Atlantic Tropical Action 2014

[Kory]

Let's just clear things up here...just because the NHC declares something an Invest, doesn't mean they expect development.  They just want to look at an area more closely.  Considering it had weak model support, I don't see why they won't.  

[ineedsnow]

Doesnt seem like it has a chance thats why there is no mention

[Kory]

FWIW, the Nam develops this area. TUTTs can work down to the surface tho?

http://www.tropicaltidbits.com/analysis/models/nam/2014090906/nam_mslp_pcpn_eus.html

Yes they can.  Here's an explanation I found.  It does appear to be enhancing a surface trough.  

 

 

 

When upper cold lows break off from their base, they tend to retrograde and force the development, or enhance, surface troughs and tropical waves to their east. Under special circumstances, they can induce thunderstorm activity and lead to the formation of tropical cyclones.

[Srain]

FWIW, the Nam develops this area. TUTTs can work down to the surface tho?

http://www.tropicaltidbits.com/analysis/models/nam/2014090906/nam_mslp_pcpn_eus.html

The NAM is useless for tropical cyclone development. Typically these mid/upper lows rarely work down to the surface.

[MarkSC]

CMC also develops it, but it's the CMC.  Surface pressures are still high in the area, so that is probably why NHC has held off.  I do think it warrants close attention, though. Water temps are quite high and shear is low. The fact that the models have backed off the front clearing the east coast this weekend could give it more time to develop and slowly move west.

[wxmx]

I agree that the area in the SE Bahamas deserves attention. There's low level vorticity, and it already started to generate more organized moderate/strong convection. Also, there's already embedded anticyclonic flow to it's north, and shear is low since it's in the middle of a big ULL. Lastly, all trustworthy models develop it to some degree, the GFS is probably too weak to get numbered, but the Euro and CMC are at least TD strong in their model depictions two days from now.

[icebreaker5221]

I agree that the area in the SE Bahamas deserves attention. There's low level vorticity, and it already started to generate more organized moderate/strong convection. Also, there's already embedded anticyclonic flow to it's north, and shear is low since it's in the middle of a big ULL. Lastly, all trustworthy models develop it to some degree, the GFS is probably too weak to get numbered, but the Euro and CMC are at least TD strong in their model depictions two days from now.

 

Yes, it is becoming slightly interesting.  Normally UL lows shear TCs apart, but with the UL vortex weakening while simultaneously vertically aligned with +PV generation below via sustained deep convection, the net effect is almost zero shear affecting the developing mid-level vortex directly below this upper low.  Hopefully NHC makes this an invest soon so RAMMB starts providing AMSU radial/height cross sections.  Those would be very useful to tell if/when a warm core begins to replace the UL cold core. 

 

In terms of reliable model support, about 10% of the 00Z ECMWF ensemble members do something (TD to perhaps weak TS) with this through 120 h. 

 

Where's our avid upper-low watcher, calm_days?

[IsentropicLift]

Granted the SREF is normally ranked with the NAM and GGEM when it comes to the tropics, but it seems to have some skill when the developing system is from a non-tropical origin. We saw this earlier this season when it did a reasonable job of sniffing out Arthur when most of the globals were still not showing much development. This morning most of the 09z SREF members are showing a well developed TC near the Western Bahamas in about 72 hours, tracking near the SE FL coast in about 87 hours.

[GaWx]

After carefully examining the 0Z GFS/Euro and 6Z GFS, I think this could be a sleeper. (This feeling has very little to do with the NAM, a poor model to determine chances for genesis.) The Euro/GFS at least suggest to me a pretty good chance for at least a weak surface low to form within the next couple of days near the Bahamas. Also, progged upper level steering/conditions are not at all looking inhospitable to me. Per the Euro, upper level high pressure would dominate near and to the north of this near and offshore the SE US/Gulf coast through the weekend (i.e., before the unfavorable long wave trough enters). Looking more closely, the winds don't look all that unfavorable all of the way up to 200 mb into much of the weekend in much of the area. When I see a potential surface low off the SE coast forming near the bottom of an upper level high that looks to persist for at least a few days, it normally at least gets my attention. In summary, I think this currently has a nontrivial chance to develop into a TC within the next couple of days east of FL and, if so, quite possibly subsequently threaten parts of the SE US/Gulf coast since there'd probably be no recurve into the weekend and upper levels would seemingly be favorable for development.

[Kory]

Any development would be slow.  Pressures are still fairly high and there's still outflow boundaries racing out of the thunderstorm complex.  Still fairly disorganized, but it also had slow movement to it's advantage which helps it organize vs. racing towards land.  

[DopplerWx]

12z gfs not showing much of anything.

[Kory]

12z gfs not showing much of anything.

Yeah, pretty much keeps it as just a trough of lower pressure moving west into the Gulf.  The shear depicted by the GFS probably has something to do with it not showing development.  

[Guest Imperator]

The NAM is useless for tropical cyclone development. Typically these mid/upper lows rarely work down to the surface.

 

Well there's a certain shock Meteorologist who's pathetically posting the NAM on Twitter to argue/hype his point, just like he was trying to do (but failed) with the current rainstorm on the Mid-Atlantic.

[MarkSC]

NHC gave in after reading this forum lol:

 

An area of showers and thunderstorms just east of the central and
southeastern Bahamas is associated with a weak surface trough of low
pressure. Slow development of this system is possible during the
next few days as it moves west-northwestward or westward at about
10 mph.
* Formation chance through 48 hours...low...10 percent.
* Formation chance through 5 days...low...20 percent.

[Weather.St]

NHC gave in after reading this forum lol:

 

An area of showers and thunderstorms just east of the central and

southeastern Bahamas is associated with a weak surface trough of low

pressure. Slow development of this system is possible during the

next few days as it moves west-northwestward or westward at about

10 mph.

* Formation chance through 48 hours...low...10 percent.

* Formation chance through 5 days...low...20 percent.

I doubt they did it because of this forum. LOL. Still a good idea to watch something like that anyways, wouldn't wanna have a sleeper wake up and suddenly cause chaos on the Gulf Coast.

[ineedsnow]

12z euro is pretty meh with it.

[Kory]

12z euro is pretty meh with it.

It gets to the Central Gulf before the front picks it up, but it's very weak. Biggest impact will probably just be increased rain for Florida and the Gulf Coast.

[Ground Scouring]

Definitely a fish on that run with a trough like that off the East Coast. But it's sub 980 mbars on that run...Big change from 00z.

Where's Ground Scouring now that his beloved model is showing significant development of 91L?

None of the reliable dynamical models shows 91L becoming a hurricane, let alone a major storm. The ECMWF and its ensemble mean keep the system as a weak TS at most. A substantial minority of models also don't develop the system. Given seasonal trends and the dry environment, I'm sticking with my prediction that 91L won't develop. If I'm wrong, it'll be a weak TS at most, at least over the next seven days. The GFS, in particular, has also been underestimating shear in the tropical Atlantic this season, so the Bahamas system won't develop either. The ECMWF, while still missing some short-lived spin-ups, has improved its ability to forecast such development in recent years--certainly more so than many other models have.

[Kory]

Looks like another CCKW will likely be making it's way into the Atlantic basin in the next week or two.  We shall see if it helps spur Edouard.  

 

Here's a look at the Atlantic Vertical Instability...the large spikes (mainly beginning of July, late July, and late August) show when the CCKW waves moved through the basin.  Corresponds well with Arthur, Bertha, and Cristobal.

 

[wxmx]

We'll probably have another Dolly-esque disturbance soon from the convection currently NE of the Honduras/Nicaragua border. Almost identical setup, track, shear, EPac cyclone, craptasticity and all.

[Akeem the African Dream]

I'm somewhat interested in this mess in the Bahamas.  

[ineedsnow]

Bahama mess probably wont be much of anything 91l has alot of dry air to fight off but may start to develop in 3 days or so but most likely staying ots so as of now seems like there isn't much to look at regarding the tropics

[Kory]

The beat of 2014 goes on.  What's surprising is that shear isn't even a problem currently.  Lack of low level convergence and upper level divergence has hampered thunderstorm activity.  Should continue to drift westward over Florida and into the Gulf.  Shear will only increase from here on out. 

 

 

[bluewave]

The beat of 2014 goes on.  What's surprising is that shear isn't even a problem currently.  Lack of low level convergence and upper level divergence has hampered thunderstorm activity.  Should continue to drift westward over Florida and into the Gulf.  Shear will only increase from here on out. 

 

 

 

 

 

It's patterns like this that even gave Florida the opportunity to extend its hurricane free streak this long.

 

http://www.weather.com/news/weather-hurricanes/florida-hurricane-free-streak-luck-run-out-20140801

 

 

Heading in to the heart of the 2014 Atlantic hurricane season, it is interesting to note that it has been 8 years, 9 months and 1 week, or 3,200 days, since a hurricane has made landfall in Florida.

This is the longest stretch of consecutive years since 1851 that no hurricanes have hit the state. The longest hurricane-free streak prior to this one was five consecutive seasons from 1980 to 1984.

This is impressive, considering the coastline of Florida spans more than 1,260 miles from the Gulf Coast to the Atlantic Ocean, and an average of 8 hurricanes have formed each year since 2005.

Equally impressive is the barrage of storms that pummeled the state before the hurricane drought.

[Srain]

I'd keep an eye on the Western Atlantic Basin over the next 7-10 days. The eastward progressing cckw should arrive next later week in the Western Caribbean into the Western Gulf. Stalled boundaries across the NW Gulf tend to fester as convection develops at the tail end of the boundary. This front will not sweep across the Gulf and end tropical development chances. We have about another 10 or so days of potential TC genesis in the SW Caribbean into the Western Gulf as a SE Ridge develops early next week. The reliable Euro and GEFS ensemble mean are indicating some enhancement for potential TC genesis. Vertical instability looks rather favorable and if we can see the shear relax, we may see tropical development in the Western Atlantic Basin.

[Kory]

I'd keep an eye on the Western Atlantic Basin over the next 7-10 days. The eastward progressing cckw should arrive next later week in the Western Caribbean into the Western Gulf. Stalled boundaries across the NW Gulf tend to fester as convection develops at the tail end of the boundary. This front will not sweep across the Gulf and end tropical development chances. We have about another 10 or so days of potential TC genesis in the SW Caribbean into the Western Gulf as a SE Ridge develops early next week. The reliable Euro and GEFS ensemble mean are indicating some enhancement for potential TC genesis. Vertical instability looks rather favorable and if we can see the shear relax, we may see tropical development in the Western Atlantic Basin.

Definitely spells a heavy rain threat along the Gulf Coast with the Caribbean moisture streaming in.

[Ground Scouring]

I'd keep an eye on the Western Atlantic Basin over the next 7-10 days. The eastward progressing cckw should arrive next later week in the Western Caribbean into the Western Gulf. Stalled boundaries across the NW Gulf tend to fester as convection develops at the tail end of the boundary. This front will not sweep across the Gulf and end tropical development chances. We have about another 10 or so days of potential TC genesis in the SW Caribbean into the Western Gulf as a SE Ridge develops early next week. The reliable Euro and GEFS ensemble mean are indicating some enhancement for potential TC genesis. Vertical instability looks rather favorable and if we can see the shear relax, we may see tropical development in the Western Atlantic Basin.

Given that the models have handled the long range very poorly this season (especially in terms of underestimating shear), I'd be really skeptical about development. All the favorable conditions have been in the EPAC this year. As for 91L, reliable models like the ECMWF and the GFDL continue to show either a weak TS in three to five days or a minimal hurricane afterward. I'd lean toward the ECMWF rather than the GFDL, which shows a hurricane.

[hurricaneman]

I think that the -PDO has lead to the east coast trough and hence is steering the hurricanes away but the PDO did turn + back earlier in the year so we may not see the effect of that until next year and the thing I noticed about +PDOs is that they tend to lead to a higher percentage of US landfalls which we haven't had much of this year and only 3 landfalling hurricanes since 2008 which is a very low percentage as opposed to 13 hurricane landfalls from 2004 to 2008 which were in a +PDO pattern

[bluewave]

First time since 1992 that there has been no named storms on September 10th in the Atlantic Basin.

[MarkSC]

Bahamas feature is starting to look better. 12Z GEM goes crazy with it again. Shows a track that would lead to some severe SE flooding.