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Atlantic Invest Thread 2011


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Posted
  • Location: Dorset
  • Location: Dorset

Invest 93L looks to have a very nice tidy circulation, however there is a lack of centred convection due to speed induced shear. Track is to the south of general model guidance into Mexico, if convection can flare and sustain this might still make a TD/TS IMO, still very unlikely but not the 0 chance that NHC have it at.

The soon to be 94L has grown considerable convection so instability is definately there, NHC have upped it from 10 to 20% chance to form a TS over the next 48 hrs, this is likely to increase further IMO over the coming 36 hrs.

Location is the biggest problem as it's an area where it can take days for a large envelope system to get the tighter circulation needed to sustain any warm core winds.

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Posted
  • Location: in Croatia
  • Location: in Croatia

93L is looking sheared.

NHC invest outlooks:

ZCZC MIATWOAT ALLTTAA00 KNHC DDHHMMTROPICAL WEATHER OUTLOOKNWS NATIONAL HURRICANE CENTER MIAMI FL200 AM EDT FRI JUN 3 2011FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...1. A BROAD LOW PRESSURE AREA CENTERED A FEW HUNDRED MILES EAST OFNICARAGUA CONTINUES TO PRODUCE A LARGE REGION OF DISORGANIZEDCLOUDINESS AND SHOWERS OVER THE CENTRAL AND SOUTHWESTERN CARIBBEANSEA. ANY DEVELOPMENT OF THIS LOW IS LIKELY TO BE SLOW TOOCCUR...AND THERE IS A LOW CHANCE...10 PERCENT...OF THIS SYSTEMBECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS. HOWEVER...UPPER-LEVEL WINDS COULD BECOME MORE CONDUCIVE FOR DEVELOPMENT AFTERTHAT TIME. HEAVY RAINS COULD CAUSE FLASH FLOODING AND MUD SLIDESOVER PORTIONS OF HAITI...THE DOMINICAN REPUBLIC AND JAMAICA OVERTHE NEXT DAY OR TWO AS THE LOW REMAINS NEARLY STATIONARY.<a name="2">2. A SMALL AREA OF LOW PRESSURE IS PRODUCING LIMITED SHOWER ACTIVITY ACOUPLE HUNDRED MILES NORTHWEST OF THE YUCATAN PENINSULA. UPPER-LEVEL WINDS ARE BECOMING HOSTILE FOR DEVELOPMENT...AND THERE IS ALOW CHANCE...NEAR 0 PERCENT...OF THIS SYSTEM BECOMING A TROPICALCYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WESTWARD AT ABOUT 15MPH.ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THENEXT 48 HOURS.$$FORECASTER BLAKENNNN

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Posted
  • Location: Dorset
  • Location: Dorset

At last we have 94L, a bit sooner than I expected tbh, but some circulation is in evidence south of Jamaica under a large cyclonic envelope with good instability and moisture.

NHC have upped this to an Orange alert with a 30% chance of developing in to a storm over the next 48 hrs, which seems reasonable. 94L should still take 48 hrs or so to tighten (if it wants to), however this could be shorter if strong convection develops over the centre later today, or longer if it stays pretty ragged re convection which it looks like now.

The path of 94L is very difficult to judge, partly as the models are not yet initialising it very well, but also because steering currents are due to be very weak, it could well stay around or to the west of Jamaica for a good 3-4 days yet. HWRF takes a beeline for the Atlantic which gives it the ability to take it to just CAT 1 status in 5 days time, but the model guidance below shows the most likely path.

Intensity looks to be a slow burner, SST's are 27.5 to 28.5 generally, so low but able to sustain a tropical storm, but it will probably take it a little longer to get going than later in the season. So Maybe a TD in 48 hrs and maybe a TS in 72, if things go well.

Certaintly a nice little invest to start this early in the season.

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post-6326-0-81891700-1307166757_thumb.pn

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Posted
  • Location: Dorset
  • Location: Dorset

um....

This could be getting better organised, see below, if it has a centre underneath that mass then thats a good CDO. However thats a big IF as without visual sat it's difficult to see whether it's just a flare up of convection on the eastside.

There could be multiple centres still so it's all very fluid.

Models are still not initialising it very well so are of little use atm.

post-6326-0-21809300-1307183029_thumb.jp

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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

93L has made landfall on the Mexican coastline as a largely naked swirl of clouds.

94L has taken a step back in terms of organisation. Messy convection resides well east of the broad, sprawling LLC. Dry air is really disrupting development by supressing convection near the system's centre. Until the environment improves, 94L is not going to develop further.

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Posted
  • Location: Dorset
  • Location: Dorset

94L has now been upped to 40% by the NHC so the chances of development are still increasing. Good convection, however it's still displaced due to shear and the instability is still very much east based.

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Posted
  • Location: Norwich, Norfolk
  • Weather Preferences: Heavy Snow, Thunderstorms & Summer Plumes
  • Location: Norwich, Norfolk

To me its really starting to wind up looking at the visible satellite, especially in the last hour or so. I'd say a the NHC will upgrade its chances to over 50% fairly soon.

http://www.ssd.noaa.gov/goes/flt/t2/flash-vis.html

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Posted
  • Location: Dorset
  • Location: Dorset

Going from the NHC the feature which is pepping up the convection to the east of the low is a moonsoonal trough stretching from the pacific through central america into that part of the caribbean.

This is probably making the system seem far more organised than it really is.

Hurricane Hunters are due to fly into the system later today on a fact finding/training mission.

However even given the above, low level circulation is evident and the convection associated with the trough might be the spark that lights invest 94L up.

Still given the above is will be awhile before anything happens, from day 3-4 onwards it should get caught in a stronger directional flow and speed should increase alot as it moves into the GOM proper on a NE path.

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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

Any update?

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Posted
  • Location: Dorset
  • Location: Dorset

94L pretty much died a death when it moved out of the move favourable environment to the west of Jamaica. It was sheared and suffered from a lack of convection, which prevented from a decent LLCC from forming.

The ITCZ atm is taking a die into S.America at the equator and is a longway from being in a good place, in fact the ITCZ is probably about as bad as you can get atm.

Personally I don't think much will change until we get the N.Hemisphere long wave length change in place which will bring us better weather for the UK. This should happen, but it's more and more looking end of June now.

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  • 3 weeks later...
Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

Now up to 90%. The circulation is well defined but the convection is not organised at present. However, with a well defined LLC in place, decreasing shear and warm sea temps, it shouldn't be long before this is rectified. Looks like we will have the Atlantic's first TD tomorrow!

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Posted
  • Location: Tiree
  • Location: Tiree

TCFA issued!

Tropical Cyclone Formation Alert

SUBJ/TROPICAL CYCLONE FORMATION ALERT//

WTNT21 KNGU 281530

RMKS/

1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN

100 NM EITHER SIDE OF A LINE FROM 20.0N 93.0W TO 20.5N 97.2W

OVER THE NEXT 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY

ISSUANCE OF A NUMBERED TROPICAL CYCLONE WARNING AT THIS TIME.

2. REMARKS: A BROAD AREA OF LOW PRESSURE OVER THE SOUTHERN BAY OF

CAMPECHE IS PRODUCING NUMEROUS THUNDERSTORMS OVER THE AREA. WARM

SEA SURFACE TEMPERATURES OF 83 TO 85 DEGREES FAHRENHEIT AS WELL AS

AN UPPER LEVEL ANTICYCLONE OUTFLOW MAY ENHANCE DEVELOPMENT OF THIS

SYSTEM. WIND SHEAR VALUES OF 20 TO 30KTS OVER THE REGION ARE NOT

CONDUCIVE FOR DEVELOPMENT AT THIS TIME BUT ARE EXPECTED TO DECREASE

OVER THE NEXT 24 HOURS.

3. THIS ALERT WILL BE REISSUED, UPGRADED TO A WARNING OR ALLOWED TO

EXPIRE BY 291530Z.//

al952011.11062818.gif

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  • 2 weeks later...
Posted
  • Location: in Croatia
  • Location: in Croatia

And we go!Inves 96L came!

Satellite image:

post-15004-0-76399500-1310046186_thumb.j

Models say Bret

post-15004-0-11991700-1310046212_thumb.g

I think 96L has biggest chances of developing if it moves NNW.

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Posted
  • Location: Taunton, Somerset
  • Weather Preferences: Snow, thunder, strong winds
  • Location: Taunton, Somerset

A small area of low pressure in the Bay Of Campeche has been declared invest 97L, and the NHC give 97L a 50% chance of becoming a tropical depression before moving inland tonight. Convection has certainly become more concentrated near the LLC but it will really have to get a move on because it only has about another 9 hours over water.

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