Atlantic Tropical Action 2014

[IsentropicLift]

The ECMWF is hinting at a very weak subtropical like entity in the long range (day 5-7). The CMC looks like its mainly a baroclinic cyclone, but the ECMWF is further south and weakly warm core in nature... something to watch.

The 18z GFS had the feature too.

[negative-nao]

On radar north of puerto rico you can see a spin

 

http://www.intellicast.com/Local/WxMap.aspx

 

Click on interactive map and move your mouse down to puerto rico and click animate

[phil882]

On radar north of puerto rico you can see a spin

 

http://www.intellicast.com/Local/WxMap.aspx

 

Click on interactive map and move your mouse down to puerto rico and click animate

 

Just an upper level wind shift right now with little evidence of a surface reflection. The models do show some surface development in the base of the trough as things slowly move WNW. 

 

Right now though, its just a PV streamer interacting with a moisture gradient... the QG upward vertical motion is producing the significant convection today with associated divergent irrotational wind.

 

[Ground Scouring]

The ensemble GFS and ECMWF mean is showing a trend toward a weak MJO signal in the EPAC / Atlantic beginning in another week. In a developing strong Niño, this weak/almost incoherent MJO signal is often strongly correlated with early-season Atlantic activity. Strong Niños very often feature a burst of early Atlantic (and EPAC) development, so we could very well see something pop in the W Caribbean right around/after June 1 this year. The ECMWF is already showing a strong EPAC cyclone developing in about a week, so it is seeing the MJO progression into that part of the world. The Atlantic will very likely be next some time afterward. If I were to bet, I would think our first Atlantic cyclone will form in the first week of June.

[AvantHiatus]

The ensemble GFS and ECMWF mean is showing a trend toward a weak MJO signal in the EPAC / Atlantic beginning in another week. In a developing strong Niño, this weak/almost incoherent MJO signal is often strongly correlated with early-season Atlantic activity. Strong Niños very often feature a burst of early Atlantic (and EPAC) development, so we could very well see something pop in the W Caribbean right around/after June 1 this year. The ECMWF is already showing a strong EPAC cyclone developing in about a week, so it is seeing the MJO progression into that part of the world. The Atlantic will very likely be next some time afterward. If I were to bet, I would think our first Atlantic cyclone will form in the first week of June.

Long-range 18z GFS supports your ideas, I agree. However it's interesting that the vast majority of ENSO warming is now in the Eastern Pacific. This may support developement in the Western Carribean or EPAC.

[Ground Scouring]

Long-range 18z GFS supports your ideas, I agree. However it's interesting that the vast majority of ENSO warming is now in the Eastern Pacific. This may support development in the Western Caribbean or EPAC.

Hmm...I don't see how the warming will do anything to foment cyclogenesis. Maybe I'm missing something. I was talking about the MJO, not the warming surface waters.

[AvantHiatus]

Hmm...I don't see how the warming will do anything to foment cyclogenesis. Maybe I'm missing something. I was talking about the MJO, not the warming surface waters.

Someone with greater knowledge can provide you with more insight but warm waters in that region can generate convection and cause wind shear downstream. Somewhat early for the el nino to wreck the Atlantic Season tho. Just wanted to add to your post, sometimes the EPAC environment expands into the Western Carribean during May and June.

 

I would really not expect anything east of 80W or so, that would require a pretty large monsoon trough and that has yet to show up on the models.

 

EPAC is generally very active during el nino events.

[Ed Lizard]

Looking at the global SST anomaly map on the ENSO thread, and I think this has been suggested before, warm water right along the Equator and in the subtropics, normal to below in the MDR, I think between this and the warm ENSO, dullest season in decades.

 

And check out how icy my part of the Gulf is...

[Ground Scouring]

What's the expected QBO phase this season and its Atlantic TC track concentration, OKpowdah? I recall your good work from a previous thread here.

[CoastalWx]

None of the tropic weenies biting on fantasy land GFS op runs?

[JC-CT]

None of the tropic weenies biting on fantasy land GFS op runs?

Would you?

 

It has had it for 6 runs in a row at least.

[Ed Lizard]

I think this is ok, because this thread probably won't reach 50 pages this entire season.

 

I was looping the NAMER GFS, to see where the possible half inch total for the entire 16 days in SETX was going to come from on May 8 and May 9th, and my eyes were drawn to the Caribbean.  I wanted to be the first to post a 15 day fantasy GFS storm.  PW suggests dry air issues on the Western side, winds suggest barely a depression, but this is the first fantasy range TC of 2014.

 

And there are a few 1004 mb or below systems in the Caribbean then per 12Z spaghetti.

     

I won the contest for first GFS fantasy storm almost a month ago.  No point being second, it is just the first loser.

 

 

 

None of the tropic weenies biting on fantasy land GFS op runs?

[Roger Smith]

A contest thread has been opened for the 2014 NATL season. Rules are posted (post 1) and if you already entered, please note that you can edit your posted forecast to include a June forecast, or amend your seasonal forecast, without needing to note any changes made as these forecasts will not be tabulated until June 2nd. The deadline for entry is Monday, June 2nd at 06z (but only slight penalties will apply after that). Please note, any forecasts posted in this discussion will not make it into the table of entries so post them in the contest thread. The consensus so far is for quite a weak season of about 11/6/2. Check the thread in June to see what the updated consensus is after more entries are received.

[Srain]

I would keep an eye on the tropical wave approaching the Windward Islands. There has been some indication via the Global operational and ensemble guidance that conditions could become a bit more favorable for development once this wave enters the Western Caribbean Sea in about 7-10 days.

 

[Superstorm93]

Cool little cyclone just off the east coast 

 

[Ground Scouring]

The operational GFS (as of 18Z) continues to suffer convective feedback issues by attempting to develop a fantasy cyclone off Honduras in about a week (156 hours)…no other reliable model, certainly not the ECMWF or its ensembles, shows anything in that time frame. The ECMWF doesn't suffer from feedback at that range, so why the GFS continues to do so is disappointing for a model used to forecast tropical cyclogenesis.

[phil882]

The operational GFS (as of 18Z) continues to suffer convective feedback issues by attempting to develop a fantasy cyclone off Honduras in about a week (156 hours)…no other reliable model, certainly not the ECMWF or its ensembles, shows anything in that time frame. The ECMWF doesn't suffer from feedback at that range, so why the GFS continues to do so is disappointing for a model used to forecast tropical cyclogenesis.

 

This is not a convective feedback issue... in fact all models suffer from convective feedback from time to time because they all have to parameterize convection. We tend to say the ECMWF is better because is has better initial conditions, so that when convection is parameterized (using the tiedtke scheme), its more likely to get it right. Indeed the convective scheme is superior to models like the NAM which use a modified convective scheme which tends to overproduce convection in the tropics (which renders the NAM pretty much useless south of 20N in the summer).

 

 

The differences in the GFS vs. ECMWF can be attributed to the placement of the mid-ocean trough, or TUTT, which is oriented quite differently between the models. The GFS has a more amplified trough oriented further southeast over the Yucatan, meaning the QG forcing for ascent is focused over the Caribbean. The resultant convection produced in the Caribbean will produce a +PV anomaly in the low-mid levels which is how the "fantasy cyclone" develops in the medium range GFS. Perhaps this convection is overdone, but such a trough configuration for this time of the year would likely aid in ample convective development over the warm Caribbean.

 

 

The ECMWF has a less amplified trough which is further west, with more limited QG forcing which is primarily focused over Central America and the EPAC. The ECMWF actually has quite a bit of convection just south the Central America along a shear axis that could be seen as an ITCZ or Monsoon trough like setup. This would probably be a scenario more favorable for more TCs across the EPAC. 

 

They key point here is that its the synoptic pattern that is dictating what happens with the convection, and not the model's deficiencies in convective processes. All global models have problems depicting convection properly in the long range, but some models have better initial conditions (e.g. ECMWF) which can allow it to make superior forecasts in the medium range. 

[Ground Scouring]

This is not a convective feedback issue... in fact all models suffer from convective feedback from time to time because they all have to parameterize convection. We tend to say the ECMWF is better because is has better initial conditions, so that when convection is parameterized (using the tiedtke scheme), its more likely to get it right. Indeed the convective scheme is superior to models like the NAM which use a modified convective scheme which tends to overproduce convection in the tropics (which renders the NAM pretty much useless south of 20N in the summer).

 

The differences in the GFS vs. ECMWF can be attributed to the placement of the mid-ocean trough, or TUTT, which is oriented quite differently between the models. The GFS has a more amplified trough oriented further southeast over the Yucatan, meaning the QG forcing for ascent is focused over the Caribbean. The resultant convection produced in the Caribbean will produce a +PV anomaly in the low-mid levels which is how the "fantasy cyclone" develops in the medium range GFS. Perhaps this convection is overdone, but such a trough configuration for this time of the year would likely aid in ample convective development over the warm Caribbean.

 

The ECMWF has a less amplified trough which is further west, with more limited QG forcing which is primarily focused over Central America and the EPAC. The ECMWF actually has quite a bit of convection just south the Central America along a shear axis that could be seen as an ITCZ or Monsoon trough like setup. This would probably be a scenario more favorable for more TCs across the EPAC. 

 

They key point here is that its the synoptic pattern that is dictating what happens with the convection, and not the model's deficiencies in convective processes. All global models have problems depicting convection properly in the long range, but some models have better initial conditions (e.g. ECMWF) which can allow it to make superior forecasts in the medium range. 

Thanks for offering such a great explanation. I'll keep it in mind as a view model runs. Compared to yesterday's 12Z run, today's 12Z Canadian shows the strongest convection over the SW Caribbean Sea rather than in the ECMWF. While unreliable as a tropical model, the Canadian is good to watch for general trends. The GFS has held firmly to its W-Caribbean-centric solution, as has the 12Z NAVGEM. While I would definitely lean toward the ECMWF, which solution would you personally prefer in this case, the GFS or the ECMWF?

[phil882]

Thanks for offering such a great explanation. I'll keep it in mind as a view model runs. Compared to yesterday's 12Z run, today's 12Z Canadian shows the strongest convection over the SW Caribbean Sea rather than in the ECMWF. While unreliable as a tropical model, the Canadian is good to watch for general trends. The GFS has held firmly to its W-Caribbean-centric solution, as has the 12Z NAVGEM. While I would definitely lean toward the ECMWF, which solution would you personally prefer in this case, the GFS or the ECMWF?

 

I'd lean towards the ECMWF just because it typically has a better track record, but in the 5-7 day range, its really a toss up with only slightly better probabilities of the ECMWF being right. Again the biggest differences continues to be in the placement and orientation of the TUTT/mid-ocean trough. The ECMWF continues to be weaker/more zonal, with the TUTT feature which favors more convective activity in the EPAC, while the GFS continues to stress the caribbean for the focal point for the most convective development.

 

And then there is the GEM/CMC... lol that would be a bonafide CAG (Central American Gyre) in the Gulf of Mexico + Developing TC on its downstream flank. Lets file that one under "unlikely"

 

http://www.tropicaltidbits.com/analysis/models/gem/2014052612/gem_z850_vort_watl.html

 

[Ground Scouring]

For what it's worth, the 18Z GFS remains just as adamant as earlier runs did re: development. It develops a weak depression over/near Honduras in five and a half days and shows modest intensification through day 7 as the depression drifts N toward wrn Cuba. Upper-level winds gradually become more favorable, weakening/backing in the same time frame. I am still against the GFS re: development but it has been very consistent to say the least. And it has kept moving the time frame closer.

[hurricaneman]

There's nothing in the Caribbean as of now but most of the major models are trying to develop something with the GFS and Canadian being the strongest with it so I wouldn't be surprised if this modeled area does indeed develop into something maybe similar to Debby in 2012 or Andrea last year

[phil882]

Both the deterministic GFS and EC are holding on to their respective solutions (e.g. GFS in Caribbean while the ECMWF is in the EPAC). The GFS ensembles are more or less split (although be careful since the SLP max over Central America is an artifact of the terrain). In the longer range (around where the model's horizontal resolution is truncated) the GFS ensembles side more with its deterministic member, favoring a gyre like disturbance producing a TC that enters the Gulf of Mexico by early June. Plenty of time to watch, but the plot thickens. 

 

[Srain]

It is not unusual to see a monsoon gyre TC develop from the Gulf of Tehuantepec, Bay of Campeche or NW Caribbean Sea in early June during a transitioning El Nino pattern. I would place the odds near 50% for potential genesis in the early June time frame in either Basin.

[phil882]

It is not unusual to see a monsoon gyre TC develop from the Gulf of Tehuantepec, Bay of Campeche or NW Caribbean Sea in early June during a transitioning El Nino pattern. I would place the odds near 50% for potential genesis in the early June time frame in either Basin.

 

The May/June time frame is also typically an active time as well for gyre-like disturbances. One key ingredient that seems to be required is zonal westerly low-level flow in the EPAC, and all of the models are suggesting this to some degree. My Master's thesis is on this phenomena, and we are near the first peak of gyre activity during the TC season (there is a secondary maxima in the late season [september-November]).

 

Gyres often produce tropical cyclones, and this potential gyre could go on to produce a tropical cyclone either in the EPAC or ATL bains. Sometimes TC events can occur in both basins (e.g. Alma and Authur 2008). 

[Ground Scouring]

As of 12Z, several of the individual GFS ensembles have shifted over into the EPAC re: placement of low pressures in five to six days. I think that we are seeing the start of a steady cave-in toward the ECMWF, and I expect the operational 00Z GFS run to follow suit. (The unreliable CMC and, to a lesser extent, the NAVGEM have also shifted into the EPAC camp.) The idea that cyclogenesis (if any) will occur in the EPAC has been solid all along, but has become even more solid given model trends. The interesting point re: the Atlantic is that the monsoonal gyre will move very little in the long range, so while EPAC development is more likely initially, down the line the same area of low pressures could become a focal point for SW Caribbean genesis in the first week of June, should any synoptic-scale forcing (i.e., a tropical wave) be present at that time. However, the presence of strong low-level ridging over the SW Atlantic in the long range suggests that whatever develops in the Caribbean might die over land in MX / have little leeway for development in the BOC.

[Ed Lizard]

The end of the Texas drought has inspired and reinvigorated my glass half full optimism.  Just becayse the more reliable Euro develops any disturbance in the Pacific doesn't mean all hope is lost for even more beneficial rainfall

 

25 years a Pacific system entered the Atlantic Basin and brought great joy to SETX, and, well, this would drive a stake through the heart of the SETX 2013-2014 drought vampire.

 

Waters off Texas far too cold to maintain a TC, so no damage for beach community residents, just rain.  Like the other TS Allison.

 

To quote the Great DR

Three meteorological phenomena led to the formation of Allison:  the remains of Pacific hurricane
Cosme, the northen portion of a tropical wave, and an upper high over the Gulf of Mexico.  Cosme
moved northward across Mexico, steered north-northeast by a deep trough across the West/High
Plains.  A blocking ridge built to its northeast, slowing down its forward movement as it entered
the Gulf of Mexico.  Heavy thunderstorms rapidly developed across the northwest Gulf of Mexico
on the 22, and became more concentrated with time.  At this time, Cosme's circulation was still
inland southwest of Brownsville, and a new low developed near the convection, and it became
Tropical Depression #2 by the afternoon of the 24th.

Becoming organized over the succeeding couple days, it strengthened into a tropical storm late
on the 25th, as verified by ship reports and later by reconnaisance aircraft.  By the morning of
the 26th, the blocking ridge to its northeast eroded, and Allison acclerated northward into the
Texas coast near the north end of Matagorda Bay late on the morning of the 26th.  After the
system which eroded the ridge moved out to the northeast, ridging redeveloped, blocking
Allison's movement as it approached Houston on the 27th.  Over the next 2-3 days, Allison
transcribed an anticyclonic loop near Houston dumping prodigious rainfall as it drifted, befor
e moving off to the northeast into Louisiana late on the 30th.

 

 

 

[CoastalWx]

You can definitely see the differences on the GFS and Euro has Phil alluded to. GFS plays around with a piece of 850 vorticity and sort of helps utilize this as it develops that gyre. Euro is further west with this. 

[wxmx]

Models are slowly converging, with three embedded pieces of energy in a gyre like configuration, a leading one that enters the BoC, a trailing piece in the NW Caribbean and finally one in the EPac, near the Tehuantepec. The GFS was very bullish with the NW Caribbean one, but it has been slowly changing it's tune, with more development with the BoC one...although it finally develops the trailing one more as the frontrunner dies and it disentangles from land influence. In this power struggle, the EPac seems to be the winner, as it slowly brews. The Euro has a more stronger leading wave, but there's just too much land, and the trailing wave struggles to develop...so it appears the EPac disturbance might surface as the victor in this three way match.

[phil882]

A lot of how this evolution plays out has a lot to do with how Amanda evolves the next 24-48 hours. The big burst of convection ongoing with Amanda is helping to amplify the downstream ridge, which will then enhance the downstream trough that will dig into the Gulf of Mexico (the upper-level cyclone over the southern Mississippi Valley right now). If Amanda collapses in the next 24 hours and doesn't produce any more convection, a more subdued trough response (e.g. like the ECMWF has been suggesting) might occur. However, if Amanda continues to remain convectively active, that has the ability to modify downstream riding and further downstream troughing like the GFS has been suggesting for the last couple of days. The GFS has been more convectively aggressive with Amanda thus far, so its not surprising to see it also has a more amplified flow pattern downstream as the tropics modify the flow more. 

[Ground Scouring]

The 00Z operational GFS has abandoned the SW Caribbean and the BOC in favor of the EPAC in five days, so Atlantic development seems much less likely, as expected. Amanda is now merely a shell of its former self, with no mechanism with which to generate convection. The ECMWF has won the battle re: an Amanda unraveling faster than what the GFS has been showing up until now (slower dissipation).