ATL: EMILY - Remnants

[Ptarmigan]

I would not be surprised if 91L develops over the weekend.

[EyELeSs1]

Overall it appears like convergence is increasing in the area with low level inflow becoming more established. Also, with an anti-cyclone located almost dirtectly over head easterly shear should not be a problem for much longer.



The thermal/wind structure also seems to be improving

[KWT]

I find it weird to see such a vigorous LLC without any convection overhead. I'm growing more and more concerned about this thing once it develops. Very impressive tropical wave.

Its a bit unusual, maybe some dry air is wafting around this system, its such a large circulation thats pretty reasonable...

Still the patttern of the system suggests once it pulls together it could blow up...not sure it's going to be too rapid to start with, it reminds me of a WPAC system...

Once it strengthens into a TS, expect it to start getting a motion close to NW...till then I think broadly WNW after its seperated from the ITCZ.

[BigA]

12Z Canadian agrees with the GFDL on a nasty storm for the northeastern Caribbean (tracking right over the Virgin Islands and Puerto Rico) and moves it dangerously close to the eastern Bahamas, a couple hundred miles west of the 00 run. This is largely due to a stronger Bermuda high and weaker east coast trough than the 00 run.

[Nimbus]

At first glance the circulation looks elongated and quite broad not something you would expect to spin up quickly. A delay might mean weak and west track just under Puerto Rico. Of course it all depends on when and where it spins up. Apparently most models are calling for a recurve before the US mainland at this point. Statistically there is often a tutt, short wave or at least a weakness that would pick up anything near the Bahamas.

[Ivanhater]

12z Canadian...watch out Luis!




Looks like ridging building back at the end

[gatorcane]

Remember the GFS is notorious for underestimating the strength of ridges in the long-range.

The ECMWF is building the ridge back in at 144 hours in the 00Z.

I tend to look at the ECMWF and CMC over the GFS for long-range synoptics.

[gatorcane]

At first glance the circulation looks elongated and quite broad not something you would expect to spin up quickly. A delay might mean weak and west track just under Puerto Rico. Of course it all depends on when and where it spins up. Apparently most models are calling for a recurve before the US mainland at this point. Statistically there is often a tutt, short wave or at least a weakness that would pick up anything near the Bahamas.

Slow development, I agree. That has been my thinking....might take several days to even be named if it does. There is still dry air out there to its west so convection may decrease some over the next few days.

Long-range is up in the air and too early to say on a U.S mainland threat. Right now we should focus on the islands as the threat is nearer term.

BTW, The ECMWF is building a ridge at 144 hours in the Western Atlantic and I wouldn't trust the long-rang GFS anyway as it tends to breakdown ridges too quickly.

Look what it did with Don..had it going in towards SE Texas not extreme S. Texas...and that was a short-term forecast from the GFS. Meanwhile the ECMWF got the track right with Don a few days out.

[Evil Jeremy]

91L is developing some really healthy inflow. There is no reason for this not to become a TC IMO. I say 40% from NHC at 2, but personally I think 50%

I think they go 60-70%, in 48hrs I dont think this will still be 91L...

Problem with the NHC is that they are slow reactors, and don't make high jumps on TWOs often.

[SouthDadeFish]

NHC might refrain from raising % until Euro jumps on board.

[Florida1118]

000
ABNT20 KNHC 291750
TWOAT

TROPICAL WEATHER OUTLOOK
NWS NATIONAL HURRICANE CENTER MIAMI FL
200 PM EDT FRI JUL 29 2011

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

THE NATIONAL HURRICANE CENTER IS ISSUING ADVISORIES ON TROPICAL
STORM DON LOCATED ABOUT 120 MILES EAST-NORTHEAST OF BROWNSVILLE
TEXAS.

A LARGE TROPICAL WAVE ACCOMPANIED BY A WELL-DEFINED LOW PRESSURE
SYSTEM IS LOCATED ABOUT 1150 MILES EAST-SOUTHEAST OF THE LESSER
ANTILLES. THIS DISTURBANCE CONTINUES TO SHOW SIGNS OF
ORGANIZATION...AND ENVIRONMENTAL CONDITIONS ARE CONDUCIVE FOR
GRADUAL DEVELOPMENT OVER THE NEXT FEW DAYS. THIS SYSTEM HAS A
MEDIUM CHANCE...30 PERCENT...OF BECOMING A TROPICAL CYCLONE DURING
THE NEXT 48 HOURS AS IT MOVES WESTWARD OR WEST-NORTHWESTWARD AT
15 TO 20 MPH.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BEVEN

[SouthDadeFish]

Still 30%. NHC not getting very creative with outlooks.

How long does something have to show organization for until they raise the %? lol.... I think the NHC has a crush on the Euro. But hey, the Euro very well could be right.

[Evil Jeremy]

Bad call IMO. Maybe the NHC is focusing on Don right now and aren't that attentive to 91L, but this has a greater than a 30% of forming by Sunday.

[Florida1118]

Still 30%. NHC not getting very creative with outlooks

For an organizing system, 30% aint to much.

[Frank2]

Not surprised NHC kept it at 30% since it really isn't more than that at this time - there's still time to watch it...

I agree that the islands do need to keep an eye on this, but they should have enough time to react if it does develop...

Frank

[lebron23]

40-50 percent IMO...

[TropicalAnalystwx13]

I don't think the question is if it will develop, but where will it go, and how strong will it get. 30% is too low, no doubt. They are giving this a 30% chance to develop into something by Sunday afternoon...could very well be a TD/TS on that day. IMO, it deserved 50-60%. It needs to separate from the ITCZ, and gain some organized convection. After that, the winds and pressure will respond. Those are the only three things that 91L needs to become a TD/TS.

[KWT]

Does anybody have a CMC run with the heights as well?

Lower pressure heading towards the Atlantic which may allow it to recurve just east of the Bahamas...a close call though, if that one misses it'd be a threat to the east coast.

[cheezyWXguy]

Another thing I dont like about the latest run of the gfs, it takes 91L into east caribbean on a straight west trajectory, then stalls it for a brief period, and shunts it north. This doesnt seem to be the most practical track imo, it would seem to me that it would take more of a gradual bend to the wnw and eventually nw. Perhaps the gfs shows very weak steering currents in this area until a weakness to the north forms, but otherwise I cant think of any other explanation. Does the gfs solution seem credible in this aspect?

[shaggy]

Does anybody have a CMC run with the heights as well?

Lower pressure heading towards the Atlantic which may allow it to recurve just east of the Bahamas...a close call though, if that one misses it'd be a threat to the east coast.

The CMC certainly is an interesting run. Would make for slightly closer approach to the east coast if the GFS is weakening the ridge too soon.