cieldumort
Moderator
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Loc: Austin, Tx
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A tropical wave nestled within a very large area of lower sea level pressure is tracking west through the Caribbean this weekend, and is in an area increasingly favorable environment for development. This feature has been tagged as Invest 99L, and now gives it a 60% chance of becoming a tropical cyclone within 48 hours.
Invest 99L has an excellent blueprint for development, and this system has the potential to become a tropical cyclone that undergoes rapid intensification, which could take many by surprise heading into the new week.
In the lower levels, the circulation is already pretty well defined, with the blueprint for future spiral banding solidly in place. In the upper levels, winds are very light, and increasingly anticyclonic. Throughout the column, the air is moist, and relatively free of the dry air intrusions which have plagued so many other tropical features this season.
As of 3:00 AM Sunday October 21, 99L was centered near 15N 75W, with maximum sustained winds estimated at around 30 MPH.
This is where to put long range best guesses on intensity and forecast track. Long range model output discussions are also appropriate here.
At present, models are basically unanimous in developing Invest 99L within the next three days, but are very split with regard to its future track.
Edited by MikeC (Mon Oct 22 2012 07:19 PM)
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danielw
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Loc: Hattiesburg,MS (31.3N 89.3W)
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Roughly 6 hours later. You can see the slight changes in 99L
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LoisCane
Veteran Storm Chaser
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Loc: South Florida
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What is most impressive in ways is how suddenly out of nothing... comes something.
It's been so quiet in the tropics and most waves have been weak, poorly formed and odd looking.
Here we suddenly have (as the models predicted) a well organized wave with rudimentary spiral banding features and the right shape, in the right place with conditions positive for intensification.
Begs you to think on the possibilities, despite my cautious mind that says it will just go NE out of the Caribbean. But, a lot depends on WHEN it forms and the exact place that surface circulation begins as to the timing of the exact real track.
Good job by the models of seeing this even when they were 15 days out.
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http://hurricaneharbor.blogspot.com/
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ftlaudbob
Storm Chaser
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Loc: Valladolid,Mx
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The models have changed.The east coast of Florida now needs to watch this close.Could have an impact by the end of this week.99l I am referring to.
(Post moved to a more appropriate Forum.)
Edited by Ed Dunham (Mon Oct 22 2012 09:58 AM)
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MichaelA
Weather Analyst
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Loc: Pinellas Park, FL
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With all of the models being in relatively good agreement this early on, before a surface system even forms, is quite interesting to me. Usually, there is a large divergence among them at this stage. Of course, a 100 mile "error" could make a world of difference.
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Michael
PWS
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doug
Weather Analyst
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Loc: parrish,fl
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I agree. It is also unusual that it would exit the Carribean heading NE and then essentially head north up 76W. The future track depends on the relative strength of high pressure exiting off SE .
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doug
Edited by doug (Sun Oct 21 2012 07:32 PM)
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ftlaudbob
Storm Chaser
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Loc: Valladolid,Mx
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Not much excitement about 99l,I think this may change in a few days.
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Survived: 10 hurricanes in Rhode Island,Florida and the Yucatan of Mexico .
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WeatherNut
Weather Master
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Loc: Atlanta, GA
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Well its now been classified as TD18. It is looking much more impressive and the parameters are there for rapid intensification. All of S Fl really needs to keep watch on this now...as well as up the east coast of the . Its quite telling that they didnt even wait for the recon. Jamaica under a TS Watch
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Born into Cleo (64)...been stuck on em ever since
Edited by WeatherNut (Mon Oct 22 2012 11:24 AM)
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bobbutts
Weather Hobbyist
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Loc: New Hampshire
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Watching this one from up in New Hampshire
If you haven't looked, check out some of the exotic solutions from the last few days model runs.
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MichaelA
Weather Analyst
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Loc: Pinellas Park, FL
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Now, TS Sandy @ 5PM EST
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Michael
PWS
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ftlaudbob
Storm Chaser
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Loc: Valladolid,Mx
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We now have Sandy,not moving at all right now.
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Survived: 10 hurricanes in Rhode Island,Florida and the Yucatan of Mexico .
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WeatherNut
Weather Master
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Loc: Atlanta, GA
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Yes some of the models have a pretty nasty looking scenario for the NE and mid Atlantic. JB has been really bullish on the scenario for the last couple of days as well. I dont buy the out to sea like the has quite yet.
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Born into Cleo (64)...been stuck on em ever since
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Ed Dunham
Former Meteorologist & CFHC Forum Moderator (Ed Passed Away on May 14, 2017)
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The 22/12Z takes a strong storm (subtropical?) into the northeast whereas the 22/18Z keeps the system well out at sea. In both cases its in the far extended range of 7 to 10 days. So far this year the has been the better performing model, but for now its probably more important to concentrate on the more immediate track of the next few days - especially with regard to Jamaica, Haiti, eastern Cuba and the Bahamas. Wind and flooding impacts will be important in those areas as well as the southeast U.S. coastline (high seas, strong rip currents and possibly beach erosion). Looks like the latest forecast track has slowed the forward motion down a bit and that could allow for a stronger storm to develop.
ED
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LoisCane
Veteran Storm Chaser
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Loc: South Florida
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I'm curious how TD 19 and Sandy interact or how if possible 19 can help steer Sandy out to sea or the opposite. So many complex things going on. How strong this front is? How fast is this front? Late October is a very difficult time to forecast such a complex tropical set of scenarios.
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http://hurricaneharbor.blogspot.com/
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danielw
Moderator
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Loc: Hattiesburg,MS (31.3N 89.3W)
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The 12Z Experimental FIM really winds Sandy up. Looks to be a hybrid after crossing Cuba, skirts the Bahamas with 25 to 30 mph sustained winds along the southern half of the Florida Atlantic Coast, moves NE and then bombogenesis begins north of 30 degrees North latitude.
I think I saw a 925 to 930mb level at 336 hours, or Nov 5th.
Perfect Storm, Part Two? We shall see.
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ftlaudbob
Storm Chaser
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Loc: Valladolid,Mx
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I am hearing more and more talk about the "perfect storm" ,should be very interesting.
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Survived: 10 hurricanes in Rhode Island,Florida and the Yucatan of Mexico .
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cieldumort
Moderator
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Loc: Austin, Tx
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Trying to remember the last time (if ever) I have read a Forecast Discussion that called for a tropical cyclone to be "Subtropical" at Day 5 (instead of the usual "Post-Tropical," or "Extratropical," or "Dissipated"). Looks like is giving some heavy consideration to model runs that do indeed show a strong possibility of a 'Perfect Storm.'
BY 120 HOURS...SANDY IS EXPECTED TO
INTERACT WITH A DEEP UPPER-LEVEL TROUGH THAT COULD INDUCE
TRANSITION INTO A SIGNIFICANT SUBTROPICAL CYCLONE. THE OFFICIAL
INTENSITY FORECAST IS HIGHER THAN THE PREVIOUS ADVISORY THROUGH 48
HOURS...AND CLOSELY FOLLOWS A BLEND OF THE ICON...IV15...IVCN
INTENSITY CONSENSUS MODELS.
FORECAST POSITIONS AND MAX WINDS
INIT 23/0300Z 12.7N 78.6W 40 KT 45 MPH
12H 23/1200Z 13.6N 78.4W 50 KT 60 MPH
24H 24/0000Z 14.8N 77.9W 60 KT 70 MPH
36H 24/1200Z 16.6N 77.5W 70 KT 80 MPH
48H 25/0000Z 18.5N 77.1W 60 KT 70 MPH...INLAND OVER JAMAICA
72H 26/0000Z 22.7N 75.8W 55 KT 65 MPH...OVER WATER
96H 27/0000Z 25.7N 75.4W 55 KT 65 MPH
120H 28/0000Z 28.2N 73.6W 55 KT 65 MPH...SUBTROPICAL
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Owlguin
Weather Hobbyist
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Seems as though the models have shifted a little west this morning.
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doug
Weather Analyst
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Loc: parrish,fl
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Interesting it is now the that jogs the storm briefly westward toward the peninsula as it slows in the Bahamas, before turning it ENE and out to sea. , takes this system off shore up the coast line as a significant NE'r. is closer to the without the jog.
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doug
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doug
Weather Analyst
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Posts: 1006
Loc: parrish,fl
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Confidence in the track ends at five days...several of the models in the ensemble have a very strong low center essentially plaguing the entire eastern coast line of the US after that...ECMWF takes the low center ashore in New England. Yikes!
GFS has it out to sea...
No reliable handle on the strength of the trough coming from the west, I guess.
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doug
Edited by doug (Tue Oct 23 2012 04:42 PM)
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