Atlantic Tropical Action 2014

[icebreaker5221]

I would be very weary of the GFS forecast beyond 120 hours... its been essentially manhandled by the ECMWF in the medium range so far with this particular entity. Just look how off the GFS 48 hour forecast has been.

 

http://www.tropicaltidbits.com/analysis/models/gfs/2014060812/gfs_z850_vort_watl_comp48.html

 

I think you meant "t(prog)/dt forecasts verifying 12Z the 10th", but the point being that 6-10 day forecasts have been horrendous. 

[phil882]

I think you meant "t(prog)/dt forecasts verifying 12Z the 10th", but the point being that 6-10 day forecasts have been horrendous. 

 

Yep ooops... I didn't mean to say the 48 hour GFS forecast was off, but the fact that the forecast verification for 12z on 10 Jun had trended away from those forecasts that were indicating a significant TC in the Gulf of Mexico in the medium range. The GFS still is suggesting something coming out of the Caribbean in the 6-8 day range, but it has no support from any of the other global models. 

[Ground Scouring]

Why has the GFS, for run after run, continued to show a SW Caribbean fantasy cyclone developing in the same area ~150 hours out? Even the GFS ensembles show a strong signal for SW Caribbean development in that time frame. An explanation would be helpful and informative. (Edit: Tonight's 00Z run [13 June] continues the trend by showing cyclogenesis in five days.)

[calm_days]

 

Some type of circulation has formed over florida, but it does not specifically show signs of continued development.  The size and shape are very tropical nonetheless.

[Ed Lizard]

 

Some type of circulation has formed over florida, but it does not specifically show signs of continued development.  The size and shape are very tropical nonetheless.

Interesting that someone would choose the WV to claim there is a tropical circulation over Florida.

 

Not using the 12Z NAM as a forecast...

[phil882]

Why has the GFS, for run after run, continued to show a SW Caribbean fantasy cyclone developing in the same area ~150 hours out? Even the GFS ensembles show a strong signal for SW Caribbean development in that time frame. An explanation would be helpful and informative. (Edit: Tonight's 00Z run [13 June] continues the trend by showing cyclogenesis in five days.)

 

Well it appears to be a systematic bias in the model given that its been doing it run after run. A quick dprog/dt animation also shows that the bias appears to be prevalent through all forecast times leading to verification (note the steady increase in convection over the Caribbean as the model forecast goes back in time from today's verification to the 192 hour forecast of the same verifying time).

 

http://www.tropicaltidbits.com/analysis/models/gfs/2014061300/gfs_ir_watl_comp0.html

 

My hypothesis is that the GFS is poorly handeling the heating from the cummulus parameterization and is over producing the latent heat release (LHR) response of convection in a highly sheared environment. The Gulf of Mexico and Caribbean have been under the influence of a broad upper-level trough for the last week or so (this was the same feature that drew up Boris into Central America).

 

As I've explained before, the GFS use a cummulus parameterization (Arakawa-Schubert scheme, AS) that only allows for convection to be prescribed in a 1 dimensional vertical column. This is to save computational time as it can be a taxing calculation to run nested within a larger model. The problem with this unfortunately is that it doesn't allow for the (initial) cloud updraft to be directly impacted by the larger scale environment. That is ok in instances where convection is growing vertically upright and producing latent heat release over a finite area. However, in instances where there is substantial vertical wind shear, it can over emphasize the latent heat release (LHR) produced at any one grid point because it assumes the updraft is upright, when in reality there is substantial vertical tilt (think like the anvil blowoff of a supercell) 

 

Another complicating factor comes in how the GFS uses this scheme... since the AS scheme is pretty complex, it needs to be further simplified in the GFS, running a simplified version that only allows for detrainment at the top of the 1d cloud model. Thus, if there is prevalent dry air in the low to mid-levels of the atmosphere, the model might not account for the proper detrainment of the cloud and produce convection that is too strong relative to reality. 

 

So the end result here is that the GFS has a tendency to overemphasize and overproduce deep convection in sheared environments and thus produce too much precipitation / latent heat release. This is important because it can feedback into the mass fields of the models. Mid to Upper-level LHR is an important step in the production of a warm-core cyclonic vortex in the low to mid-levels of the atmosphere... an ingredient that can lead to tropical cyclogenesis. If the model overproduces convection and LHR, then it can overproduce the low to mid-level cyclonic vortex that acts as the catalyst of a tropical cyclone. That could probably be what is happening in this case. 

 

PS if you want to learn more about model cumulus parameterization (and really any other meteorological topic)...Met Ed (below) is an awesome resource. Note you have to register to access the material, but it should be free to register. 

 

https://www.meted.ucar.edu/nwp/model_precipandclouds/navmenu.php?tab=1&page=3.5.1

[calm_days]

Interesting that someone would choose the WV to claim there is a tropical circulation over Florida.

 

 

Yes; to be honest I am one of the most amateur participants on this forum.  The water vapor imagery is something I will overuse, although there are always interesting dynamics to be seen there!  

[Superstorm93]

June STJ raging across the entire basin with well above normal shear in the western Atlantic through the Caribbean. 

 

Definitely going to be a rough year for this thread. 

 

 

 

[Eyewall2005]

Its june 14...

[SnoSki14]

It really opens up the subtropics with the shear focusing in the MDR region and much lighter shear to the north.

[wxtrackercody]

Its june 14...

Regardless, this is the type of shear configuration you would expect in an El Niño season, with a highly amplified subtropical jet passing through the Gulf, Caribbean, and tropical Atlantic. We'll see how well the subtropics do since shear is lower there...some years see a lot of activity and others are quiet throughout the Atlantic.

[Superstorm93]

ECMWF June seasonal forecast is out for ASO

 

 

 

[andyhb]

ECMWF June seasonal forecast is out for ASO

 

That's...pretty much the worst look possible for the Atlantic basin.

[Sunny and Warm]

I guess we'll see Josh next year then.

[thewxmann]

It really opens up the subtropics with the shear focusing in the MDR region and much lighter shear to the north.

 

Awesome, can't wait for more sheared subtropical halfastorm namewasters.

[Ground Scouring]

I guess we'll see Josh next year then.

Not if the EPAC does its own equivalent of 2005 in the Atlantic. We only need a couple of intense LFs in MX.

[hurricaneman]

some storms that formed in the subtropics aka north of the Caribbean islands that have been real eye candy

 

Gordon 2012

Kirk 2012

Michael 2012

Isaac 2006

Nate 2005

Ophelia 2005

Epsilon 2005

Alex 2004

Juan 2003

Kyle 2002

Humberto 2001

Michael 2000

Dennis 1999

Karl 1998

Erin 1995

Florence 1994

Bonnie 1992

Charley 1992

Bob 1991

Claudette 1991

Earl 1986

Kate 1985

Diana 1984

Josephine 1984

Debby 1982

Ivan 1980

Ella 1978

Belle 1976

Candice 1976

Gloria 1976

Doris 1975

Becky 1974

Betty 1972

Ginger 1971

HU9 1970

Gerda 1969

Inga 1969

Kara 1969

Ginny 1963

Alma 1962

Ella 1962

Hannah 1959

Daisy 1958

Carol 1954

HU8 1954

Barbara 1953

Able 1951

 

so while most tropical systems that form in the subtropics tend to be loose cored some of them like the ones on the list can be fun to track and in some cases be quite picturesque and this may be the predominant form of systems this year

[AvantHiatus]

SSTA are primed for a good ST season...note the cooling over the Central Atlantic, a semi-permanent feature that existed last year.

 

Hurricanes Move Away from Equator with Expanding Tropics

http://www.scientificamerican.com/podcast/episode/hurricanes-move-away-from-equator-with-expanding-tropics1/

[PSUBlizzicane2007]

Awesome, can't wait for more sheared subtropical halfastorm namewasters.

 

Those aren't even going to happen this year.  I said everyone was overestimating the seasonal totals in the prediction thread for this very reason.

[phil882]

Those aren't even going to happen this year.  I said everyone was overestimating the seasonal totals in the prediction thread for this very reason.

 

Why aren't they? I think people on here have been outlining for a while that the environment is favorable for (tropical transition) TT occurrence. 

[Ed Lizard]

I screwed up June in the contest, I figured a big El Nino season, and I was hearing 1997, I figured 3 or 4 non-tropical June and July deverlopments before the season really shut down.

 

I should have done 0/0/0 for June, because I see no signs now of anything non-tropical getting a chance.  Stupid me, assuming ENSO alone would be a good predictor.

 

I do see a decent early season wave around 45ºW, but shear is already 20 to 30 knots and looks to get stronger to the West.  On the positive side, after at least a week of almost every GFS run developing a Caribbean TC between 6 and 8 days out, it seems to be chilling on that one.

[phil882]

12 UTC ECMWF looks mildly interesting along the Florida coast... develops a weak low-level circulation that is embedded in the low shear environment north of the subtropical jet. It looks like the circulation is strongest in the mid-levels but with 28-29C SSTs its worth keeping an eye on it. Low probability event, but these can sneak up on the global models.

 

 

[Eyewall2005]

Interesting comments from wxman57 promet on storm2k..

 

El Nino is definitely looking to be a bit weaker than was forecast. Possibly < 1C above normal through peak season. A weaker El Nino has less of an impact on development. Could be just a little below normal this year, but more hurricanes than last year.

[wxmx]

Interesting comments from wxman57 promet on storm2k..

 

El Nino is definitely looking to be a bit weaker than was forecast. Possibly < 1C above normal through peak season. A weaker El Nino has less of an impact on development. Could be just a little below normal this year, but more hurricanes than last year.

I still think El Niño (if one forms) will peak above 1C...but if it doesn't or barely does, and we have a displaced/split Azores ridge (a Bermuda ridge), I would put chances on Florida action above to well above normal.

[Srain]

I still think El Niño (if one forms) will peak above 1C...but if it doesn't or barely does, and we have a displaced/split Azores ridge (a Bermuda ridge), I would put chances on Florida action above to well above normal.

I also would not be surprised to see an increase in the number of Hurricanes ~vs~ last season. While the number of named TC's may be a bit less , I do believe there is some potential for more quality TC's and even and an impressive Major or two.

[Eyewall2005]

I still think El Niño (if one forms) will peak above 1C...but if it doesn't or barely does, and we have a displaced/split Azores ridge (a Bermuda ridge), I would put chances on Florida action above to well above normal.

Me likes!!

[calm_days]

 

Here are two tropical sized low circulations in the atlantic, one very close to the southeast coast, and the one north of the carribean being impacted by the... clockwise rotation of moisture from the large storm complex that formed over the midwest, and moved over the northeast and then to the ocean.  They may not be traditional developments, but, they are in tropical locations near the beginning of the season so it is good to mention/archive.

[phil882]

Here are two tropical sized low circulations in the atlantic, one very close to the southeast coast, and the one north of the carribean being impacted by the... clockwise rotation of moisture from the large storm complex that formed over the midwest, and moved over the northeast and then to the ocean.  They may not be traditional developments, but, they are in tropical locations near the beginning of the season so it is good to mention/archive.

 

These are upper-level cyclones which pose little chance for immediate tropical development. It would take many days of continued convective production to remove the upper-level cyclone and build a warm core low-level circulation that is more supportive for tropical cyclone development. 

 

The feature I was pointing out yesterday is a mid to low-level vorticity max further south over the Bahamas and Southern Florida. Its under a little bit of westerly shear from the upper level low to its north so it doesn't look like its going to do much the next 12-24 hours, but it could be a heavy rain producer for a lot of Florida. 

[icebreaker5221]

That blob east of Nicaragua is mildly interesting.  It would need to continue dropping south, closer to S. Nicaragua / N. Costa Rica, to have any chance of surviving with that shear.  Even then, it would most likely run the risk of moving inland.  Still, not much else to look at ATM. 

[phil882]

Still watching the weak disturbance just offshore of Florida. HRRR has had a couple of interesting forecasts (although its not quite as aggressive as some of the afternoon runs). Don't be surprised if things look rather interesting before the end of the diurnal max tonight though.