Antilles climb into the low to middle 80s. This is a few degrees warmer than many of the buoy readings east of the islands. The Gulf of Mexico is even warmer. Many buoys show readings in the upper 80s. It’s early, but models like the GFS, NAVGEM, and Canadian suggest Invest 96L may thrive off of these tropical waters early to mid work week next week.

Caribbean and Atlantic Water Temperatures

For most of the 2014 Atlantic season wind shear values across the Caribbean have been moderate to high squashing chances for tropical depression/storm development (along with tons of dry air). The question remains just how much these values may relax over the weekend/next week. This is when computer models suggest Invest 96L may move into this region. The 12Z GFS suggests a belt of moderate to high wind shear sits over parts of the western Caribbean into the western Atlantic.

GFS Wind Shear

Early computer model runs on Invest 96L show a west-northwest track over the Lesser Antilles late Thursday or Friday. Over the weekend possible Tropical Storm Cristobal could pass near Hispaniola followed by possible interaction with Cuba on Monday. From there Invest 96L could enter the Gulf of Mexico. As always with long-range forecast there lots of “ifs” with the track and intensity. Interest in the Caribbean need to keep an eye on the tropics the next few days.

Invest 96L Models

It’s just one computer model run and over a week away but the 12Z GFS suggests Invest 96L makes it into the southern Gulf by Tuesday and could head for the northern Gulf coast late Thursday into Friday.

GFS MSL and Precip Rate

Dry, dusty stable air form the Saharan Air Layer (SAL) extends from the western Caribbean to the Cape Verde Islands. The extend of this dry air has eroded a bit over the past week near the ITCZ with more tropical waves rolling through the region. This makes sense with the climatological peak of season about three weeks away. The graphic below is courtesy the University Wisconsin at Madison.


Here is the Saharan Air Layer just 10 days ago on August 9th. Notice little to the convection along the monsoonal trough.



Slow Development Possible in South Central Atlantic

August 17th arrives and there are still just two named storms this Atlantic season. Climatologically the third named storm (Cristobal this year) forms on August 13th. The main reasons for just two named storms are hostile upper levels winds, plenty of dry air, and below average water temperatures in spots early this Atlantic season. Wind shear took a toll on Invest 95L near the Cape Verde Islands Saturday and it fell apart. Upper levels aren’t quite as hostile in the central Atlantic but there is a ton of dry stable, African air north of the ITCZ. Not all models are on board, but a few suggest that weak low pressure between the Lesser Antilles and the Cape Verde Islands may slowly develop in the coming days. As of Sunday morning convection is very limited and organization, if any, will be a gradual process as the low crawls westward. The National Hurricane Center gives this area of disturbed weather a low 10% chance of tropical depression development by Tuesday and a 20% chance by Friday.

Floater IR Enhanced 2

Moisture builds off the coast of Africa with tropical waves moving into this region every few days. However, there is still plenty of dry air in the eastern Caribbean and north of ITCZ. This stable air makes it tough for tropical waves to survive long-term.

Floater IR Enhanced to Water Vapor

The 0Z European model suggests the tropical wave won’t move much into mid-week. By Wednesday it may thrive off of enough moisture for low pressure to deepen.

ECMWF MSLP and Precip Rate

Over the weekend (while it’s just one model and one computer model run) the 0Z Euro brings the weak low towards the Lesser Antilles before it rides a break in the subtropical ridge and heads out to sea. The GFS shows a similar situation with a different tropical wave late work week. Stay tuned.

ECMWF MSLP and Precip Rate 2



Invest 95L Disorganized Near the Cape Verde Islands; Environment Not Favorable For Significant Development

As suspected the tropical wave we’re tracking near the Cape Verde Islands (now Invest 95L) isn’t particularly organized Saturday. Convection flared up Friday night but this was short-lived as Invest 95L battles moderate 20-30 kt shear. These values stay elevated into mid work week so significant organization is not expected. Not to mention plenty of dry air lingers north and west of this feature. Water temperatures near the Cape Verde islands run 1-2 degrees below average too. Regardless some squalls are possible over the Cape Verde Islands Saturday afternoon as the disturbance drifts slowly west-northwest. The odds of tropical depression development sit at a low 20% chance of development over the next five days per the NHC (as of Saturday morning).

Floater IR Enhanced 2

So far this Cape Verde season tropical waves have basically been swallowed by dry air by the time they make it to the central Atlantic.  If Invest 95L survives hostile upper level winds the next few days this may also be the case. Notice that with more tropical waves riding off of Africa there is a bit more moisture east and south of the Cape Verde Islands. This environment isn’t quite as dry as it was just a few weeks ago. We would expect this as the peak of the Atlantic season nears on September 10th.


Many computer models suggest Invest 95L will linger near the Cape Verde Islands through Monday. Others suggest the tropical wave will pass over the Lesser Antilles and then head into the dry open Atlantic.

Invest 95L Models

The reliable European models suggests Invest 95L (or possibly the tropical wave a few hundred miles to its west struggling dry at the moment) may make it to the central Atlantic Wednesday morning. At this pace possible weak low pressure could bring leftover tropical downpours to the Lesser Antilles Friday or Saturday.

ECMWF MSLP and Precip Rate

Meanwhile in the eastern Caribbean former Invest 94L brings scattered tropical downpours to the northern Lesser Antilles, the Virgin Islands and Puerto Rico. Much of the region is in a rainfall deficit so this is welcomed. While this tropical wave looks somewhat healthy early Saturday it will interact with significant dry air in the mid levels of the atmosphere Sunday and Monday as it drifts west. Upper levels are unfavorable during this time frame too.

Eastern Atlantic IR Enhanced

Caribbean WV

Tropical Wave Near Cape Verde Islands Not Expected To Develop

As we continue to get deeper into the climatologically active portion of the Atlantic Hurricane Season, we really start looking farther east for more tropical breeding grounds – particularly the Cape Verde Islands. Tropical waves that move off the west African Coast this time of the year have a better chance of becoming storms thanks to warmer Atlantic waters and a generally moister environment. And like clockwork, we are watching an area of low pressure just south of the Cape Verde Islands.

Eastern Atlantic IR Enhanced

While that area of showers and storms looks decently organized, the environment it’s in is not necessarily as conducive to development as it typically would be this time of the year. Notice the extent of dry air associated with the SAL (Saharan Air Layer) throughout the Atlantic and especially on the northern fringe of this area of low pressure.


In addition to the dry air in place, winds are not favorable for development either. The wind shear forecast from the GFS shows moderate to even high wind shear on the southern side of this potential storm through at least the middle of the week.

GFS Wind Shear

One final piece of evidence against tropical formation of this low are sea surface temperatures. While SST’s are sufficient across the Atlantic for tropical formation, they’re not particularly impressive. In fact, SST anomalies show temperatures at or slightly below average across much of the Atlantic between the Cape Verde Islands and the Lesser Antilles.

SST Atlantic Anomalies

Having said all of this, we still need to watch the next couple tropical waves coming off the African Coast. In fact, the GFS model has been hinting at some lower pressure working into the central Atlantic by the end of next week. We will certainly continue to keep an eye on that area.

GFS MSL and Precip Rate


Wednesday is 10 Year Anniversary of Hurricane Charley

Invest 94L dissipated in the central Atlantic Tuesday and the tropical wave is nothing more than a batch of scattered clouds Wednesday afternoon.  There’s plenty of dry African air west of this diffuse feature too so impacts by the time it passes near the northern Lesser Antilles in a few days look minimal. A tropical wave south of Cape Verde islands struggles with moderate shear and is no threat for development. No tropical cyclone development is expected over the next five days as there is two much dry air in the Atlantic.

Floater IR Enhanced 2

Caribbean WV

While the Atlantic Basin is quiet Wednesday, 10 years Hurricane Charley made landfall in southwest Florida as a category four hurricane.  On August 13, 2004 it rapidly intensified in a six hour period. The center officially made landfall in Cayo Costa, just north of Captiva with 150 mph sustained winds. Parts of central Florida saw 6-8″ of rain from Charley and there were 9 tornadoes in the Sunshine State. Charley is directly responsible for 10 deaths.

There were a lot of lessons learned from Charley. The hurricane was a good reminder that tropical cyclones can have both big coastal and inland impacts, and each system behaves differently. The original forecast called for a landfall in Tampa Bay but a few hours before landfall Charley took an east jog and came ashore in southwest Florida. Residents of Tampa Bay that evacuated from the coast set up shop inland (many in Polk county) where Charley actually brought tremendous rainfall and hurricane force winds. Believe it or not a day before Charley made landfall the 24 hour track forecast error was 40 miles (according to the National Hurricane Center). This actually below the long-term average. It is important to never focus on the center line in the middle of the “cone of error”.  According the National Hurricane Center tropical cyclones stay in the “cone of error” 60-70% of the time (based on forecasts from 2009-2013). The animating radar image below is courtesy of the Tampa Bay radar at Ruskin.  Watches are now issued 48 hours in advance and warnings are issued 36 hours in advanced so there is more time to prepare.

Charley was the first of  four hurricanes to hit Florida during the historic 2004 season. Jeanne made landfall in southeast Florida on September 5th. Frances did too a few weeks later on September 25th. Ivan came ashore near Pensacola on September 16th. Charley, Jeanne and Frances all crossed paths in south central Polk county. The last hurricane to hit the state of Florida was Wilma on October 24, 2005.

2004 Hurricane Season Tracks and Facts 2

Invest 94L Fizzles; Tons of Dry Air Keep Atlantic Quiet

Invest 94L loses its battle with dry air and moderate wind shear Tuesday west of the Cape Verde Islands. Convection completely falls apart and it is no longer a threat for tropical cyclone development during the next five days. By Saturday moisture from the tropical wave may impact the northern Lesser Antilles. A new tropical wave rolls off the coast of Africa Tuesday morning.  It will struggle was some of the same dry air and hostile upper level winds that caused Invest 94L to fizzle.

Eastern Atlantic 2D IR Enhanced

The Saharan Air Layer (SAL) extends from the coast of Africa through the central Atlantic and into the eastern Caribbean. This air mass makes it extremely difficult for healthy tropical waves to hold together for more than a couple of days. None of the reliable computer models hint at tropical depression/tropical storm development over the next five days. Yet again the long-range GFS suggests next week will be a little more active in the Atlantic but that’s a ways off. The graphic below is courtesy the University of Wisconsin at Madison.


Computer models no longer run data on Invest 94L as of 12Z but as of 06Z models suggests that remnants of the weak tropical feature may make it to the northern Lesser Antilles Saturday. Scattered tropical downpours and gusty wind are possible during this time.

Invest 94L Models


Watching Invest 94L Near Africa This Week; Plenty of Dry Air in its Path

It will battle plenty of dry African air in the coming days but for now Invest 94L holds its own southwest of the Cape Verde Islands. There is noticeable spin on enhanced satellite imagery Monday afternoon. Convection is scattered over a temporary moist environment. Wind shear is moderate Monday but some models suggest these values drop later this work week as the broad low heads generally west at 15-20 mph. As of Monday afternoon the National Hurricane Center puts the odds of tropical depression or Tropical Storm Cristobal development at 0% by Wednesday and at 20% by Saturday. Climatologically the third named storm of the Atlantic season forms on August 13th (this Wednesday).

Floater IR Enhanced 2

Plenty of dry, dusty and stable African air sits north and west of Invest 94L so development, if any, will be a gradual process. Models like the GFS and European don’t do much with this feature but they do bring it towards the Lesser Antilles enhancing rainfall over the islands on Saturday.  While dry air is a big obstacle Bertha made it through this environment in early August. So did TD 2 (briefly) in late July.

Floater 1 WV

Some computers bring Invest 94L westward and dissipate it later this work week east of the Lesser Antilles. Other models track the broad low west-northwest north of the eastern Caribbean islands around the subtropical ridge on Sunday. It’s a wait and see situation to see how Invest 94L handles the Saharan air layer and how far west or west-northwest it heads this work week into the coming weekend.

Invest 94L Models

The 12Z GFS suggests another healthy tropical wave may roll off the coast of Africa this weekend. It also keeps Invest 94L as an open wave with enhanced rainfall over the northern Lesser Antilles Saturday afternoon. Cape Verde season may be in full swing over the next few weeks. As more waves move through the south central Atlantic they may moisten up this region and dry air will be less of an obstacle. This is when the strongest named storms (often hurricanes) form. The peak of the Atlantic season is September 10th, about a month away.

GFS MSL and Precip Rate

Tropical Hurricane Frequency Graph-WTVT



Watching Invest 94L Near Africa-Slow Development Possible

Cape Verde season tends to heat up in the coming weeks and right on cue we are watching a tropical wave between Africa and the Cape Verde Islands. The environment north and west of Invest 94L is extremely dry and stable but for now convection is widely scattered near this feature. It battles moderate 20-30 kt shear Sunday but these values relax early this work week.  Development, in any, will be slow this week as it tracks west at 15-20 mph. The National Hurricane center gives it a low 10% chance of becoming a tropical depression by Tuesday and a medium 30% chance by Friday.

Eastern Atlantic IR Enhanced

Early Sunday morning computer models hint at a west-northwest track this work week into the batch of Saharan air. This will highly disrupt organized convection. It’s early, but worth watching this feature. It’s only a matter of time, especially as the peak of hurricane season nears in early September that a few more healthy easterly waves move into the east central Atlantic and moisten the environment.

Invest 94L Models

Notice the extent of dry African air across the Atlantic. The graphic below (courtesy of the University of Wisconsin at Madison) shows most of this air mass is north and northwest of the tropical wave. If Invest 93L tracks due west it may have a chance but a west northwest through this stable environment could be a major struggle. The GFS and European bring Invest 94L towards the Lesser Antilles Saturday.


Hurricane Special-Cape Verde Hurricanes

Hurricane Julio will pass several hundred miles north of Hawaii Sunday into early work week and is no threat. The remnants of Iselle continue to move away from the Aloha State too. Wave heights stay elevated Sunday with Julio in the vicinity. Buoy data shows surf climbs to near 7 feet near the Big Island and Maui.

Tropical Track Pacific 2

Caribbean and Atlantic Wave Heights

In the central and western Pacific there are two named storms. While Typhoon Genevieve is no threat Tropical Storm Halong slammed Japan with heavy rain Saturday. Slow moving Halong made landfall in southern Japan Saturday night EDT with 70 mph max sustained winds. Parts of southern Japan received over 15″of rainfall and a rare evacuation order was issued for more than one million people in Mie prefecture, west of Tokyo. An all time record 24 hour rainfall of about 17″ was recorded here.

Floater IR Enhanced