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Tropical Storm Dorian


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

The fourth tropical depression of the Atlantic season has formed in the Eastern Atlantic. Winds are at 30kts. Strengthening is expected initially, but dry air, increasing shear and marginal sea temps are expected to dampen significant strengthening on the west-northwest track.

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

The small tropical depression has intensified this afternoon, and is now Tropical Storm Dorian, with sustained winds of 45kts. Banding features have formed this afternoon, encircling the convection covered LLCC. Dorian could strengthen a little more over the next 24hrs as shear remains low and waters warm. Beyond this time, Dorian will move over cooler waters and into a dry and stable airmass, which will likely cause the small storm to weaken. As Dorian moves just to the north of the Eastern Caribbean in about 4 days time, shear is currently expected to rise, but waters will warm up again along track. It is unclear just how this will affect Dorian. If the shear is less than expected, Dorian could strengthen significantly at this time.

 

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Edited by Somerset Squall
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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

Definitely an interesting track. If it makes it the important point will not only be shear but whether a trough picks it up. 

 

As an optimist and with it being July i'll plump for a category 2 hitting the Carolina's.

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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

Now at 50mph and looking very good.

Cooler waters not expected to be a significant issue now so we may well see steady strengthening for the next 4 days. Its main challenge is an ULL over the Bahamas which could shear it, although it also slows down significantly over these warm waters and if it becomes a large storm may fight the ULL. Afterward I would expect strengthening as it approaches shallow coastal waters close to landfall or gets barlonic forcing as it is picked up.

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Posted
  • Location: Eastbourne, East Sussex (work in Mid Sussex)
  • Location: Eastbourne, East Sussex (work in Mid Sussex)

 

Tropical Storm Dorian Moves West Across the Atlantic Ocean
 
Tropical Storm Dorian moved across the Atlantic on a westward path that may take it to the Caribbean Sea, the U.S. National Hurricane Center said.
 
Dorian, with top sustained winds of 50 miles (80 kilometers) per hour, was about 615 miles west of the Cape Verde Islands, according to a center advisory at 11 p.m. New York time yesterday. It was moving west-northwest at 20 mph. Little change in Dorian’s strength is forecast for the next 48 hours and maximum sustained winds will remain near 50 mph, according to the advisory. A west-northwestward to westward motion at a similar forward speed is forecast through tomorrow, the center said.
 
Dorian is the fourth tropical storm of the Atlantic season, which runs from June 1 through Nov. 30. It’s ahead of schedule: from 1966 to 2009, the fourth system typically formed by Aug. 23, according to the hurricane center. Weather models are in good agreement that Dorian will continue to move west, Stacy Stewart, a senior specialist at the center in Miami, said yesterday. Forecast maps, which project only five days ahead, show it tracking north of Puerto Rico by July 29. The storm may encounter wind shear, cooler ocean water and dry air, which may rob it of strength or tear at its structure.
 
U.S. Threat
 
If Dorian can hold together as it crosses the Atlantic, there’s a possibility it may bring wind and rain to the U.S. South or the Bahamas early next week, Michael Schlacter, founder and president of Weather 2000 Inc. in New York, said yesterday. “It does have some hoops to fly through,†Schlacter said by phone. “If we get past 96 hours and it’s still some sort of system, then all of a sudden things will start to become clear to people. There’s a built-in risk of an anticlimax here because it is off of Africa. We have a long, long time to watch this.â€

 

 

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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

60mph and a beauty, bit of dry air though.

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

Dorian has strengthened to 50kts. The storm retains some persistant convection over the LLCC, and good banding features. A wall of dry air is awaiting Dorian however, which could weaken the small storm over the next day or two. Thereafter, it looks like Dorian could strengthen again as shear is not expected to be as high as previously thought in a few days time, and Dorian should move into a moister airmass again.

Edited by Somerset Squall
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Posted
  • Location: Dorset
  • Location: Dorset

Evening, been watching Dorian for a little while its a very classy looking storm. Totally right SS, its going to have a tricky 48 hrs, all the models agree on this, with both dry area, slightly higher shear and some limited inflow according to the NHC discussion.

The models pick up on this and introduce stronger southerly shear for its whole life, something which NHC havent really mentioned. Most of the models have the shear possible stopping the LLCC. ECM the strongest, while GFS shows the shear with far less effect.

Path once we get to the islands is very variable as well, depending on how developed the storm is.

It will be interesting to watch it over the next day or 2 to see how its effected.

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Posted
  • Location: s yorks
  • Weather Preferences: c'mon thunder
  • Location: s yorks

,Has had impressive convection from the outset and the current wedge of dry air to the NW is diminishing by the hour,
the earlier "nearly closed low level eye" was interesting, as is the proximity of warmer sst`s (entering higher sst`s very soon) AND disputed SWerly shear forecasts in its path on approaching 60W
Dorian is a very interesting little storm and has every chance of packing more of a punch than Chantal with heightening concerns for the eastern seaboard,
we`ll just have to follow the US conus surface maps for any troughs or shortwaves (lack of?) and Bermudan ridging to try seeing where this goes, IF it progresses? which looks more and more likely, something fun to monitor over the weekend Posted Image

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

Latest satellite imagery shows Dorian becoming cut off from the moist southwesterly inflow from the ITCZ. Convection appears to be weakening too currently, will be interesting to see if this persists. Now the system is losing the support from the ITCZ, I think it may suffer over the next day or so.

post-1820-0-07857000-1374793113_thumb.jp

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

As expected, Dorian has weakened to 45kts this morning as dry air engulfs the storm. Dorian has only meager convection over the LLCC, but should still eventually recover once it heads west of 60W. Dorian is expected to pass close to the northern coast of Hispaniola on the current track, so if Dorian is restrengthening at this stage it could bring flooding rains here. The impact will be lessened by a more northerly track.

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Posted
  • Location: Dorset
  • Location: Dorset

Yep, Dorian is being effected by the dry air, also the cut off inflow and the southerly shear is very evident. A chance imho that the LLCC will be lost due to mentioned factors and the faster forward speed as the LLCC seems to be struggling to keep up with the faster pace convection.

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Posted
  • Location: Eastbourne, East Sussex (work in Mid Sussex)
  • Location: Eastbourne, East Sussex (work in Mid Sussex)

 

Tropical Storm Dorian Weakens in Path Across Atlantic
 
Tropical Storm Dorian weakened as it moved across the Atlantic, according to the U.S. National Hurricane Center. Dorian, with maximum sustained winds of 50 miles (80 kilometers) per hour, was about 1,550 miles east of the northern Leeward Islands and moving west-northwest at 20 mph, according to a center advisory. “Little change in strength is forecast through late Saturday,†according to the advisory. The storm is forecast to continue on its current trajectory before a gradual turn to the west with an increase in forward speed later today. The center’s five-day projection has Dorian passing north of Puerto Rico on the evening of July 29.

 

 

http://www.bloomberg.com/news/2013-07-26/tropical-storm-dorian-maintains-strength-on-path-across-atlantic.html

 

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Posted
  • Location: s yorks
  • Weather Preferences: c'mon thunder
  • Location: s yorks

Plagued by the Dry air  clearly visible and really struggling after initial signs of a decent system?

Overall consensus that degeneration into a wave now favored?

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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

Plagued by the Dry air  clearly visible and really struggling after initial signs of a decent system?

Overall consensus that degeneration into a wave now favored?

Too early to suggest at this stage. Its clearly being sheared to the south but its still fairly tight and only lost 2mb between advisories. I'd suggest that it would be better to see what it does tonight and evaluate tommoro
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Posted
  • Location: Eastbourne, East Sussex (work in Mid Sussex)
  • Location: Eastbourne, East Sussex (work in Mid Sussex)

Tropical Storm DORIAN: Probability of Cat 1 or above winds to 117 hours lead

 

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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

Dorian struggling and worse than earlier but it does still have persistent convection over the center. Tracks are very mixed as some weak runs even now have it slide under Haiti and then head for Texas.

Question, I have heard previous that some systems can be shielded from shear. Would the semi circular cloud rotating from its north to west act in such a way?

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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

Now up at 1006mb, this thing needs a good night or its dead.

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

Intensity now down to 40kts, I don't think Dorian is long for this world unless he comes back tonight as you say SB. Dangerously close to opening up into a wave IMO, the fast forward speed and associated shear/dry air have really hit Dorian, hard. With Dorian is such a weak state, I find it difficult to see how it can survive at least another 2 days of environmental hostility.

 

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Edited by Somerset Squall
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Posted
  • Location: s yorks
  • Weather Preferences: c'mon thunder
  • Location: s yorks

Dorian has commonality with our Winter watchers who experience the high and low rollecoaster rides :D as although it looked done last night then recent improving convection has reformed somewhat and ASCAT passes still give evidence to maintain TS structure with 40kn winds.

After the mid and lower separation mentioned above yesterday he was in tatters but popcorn convection boomed just after mid night and has clearly put Dorian back in the fore IMO so a couple more advisories at least?

Disputed shear levels ahead as original high forecasts are now lowering?

With favorable sst`s on the home run and the last dry air has been rolled in then I think Dorian will prosper but i guess no one has absolute proof of his longevity?

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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

Its extremely weak but the center does appear to be aligned again which is a positive. Relative shear could be an issue with the speed but for now its purely dry air that looks to be the issue unlike shear which was tearing it to peices yesterday.

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

Convection definitely on a downward trend again this evening. Dorian has done well to last this long but dry air still a big problem as SB said, and though shear is lower, it is not ideal, especially for a system this weak. He made it through last night after looking dead, can he do it again?

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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
Convection definitely on a downward trend again this evening. Dorian has done well to last this long but dry air still a big problem as SB said, and though shear is lower, it is not ideal, especially for a system this weak. He made it through last night after looking dead, can he do it again?[/quote

He looks a little better than this time yesterday though as the core has tightened with lower shear, there's little respite until Monday though. If he makes it to Monday then we have 2 days of interest as Dorian will be in a divergent flow, slowing and move into a moister region with higher sea temperatures, Wednesday and Thursday however see less divergence and increased shear before landfall wherever.

By the looks of things the NHC don't think he will exploit the conditions on Monday and open him up.

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

Dorian is no longer a tropical cyclone and has opened up into a wave. Dry air and shear are expected to prevent regeneration.

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Posted
  • Location: s yorks
  • Weather Preferences: c'mon thunder
  • Location: s yorks

Well the last advisory is Dorians post-mortem but it had me puzzled throughout its lifespan although I`d chuckle to myself if a new invest turned up somewhere in the N caribbean sea next week?Posted Image

Good spot fellas with the MLC seperation from lower indicating early signs of demise but its mighty interesting trying to monitor dry and stable air and how it interacts with these small systems in terms of preventing vertical stacking et-al, or is/was that a sole retribute of the shear that this cyclone fought as I can`t recall many strong values?

Edited by mezzacyclone
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