atlantic hurricane season Atlantic hurricane season/invest thread

[Nouska]

Invest 99L - GFS 06Z run.

That would be a huge boost to the Atlantic basin ACE (accumulated cyclone energy) and a worrying time for forecasters!

An edit for the 12Z .... into Gulf of Mexico on this run!

It will keep folk on their toes for a few days.

Edited August 19, 2016 by Nouska

[mezzacyclone]

7 hours ago, Nouska said:

Invest 99L - GFS 06Z run.

Etc etc

All eyes on the next ECM models as they are still more or less out on their own with little to no development,

I reckon their next outputs (00z) will start to show signs as 99L has REAL potential!

Edited August 19, 2016 by mezzacyclone

[Nouska]

The 12Z ECM does nothing with it - open wave on a very southerly path. ECM does develop the wave behind and goes fishing with a tropical storm in late run.

Latest satellite. Fiona is the little storm to the NW.

Good sense of broad circulation - potential for a big storm if it does develop per GFS

[summer blizzard]

GFS18z is an east coast hit at 979mb (cat 2).

GFS seems to have decided it wants development, the question is how strong the ridging is. 

Of course the Euro kills it. 

[mezzacyclone]

So the euro develops it but fades east of the bahamas,

But bombs the current aew or "pouch 23"? (NHC 40% thru 5 days)  Rolling through senegal, guinea-bissau, guinea, SL etc now! Albeit another "fiona flounder" no westward than 60degs?

crazy MDR volatility with a uber-busy atlantic at last.

Lots to follow in the short term with high possibilities of an east coast major long overdue?

 

[summer blizzard]

3 of the last 4 GFS runs have had 99L in the Gulf. 

[damianslaw]

I thought this year was forecast to see a more active hurricane season than many recent ones? What has caused the long run of very quiet seasons - is this normal? 2005 was the last active one I think..

[Nouska]

For this year, a more definite La Nina was expected by this stage - considered to be more favourable for development.

Looks like invest 99 potential is being downgraded and focus now on the pouch (future 90L) about to emerge. Unusual to see the NHC so bullish about a system this early.

http://www.nhc.noaa.gov/gtwo.php?basin=atlc&fdays=2

2. A tropical wave located inland over western Africa is producing a large area of cloudiness and thunderstorms. This wave is expected to move offshore tonight and environmental conditions appear conducive for gradual development while it moves generally west-northwestward over the eastern tropical Atlantic Ocean during the next several days. * Formation chance through 48 hours...low...10 percent * Formation chance through 5 days...medium...50 percent Forecaster Cangialosi

The 168 charts from ECM and UKMO - quite a lot going on - just need to wait for the models to sort it all out.

     

http://ruc.noaa.gov/hfip/tcgen/

 

[mezzacyclone]

50 minutes ago, Nouska said:

Unusual to see the NHC so bullish about a system this early.

 

Indeed, cant recall a disturbance & "unofficial" invest (90l) over east african land before?

maybe its simply the shear mass & broadness of these latest waves thats got everyone on alert besides the relatively positive conditions for developments?

recon for 99l out tuesday pm btw! 

*UPD* euro trickling out now but 12z gfs develops (future?) 90l to a cat3 953mb 'cane now perilously close to long island! :o but thankfully staying off-shore. I assume FI has zero credence with eastern seaboard folk? 

Edited August 20, 2016 by mezzacyclone

[Mapantz]

5 hours ago, Nouska said:

For this year, a more definite La Nina was expected by this stage - considered to be more favourable for development.

Lag effects of the immense El Nino still creating pertinent vertical shear? I must admit, I haven't followed much of this progress this year. Has there been many tropical depressions this year, that have just dissipated?

Edited August 20, 2016 by Mapantz

[Jack Wales]

HI  I'm currently in Florida so watching both 99l and 90l with great interest.   The Atlantic ridge into the USA seems to be robust so it's likely that both systems will end up close to my location.  The only mitigating factors appear to be dry air entrainment...  Any thoughts anyone? 

[Nouska]

10 hours ago, Mapantz said:

Lag effects of the immense El Nino still creating pertinent vertical shear? I must admit, I haven't followed much of this progress this year. Has there been many tropical depressions this year, that have just dissipated?

I think so and MJO phase is currently not the best for Atlantic basin activity. I think anything that made TD status has been named so it's not that they faded, just very little activity till now. Six named systems with two out of season may also skew the perspective. Earl was a long tracker but, typical of recent years, couldn't stack and competing vortices till land interaction both weakened and stacked.

This is the classic time of year for the long track Cape Verde systems and we may have a nice one to look at this coming week - models are all over 90L this morning. The big three below at day 6.

9 hours ago, Jack Wales said:

HI  I'm currently in Florida so watching both 99l and 90l with great interest.   The Atlantic ridge into the USA seems to be robust so it's likely that both systems will end up close to my location.  The only mitigating factors appear to be dry air entrainment...  Any thoughts anyone? 

The models all downgrading Florida threat but it's while away - keep looking!

[summer blizzard]

On 8/20/2016 at 17:02, damianslaw said:

I thought this year was forecast to see a more active hurricane season than many recent ones? What has caused the long run of very quiet seasons - is this normal? 2005 was the last active one I think..

Ha. 2005 was the most active season on record with more than twice the average named storms. 

2007, 2008, 2010, 2011, 2012 and 2013 were all above average. 

The season to date looks on track to match the NHC forecast of the most active since 2012, by the time August is out we may have seen our first major.

..

You may imagined the other seasons being poor due to quality, 2012 and 2013 failed to produce even one category 4 and the last seasons were on the lower end of average (though the quality went up markedly). 

 

[mezzacyclone]

Gaston AND Hermine next sunday anyone? :O

[knocker]

 

[mezzacyclone]

90l (or td7 later today? given shear size taking time to come together): Euro & gfs both offer a cat 3/4 NW-wards near bermuda then sharp NE turn between azores & NE conus ridges,

99l shows a messy low around the bahamas & S fla,

wild variations for a few more days but with all emphasis rightly on 90l & its fishy future then i'm sure 99l is not totally discarded & could still be a far bigger player when alls done? (99l Recon still poss & yet to be confirmed for tues?)

 

[Nouska]

90L has a big, broad circulation seen on mimic Pwat - enough moisture envelope to fight off any dry air?

Should be classed TD shortly and maybe Gaston by tomorrow.

http://tropic.ssec.wisc.edu/real-time/mimic-tpw/natl/main.html

 

[Singularity]

Snapshot courtesy of the Earth Nullschool site;

There's Fiona in the top-left, which has started firing persistent deep convection again having survived a region of near 30 knot wind shear. There's a window of lighter wind shear and SSTs rising to near 30*C which could allow a bit of a resurgence before a new area of strong wind shear may well signal the end for this cyclone... or maybe not, given its resilience so far.

Southeast of that is 99-L. Despite firing plenty of deep convection over the past 6 hours or so, the low level circulation needs some work to close off - though a relatively tight one might well be close to establishing now.

Lower-right of the image is 90-L. This system seems freakishly large, and I have seen an upper-level low plotted in its location on some weather maps... meaning we are looking at a stacked cyclone of gargantuan proportions that already extends through much of the troposphere. Given an often favourable environment ahead of it, it seems little wonder that GFS and ECM are consistently producing a category 5 out of it. This occurs while it's tracking well offshore from America, and the storm appears highly likely (Bermuda could take a hit, but being small, the odds are automatically low at this range) to 'recurve' and head into the Atlantic without landfall as a tropical cyclone. If that happens it will be among the only - or perhaps the first - category 5 hurricanes not to make landfall, due to the rest having occurred well within the tropics and hence closer to the Americas. I wonder if it could also be one of the very largest hurricanes - more akin to a Pacific super-typhoon.

[Nouska]

A super wide view of tropical activity - it's been a long time since we have seen such a potentially busy picture in the Atlantic.

Just caught your post there @Singularity I don't need to point out which is which - you've explained nicely. Another big blob of convection about to depart Africa - it's all go.

Edited August 22, 2016 by Nouska

[mezzacyclone]

So all we are missing is a well defined circulation ???

forgive me but everything including the kitchen sink is right in their on the latest images!

hold the front page!?

we finally have TD7! (New NW thread TD7)

 

Edited August 22, 2016 by mezzacyclone

[summer blizzard]

99L appears to be getting some model support for development, the last Euro's especially have had the panhandle seeing a cat 2/3. It's also firing -80C cloudtops this morning.

Currently we do have a broad low underneath the convection and now a 60% chance of development.

Looks like dry air is the main problem as well as Fiona's remains. 

Edited August 23, 2016 by summer blizzard

[mezzacyclone]

2 hours ago, summer blizzard said:

99L appears to be getting some model support for development, the last Euro's especially have had the panhandle seeing a cat 2/3. It's also firing -80C cloudtops this morning.

Currently we do have a broad low underneath the convection and now a 60% chance of development.

Looks like dry air is the main problem as well as Fiona's remains. 

Easy to see why folks are concentrating on this more than TS Gaston across the pond!

oh, recon off this evening (BST time) to investigate

Edited August 23, 2016 by mezzacyclone

[summer blizzard]

1 hour ago, mezzacyclone said:

Easy to see why folks are concentrating on this more than TS Gaston across the pond!

oh, recon off this evening (BST time) to investigate

Circulation is too broad and not really closed off. It won't be declared tonight however it's making progress. 

[Jack Wales]

99l is definitely firing up with very cold cloud tops and signs of it beginning to establish a circulation. Proximity of dry air doesn't seem to be affecting the system at the moment and with it moving into a much more favourable environment, there's definitely scope for significant intensificstion by the end of the week.  What's more of a concern is that models are becoming more aligned with the forecast track taking 99l across the Bahamas and Florida. 

[mezzacyclone]

well recon`s off out from the US virgin islands and headed east over Antigua so its data findings wont be long