Re: 2017 General Tropical Cyclone Discussion Thread

[jmanley32]

Well holy crap GFS!! Long ways off but GFS has been on this system since middle of last week.

[jmanley32]

Okay my bad the NHC has taken note of the system in the atlantic currently 10/40 chance development, this is the system the GFS blows up. Long tracker too and from a area that is not normal for beginning of July. If this does develop it will moisten the air for many more to form with less obstacles.

[Snow88]

12z CMC has the tropical system moving west towards Florida at 240 hours while the 18z GFS blows it up but stays way OTS.

[weatherwatchermom]

Any news on that trop depression....we are making our trek home will be making final push from Manasquan inlet to Sandy Hook next Tuesday

[sabamfa]

Anything in the next 11 days that can impact between here and Bermuda for a cruise?

[jmanley32]

Nope and the TD is expecxted to dissipate, GFS made too big a deal about it. I think tropics will remain mainly quiet into August when things MAY ramp up big time going into mid august sept. and Oct.

[sroc4]

Not too fast Jman.  There is a fairly robust moisture laden wave about to exit the W African coast.  You can see in the loop below fairly high precipitable water coming off the coast. As long as the wave isn't too fast to catch the dry air out ahead it should have decent conditions to work with once out over the open waters of the MDR(main development region). We shall see. Obv a long way to go, but this one may have to be watched in the area of the Antilles in about a week +/-.

[jmanley32]

Not too fast Jman.  There is a fairly robust moisture laden wave about to exit the W African coast.  You can see in the loop below fairly high precipitable water coming off the coast.  As long as the wave isn't too fast to catch the dry air out ahead it should have decent conditions to work with once out over the open waters of the MDR(main development region).  We shall see.  Obv a long way to go, but this one may have to be watched in the area of the Antilles in about a week +/-.

I said mainly quiet but yes forgot to mention that wave and the GFS has been show that one heading to the US infantasy range but just checked the Euro and it has a 972mb hurricane hitting PR in 10 days. Since the Euro is already bullish on this it may very well be a big one to watch. Don, which is the next name has some significance in my life at this time, call me superstitious but thats also my deceased grandfathers name and he was no one to mess with LOL. Maybe he is coming to pay me a visit, hey he was the one to give me my first weather radio!

[jmanley32]

And strangly enough the CMC does not develop it at all until its off the carolinas as a weak 1001mb system, hmm Euro does well with the tropics.

[jmanley32]

18z gfs fantasy range is really scary for the area 955mb guessing cat 3 cane headed due North to LI. If we knew the gfs were ever right which almost never is I'd prepare now. I always said a li expess redux was going to happen one day. Don't get all bent out of shape I'm not wishing that to happen to anyone but boy would that be one nail biting one to track. Nhc should b mentioning this wave soon.

[nutleyblizzard]

18z gfs fantasy range is really scary for the area 955mb guessing cat 3 cane headed due North to LI. If we knew the gfs were ever right which almost never is I'd prepare now. I always said a li expess redux was going to happen one day. Don't get all bent out of shape I'm not wishing that to happen to anyone but boy would that be one nail biting one to track. Nhc should b mentioning this wave soon.

Well I for one is wishing it. This board has been dead for too far long... what the GFS depicts would certainly raise the stakes. Don't get me wrong JMAN I'm not wishing death and destruction but there's nothing better than the thrill of tracking a major cane or blizzard!

[jmanley32]

18z gfs fantasy range is really scary for the area 955mb guessing cat 3 cane headed due North to LI. If we knew the gfs were ever right which almost never is I'd prepare now. I always said a li expess redux was going to happen one day. Don't get all bent out of shape I'm not wishing that to happen to anyone but boy would that be one nail biting one to track. Nhc should b mentioning this wave soon.

Well I for one is wishing it. This board has been dead for too far long... what the GFS depicts would certainly raise the stakes. Don't get me wrong JMAN I'm not wishing death and destruction but there's nothing better than the thrill of tracking a major cane or blizzard!

That is true, and i said it would be quite a thing to track, if the wave holds i expect a chances area to go up in the next several days. That GFS run was very close to the LI express track. 955mb COULD be cat 4 depending on the high resolution and winds, but thats 384 hrs away lol, through day 10 it def develops and that entire run it hit a lot of areas but gets most intense heading up EC, thats interesting.

[jmanley32]

You know in the last frame it actually takes a slight jog NW, may we be looking at the future of a possible retrograding system, thats been going on for a few years since sandy, though it did not happen joquin was one. Just for giggles (not to be taken verbatim and I stress that intensely, I have learned well over the years not to get hyped on anything 16 days out.) Previous run did not even have it, but def something to watch. Anyways 18z GFS end of run

[jmanley32]

GEFS actually gives a EC run wow, ensembles on this already.

[sroc4]

Looking at the global models(don't care which one) regarding tropical systems in the 10-16day time frame is like getting excited for a pitcher to throw a no hitter or perfect game after he strikes out the first batter in the first inning.  LOL Of course it can happen but what are the odds of it happening after the first batter in the first inning?  Usually we don't get too excited for a No No until at least the 7th inning.     

In looking at tropical systems you have to look carefully at current observations/conditions (ie: SST, trade winds, Pwats, SAL, wind shear, vorticity, upper level divergence, low level convergence, positioning/timing/strength of mean troughs and ridges, MJO phase, SOI to name just a few) in and around any given topical wave or entity and try to predict what/how these factors are/will affect a tropical entity in the 3-5days time frame at most.  Last year was a prime example of how quickly these parameters can shift, change, and/or not change relative to what models thought were going to happen in the short and medium ranges.  Case in point:  Hurricane Hermine.  What it was going to do, where it was going to go, and how strong it was from the beginning in the Fla Straits, to the Gulf Coast landfall, to where and how it would track off then up the EC was in question beyond 2-3days the entire time.


If even one of these parameters is not handled correctly on a given model the margin of error on the soln of a tropical entity grows exponentially with time as a result; esp when looking at a wave or weaker tropical system.   The stronger a system becomes the higher probability it will do what IT wants to do vs being dictated by what the environmental conditions surrounding it would want it to do.  So for now we watch the MDR(Main Development Region--between western African coast and the Eastern Caribbean Islands) as there seems to be a fairy active African wave train for the moment, with warm SST anomalies in the MDR, an MJO flirting with phase 2, and broad scale ENSO neutral like conditions which tends to lead to a favorable Walker Cell configuration for Atlantic basin tropical development. Even if one of these tropical waves does not develop in the MDR if they survive as they continue west into the Caribbean Ocean, GOM, or N of the lesser/greater Antilles towards the Bahamas and EC they can still develop there too should conditions dictate. For now development is not imminent.

[rb924119]

Fantastic post, Scott!! As per usual, no doubt haha one thing that I'd like to add, and maybe to fuel Jman's fire a bit (NOT, NOTTTTTTTTT, saying it's definitive) but I would like to pose the following questions for you all to think on, as I already have my own personal views on the subject: Given this season's tendencies for troughing in the eastern CONUS and the incredibly below average SSTs off the Mid-Atlantic and New England coasts, what impacts could those have on the brilliant list of factors mentioned above? Also something to consider, given the MJO projections as stated in coordination with the atmospheric projection of a weakly warm ENSO state basis the SOI, how could those impact the overall development of the system in question?

[jmanley32]

Lots to figure out sroc great post and yes there are a bazillion things that can and do effect possible tropical developmrnt. This morning lr gfs run had a cane into midatlsntic 18z no real development so it's just as u said no point in looking at things deeply until we have something and we have an idea of where it may go. July is not often a super active month but there is a active wave train as u said. Haha rb fyel my fire. No real fire to fuel as who knows what's in store for the end of July. But you post a good pts.

[sroc4]

Not too fast Jman.  There is a fairly robust moisture laden wave about to exit the W African coast.  You can see in the loop below fairly high precipitable water coming off the coast.  As long as the wave isn't too fast to catch the dry air out ahead it should have decent conditions to work with once out over the open waters of the MDR(main development region).  We shall see.  Obv a long way to go, but this one may have to be watched in the area of the Antilles in about a week +/-.

Here is an update on the tropical wave that was about to exit the African coast I mentioned on Friday.  As you can see below this wave is now around 30W Longitude and there is a second wave just exiting the African coast.




Now if you have been following the GFS and Euro the last couple of days you would have noticed the GFS has fairly consistently wanted to develop this wave into an organized tropical system east of the Lesser Antilles and eventually land falling as a trop storm or hurricane somewhere over the Island chain in about 5-7days; whereas, the Euro consistently keeps it as an open wave giving the Islands of the Lesser Antilles nothing more than windy conditions and rain and thunderstorms in this same time frame.  Ironically the GFS soln has had support by its ensembles, and the Europeans weaker soln is also backed up by its own ensembles.  So which soln is correct?  

Well lets look at just a few conditions.  First lets look at what's going on at a broad scale.  

The base state of the SOI(southern Oscillation Index) has been weakly negative with the 30day Avg flirting with El Nino status briefly for a few days; however, since about June 25th a mostly positive to weakly positive bursts has been occurring.  Overall the SOI over the last 30-60days has fluctuated back and forth with negative and positive bursts leaving both the 30 and 90 day Base states in neutral territory with a negative lean.  
https://www.longpaddock.qld.gov.au/seasonalclimateoutlook/southernoscillationindex/30daysoivalues/

Overall the Walker cell configuration associated with the current ENSO status has been consistent with a La Nina or Neutral ENSO conditions as far as the "text books" would state as seen by the trends of the OLR(outgoing longwave radiation) over the last month.  This makes sense given that we are coming off a weak La Nina over the winter and current SST, SOI, and ONI values all are consistent with neutral conditions.  The cooler colors on the OLR map indicates where broad area of convection(Convection means rising air) in the trop Pac is occurring; whereas, the warmer colors indicate where broad areas of sinking air in the trop pac is occurring.  If there is rising air in one area then there will be sinking air in another.  The Walker cells are these broad areas of rising and sinking air.  To read more about what the Walker Cell is see here: https://www.climate.gov/news-features/blogs/enso/walker-circulation-ensos-atmospheric-buddy
 



Again as you can see from the images about La Nina or neutral ENSO conditions tends to favor rising air in the Atlantic basins.  The current OLR maps support this tendency.




Ok so we have large scale atmospheric conditions that tend to favor rising air in the tropical Pacific.  This doesn't mean that at any given time the smaller scale conditions will be right.  Lets look at a few more locally environmental/atmospheric conditions with respect to the trop wave(s) in question.  As you can see by the MSLP map below by 00z Wed July12th the wave has made it to about 40-45west Longitude on both models.  The GFS has this wave as a more closed and organizing system; whereas, the Euro keeps it as an open wave with the thunderstorm activity disorganized.  




Looking at the shear maps for this same time frame one can see that both models have fairly low shear throughout the MDR region, but there is a huge difference between the two models by 00z July 12th.  The GFS has a fairly organized region of anticyclonic activity in the upper levels over top of the trop wave by this time frame.  Anticyclone(clockwise winds) in the upper levels acts as an exhaust if you will enhancing lower level convergence which supports additional organization.  If the air above a system moves away from itself then the air beneath it is forced to rise to replace it.  The euro however has no such organized anticyclonic activity.  Thee is some weak anticyclonic organization at best.  




The last parameter I will look at is the relative humidity(RH) at the mid levels.  Specifically 700mb.  As you can clearly see the environment on the GFS is much more moisture laden when compared to the Euro.  On the Euro 700mb RH map you can plainly see much more mixing in of the dry air into the area between 40-45West Longitude.  This dry air mixing limits the ability for thunderstorm activity and prevents organization to the trop system.  




Recall this sentence in the post from Friday: "As long as the wave isn't too fast to catch the dry air out ahead it should have decent conditions to work with once out over the open waters of the MDR(main development region)."  If I had to guess the Euro is likely going to win out as the lead wave will likely be consistently infiltrated by dry air mixing in at the mid levels preventing its organization to the lead wave, but recall this image from above:





The second wave seems to be more protected from the dry air so maybe this is infact the wave the GFS is trying to key in on whereas the Euro cont to key in on the first one.  We shall see over the next couple of days.  Then we re-evaluate all prev mentioned conditions for the next 3days.

[weatherwatchermom]

Thank you Sroc for the anaylsis...easy to understand as always!!

[jmanley32]

All I have to say is if the GFS is right it has been spitting out some seriously bad east coast situations with many runs making a direct hit on the area, 18z was a double take jeeze.  But the fact remains we do not even know as sroc so elequently wrote about which wave will be the one to develop, or which model is right. And how many factors are at play here. Seems theres way more that has effects on tropical systems than that of winter systems. Very complicated.  I can see how it may be the second wave but its really a wait of at least 5 plus days before we will be within 240 hrs which is still  a long way out. Hour 240 on the GFS places it (Don to possibly be) a 961mb storm to the east of FL and if you go all way out has a disastrous run. I will say when I saw the first retrograde sandy track 8 days out I said thats just too bizarre a output NOT to happen, and it did. Just saying, models can't always be wrong but I would not be surprised to see the GFS lose this solution as even 3 similar runs this far out is nothing to worry about. Also I do not recall seeing these kind of model runs in July, usually we are tracking in the more active period of August to October. Climo wise how likely is a system to develop get that strong and come up the east coast? Has that ever happened? We wait, cant track yet lol

[jmanley32]

Okay now we can start to track, only a 20% chance in the 5 day of development but its the first NHC notification, lets see where it goes. The wave does have some spots of good convection, i really love watching these go from this to sometimes a big strom, its amazing how it can all comes together.

[Snow88]

951 low on eastern Florida at 240 hours on the GFS

[sroc4]

The Euro will likely lead the way on this one. At least that's the way it looks now.

[jmanley32]

The Euro will likely lead the way on this one.  At least that's the way it looks now.  

well the gfs has no other support and euro does so that could very well bbtrue. Now gfs is on a go track. Isn't euro overall better with tropics anyways? Certainly nailed Sandy smoung others.

[jmanley32]

People on other chats seem to feel x t 4 might become something. It's def not gone but nhc doesn't think so.

[sroc4]

People on other chats seem to feel x t 4 might become something. It's def not gone but nhc doesn't think so.

I doubt it.  Although there is decent upper level divergence and low level convergence the ULL spinning to its north is creating a significant amount of shear in the N and NW quadrants.  In addition it may be ingesting dry air from the west.  The vorticity is very spread out and not focused at all.  Maybe if it gets into the GOM it may have a chance.  

[jmanley32]

Yeah and like you said earlier the wave off africa had to move slow, its moving at 20mph, catching the saharan dust, the GFS is out to lunch. NHC also lowered its chances in 5 day to 10%, what I do not get honestly is what is the point of the GFS going to 384 hrs? Its not even accurate within 240 hrs, as we call it fantasyland. Since the gfs is publicly available those that do not know could easily take it verbatim. Yeah its fun to watch the runs but it seems pointless and drives me nuts lol, i try so hard to only clock through 240 hrs at most lol but sometimes my interest just goes where it shouldn't lol

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