It’s official. The 2016 Atlantic hurricane season wraps up Wednesday with 15 named storms, 7 hurricanes and 3 major hurricanes. It is the busiest Atlantic season since 2012. On average there are 12 named storms, 6 hurricanes and 3 major hurricanes, so there was an above average number of named storms and hurricanes in 2016. The slightly above average season is in line with predictions from NOAA and Colorado State University. In their late summer update NOAA upped their forecast to 12-17 named storms, 5-8 hurricanes and 2-4 major hurricanes. Colorado State anticipated 15 named storms, 6 hurricanes and 2 major hurricanes. Prior to the start of the 2016 season La Niña conditions were anticipated at the peak of season late in the summer. With possible lower wind shear and warmer waters tropical cyclone development would be enhanced. This never panned out and the La Niña Watch was dropped in early September. Even without the presence of a weak La Niña a slightly above average Atlantic season occurred.Several storms were strong and long-lived in 2016. When we analyze the total energy output of all tropical systems during the entire hurricane season, or ACE, the number is high is 2016. According to Dr. Klotzbach at Colorado State University the ACE this year is 134. This is more than double the ACE from 2015. Two hurricanes made landfall in the U.S.. Hermine is the first hurricane to hit Florida since Wilma in 2005. Hurricane Matthew paralleled Florida and Georgia and made landfall in South Carolina as a category 1 hurricane. Matthew was a category 5 hurricane in the Caribbean. It is the first category 5 hurricane in the Atlantic Basin since Felix in 2007. Tropical Storm Colin made landfall in Florida and Bonnie struck South Carolina as a tropical depression in South Carolina. Julia threw a curve ball. It formed over Florida, the first named storm to form over the Sunshine State. Hurricane Otto made landfall in Nicaragua on Thanksgiving. It is the latest hurricane to make landfall anywhere in the Atlantic Basin.The 2016 season started well before June 1st. Hurricane Alex formed in rare fashion in January and made landfall in the Azores. It is the first January Atlantic hurricane since 1938. Hurricane Alice formed in late December 1954 and maintained hurricane strengthen in early January 1955 too. Fast forward to late May and Tropical Storm Bonnie also formed before June 1st. It formed over the warm Gulf Stream in the western Atlantic and made landfall near Charleston as a tropical depression. Bonnie drenched the Carolinas and brought rip currents to the coastline Memorial Day weekend.A third named storm formed in early June. Colin was a sheared tropical storm that made landfall in Florida’s Big Bend. Most of the rain was on the eastern side of the storm. Parts of Tampa Bay had over 15 inches of rainfall from tropical moisture associated with Colin. The storm brought rough surf and rip currents to the Mid Atlantic a few days later. In mid-June Danielle formed in the Bay of Campeche. It was a short-lived storm that made landfall in mountainous east Mexico.We waited another 6 weeks for the next named storm. Earl originated as a tropical wave off the coast of Africa. It became the 2nd hurricane of 2016 in the Caribbean in early August. It made landfall as a category 1 hurricane in Belize and made a second landfall in Mexico as a tropical storm. Landslides and heavy rain brought significant damage to the region. Cape Verde season was in full swing and in mid-August Tropical Storm Fiona formed over the open central Atlantic. It dissipated due to plenty of dry African air and wind shear a few days later. Gaston became the first major hurricane of the season on August 28th. Fortunately it stayed over the central Atlantic and didn’t affect any land masses. Gaston was quite resilient and maintained tropical cyclone status for 12 days. Its remnants brought squalls to the Azores.Hurricane Hermine put an end to the hurricane landfall drought it Florida. It made landfall in the Big Bend region on September 1st as a category 1 hurricane. It is the first hurricane to hit the Sunshine State since Wilma in October 2005. Hermine is also the first hurricane to hit the U.S. since Arthur in July 2014. It brought a record 7.5 feet storm surge to Cedar Key. The Tampa Bay area had a 2-4 foot surge. Parts of north and central Florida had over a foot of rain, including 22.36″ at Lake Tarpon Canal in Pinellas counties. Heavy rain moved on to the Southeast and Mid Atlantic.September was an active month. Tropical Storm Ian formed over the central Atlantic in mid-September. It stayed out to sea. After Ian is Julia. Oddly enough Julia formed over northeast Florida in mid September. It is the first tropical cyclone to form over the state of Florida. Julia meandered off of South Carolina and brought rough surf and rip currents to the state. Long-lived Tropical Storm Karl neared hurricane strength northeast of Bermuda in late September. Outer rain bands brought tropical storm wind gusts to Bermuda International Airport on September 24th. Tropical Storm Lisa formed west of the Cabo Verde Islands in late September. It dissipated a few days later over the open Atlantic due to strong wind shear and dry air.
In 36 hours Tropical Depression 16 becomes Hurricane Otto in the southwest Caribbean. Otto is the 7th hurricane of the 2016 Atlantic season and is set to make landfall on Thanksgiving as a hurricane near the Nicaragua/Costa Rica border. According to the National Hurricane Center Otto is the latest hurricane formation on record in the Caribbean Sea, surpassing Martha in 1969. As of 4 PM EST max sustained winds are at 75 mph and Otto meanders west at 2 mph. Pressure is down to 984 mb. Otto thrives over warm Caribbean waters. Wind shear is marginally favorable for a bit more strengthening before landfall on Thursday. Enhanced satellite imagery shows a more defined tropical cyclone Tuesday afternoon. Hurricane hunters will investigate Otto for the second time Tuesday late in the day. Hurricane force winds only extend out 10 miles from the center while tropical storm force winds extend out 70 miles. A small wobble north or south will make the difference in damaging winds in Nicaragua and/or Costa Rica. Costa Rica has never had a direct hit from a hurricane.
Here is the late day advisory on Otto. The NHC brings Hurricane Otto near the Nicaragua/Costa Rica border Thursday afternoon (Thanksgiving). By Friday if a tropical storm still holds together Otto will keep its name in the East Pacific.
Late November named storms are extremely rare. Only 16 named storms have formed in the Atlantic Basin from November 21st to November 30th since 1851. Notice two origin points similar to the formation location of Otto north of Panama. The graphic below is courtesy Google Earth.
Heavy rainfall is the primary threat. Parts of Nicaragua, Costa Rica and Panama could see 6 to 12 inches of rainfall through Thursday. In northern Costa Rica and southern Nicaragua closer to landfall isolated amounts of 15 to 20 inches are possible. Flash flooding and mudslides is likely near higher terrain. The GFS brings Otto inland over south Nicaragua Thursday afternoon. The Euro also shows a landfall in south Nicaragua. It suggests a stronger more compact hurricane at landfall.
After a week of watching and waiting Tropical Depression 16 forms in the southwest Caribbean early Monday. It quickly became upgraded to Otto, the 15th named storm of the 2016 Atlantic season Monday afternoon. Tiny Tropical Storm Otto is stationary at 1PM EST with max sustained winds of 50 mph. It is embedded in a pocket of moderate southwesterly shear but sits over very warm Caribbean waters. Gradual organization is likely early this week. Hurricane hunters will investigate the disturbance Tuesday. Otto headed for Nicaragua and Costa Rica Thursday as a possible category 1 hurricane. Remnants of Otto will emerge in the east Pacific Friday and Saturday. November named storms rare. Late November named storms are even rarer. According Dr. Klotzbach of Colorado State University the formation of Otto in the western Caribbean is the 4th latest on record since 1851. Just last year there was a November named storm, Hurricane Kate. Kate formed in early November.
The 12Z GFS is in line with the official NHC intensity forecast and develops Hurricane Otto by Thursday morning. By Friday, this model suggests a strengthening hurricane will make landfall in southeast Nicaragua. This is a little further north than the NHC forecast. Meanwhile the 0Z ECMWF model keeps Otto much weaker with a landfall further south near the Nicaragua/Costa Rica border Thursday afternoon. There are still a couple days to tweak this forecast.
The main threat for portions of Central America will be heavy rainfall. Parts of Nicaragua, Costa Rica and Panama will see several inches of rain mid to late work week. Some areas could pick up 10 to 15 inches off rainfall near higher terrain. Flash flooding and dangerous mudslides are possible.
While convection increases near Invest 90L in the extreme southwest Caribbean Saturday the disturbance is still disorganized. The broad area of low pressure has not moved much over the past few days and it will continue to meander uncomfortably close to Central America in the days ahead. Wind shear is moderate overhead which limits organization in the short-term. Tropical depression development is unlikely the next 2 days but there is medium 50% chance by Thursday.
The 0Z Euro is still the most aggressive model in development over the next 7 days. By Thursday morning a weak tropical depression sits east of Nicaragua and Panama. By next weekend this model brings heavy rain and a weak hurricane to this area. Meanwhile the 06Z GFS brings a weak Tropical Storm Otto into Nicaragua Thursday morning with deep tropical moisture exiting by late week/next weekend.
Regardless of development heavy rain is possible for portions of Central America by mid to late work week. Of course specific amounts depend of the exact track. The GFS brings several inches of rain to Panama and Nicaragua between now and Friday afternoon.
As of Wednesday afternoon, Invest 90L in the Southwest Caribbean remained very disorganized and lacked much convection. However, a modest swirl was still evident on enhanced satellite imagery, and the odds of development are still rather high over the next 5 days. The National Hurricane Center has 2 day odds at 30%, but 5 day odds at 80%.
Regardless of development, 90L will be a slow and erratic mover. There is little steering current in the Southwest Caribbean over the next week, and so the models are split in every which direction of where 90L will meander. Below are several model forecasts through next Tuesday.
As for actual development, the European model has been the most aggressive. By the middle of next week, the operational run shows Tropical Storm Otto in the Southwest Caribbean, and several of its more prominent ensemble members show the same solution. They also show little in the way of movement in that timeframe. Here is the forecast from the ECMWF for one week from today.
Meanwhile, the GFS hasn’t showed as much development, and keeps 90L as a tropical depression, or even just a broad area of low pressure. Here is the GFS solution for the middle of next week.
Even though its late in the season, there are a couple factors working in favor of tropical development for Invest 90L. The wind shear over the Southwest Caribbean will remain quite light over the next week, and sea surface temperatures are above average (~1° above normal).
Regardless of development, the biggest threat for 90L looks to be heavy rain. While most of the models keep the heaviest rain offshore, a wobble or shift west in the track could mean very heavy rain for portions of Central America.
An area of disturbed weather, now pinned Invest 90L, shows some signs of gradual organization Tuesday in the southwest Caribbean. Outflow has improved, pressure has dropped some and convection is scattered. A tropical depression/Tropical Storm Otto is likely to form later this week or this weekend. Invest 90L will move little in the days ahead and meander near Central America.
Wind shear favors gradual strengthening in the Caribbean. Wind shear is low overhead at 5-10 kts. Hostile upper level winds will remain well north of Invest 90L. The graphic below shows the green favorable shear over the area of disturbed weather and the red unfavorable shear over the Gulf of Mexico and northwest Caribbean. The graphic below is courtesy the University of Wisconsin.
There won’t be much steering to guide Invest 90L and it could meander in the Caribbean near Central America for 7+ days. This could spell a heavy rain threat for some . Strong high pressure over the eastern U.S. will keep this disturbance well south of Florida and the U.S.. Here is the 18Z computer model forecast through next Monday. A wobble west towards Central America or north and east towards Jamaica and Hispaniola will make a huge difference in any tropical impacts in these locations.
While the future track of possible Otto remains unknown, so is the future intensity. Some models are more aggressive than others. The 12Z Euro shows a stronger possible Hurricane Otto over the warm Caribbean waters by next Tuesday. The 12Z GFS shows a weaker Tropical Storm Otto closer to Central America. This would mean a heavy rain threat and tropical storm conditions for portions of Central America. Stay tuned as this is a ways off.
The southwest Caribbean is a place to watch for tropical depression development this week. Only 5% of named storms form in November so it is rare, but not impossible. Most recently Kate became a hurricane in November 2015. On Monday it’s a wait and see situation. Wind shear is low in the extreme southwest Caribbean and broad low pressure may form over the next 5 days. Officially, there is a medium chance of tropical depression development by Saturday. The next named storm is Otto. The movement would be slow north or northeast.
This is a favorable spot for a tropical low to develop. Sea surface temperatures in the low to mid 80s are plenty warm for organization.
Computer models and some ensembles are on board with tropical depression development late work week/this weekend. The 12Z European model shows a tropical depression/possible weak Tropical Storm Otto Friday near Central America. The 12Z GFS is slower to develop this feature but does show pressure lowering in the vicinity Friday.
One change in the computer models over the past few days is the slow movement of the possible future tropical depression/named storm. With a series of highs building in over the Southeast U.S. the low may be suppressed south and meander in the Caribbean for several days. This could pose a heavy rain threat for Central America/some of the islands. Below is the 12Z European model versus the 12Z GFS model Monday afternoon. The Euro shows a weak Tropical Storm Otto drifting near Hispaniola. The GFS suggests an even slower moving and also weak tropical cyclone over the warm waters of the southwest Caribbean.
Meanwhile the GFS does not develop a tropical feature as wind shear may be too high. Below is the wind shear forecast for Thursday morning. Regardless, we will monitor the Caribbean this week for any developments.
It’s the final stretch of the 2016 Atlantic Hurricane season. Wind shear has kept the Atlantic Basin in check. On Monday upper level winds are unfavorable for tropical depression development in the Gulf of Mexico, northwest Caribbean and Atlantic. There are no signs of any tropical depression development over the next 5 days.
It’s a ways off, but long-range models hint that the western Caribbean is a place to watch in about 7-10 days. While wind shear has been high in the northwest Caribbean it has been significantly lower in the southwest Caribbean. Below is the forecast as pressure begins to lower next Monday evening. Climatology favors a northeast track mid-week next week. We’ll keep you posted if model trends continue.
The final month of the 2016 Atlantic hurricane season begins Tuesday. It’s typically the quietest month of the season. Only 5% of named storms form in November. While named storms in November are less common compared to other months, they do occur. Most recently, Kate became a hurricane in the Atlantic in 2015. According to the National Hurricane Center more than 100 tropical cyclones have been tracked during November.
Tropical systems that form in November often originate in the western Caribbean or near the Bahamas. This can be along decaying frontal boundaries. Any storms that do form and gain tropical characteristics tend to track northeast over the open Atlantic. High wind shear and cooler water temperatures limit tropical cyclones in November.
Wind shear is incredibly high in the Gulf of Mexico, the northwest Caribbean and the western and central Atlantic Tuesday. This is indicated by the unfavorable red color on the graphic below (courtesy University of Wisconsin). There are a few pockets of slightly more favorable upper level winds in the south and eastern Caribbean. We’ve been eyeing a weakening area of low near Puerto Rico. Clearly high westerly shear took a toll on the low as it moves northeast. Officially, per the NHC, no tropical depression development is expected over the next 5 days.
As mentioned over the weekend the GFS and European model hint that low pressure will spin up over the open central Atlantic later this work week. That is still the case Tuesday. At this point this appears to be a non tropical area of low pressure and won’t impact any land masses.