Atlantic Tropical Action 2014

[Ground Scouring]

 IF the just released Euro weeklies are accurate for mid to late August, there would be no long lasting above normal heat in the SE though there could be in the NE with a little above normal 500 mb ridging centered nearby. The SE would be below that ridging, which would keep it from getting too hot for too long there. Also, with this setup, IF there are any tropical cyclones offshore the SE coast, this/these may not recurve easily off the SE as is the case with Bertha. Looking at precip. anomalies, the weeklies have the tropics pretty dry overall for weeks 2-4 with wetter above that in the subtropics in the general vicinity of 25-30 N over/near the SE US.

Considering that conditions in the MDR/off W Africa will be mostly unfavorable this year, this set-up may actually reduce the threat to the U.S., as troughs that would otherwise promote homegrown genesis in the Gulf / SW Atlantic will fail to drop so far south. We had a strong, west-based Bermuda High last year during peak season, but because the MDR was so dead the ridging made no difference to the U.S. Mid to late August looks quiet TC wise based on the long-range models thus far.

[bluewave]

Based on those charts it's safe to say this season has overperformed. Pretty good.

 

North of the tropics where there have been more favorable conditions.

 

 

 

 

[bluewave]

I would be careful in my interpretation of that.  Without a doubt, the last several seasons have been drier than normal; but NCEP/NCAR reanalysis also shows a drying trend for most of the globe, with many regions shown to be 10% or more drier now than they were in the 50s.  I don't believe ERAI shows a similar pattern globally (even accounting for the fact that ERAI only goes back to 1979). 

 

That extreme moistening over Nino 1-2 also looks suspect to me.

 

Mg7RjNXbg2.png

 

But we can agree that the Tropical Atlantic is experiencing the driest conditions since at least 1970.

 

http://www.climatecentral.org/news/what-happened-to-the-2013-atlantic-hurricane-season-16616

 

This season, the dry air “made a huge difference” and “squashed all the other factors that looked good,” he said.

Klotzbach said the area where most tropical storms and hurricanes form had the driest mid-to-lower atmospheric conditions during the Aug. 1 to Sept. 25 period since reliable records began in 1970.

[Ground Scouring]

Both the ECMWF and the GFS are honing in on possible development off Cape Verde in eight to 10 days. The runs have been consistent in showing the ITCZ lifting north and spawning something as a convectively-coupled Kelvin wave (CCKW) moves over the MDR in the time frame mentioned. The models also show a weaker Azores high that causes the trades to slacken as the W African monsoon extends into the MDR. Overall, odds of development look better than normal at this stage. One caveat is that the models suggest that any potential system may form too far NE to reach land other than the CV islands.

[Superstorm93]

Both the ECMWF and the GFS are honing in on possible development off Cape Verde in eight to 10 days. The runs have been consistent in showing the ITCZ lifting north and spawning something as a convectively-coupled Kelvin wave (CCKW) moves over the MDR in the time frame mentioned. The models also show a weaker Azores high that causes the trades to slacken as the W African monsoon extends into the MDR. Overall, odds of development look better than normal at this stage. One caveat is that the models suggest that any potential system may form too far NE to reach land other than the CV islands.

 

This is a bias that we saw play out much too far north last year around the same time frame. 

 

I do agree that over the next 14 days things should become favorable for the Atlantic to produce tropical cyclones. I would definitely watch for any waves that exit African and wind up near the Lesser Antilles, as the heat potential in the Caribbean is a bit higher than normal. 

 

ITCZ has been gradually lifting north

 

 

[GaWx]

 On 7/25,  the Euro ens. was predicting a very favorable (for genesis) strong MJO phase 3 covering 8/4-8+. However, we're instead in a modest phase 2, which is still somewhat positive for TC genesis, and it is now predicting a modest phase 2 to continue for much of the next two weeks (see graph below). This change is not surprising because there have been many more phase 2 days (88) than phase 3 days (32) during AUG of 1995-2012. The AUG MJO phase historical stats going back to 1995 suggest that conditions aren't as favorable as they would have been had we gone to a strong phase 3 (see table below). Nevertheless, phase 2 has still been one of the more active in August outside of phase 3 and it produced the U.S. hitting Isaac of '12, Gustav of '08, and Bonnie of '98:

 

Aug. geneses 1995-2012 by phase:

MJO phase: MJO # days; # TC geneses/# MDR TC geneses/# US direct H hit TC geneses;      TC geneses per day/MDR TC geneses per day/US direct H hit TC geneses per day

 

1: 63; 9/5/1;  14%/8%/2% (Bret ’99)

2: 88; 17/8/3; 19%/9%/3% (Isaac ’12, Gustav ’08, Bonnie ’98)

3: 32; 12/8/1; 38%/25%/3% (Fran ’96)

4: 15; 0/0/0; 0%/0%/0%

5: 34; 5/4/0; 15%/12%/0%

6: 36; 7/5/1; 19%/14%/3% (Charley ’04)

7: 14; 1/0/0; 7%/0%/0%

8: 22; 4/2/2; 18%/9%/9% (Frances ’04, Earl ’98)

C: 254; 25/13/2; 10%/5%/1% (Irene ’11, Katrina ’05)

 

ALL: 558; 80/45/10; 14%/8%/2%

 

***Edit: the brand new Euro weeklies fwiw still keep it pretty dry in much of the MDR and Caribbean through week #4 (which goes through 9/7) but still somewhat wetter to the north near the SE and in the E GOM.

 

 

[Srain]

There is a rather impressive wave crossing Central Africa near or just N of 10. The 00Z Euro and GFS suggest this wave may have a chance to develop as it exits the West Coast of Africa.

[Kory]

I'm interested in the little tropical wave moving WNW in the eastern Caribbean.  Has a nice vorticity with it and shear doesn't look nearly as bad as it has been the last few weeks.  Perhaps it is of some interest later on down the road?

 

 

 

[icebreaker5221]

I'm interested in the little tropical wave moving WNW in the eastern Caribbean.  Has a nice vorticity with it and shear doesn't look nearly as bad as it has been the last few weeks.  Perhaps it is of some interest later on down the road?

 

Despite a current SW'erly shear vector, too much dry air from the north / near Puerto Rico has already been ingested.  That's a T/Td of -5.9 / -39.9 at 500 mb, which equates to an RH of 5%

 

[Ground Scouring]

Considering how dry the basin is/has been, I'm not surprised that the ECMWF and the GFS don't develop the W African system much once it leaves the coast in about a week. We will need to see major changes in the pattern for development to occur in the MDR.

[GaWx]

I'm interested in the little tropical wave moving WNW in the eastern Caribbean.  Has a nice vorticity with it and shear doesn't look nearly as bad as it has been the last few weeks.  Perhaps it is of some interest later on down the road?

 

 The Euro ens. mean is still predicting mainly MJO phase 2 for the next two weeks. Looking at AUG during the period 1995-2013, there were 17 TC geneses during MJO phase 2 that later became TS+'s (88 MJO phase 2 days). Of these 17, a respectable 6 first became TC's either in the Caribbean or the GoM:

 

- Harvey of '11 (W. Carib.)

- Claudette of '09 (E GoM)

- Fay of '08 (Carib. W. of P.R..)

- Gustav of '08 (E. Carib.)

- Erin of '07 (W. GoM)

- Charley of '98 (W GoM)

 

Regardless, conditions don't appear to be favorable for a TC genesis there as of now.

[Floydbuster]

Lookin' much more moist off Africa than last year...

 

[Ground Scouring]

Lookin' much more moist off Africa than last year...

 

wv-l.jpg

WV imagery only captures the upper levels. You can't see all the record dryness in the low to mid levels.

[bluewave]

This July came in drier than last year at the midlevels from India to right across the Caribbean.

So our best ACE so far is north of the tropics in the Atlantic Basin.

 

 

 

 

 

 

[Superstorm93]

We may have something to keep an eye on: 

 

 

[tmagan]

Since 2013, there have been as many hurricanes in the Central Pacific as there have been in the Atlantic Ocean.

[Superstorm93]

Going to be interesting to see whether or not this will trend south. 

 

 

[Kory]

The Atlantic basin, as far as shear, is now near or below normal in all zones. 

 

Here's the Caribbean where that tropical wave is located.  Shear has calmed down considerably.  Might have to do with the continued cooling of Nino regions 1 and 2.  

 

 

Tropical Atlantic shear has decreased significantly as well.  May give the waves emerging from Africa a fighting chance.  Remember, we're entering the Cape Verde season now.  

 

[Ground Scouring]

We may have something to keep an eye on: 

 

ScreenHunter_86 Aug. 08 16.14.png

 

grearth 2014-08-08 16-12-20-57.png

I wouldn't look at absolute shear (850-200 mb) in this case. Mid-level shear is too high due to the very strong trades in the vicinity, so the surface wave reflection won't have time to slow down before interacting with Hispaniola. And absolute shear increases as the wave moves into the W Caribbean Sea over the next few days.

[phil882]

Going to be interesting to see whether or not this will trend south. 

 

2339.20.jpg

 

2338.20.jpg

 

If you look at the simulated IR from both the GFS and ECMWF, its completely devoid of convection after it emerges off Africa. Probably a non-event.

[Ground Scouring]

If you look at the simulated IR from both the GFS and ECMWF, its completely devoid of convection after it emerges off Africa. Probably a non-event.

And that would be a nasty waste of a good pattern. Models and teleconnections suggest that a west-based Bermuda High will slowly emerge in eight to 10 days. If nothing were to form in that time frame, it would allow precious time for a U.S./island impact to slip away. Long-range indicators suggest that activity may not pick up before early September, when a strong East-Coast trough is likely to re-emerge. And we have El Niño to contend with once late September rolls around. I'd say the season is toast.

[andyhb]

And that would be a nasty waste of a good pattern. Models and teleconnections suggest that a west-based Bermuda High will slowly emerge in eight to 10 days. If nothing were to form in that time frame, it would allow precious time for a U.S./island impact to slip away. Long-range indicators suggest that activity may not pick up before early September, when a strong East-Coast trough is likely to re-emerge. And we have El Niño to contend with once late September rolls around. I'd say the season is toast.

 

Can we just wait a bit and see how everything develops before constantly jumping through hoops and writing off the season like this?

 

I mean, long-range indicators haven't been on point this year with various synoptic details, so don't be too surprised if things look very different in one way or another down the line as peak season approaches. Let's not forget that the W Caribbean and Loop Current is locked and loaded should any wave develop outside of the MDR (perhaps towards the Carla Cradle).

[hurricaneman]

Can we just wait a bit and see how everything develops before constantly jumping through hoops and writing off the season like this?

 

I mean, long-range indicators haven't been on point this year with various synoptic details, so don't be too surprised if things look very different in one way or another down the line as peak season approaches. Let's not forget that the W Caribbean and Loop Current is locked and loaded should any wave develop outside of the MDR (perhaps towards the Carla Cradle).

You're right Andy, and while the models do nothing couldn't it be a case like with Bertha where the models barely do anything with it just for it to out perform the models

[wxtrackercody]

Things look quiet across the Atlantic basin in the short term, but I suspect activity will pick up some as we enter mid-August. For one, sea surface temperatures across the Atlantic have slowly been warming in recent weeks (as you would expect as we approach the peak). Secondly, ocean temperatures in the Gulf of Guinea have trended way down in recent weeks, which will tend to promote a healthier and farther north Intertropical Convergence Zone. Third, the MJO has been focused across the Indian Ocean for the past few days, also aiding in the formation of stronger-than-average tropical waves. This feature is forecast by the GFS to move into the Atlantic as we head towards the end of next month, which may help fight the overall bone-dry atmosphere. The CFS is also forecasting the progression of a convectively-coupled kelvin wave, albeit nothing particularly impressive, across the central Atlantic in the mid-late portions of the month.

[jaxjagman]

The control is showing some systems in the GOM in the long range,if they get sheared out or is real is another thing but at least we see something to look at

[wxtrackercody]

The tropical wave that just moved off Africa has organized quickly this evening. We'll see if that trend holds. In the absence of a CCKW or the MJO, I have doubts about this developing, but the GFS tracks this as a discernible feature across the tropical Atlantic, through the Caribbean, into the Bay of Campeche (where it finally organizes into a tropical storm), and ashore Mexico over the next two weeks.

 

[Superstorm93]

The tropical wave that just moved off Africa has organized quickly this evening. We'll see if that trend holds. In the absence of a CCKW or the MJO, I have doubts about this developing, but the GFS tracks this as a discernible feature across the tropical Atlantic, through the Caribbean, into the Bay of Campeche (where it finally organizes into a tropical storm), and ashore Mexico over the next two weeks.

 

 

 

 

Interesting. 

 

http://mp1.met.psu.edu/~fxg1/GFSTROPATL_0z/gfsloop.html

 

The GFS keeps this as a strong tropical wave that really could develop at any time on its way to the Caribbean. Wave actually looks decent with a sharp inverted-v look to it as well as plentiful convection. 

 

TROPICAL WEATHER OUTLOOK

NWS NATIONAL HURRICANE CENTER MIAMI FL

200 AM EDT SUN AUG 10 2014

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A tropical wave located just offshore of the coast of west Africa

is producing an area of disorganized showers and thunderstorms.

Any development of this system is expected to be slow to occur over

the next several days while it moves to the west at 15 to 20 mph.

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

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

$

Forecaster Blake

 

 

[GaWx]

The tropical wave that just moved off Africa has organized quickly this evening. We'll see if that trend holds. In the absence of a CCKW or the MJO, I have doubts about this developing, but the GFS tracks this as a discernible feature across the tropical Atlantic, through the Caribbean, into the Bay of Campeche (where it finally organizes into a tropical storm), and ashore Mexico over the next two weeks.

 

 

 Wow, this wave, aka pouch 013L, is surprisingly looking quite impressive. The 0Z Euro (just coming out), just like the 12Z Euro, does less with it (virtually no organization) through hour 156 vs. the 0Z GFS (no surprise). Regarding the MJO, it is now in phase 2 and forecasted to stay there for at least another week to ten days. This is actually not an unfavorable phase per 1995-2012 August stats as I mentioned earlier. These phase 2 stats by themselves (i.e., without taking into account the current and forecasted atmospheric setup) loosely suggest ~50% chance of it becoming a TD within the MDR over the next week or so fwiw.

[Srain]

There are at least two easterly waves that are worth monitoring, one that is offshore of Africa and another nearing Western Africa that may combine and track fairly far S along the ITCZ along or just S of 10N. The ensembles are suggesting that as the waves passed 40 and near 50W, the chances of TC genesis could possibly increase. Check back tomorrow and see if the convection is still active as these waves move W around 20 MPH. There is still a good bit of dust across the MDR and convection would need to remain attached to the ITCZ to survive the trek across the Atlantic in the short term. 94L has been designated for this disturbance.

[Kory]

Subtropical ridge looks to hold a bit strong with this wave than with Bertha.  Practically a W to WNW track from it.