All Eyes on Invest 99L; Florida and the Southeast U.S. Need to Watch Closely

Confidence is increasing that Invest 99L/future Hermine could pose a threat to Florida by early next week. On Tuesday convection and outflow increases some as it erodes dry air. Hurricane reconnaissance aircraft investigated the disturbance early Tuesday. Data from the mission showed an elongated area of low pressure and a poorly define circulation. They are scheduled to re visit Invest 99L Wednesday afternoon. Data from these missions is essential. It will help computer models fine tune the future strength and track of this system when it may approach the U.S. by early next week. As of Tuesday afternoon the odds that a tropical depression/Tropical Storm Hermine may form since at 60% over the next 5 days per the NHC. Convection reaches the Lesser Antilles Tuesday night, Puerto Rico mid-week, and possibly Hispaniola, Turks and Caicos and the southeast Bahamas Thursday and Friday. A Flash Flood watch is in effect for the Virgin Islands and Puerto Rico late Tuesday night until noon on Thursday.

Floater IR Enhanced with Streamlines

When you look at the big picture of 12Z computer models there is an obvious trend in the track by Sunday, Monday and Tuesday. Models focus in on a path over the Bahamas and towards south Florida. With this west or west north track a trip into the warm Gulf of Mexico is not out the question early to mid-week next week.

Invest 90L Models

With strong high pressure settling into the eastern U.S. early next week this pattern favors a westerly track towards south Florida. Before a future possible landfall rapid strengthening is possible over the very warm waters near the Bahamas. It’s still a wait and see situation and margin for error remains high since landfall isn’t likely for 5-6 days (if at all). If the storm makes landfall in the Florida or the U.S. it wouldn’t be until Sunday. The last hurricane to make landfall in the U.S. is Wilma. It made landfall in October 2005, so it’s been almost 11 years.

Hermine Explainer

The GFS has been wishy-washy and the model isn’t sold on development in recent runs. The more reliable European model has a trend of its own. The past few runs show a strengthening tropical storm over the Bahamas late week/early weekend with a b-line for Southeast Florida Sunday or Monday as possible Hurricane Hermine. That’s the thought with the latest 12Z Euro. Here’s its forecast for Sunday morning. This is similar to the past two runs but the timing has sped up. The Euro suggests a weak hurricane and southeast Florida landfall. Beyond a possible Florida landfall a trip into the warm Gulf of Mexico is possible. A major hurricane is not off the table too as hinted by the European model. If future Hermine makes it into the Gulf it wouldn’t be for another 7 or 8 days. There is plenty of time to keep an eye on things but it’s important to stay tropical weather aware.

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Elsewhere in the Atlantic Fiona dissipated at 11 AM. Meanwhile Gaston continues to get its act together and will likely become the next hurricane of the season by Wednesday. At 5 PM Gaston approaches hurricane strength with winds up to 65 mph. It will stay well east of the U.S. and possibly Bermuda too.

Gaston

 

Tropical Depression 7 Forms Near Africa-To Become Gaston; Uncertainty With Invest 99L

It’s official, as expected Invest 90L is upgraded to Tropical Depression 7 at 5 PM  Monday. The tropical low organized Monday and will likely become the 7th named storm of the 2016 season, Gaston, Monday evening or Tuesday. While it will interact with some stable dry African air early week a hurricane is likely over the open Atlantic by mid-week. Several long-range models indicate a strong hurricane is possible over the next 7-10 days. The good news is a track well east of the U.S. is expected at this time but Bermuda should keep a close eye.

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Of the three tropical disturbances we’re monitoring in the Atlantic the one of most interest is the one that is not named as it could impact the U.S/Florida in about a week. Invest 99L will battle dry air over the next several days which will slow development as it enters the Caribbean. Squalls are likely for the Windward Islands late Tuesday and Wednesday. By Friday the area of disturbed weather will move over very warm waters near the Bahamas. This is when intensification may occur. The question remains how long Invest 99L will linger near the Bahamas late week and over the weekend and how a ridge of high pressure to the north may guide it (towards Florida and eventually into the Gulf, north to the east coast, or out to sea). Again we have a full week to closely monitor the progress of this system.

Invest 90L Models

Here’s the suite of models Monday afternoon. A few have Invest 99L dissipating due to dry air before it even reaches the Caribbean. The general trend is a west-northwest track towards the Bahamas by Friday. As of Monday afternoon the odds of development sit a 20% the next 2 days and 50% by Saturday per the NHC. Computer models are initializing all over the place as there no center of circulation just yet.

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Models like the European and GFS have been back and forth on if Invest 99L becomes Hermine and if it makes landfall. They will likely continue to change in the coming days. The Euro was not sold on development until late Sunday. As of Monday afternoon the models shows Hermine thriving off of the steamy waters near the Bahamas over the weekend with a hurricane possible near southeast Florida by Monday. Remember this is one week away.

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Meanwhile the GFS which was aggressive at times on development still shows an open wave Monday morning over the Bahamas south of Florida. Both the latest GFS and Euro show low pressure passing over the Sunshine state with some intensification over the eastern Gulf by early to mid-week next week (in the Euro’s case rapid intensification). The bottom line is Invest 99L is still a ways off and we just need to keep an eye on things for now.

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Lastly Fiona is a still a tropical depression over 500 miles southeast of Bermuda at 5 PM. The official forecast calls for Fiona to become a remnant low by Wednesday. By late week the remnants of Fiona may head more northwest due to a weakness in the Atlantic ridge. Right now ex Fiona looks to stay south and west of Bermuda.

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Fiona Hangs on; Watching Two Other Tropical Waves in the Atlantic

The Atlantic remains active Sunday with several areas to watch in the long-range. In the short-term the sixth named storm of the Atlantic season, Fiona, hangs  on over the open Atlantic. As of 11 AM EDT max sustained winds are at 40 mph and it moves west-northwest at a brisk 16 mph. The small tropical storm battles dry air and wind shear. Strong westerly shear exposed its center early Sunday. Some showers and storms fill back in late Sunday morning but the storm is still very disorganized.  If Fiona can survive this hostile environment wind shear relaxes some early work week as it heads west-northwest. The 11 AM forecast calls for Fiona to dissipate by early Tuesday but the remnants may bring some rain/squalls near Bermuda if any convection remains. Regardless, Fiona is no threat to the U.S..

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Fiona

On the heels of Fiona is Invest 99L between the Lesser Antilles  and the Cape Verde Islands. There is still high uncertainty on the future of Invest 99L. On Sunday morning it is nothing more than a tropical wave with some scattered convection. While wind shear is favorable for development plenty of dry African air will keep this process slow, if at all.  The NHC bumps the odds of development down to 20% over the next 2 days and 50% over the next 5 days. Squalls will approach the Leeward Islands mid-week.

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Water Vapor Floater

Until a low-level center forms, if at all, there is error in the computer model forecast for Invest 99L. More models early Sunday trend towards a weak system/open wave through mid-week with a track near the Lesser Antilles Wednesday and Puerto Rico/Hispaniola Thursday. By late week and over the upcoming weekend Invest 99L may tap into some enhanced energy over the warm waters near or east of the Bahamas. The 06Z GFS (which has been all over the place with track and intensity) bites on this solution. Meanwhile the Euro is luke warm on any development at all. The next named storm is Gaston.

Invest 90L Models

 It looks like Invest 90L will beat Invest 99L to the punch and become our next named first (the next two names are Gaston and Hermine). The vigorous tropical wave is south of the most extensive dry African air in the Atlantic. There is a bit of moderate wind shear in the vicinity but upper levels are generally conducive for organization. A tropical depression is likely over the next few days as Invest 99L moves westward. The good news is while development appears likely models show a track out to sea (similar to Fiona).

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While the long-range forecast calls for a track west-northwest out to sea many intensity models suggest a hurricane is likely over the next 5-7 days. The 12Z suite of models shows anywhere from a tropical storm to a category two hurricane is possible by next Sunday (7 days from now). The future intensity of Invest 90L may play a role is the future intensity of Invest 99L. If Invest 90L becomes a full-blown hurricane Invest 90L is less likely to become a nearby strong tropical system. Stay tuned. There is plenty of time to watch both of these features here in the U.S..

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Active in the Atlantic; Watching Invest 99L as it Approaches the Caribbean

The Atlantic Basin comes alive this weekend with three areas of interest. Fiona hangs on while it battles dry air and moderate southwest wind shear. As of 11 AM Saturday it is barely a tropical storm. Max sustained winds top out at 40 mph and it heads west-northwest at 14 mph.. Fiona will weaken to a tropical depression by Saturday evening or Sunday morning. The remnants may make it to the eastern Bahamas mid-week but the official forecast is further east. Floater IR Enhanced with Streamlines 2 Fiona

Southeast of Fiona is Invest 99L. It sits at a more favorable latitude to enter the Caribbean. This is one to watch but development isn’t expected until mid to late work week. Officially, there is a 10% chance of tropical depression/tropical storm development the next 2 days and a higher 50% chance over the next 5 days. The Atlantic disturbance is quite broad and disorganized Saturday. There is moderate wind shear overhead and dry air nearby. Organization of this feature will be a gradual process. Invest 99L will encounter a robust area of wind shear early this work week east of the Lesser Antilles too.

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As always with a tropical disturbance that has not developed yet  (and a weak one for the time being) there is low confidence in the long-range forecast. One thing for sure is that Invest 99L passes over the Lesser Antilles mid-week. By next weekend the models have a quite a spread of solutions from just east of the Bahamas to the central Caribbean. A weaker system would head more west and a stronger system would take more of a northerly track. If Florida were to see any impacts it wouldn’t be until late next weekend, over a week away. There is plenty of time to watch.

Invest 92L Models

If Invest 99L survives the dry air and hostile upper level winds in the central Atlantic a more favorable environment for organization lies ahead. Water temperature are in the mid to upper 80s in spots. Waters near the Bahamas and Florida Straits are especially warm. These could favor rapid intensification.

Caribbean and Atlantic Water Temperatures

The final feature we’re watching emerges off the coast of Africa Saturday. The robust tropical wave is south of the most extensive dry air associated with the Saharan air layer. A bigger factor to slow development in the short-term is wind shear. Gradual development is expected over the next 5 days. Those odds sit at 50% per the NHC.  This disturbance may take a more northwesterly track similar to Fiona. Models are more aggressive on development with this one. The GFS and Euro suggest a hurricane is possible but fortunately the path is out to sea. The next named storms are Gaston and Hermine. Stay tuned.

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Tropical Storm Fiona Not Expected to Strengthen; Watching Other Tropical Waves

Tropical Storm Fiona was a fairly small storm on Friday situated in the middle of the Atlantic. The storm has maximum sustained winds of 45mph but those winds only extended outward about 45 miles from the center. Fiona is moving WNW at 10mph and has a minimum central pressure of 1006mb. The storm is expected to remain on a west-northwest track over the next several days with little change in intensity or gradual weakening. By mid-week next week, a weak tropical depression or remnant low should still be southeast of Bermuda.

Fiona

Fiona is located in fairly low wind shear right now, but as it moves westward it should encounter higher wind shear and thus, hostile conditions for any strengthening. The map below (courtesy the University of Wisconsin) shows moderate to high southwesterly wind shear just northwest of Fiona.

wind shear around Fiona

In addition to wind shear, Fiona will be encountering dry air. For now, dry air has yet to be pulled deep into the circulation. However, the low-level center of Fiona has, at times, been exposed from the bursts of deep convection and therefore is susceptible to dry air affecting it. In addition, the layer of dry air is fairly significant on the western flank of the storm which should gradually affect the storm more in the coming days.

Caribbean WV

While Fiona may ultimately fizzle out, there is another tropical wave in the Atlantic that bears watching. Invest 99L is located just southeast of Fiona, about 500 miles southwest of Cabo Verde. It is fairly disorganized right now but that should change in the coming days.

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Invest 99L is south of much of the dry air associated with the Saharan Air Layer (SAL) and will be moving into a more favorable upper level wind pattern. Because of its south positioning, interests in the Lesser Antilles should pay close attention to the forecast in the coming days. The models are fairly consistent in bringing the tropical wave near the Islands by later next week.

Invest 99L Models

Some of the models used to predict tropical development do show development of the system next week. One of those models, the GFS model, is very aggressive and shows a large tropical storm or hurricane near the leeward islands late next week. However, not all models are on board with this solution.

GFS MSL and Precip Rate 99L

Obviously, since we’re still a week away from any land interaction for 99L, much can change in the forecast and likely will. Nonetheless, we’ll pay close attention to it. The current odds for development from the National Hurricane Center are 10%/50% for 2-day/5-day. There is also another tropical wave behind 99L that is expected to emerge from the African Coast into the Cape Verde islands at some time on Saturday. The NHC puts the odds of development over the next 5 days at 30%.

NHC 5 day probabilities

Tropical Depression Six Forms in Central Atlantic; To Become Fiona

As expected Tropical Depression Six formed Tuesday evening west of the Cape Verde Islands. Wind shear is light and water temperatures are warm Wednesday near the tropical depression. There is plenty of dry air north and west of TD6 but an upgrade to Tropical Storm Fiona is expected late Wednesday. The official National Hurricane Center track shows a west-northwest track through the weekend. They anticipate a weak tropical storm through this period as future Fiona will run into dry air, increased wind shear and move over slightly cooler waters. Due to these obstacles a weaker Fiona may head more west-northwest as opposed to due northwest in the Atlantic. At this time it is no threat to Florida or the U.S.. If it holds together Bermuda should keep a close eye into next week. The long-range forecast is a bit more questionable.

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Fiona

An extensive layer of dry air sits in future Fiona’s path over the next several days. This will make it difficult for Fiona to gain strong tropical storm or even hurricane status. Not to mention a series of upper lows enhance wind shear at times too.

Water Vapor Floater

A series of African waves will roll into the eastern Atlantic in the coming weeks. Right behind future Fiona is a large cluster of convection near the coast of Africa. Several models hint that this area of disturbed weather could become our next tropical depression/named storm (Gaston) by early next week. We’ll be monitoring the progress of this feature later this week and especially this weekend. Long-range models have backed off on a third Cape Verde wave (circled over central Africa in white) but Cape Verde season is definitely awakening.

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The Euro picks up low pressure developing near Africa this weekend and deepening early next week. The 0Z suggests Tropical Storm Gaston may be on the map early next week in the east central Atlantic. Stay tuned.

ECMWF MSLP and Precip Rate

Watching Invest 98L Near Africa; Cape Verde Season Brewing

The tropical wave we pointed out Sunday is now Invest 98L. Invest 98L may be the start of multiple healthy tropical waves rolling off of Africa in the coming weeks, or Cape Verde season. For the time being Invest 98L is south of the most extensive dry air from the Saharan air layer but there is some drier air in its path. There is a pocket of moderate wind shear nearby inhibiting organization in the short-term. Gradual organization is possible in the coming days. As of early Monday there is a 20% chance of tropical depression/Tropical Storm Fiona develops by Wednesday and a 30% chance by Saturday per the NHC. Models suggest a west/northwest track. It’s way too early to say if Invest 98L stays over the open Atlantic or enters the northeast Caribbean in the long-term.

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Below is the extent of dry air from the Saharan air layer via the University of Wisconsin and NOAA. Notice a huge area of dry stable air north of Invest 98L and some dry air (but less extensive) in the central Atlantic. If Invest 98L holds together it may carve the path for future African waves too.

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Both the reliable GFS and ECWMF suggest the Atlantic heats up with multiple Cape Verde type waves in the next 1-2 weeks. The GFS is a bit more aggressive. The 0Z Euro shows (circled in white) 3 tropical lows in the central and east Atlantic by next Sunday. Stay tuned. It’s a good idea to pay attention to the tropics in the coming weeks. The climatological peak of the Atlantic season is on September 10th so this is right on schedule.

ECMWF MSLP and Precip Rate

 

 

Quiet in the Atlantic; Peak of Season Less Than One Month Away

It’s been more than a week since Earl dissipated over Mexico. With less than one month until the climatological peak of the Atlantic season (September 10th) we expect an increase in tropical cyclone development in the coming weeks. In the short-term the Atlantic Basin is stable and should stay that way for a bit longer. On Sunday we are monitoring a few tropical waves and an upper low near Florida. The most vigorous tropical wave sits southeast of The Cape Verde Islands near Africa. The Euro hints low pressure may organize some over the open Atlantic, but it will run into trouble with dry African air in its path during the days ahead. Officially per the National Hurricane Center no named storms/tropical depressions are expected over the next 5 days (at least).

Peak of Hurricane Season With Season Recap

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Despite the tranquil spell in one of most active months in the Atlantic season  NOAA upped their forecast some late last week. Including the 5 named storms and 2 hurricanes we’ve seen so far they are expecting 12-17 named storms, 5-8 hurricanes and 2-4 major hurricanes. This calls for a 35% chance of an above average season (on average there are 12 named storms, 6 hurricanes and 3 major hurricanes). NOAA forecasts the busiest Atlantic season since 2012 as El Niño is ending and lower wind shear is expected during the most active months. Keep in mind the first major hurricane typically doesn’t form until September 4th.

NOAA Hurricane Outlook

While this feature is not tropical in nature it certainly had a tropical connection (the moist Gulf of Mexico). Parts of southern Louisiana have seen 20″+ of rainfall since late Thursday and more rain is on the way. Fortunately low pressure over the northern Gulf coast will merge with a cold front and lift northward. The amount of rainfall will be lower in the days ahead but rivers continue to swell and any additional rainfall will exacerbate flooding.

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48 hr Rainfall Totals - Location

 

 

Watching a Trough in the Northeast Gulf

We continue to watch a trough of low pressure in the Northeast Gulf Saturday afternoon. Abundant moisture is supplying a train of heavy rain to coastal portions of Florida, especially near the Big Bend.Precipitable Water

The area of clouds and showers has a 20% chance to develop into a tropical depression over the next few days before it moves inland over the Southeast.

Tropical Development

Even if it doesn’t develop tropically, this trough of low pressure will continue to bring very heavy rain to portions of Florida. The heaviest rain will fall closer to the coast where Flood Watches are in effect through Tuesday. When all is said and done, a widespread 3″-6″ of rain is possible for most of the Panhandle and parts of the Peninsula. Meanwhile, closer to the coast and within the Flood Watch, more than a foot of rain will be possible.

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While it looks like the heaviest rain will fall near the Big Bend, there still remains some uncertainty just how far south and inland the heavy rain will fall. Stay tuned for updates on any shift in the heavy rain path.

 

Earl Weakens Over Mexico; Watching Deep Moisture in Gulf Next Week

Tropical Storm Earl made landfall late Wednesday night near Belize City as a Category 1 hurricane with winds of 80mph. Rainfall was heavy through Belize, Guatemala, Honduras, and parts of Mexico with gusty winds as well. The storm is currently a weak tropical storm over southern Mexico with maximum sustained winds of 40mph and a minimum central pressure of 999mb.

Colin

Earl will continue to traverse westward while weakening, likely becoming a remnant low at some point on Friday or Saturday. Nonetheless, rainfall from the system will be dangerous into Central Mexico through the weekend. We’ll also have to watch the system early next week as it may re-emerge in the Pacific and regenerate into a tropical storm.

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Meanwhile, not much else is happening across the rest of the Atlantic and Gulf of Mexico. However, the models do point to a broad area of low pressure developing in the northeast Gulf early next week. Whether it becomes a tropical depression or not is certainly still up in the air but regardless heavy rain will be a distinct possibility from New Orleans to Tampa.

GFS-Precip Acc

In the Pacific, the brigade of storms continues Tropical Storm Ivette gaining steam south of the Mexican Coastline. All signs point to Ivette strengthening a bit over the next couple of days before it meets cooler waters next week. Nonetheless, its trajectory toward Hawaii should have interests in that area paying close attention to the forecast in the coming days.

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