User blog:Hurricane Layten/June 10, 2017 Discussion

OK, so I have decided to start doing these blogs whenever there is something to talk about, pretty much like I did for active storms last year when I had the chance. Today's Discussion will be mentioning the two invest areas currently active, as well as an Area of Interest highlighted by the National Hurricane Center, along with my June hurricane season analogues.

So, as I said, I will begin with the tropical weather discussion side of this post, where we currently have 2 invest areas, along with another area of interest that is currently being monitored by the NHC.

Invest 96W is currently being monitored by the JTWC, and has a medium potential of becoming a tropical cyclone within the next 24 hours as it moves off towards the northwest. The disturbance is currently located in an ideal environment, with low shear, and warm waters of around 28C to work with. the disturbance is, however, interacting with a monsoonal low over the Philippines, which is enabling the convection to blossom over a developing low level circulation. It is worth noting that whilst the track forecast for the system is tightly clustered, that the same cannot be said for the intensity forecast, with the GFS calling for a 60 mph tropical storm at peak in around 2 days, before being pulled apart by shear and land interaction as it makes landfall in China. On the other hand, the HWRF shows a mid range category 1 typhoon active in 2 days, before meeting a similar fate that is shown on the GFS, but at a slower pace. the European model, on the other hand, is showing a 45 to 50 mph tropical storm peaking in 2 days, before rapidly dissipating as it reaches the coast of China. Whichever model turns out to be correct will remain uncertain, of course, until the event takes place. However, one thing can be said, and that is that modelling is pretty much certain that a significant tropical cyclone will develop from this low in the coming days. Looking at the moisture modelling, both the GFS and European models show the potential system interacting with the monsoonal low, making it highly likely that the system will be a concern for heavy rainfall, for as long as it continues to interact with the low over the Philippines.

Now, moving onto Invest area 96B, which is also embedded within a monsoonal trough. The future of this low remains uncertain, with the European model showing no development of the system, along with the HWRF. On the other hand, the GFS develops a brief tropical depression in the region, before taking the low into Bangladesh as it is forced north by the aforementioned monsoonal trough. One thing is clear though with this low, and that is that it is going to be a heavy rainfall concern, regardless of any potential development before it moves inland in around 3 days time.

Now, onto the final area of interest, highlighted by the NHC in the eastern Pacific. The area of interest concerns a tropical wave that is interacting with a monsoonal trough over the Gulf of Tehuantepec. A broad low pressure area area has developed with this low over the last 12 hours or so, and whilst shower and thunderstorm activity does remain disorganised, modelling is continuing to show a potential development out of the system in the medium range forecasting. Even though the GFS has dropped the development of an eastern Pacific tropical cyclone, the European model does have the potential for a weak tropical storm to develop, before making landfall in Guatemala and crossing out into the Gulf of Mexico as a broad, most likely cyclonic in nature gyre. Whilst this is in the medium range of the modelling, it is interesting to note that this is the scenario that was being noted by the GFS yesterday, before they dropped any potential development. Either way, regardless of any development of the system, it is very likely that very heavy rainfall could be a concern, especially if it hugs the coast, as some of the modelling suggests.

Now, onto the finishing touches, my current analogues. After looking through the CPC ENSO data last night and this morning, it has come into my interests to list 1994, 1981, 2012, 2001 and 2002 as my June period analogues, which has been done by using the Mar-Apr-May 3 month period. It is interesting to note that most of the seasons in the analogue period were average to above average, which raises the question of "what will this year throw at us?".Well, whilst it is still too early to answer that one for certain, it could be that we are set up for an active hurricane season.

Taking into account the impressive anomalies in the Atlantic basin, the positive AMO appearance, and the very warm MDR, there would appear that there is the potential for a busy season this year in the Atlantic. Coupling this with the negative PDO appearance that has appeared the eastern and central Pacific over the last few months, and this also would appear to favour the Atlantic basin slightly more than normal. However, again, it is still too early to say just how busy the Atlantic basin will actually be. My May 14 forecast called for between 15-17 named storms, 7-9 hurricanes, 3-5 major hurricanes, and an ACE index of between 120 and 150 units, which was based off the current highest confidence analogue of 1996 at the time, along with the very warm main development region, which still remains the case for the latter.

Other factors that influences the Atlantic is the Saharan Air Layer, a layer of dry, stable air that moves off the African coast in the deep tropics periodically, and inhibits tropical cyclone development. Wind shear and the trade winds also play a big role, and when the trades blow west to east, it tends to inhibit tropical cyclone development, whilst a vise versa set up tends to favour tropical cyclone development. With a new MJO phase potentially in the Atlantic in the near future, it seems that a tropical wave moving off the coast of Africa, some of which are well organised whilst coming off the coast, it only takes one of them to develop, and there's the potential for chaos. Yes, it's early season, and yes, it's unlikely that a tropical wave in the MDR will develop, but its always a good idea to keep an eye out for potential development, because, afterall, it is hurricane season.

Either way, this forecast could completely bust, whether the season turns out to be higher or lower than expected in terms of activity, or it could prove to be about right. Who knows? No one, until it actually happens.