Get a whiff of this

Ok, just to clarify for all of you "sick-minded" people out there, lol (jk) I'm not talking about this... 

No, I'm actually talking about a comment I recently made to Jacob Thorne on his blog, obviously him taking about a tropical system going into the Bahamas or the Gulf got me all riled up into making a very long response, which I think is worth mentioning here. 

I'm glad you liked it, but I am not going to hang my hat on any solution at this point, as these types of situations where we have an upper level low pressure system transitioning to a warm-core tropical system, not to mention a few easterly waves getting involved, this type of set-up is naturally hard for the models to handle. Also, with such small scale features such as an upper level low pressure system in an overall region of relatively high pressures, the models can tend to miss these kinds of systems they "slip under the radar" per say and of course when you have a small-scale feature such as an upper level low pressure system forming in a relatively high pressure environment, the resulting tropical cyclone (if one even forms) tends to be small & compact in nature. It's these environmental factors in a storm's formation that help to determine the overall "personality" of a tropical cyclone and make each one unique (factors like size, convective structure, etc..), & if we had this storm system forming out of the monsoonal circulation over central America, then this storm would tend to be rather large in nature as the environment in that region is relatively low in overall pressure and the convective disturbances in that region are also rather large, which lead to the formation of large tropical cyclones (The East Pacific's Hurricane Cosme is a great recent example, Tropical Storm Arthur in 2008 and Arlene in 2011 are good examples for Atlantic storms).  

Tropical Storm Arthur (2008)  

Tropical Storm Arlene (2011)  

Also what needs to be taken into consideration when determining the characteristics of a tropical system when dealing with potential formation is the amount of time that it takes for a tropical system to form, usually smaller storms tend to form much more quickly compared to larger storms as the sudden strengthening forces the circulations of the system to tighten up and shrink, forcing the overall structure of the storm to shrink as well and the opposite can be applied to when dealing with larger storms. This concept can actually complicate matters somewhat if other environmental conditions dictate that such a storm is to be smaller in overall size (like higher than normal pressures, formation in a high pressure environment), as slower formation can induce the circulation to be larger and broader in nature than it would otherwise if it didn't develop slowly.  

The opposite can be said about a storm that forms rather quickly in a relatively low pressure environment or from rather large convective features, hurricane Andrew in 1992 may be a decent example of this as it initially formed from a tropical easterly wave, which although usually result in storms that are around average in size Andrew ended up being extremely small and this can be attributed to the fact that it underwent a period of extremely rapid intensification, in fact a drop in pressure of 47 millibars on August 22nd ( a pressure drop of 2 millibars per hour) to 922 millibars, and it weakened slightly over the Bahamas because of some land interaction and an eye wall replacement cycle, but was able to attain a minimum central pressure of 922 millibars once again upon landfall in south Florida in Elliot Key, making it the 4th lowest minimum central pressure of any tropical cyclone making landfall on the US coast, behind the Labor Day hurricane of 1935 (892 millibars), Camille (1969) (909 millibars) and Katrina (2005) (920 millibars).  

Hurricane Andrew (1992) 

 

Here's part one of a series of videos that deal with the coverage of hurricane Andrew in 1992, this one has the best meteorological information & perspective of all of the videos.

The strengthening of Andrew can also be attributed to an equatorial Kelvin Wave (I talked about this at weatheradvance) which was detectable by the fact that the SOI (Southern Oscillation Index) dropped steeply negative about the exact same time Andrew underwent rapid intensification, and when the SOI is negative that is indicative of lower than normal pressures at Tahiti, French Polynesia in the central Pacific and Darwin, Australia (these two observations sites and their associative pressure differentials in comparison to normal is what determines SOI, and the SOI is also a good indicator of the ENSO index, which in large -SOI events usually goes into its el nino state because when you have lower than normal pressures towards Tahiti along with pressures being higher than normal towards Darwin, Australia, this indicative of higher pressure towards the western Pacific along with lower pressure towards the eastern Pacific, where air flow under high pressure naturally spreads out in all directions, thus forcing anomalous westerly winds in the Pacific. this disturbs the natural easterly trade winds found in the tropics under the Hadley Cell, thus leading to el nino as the warm pool of water naturally found in the western Pacific is forced to slosh westward, and this is what occurred in 1992 that led to the el nino that year which subsequently led to an overall inactive hurricane season as well. 

This video helps to explain the relationship between easterly trade winds, el nino, and la nina as well as the Walker Circulation  
 (copy & paste the link into a new window)
http://www.youtube.com/watch?v=tyPq86yM_Ic
Also, another factor that I have considered in Andrew's sudden intensification is its relationship to the abnormally strong Bermuda High pressure to its north, where in this scenario the high pressure in this position not only blocks Andrew's forward progress towards the northwest and forces it farther to the west, but the pressure gradient between Andrew and the high pressure forces air to pile up and converge into Andrew, inducing a favorable environment for which Andrew can intensify in. However, such a strong pressure gradient over a relatively short distance, while forcing air to pile up into Andrew can be detrimental as this enhances the easterly trade winds at the surface and with these trade winds forced to speed up in the vicinity of Andrew under the abnormally strong high pressure, this induces surface divergence which induces higher than normal pressures at the surface that can severely disrupt surface circulations. This is the reason why in the central Caribbean, the region from the longitude of Puerto Rico to Jamaica is generally referred to as a "dead zone" as the pressure gradient between the Panama-Columbian Low and the Bermuda high induces surface divergence (especially early in the hurricane season) that disrupts surface circulations and severely limits tropical development. Also, the trade winds from the deep tropical Atlantic are also forced to be squeezed in between the Greater Antilles & South American coast that forces winds to speed up in this area along with the strong pressure gradient. However, you might say, well how about Hurricanes Allen (1980) 

Allen (1980)

 

& Dean (2007) 

Hurricane Dean (2007) 

 

 which were very strong hurricanes, (in fact Hurricane Allen had the lowest recorded surface pressure in the Atlantic until Gilbert broke that record in 1988) in the central Caribbean,   

Here's a great video of hurricane hunters in the center of hurricane Gilbert, with meteorologist Jeff Masters and another scientist helping to describe the experience the hurricane hunters went through in Gilbert, and you should note the significant mentions of hurricane Allen back in 1980, which at this time was the "benchmark" storm, having the record for lowest minimum central pressure. 

So how could this possibly happen? Well, I thought about this, & I think that this "feast or famine" scenario where storms that aren't fully developed don't intensify, as opposed to hurricanes that are already quite powerful continue to intensify, sometimes rather rapidly in the central Caribbean, I think that storms that are fully developed have a quality about them that allows them to turn the seemingly unfavorable environment with stronger trade winds inducing surface divergence to a very favorable environment that can allow for rapid intensification. When you think about fully developed storms as opposed to systems that are still trying to close off surface circulations, their wind fields are much larger and more organized with westerly, northerly, southerly, & easterly winds over a much larger area. These well organized winds fields essentially are able to "bend" the strongly easterly trade winds around them into a tropical wave like structure where winds in the wake of the wave are out of the southeast & winds ahead of the wave are out of the northeast. Using what we know about tropical waves where thunderstorms and convective activity are usually favored along and behind the tropical wave axis, this means that if we consider the well developed tropical cyclone in the central Caribbean reminiscent of a tropical cyclone, this would lead us to conclude that the circulation of the tropical cyclone is in the middle of the wave axis, thus in a favored position of the tropical wave where convergence is favored as the easterly trade winds, especially on the southern side of the tropical cyclone, are forced to change direction from easterly to southerly and southeasterly & if you apply the concept of turning a sharp corner in a vehicle, where the vehicle's inertia forces you to slow down once you reach the corner, the same concept can be applied to the trade winds in this case, which change direction as a result of the tropical cyclone, are forced to slow down and when air slows down over a distance, that leads to a piling up of air, which is then forced to rise, leading to surface convergence that is actually favorable for tropical cyclone development despite the central Caribbean naturally being a "dead zone" for tropical development due to enhanced easterly trade winds that severely disrupt surface circulations.

Here's a few pictures of a tropical wave & its structure to help to explain some of the phenomena I was referring to in the paragraph above

Ok, I really wasn't expecting this long of a response to your comment, but I guess when things started flowing for me I really couldn't stop, lol. I hope you enjoyed this post & learned a lot after reading this.