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Atlantic Invest Thread 2010


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Posted
  • Location: Western Isles
  • Location: Western Isles

    This thread is for discussing invests as and when they form.

    The low off Brazil has been declared and invest see the link below

    90L

    11_16482_eb5fbb1718281d1.jpg

    sastorm2.gif

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Invest 90Q looks very well organised, and we couldbe on for a very rare tropical cyclone formation in the normally hostile South Atlantic. 90Q is evidently still suffering moderate to high levels of shear, but a strong circulation has developed despite this, and convection is deep to the east of the LLC. I give this one a 50% chance of becoming a tropical cyclone in the next couple of days. Seems very odd to be discussing an invest in the South Atlantic. They really are rare creatures!!

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    Posted
  • Location: Warwick and Hull
  • Location: Warwick and Hull

    The ever reliable wikipedia says this is a subtropical system. Dunno if that's already been mentioned here, but if not, consider yeselves informed =)

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    Posted
  • Location: Liphook
  • Location: Liphook

    Without any doubt that is a tropical storm in all but name, but because of the lack of naming conventions down there and the fact Brazil just will not ever accept tropical cyclones can develop down there, even if rarely (I'm guessing it'd hurt thier tourist trade possibly?) is probably why this one will never get named/numbered...depsite it so obviously being a tropical storm right now.

    Operationally its being called just a low, though its winds are at 40kts, with a small and tight CDO slightly displaced to the SE of the system due to some shear being imparted on the system. Its a marginal evolution hence the convection isn't very deep at all but we've seen similar systems develop in the Atlantic, esp the NE part of the basin so no reason to think this one is any different.

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    Posted
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield
  • Weather Preferences: Any Extreme
  • Location: Sheffield South Yorkshire 160M Powering the Sheffield Shield

    Is this one of the earliest????

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    Posted
  • Location: Warwick and Hull
  • Location: Warwick and Hull

    There have been earlier tropical systems in the North Atlantic (The Groundhog Day storm in Feb 1962 for one), but the South Atlantic doesn't get included in this given that its "season" peaks at opposite times to the North Atlantic.

    Also, it appears the system has been declared fully tropical as Invest 90Q. http://www.nrlmry.navy.mil/TC.html

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    Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds. HATE:stagnant weather patterns
  • Location: Taunton, Somerset

    Been classified now as a tropical storm by NWS:

    NWS HYDROMETEOROLOGICAL PREDICTION CENTER CAMP SPRINGS MD

    847 AM EST WED MAR 10 2010

    GFS DATA AT FTPPRD.NCEP.NOAA.GOV/PUB/DATA/NCCF/COM/GFS/PROD/

    SYNOPSIS (VALID FROM 00Z MAR 10). THE UPPER LEVEL ANALYSIS SHOWS

    A CLOSED LOW NEAR 33S 45W EXTENDING A SHORT WAVE TROUGH TO THE

    NORTHWEST INTO BRASIL ALONG 20S 50W. THIS FEATURE IS DECOUPLING

    FROM A WARM CORE SURFACE LOW OFF THE COAST OF BRASIL...WITH

    CLOSED CIRCULATION ESTIMATED NEAR 29.6S 48.2W. ALTHOUGH A

    TIGHT/COMPACT STORM...IT IS NOW CLASSIFIED AS A TROPICAL CYCLONE

    RATHER THAN SUBTROPICAL.

    A rare beast!

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    Posted
  • Location: Liphook
  • Location: Liphook

    Yeah NOAA have also stated its a tropical depression, though quite clearly data supports a tropical storm right now, as does the offical best track at 40kts.

    Still its not going to get named because there is not a naming convention down there, probably because of the relative rarity of it. The NHC won't interfere this time like they did with Carina unless it really powers up but shear conditions and water temps are only marginal so strengthening isn't likely to be impressive, if it strengthens any more at all.

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    • 2 months later...
    Posted
  • Location: Liphook
  • Location: Liphook

    I'd personally wait for another 24-36hrs before doing anything with this system.

    Anyway we have an extratropical low which is being enhanced by the upper low nearby with the shear actually developing the low via Baroclinic forces (in simple terms, non-tropical development) and 90L right now very likely isn't at all tropical right now. Shear is clearly high over the system and therefore conditions don't appear condusive for development for a while yet IMO.

    That being said the global model solutions take this system westwards and deepening it and I think 48-72hrs time things will become increasingly interesting because the track takes this system over the Gulf Stream where waters are high enough for a system to transtion to at least subtropical and I think thats certainly a real possiblity, though the process is already possibly underway because whilst SST's aren't quite warm enough the upper level low has brought colder then normal upper temps with it meaning the lapse rates will lead to similar development to what you'd normally expect in borderline SST's (say 26C).

    Anyway Subtropical development is very possible, tropical development is also something I wouldn't totally rule out if shear eases over the Gulf Stream...either way it seems this system may well get quite close to the coast if the global models are to be believed.

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    Posted
  • Location: Dorset
  • Location: Dorset

    Completely agree shear is very high 40+ atm, with a let off in shear this could turn into something, but that's not going to happen soon, still nice to see an invest already.

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    Posted
  • Location: Dorset
  • Location: Dorset

    Shear is letting up a little, but is still effecting it alot.

    It's had a pep up from the nearby none tropical low.

    The big question is whether this is tropical or not, NHC are saying not atm, with the reason that the convection is not based around the core.

    However Phase analysis does make it marginally tropical and the lack of convection near the centre could be just down to shear.

    Shear might well ease of enough over the next day or two to allow this to become a TD/TS, the hurricane models are still keen to give 40/50 kt winds

    A case of looking at the visible loops and see where the circulation is.

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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    http://www.ssd.noaa.gov/goes/east/catl/avn-l.jpg

    Definitelty sub-Tropical now looking at the satelite images.

    Wave near 40W has also turned north west, so this could be the best candidate for development in the next few days.

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    Posted
  • Location: Dorset
  • Location: Dorset

    NHC now have an orange alert

    SPECIAL TROPICAL WEATHER OUTLOOK

    NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

    825 PM EDT SUN MAY 23 2010

    FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

    A NON-TROPICAL LOW PRESSURE SYSTEM CENTERED ABOUT 500 MILES

    SOUTH-SOUTHWEST OF BERMUDA IS PRODUCING A LARGE AREA OF

    DISORGANIZED SHOWERS AND THUNDERSTORMS OVER THE SOUTHWESTERN

    ATLANTIC OCEAN ALONG WITH GALE-FORCE WINDS. THIS LOW IS EXPECTED

    TO MOVE SLOWLY TOWARD THE NORTH-NORTHWEST AND HAS SOME POTENTIAL

    TO GRADUALLY ACQUIRE SUBTROPICAL OR TROPICAL CHARACTERISTICS DURING

    THE NEXT COUPLE OF DAYS. THERE IS A MEDIUM CHANCE...30

    PERCENT...OF THIS SYSTEM BECOMING A SUBTROPICAL OR TROPICAL CYCLONE

    DURING THE NEXT 48 HOURS. FOR ADDITIONAL INFORMATION...PLEASE SEE

    HIGH SEAS FORECASTS ISSUED BY THE NATIONAL WEATHER SERVICE...UNDER

    AWIPS HEADER NFDHSFAT1 AND WMO HEADER FZNT01 KWBC. THE NEXT

    STATEMENT ON THIS SYSTEM WILL BE ISSUED BY MIDDAY MONDAY.

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    Posted
  • Location: Dorset
  • Location: Dorset

    Yep Shear of around 30kts will make it difficult to get good centered convection, rather than the frontal stuff that is still evident now.

    However if this does make a move to develop tropical charecteristics it will immediately be a named TS given the current winds.

    Still a 50/50 chance of getting a TS in May IMO.

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    Posted
  • Location: Liphook
  • Location: Liphook

    Still not that impressed with this system, 90L is currently a multiple low system with at least 2 centers currently rotating around a broad circvulation. Given the convection is still being sheared off to the NE I'd expect the northern low eventually take over in the next 12-18hrs and the circulation further south to open up and weaken...

    Once that does happen then the chances of the NHC calling this system will increase however shear profiles are still causing problems for this system and whilst they are probably just good enough for development of a lop-sided system, whether the NHC pulls the trigger remains to be seen...very much 50-50 as Iceberg said.

    My call would probably for this to not get upgraded but its going to be very close, there is probably a weak warm core with this system which means it probably would be sub/tropical in nature now, though it may start to lose those properties again in the next 24-36hrs as it moves northwards and the upper low which has helped to increase the lapse rates and allow the formation of a small warm core in the first place. Whether or not it can sort itself out in the next 24-36hrs is very much in the air, I wouldn't rule it out but at the same time I wouldn't expect it either.

    whatever happensi t should lift northwards slowly before heading NE as an upper low moves eastwards to the systems north and takes whatever is left out to the cold Atlantic but I'm sure we will have plenty more invests even if this one doesn't make it!

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    Posted
  • Location: Dorset
  • Location: Dorset

    Still alot of dry air around and shear is definately hampering things, some precip sparking near the centre but it's quickly being displaced NE.

    The secondary centre is almost dead now,

    Visual loops show good circulation though and it all depends on an environment getting a little less harsh.

    Personally the firing up of convection hear the centre would indicate at least sub-tropical charecteristics but agree that currently there is not enough for it to be truely tropical.

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    Posted
  • Location: Liphook
  • Location: Liphook

    Very interesting system but still doesn't appear any further along the way to being upgraded. I'd suspect this system probably does have a slight warm core and thus I'd say its likely a subtropical system however convection is still well displaced from the center.

    Looking at all the maps whilst the shear has eased down the convergence is stidll shunted well N/NW of the systems center which not really helping to develop convection closer to the center, which is generally whats going to be needed to getm this thing upgraded.

    Conditions generally probably about as good as they are going to get in the next 18hrs or so as it slowly moves NNW towards the Gulf Stream, however at the same time the upper low is weakening so any gains in the sea surface temperatures that the4 system will see in the next few days as it moves towards the Gulf may be nuillified by decreasing upper temps, will need to be watched though in case this doesn't happen...

    Right now I'd put the risk somewhere between 20-30%, if convergence increases near the center of the system then I still wouldn't totally rule it out becoming a STS but I wouldn't think its that likely right now, the convection must start to develop closer to the systems circulation center if its going to get an upgrade, probably has another 24-48hrs of decent conditions aloft before it slowly gets ejected eastwards as the upper level trough to the north of the system moves eastwards away from E.Canada.

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