ATL: KARL - Post-Tropical - Discussion

[cycloneye]

Up to 30%-50%

A broad area of low pressure, associated with a tropical wave,
located a couple of hundred miles east-southeast of the Cabo Verde
Islands is producing a large area of disorganized cloudiness and
showers. Slow development of this disturbance is possible during
the next several days while it moves west-northwestward at 10 to 15
mph over the tropical Atlantic. Regardless of development, locally
heavy rains and gusty winds are likely over portions of the Cabo
Verde Islands through Wednesday.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...medium...50 percent

[GCANE]

At this point, COAMPS is having it head due west as a wave thru 120 hrs.

http://www.nrlmry.navy.mil/coamps-web/w ... 50&tau=999

[abajan]

Vigorous looking system for sure:

[alienstorm]

Another area that will be OTS

[LarryWx]

Another area that will be OTS

That would usually be the best bet as I assume you and most others here realize whenever a CV system, especially one that has already formed into a TC, is not moving WSW, westward or just north of due west in the eastern Atlantic at least as regards getting as far west as 75W. Moving WNW initially in the E Atlantic as a TC for a day or more knocks down chances quite a bit vs if it were moving westward and even more vs if it were moving south of due west. Whereas moving WNW is not a guarantee of recurving safely, moving NW initially just about is.
Always keep in mind that about 80% of all CV TC's don't make it to 75W and that number is higher now vs what it is in August. Also, it is higher than 80% if one just looks at CV TC's that are moving steadily WNW from the get-go.

[Kazmit]

I see this as a potential Bermuda threat. I'd also keep an eye on this one if I was in the Leewards, or up in Newfoundland.

[Gustywind]

I see this as a potential Bermuda threat. I'd also keep an eye on this one if I was in the Leewards, or up in Newfoundland.

That is clearly evident my friend, we have to monitor it in case of because we're in the peak and ant twaves can be very suspicious for sure. Do not let our guard down during this periode.

[cycloneye]

A broad area of low pressure, associated with a tropical wave,
located a couple of hundred miles east-southeast of the Cabo Verde
Islands is producing a large area of disorganized cloudiness and
showers. Slow development of this disturbance is possible during
the next several days while it moves west-northwestward at 10 to 15
mph over the tropical Atlantic. Regardless of development, locally
heavy rains and gusty winds are likely over portions of the Cabo
Verde Islands through Wednesday.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...medium...50 percent

[Gustywind]

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
153 PM EDT TUE SEP 13 2016


Tropical wave extends from 13N21W to 20N23W moving W at 10-15 kt.
A 1010 mb low is centered at the southern extent of the wave axis
and remains embedded within the Monsoon Trough. Convection
continues to organize and currently forms two bands of scattered
moderate convection from 11N-15N between 19W-27W...and from 15N-
18N between 18W-24W. The low is expected to track W-NW across the
southern Cape Verde Islands and bring increased precipitation and
possible gusty winds to the islands through Wednesday night.

[gatorcane]

BIG shift west by the ECMWF:

[OntarioEggplant]

Wow it looks like 95L will miss the trough based on the 240 hr Euro

[cycloneye]

Ends this way with a strong Hurricane.

[gatorcane]

12Z ECMWF 500MB loop from hour 120 to 240:

[PTrackerLA]

Interesting run on the today's 12z Euro. Looks like 95L would be forced west quite a bit more looking at the ridging over the mid-Atlantic. However, this run is vastly different from the 00z so we'll just see how the trends go.

[AutoPenalti]

12Z ECMWF 500MB loop from hour 120 to 240:

Turns west on the last frame of that run, high building in?

[Steve H.]

Most of the deep tropical models take it pretty far west. I have to think that as Ian pulls away, the ridging will build back in it's wake. Whether or not the ridge over the middle Atlantic states will be as depicted on this run will be seen in about a week. I believe the global models will start trending west though, as they typically do. How far, and if there is a ridge handover in a week, is obviously to be seen.



The posts in this forum are NOT official forecast and should not be used as such. They are just the opinion of the poster and may or may not be backed by sound meteorological data. They are NOT endorsed by any professional institution or STORM2K. For official information, please refer to products from the National Hurricane Center and National Weather Service.

[GCANE]

GFS 12Z 350K PV looks like it would be a challenge for anything to spin up in the near term.
IMHO, this stays a wave or a sheared tropical low for the next few days giving it an opportunity to maintain a due west track.

http://tc.met.psu.edu/tcgengifs/GFS/201 ... 350PV.anim

[gatorcane]

12Z UKMET weaker:

[gatorcane]

Another area that will be OTS

That would usually be the best bet as I assume you and most others here realize whenever a CV system, especially one that has already formed into a TC, is not moving WSW, westward or just north of due west in the eastern Atlantic at least as regards getting as far west as 75W. Moving WNW initially in the E Atlantic as a TC for a day or more knocks down chances quite a bit vs if it were moving westward and even more vs if it were moving south of due west. Whereas moving WNW is not a guarantee of recurving safely, moving NW initially just about is.
Always keep in mind that about 80% of all CV TC's don't make it to 75W and that number is higher now vs what it is in August. Also, it is higher than 80% if one just looks at CV TC's that are moving steadily WNW from the get-go.

Seems the models are trending towards a due W or even south of due west movement after about 72 hours or so and this motion continues for a several days as it traverses the MDR. It's a longshot for this to impact the CONUS but there is definite uncertainty looking at the model runs today especially the long-range Euro. Still need to watch the Northern Lesser Antilles as usual in case it gets pushed far enough west. Perhaps the bigger question is whether this will even develop in the first place though I tend to think so given the good appearance on SAT imagery.

[LarryWx]

Another area that will be OTS

That would usually be the best bet as I assume you and most others here realize whenever a CV system, especially one that has already formed into a TC, is not moving WSW, westward or just north of due west in the eastern Atlantic at least as regards getting as far west as 75W. Moving WNW initially in the E Atlantic as a TC for a day or more knocks down chances quite a bit vs if it were moving westward and even more vs if it were moving south of due west. Whereas moving WNW is not a guarantee of recurving safely, moving NW initially just about is.
Always keep in mind that about 80% of all CV TC's don't make it to 75W and that number is higher now vs what it is in August. Also, it is higher than 80% if one just looks at CV TC's that are moving steadily WNW from the get-go.

Seems the models are trending towards a due W or even south of due west movement after about 72 hours or so and this motion continues for a several days as it traverses the MDR. It's a longshot for this to impact the CONUS but there is definite uncertainty looking at the model runs today especially the long-range Euro. Still need to watch the Northern Lesser Antilles as usual in case it gets pushed far enough west. Perhaps the bigger question is whether this will even develop in the first place though I tend to think so given the good appearance on SAT imagery.

Good point, gator! I did see the 12Z Euro run. So, we can't write this off yet for possible impact in the Caribbean and/or CONUS. I'm not writing it off though as you said it has to be considered a longshot as of now. Let's see what happens.

Fwiw, the last year we had a season after a super El Nino, 1998, had Georges form on 9/15 and which went on to becoem the strongest storm of the season and included Caribbean/CONUS impacts:

http://weather.unisys.com/hurricane/atl ... /track.gif

This one did move WNW from the eastern Atlantic though it started at a very low latitude, 10N.