The Atlantic Hurricane Season officially ends Saturday. With the exception of a weak non tropical area of low pressure in the east central Atlantic all is quiet in the Atlantic Basin. Former Invest 90L showed some signs of “life” Thursday but its chances of tropical depression development are now slim to non. Enhanced satellite imagery shows a ragid and disorganized structure. The weak low generally moves northeast over cool east Atlantic waters. The National Hurricane Center gives it a small 10% chance of becoming a subtropical cyclone by Sunday.
The 2013 Atlantic Season wraps up with 13 named storms, 2 hurricanes, and no major hurricanes. This is the first time there are no major hurricanes since 1994. This is also the fewest number of hurricanes since 1982. There will be a full recap of the unusual season posted Saturday.
The last work week of the 2013 Atlantic season start off on a very quiet note. The remnants of former Tropical Storm Melissa have completely fallen apart east of the Azores. This energy is absorbed into a frontal boundary in the eastern Atlantic. A cold front draped across the central Atlantic doesn’t spell tropical trouble. However, at the tail end of this boundary in the Gulf of Mexico is a non tropical area of low pressure. This surface low heads for the northern Gulf coast Monday and on to the northeast Wednesday. This frontal system spells all sorts of Thanksgiving travel issues including rain, strong thunderstorms, snow, wind and ice.
The two most reliable computer models both hint at some sort of area of pressure developing in the open Atlantic late work week. Regardless of tropical classification or not this possible low lifts north and stays out to sea. The GFS model shows a weak area of low pressure over the central Atlantic Friday night.
The European model is a little more aggressive. The 0Z run shows a strengthening low west of the Azores ahead of an old frontal boundary. Water temperatures in this area of Atlantic are still close to the threshold for tropical development. Forecasted sea surface temperatures estimate 75-80°.
In other parts of the world Cyclone Lehar strengthens in the Bay of Bengal Monday. It eyes populated southeast India and could strengthen to a major category three storm before landfall Wednesday.
Saturday marks one week until the end of the Atlantic Hurricane Season. It is likely to wrap up with no major hurricanes, the first time since 1994. There are no signs of life in the Gulf of Mexico, Caribbean, or Atlantic Saturday. Remnants of Tropical Storm Melissa toss extra clouds and isolated showers towards the Azores. In the Gulf of Mexico energy (non tropical in nature) gathers along a frontal boundary. This developing area of low pressure will bring showers and thunderstorms to the northern Gulf coast early work week. There is way to much dry air in the Caribbean for anything to get going this work week.
Tropical Storm Melissa is the first November named storm since Tropical Storm Sean in early November 2011. Just like most systems in 2013 Melissa was short lived and intensity was halted due to stronger upper level winds and dry air. Of the 13 named storms only two reached hurricane strength. Only one named storm, Andrea, made landfall in the U.S.
It’s not uncommon for subtropical areas of low pressure to develop along frontal boundaries (as was the case with Melissa). The European model hints at a similar type low pressure set up just days before the official end of the Atlantic season. Regardless of subtropical/tropical classification this possible low appears to be no threat to land.
Our latest tropical storm, Melissa, has dissipated into a remnant low near the Azores. Just like most of the storms this season, Melissa never reached hurricane status, and was relatively short-lived. That now brings our seasonal total to 13 named storms. Interestingly enough, this is actually above average for a season (avg = 12). However, since there have only been 2 hurricanes this year and no major hurricanes, the season was by all accounts a quiet one. In fact, the ACE (accumulated cyclone energy) was only about 30% of a normal season.
A quick look at the Atlantic shows nothing really happening. There is some typical convection across the Central Atlantic associated with a stalled boundary, and a cold front nearing the northern Gulf. However, none of this activity is expected to develop into anything tropical in nature.
Meanwhile, the Caribbean (a usual hotspot for November activity) has shown little life in recent days. Part of the reason has been quite a bit of dry air in place over that part of the world. The water vapor imagery identifies this dry air with darker shades of yellow and orange over that region.
While the season officially ends November 30th, it doesn’t mean that we can’t see tropical activity beyond that date. In fact, the Euro model shows an area of low pressure developing across central Atlantic later next week. It’s too early to tell if it would be even sub-tropical in nature, and but either way it will likely pose no threat to land.
Subtropical storm Melissa strengthens about 600 miles east of Bermuda Tuesday. Its main energy has now separated from the frontal boundary it originated along. Melissa could transition to a full-blown tropical storm later today over Atlantic water temperatures in the mid 70s. During this transition winds could approach minimal hurricane strength. There are already signs that the core of the tropical storm is warming. The 13th named storm of the Atlantic season rapidly tracks northeast later this work week and eventually fizzles over cooler north Atlantic waters. It is no threat to land and will pass well east of the U.S.
Climatologically only 5% of named storms form in November. During the last month of the Atlantic season water temperatures cool below the 80° threshold. Wind shear also increases and drier air settles in behind cold fronts. While November named storms are rare November hurricanes are even rarer. Since 1980 only 16 hurricanes formed during this time frame. Of these 16 hurricanes only three brought impacts to the U.S. Most recently Hurricane Ida formed on November 8th, 2009. If Melissa briefly gains hurricane status it will be the first time a November named storm becomes a hurricane in over four years. So far in 2013 there are two hurricanes and no major hurricanes.
Subtropical Storm Melissa becomes the 13th named storm of the Atlantic season Monday. Convection drastically organized early Monday east of Bermuda and the area of low pressure was classified as a subtropical system. If thunderstorms gather near its center and warm the core Melissa could gain full tropical strength early this work week. Regardless or subtropical or tropical characteristics Melissa is no threat to the U.S. or any land masses. Melissa will rapidly strengthen through Wednesday over luke warm north Atlantic waters. It could approach hurricane strength Tuesday or Wednesday. The same strong trough that steers Melissa away from the U.S. will enhanced wind shear late work week. Eventually Melissa with absorb with this extra tropical low late in the period. Gale force winds may reach the British Isles by the weekend.
The graphic below shows forecasted Atlantic, Caribbean, and Gulf waters Monday afternoon. Notice how much cooler temperatures are in the north Atlantic. Cooler waters and hostile upper level winds will lead to dissipation of Melissa late work week.
Hurricane season ends November 30th. It is likely to wrap up with no major hurricanes. This is the first time since 1994. September is the busiest month of 2013 with two hurricanes. The first named storm of 2013, Andrea, is the only tropical cyclone to make landfall in the U.S.
With the end of the tropical season just two weeks away, we typically don’t see too much activity this time of the year. However, that doesn’t mean that it is impossible and an area of low pressure in the Central Atlantic is proving just that. As we have been talking about for much of the last week, models continue to hint at a subtropical or tropical low developing in the next few days. And now, the enhanced satellite picture is backing up those predictions. Take a look at the enhanced satellite below, showing an area of showers and storms associated with a non-tropical low in the Central Atlantic. There is some deep convection associated with this low, and a noted circulation in the satellite loop.
The environment is fairly conducive for some development of this system in the next few days. While upper level shear is moderate north of the system, the air mass is fairly moist (with dry air located well to the southwest of the system) and sea surface temperatures are warm enough for some development.
Most models do develop this system into a tropical or subtropical low (more likely subtropical, but not out of the realm of possibility that this becomes tropical). The GFS model below shows a developed system by Tuesday morning, though it would be quickly absorbed by an extratropical low to its north later in the week. The NHC gives this area a 50% chance to develop by Tuesday evening, and a 70% chance over the next 5 days. We will continue to watch this area closely over the coming days, though it doesn’t look to pose any threat to land at this point.
The final countdown is on to the end of the 2013 Atlantic Hurricane. With two weeks to go we are watching an area of interest in the central Atlantic. An area of low pressure is developing along a stalled frontal boundary Saturday. As it deepens late in the weekend/early work week it could gain at least some tropical characteristics. Water temperatures in this region have cooled to a luke warm 80° or cooler. Regardless of full-blown tropical or just subtropical development the developing disturbance is no threat the U.S. The Azores could eventually see squalls from this feature next weekend. The National Hurricane Center puts the chances of tropical cyclone development at only 10% by Monday but 50% by Thursday. If Subtropical or Tropical Storm Melissa forms it will be the 13th named storm of the Atlantic season.
Our most reliable computer models are on board with a strengthening low on Monday. Below is the 06z GFS Monday afternoon. The model run shows Subtropical Storm Melissa well east of Bermuda. A deepening trough on the east coast will steer the possible named storm northeast away from U.S. late this upcoming week.
A mid-to-upper level piece of energy will move through the Gulf of Mexico on Friday. As this source of energy taps into ample Gulf moisture, it will bring rain along the coast from southern Louisiana to much of Florida. That “train” of moisture will eventually push eastward, but should remain over much of Florida through Saturday, making for a soggy start to the weekend. Despite the energy and moisture in place, no tropical system is expected to form from this area.
Across the rest of the Atlantic, all remains quiet. Some convection continues to fire up along a stationary boundary in the central Atlantic but nothing is expected to form from this in the next 48 hours. Meanwhile, the convection across the Gulf is associated with a mid-upper level feature (as previously mentioned) and is not expected to form into anything tropical. Finally, an area of clouds and showers near the Cape Verde islands continues to be nearly stationary, and is not expected to produce tropical activity in the short-term (Cape Verde storms are rare for this time of the year).
The computer models have continued to hint at an area of low pressure developing along the stationary boundary in the Central Atlantic early next week. The system would likely be sub-tropical in nature if it did form, and would be quickly absorbed into an approaching extratropical low to its north by later in the week. Below is the 00Z run of the GFS model, continuing to show lower pressures in this region early next week. This model now has support from two other reliable models, the UKMET (UK) and the ECMWF (Euro).