ATL : TROPICAL DEPRESSION ERIKA (06L)

[Ptarmigan]

I think this will be Erika soon.

[vbhoutex]

Looking at both infrared and visible sats
I see two things as current possibilities/probabilities-1 it is consolidating ever so slowly near where The Eyewall suggested or 2 it is elongating sw-ne and biding its' time. If it is the latter it is not going to feel any weakness in the ridge and continue W. If it is the first it could feel the weakness and start heading more NW. Definitely has aot more work too do!!

[Aric Dunn]

Yeah got to admit the structure is pretty decent, indeed its much improved from this time yesterday I think, however it still needs some convection to really get going and have the final push.

the northern possibility is quickly fading this afternoon as the curved banding features are becoming more dominate farther south. I at this point now do not see a circ closing off farther north.. but a quick jog in a wnw to even north west briefly do to some rotational dynamics is a possibility.

[Gustywind]

Estimated position estimates over the last day

Current = 11.9N 47.5W
12z 8/30 = 11.8N 46.3W
6z 8/30 = 11.2N 45.1W
0z 8/30 = 10.7N 43.4W
18z 8/29 = 10.6N 42.0W


That's a gain of 1.3 deg of latitude and 5.5 deg of longitude in the last 24 hours.

If you extrapolate that movement out (of course this could change over time), you would get to the following points:

13.2N 53.0W
14.5N 58.5W
15.8N 64.0W
17.1N 69.5W

well actually thats not to far off from the euro which brings it into DR

Not pretty optimistic... for all the Leewards especially Guadeloupe near Basse-Terre.

[KWT]

Yeah Aric indeed that option is slowly decreasing over the last few hours. Something to note is the models have quite a decent area of shear where this system is heading, it probably needs to stay south of 18N upto about 65W for it to miss it totally. Will be worth watching IMO.

Quite possibly will be our next tropical depression in the next 24hrs if it gets a good burst.

[Ola]

Reading Weather Underground's post, about GFS picking up on a secondary vortex to its north east, and tracking that one, which they think is incorrect, I believe that what will happen is that the mid level spin to the south will not become the dominant center, and the northern part will become dominant overnight and then it will track north-west and miss us in the Antilles.

[x-y-no]

SSD Dvorak

I dont see the recurve yet.

30/1745 UTC 11.9N 47.5W T1.5/1.5 94L -- Atlantic

http://www.ssd.noaa.gov/PS/TROP/tdpositions.html


Who said recurve?

30/1745 UTC 11.9N 47.5W
30/1145 UTC 11.9N 46.1W

drifting west

1.4 degrees longitude in 6 hours at 12N is about 14 knots. That's better than "drifting" I'd say.

[jinftl]

Moving west as opposed to 'drifting west' is very different....one implies definite direction and purpose, the other is more ambiguous. If 94L is moving west, even slightly north of west, the models are not performing well at all.

SSD Dvorak

I dont see the recurve yet.

30/1745 UTC 11.9N 47.5W T1.5/1.5 94L -- Atlantic

http://www.ssd.noaa.gov/PS/TROP/tdpositions.html


Who said recurve?

30/1745 UTC 11.9N 47.5W
30/1145 UTC 11.9N 46.1W

drifting west

1.4 degrees longitude in 6 hours at 12N is about 14 knots. That's better than "drifting" I'd say.

[x-y-no]

Reading Weather Underground's post, about GFS picking up on a secondary vortex to its north east, and tracking that one, which they think is incorrect, I believe that what will happen is that the mid level spin to the south will not become the dominant center, and the northern part will become dominant overnight and then it will track north-west and miss us in the Antilles.

Well, the convergence looks better at the northern end of this thing than it did yesterday, so it's a possibility. But in my opinion the southern end has more going for it since it has both decent convergence plus very strong divergence aloft, which is sustaining pretty good convection in the vicinity. I think if the northern end is going to take over it needs to get some decent convection going and so far I see no sign of that happening.

[KWT]

The ECM seems to have a decent solution with regards to track at the moment, takes this only a little bit north-east of the LA then takes it westwards.

Anyway until this starts picking up decent latitude and actually gets upgraded with a solid LLC the models aren't to really be trusted. The system may well miss the very worst of the shear if it can track WNW towards the NE Caribbean, though the models really are suggesting pretty hefty shear.

[Sanibel]

IR shows it is hitting a wall.

Surface structure is improving.

Lifting out WNW then NW now.

This is already a TD IMO.

[Ivanhater]

12 z Euro out..does not develop it much, but that it the feature on the north coast of Cuba..

[cycloneye]

18 UTC Best Track

AL, 94, 2009083018, , BEST, 0, 121N, 475W, 25, 1007

ftp://ftp.tpc.ncep.noaa.gov/atcf/tcweb/ ... 009.invest

SSD Dvorak=11.9N 47.5W

Almost the same position between both.

[HurricaneMaster_PR]

[cycloneye]

Almost all BAMS are Caribbean bound.

18 UTC Bam Models

015
WHXX01 KWBC 301902
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1902 UTC SUN AUG 30 2009

DISCLAIMER...NUMERICAL MODELS ARE SUBJECT TO LARGE ERRORS.
PLEASE REFER TO NHC OFFICIAL FORECASTS FOR TROPICAL CYCLONE
AND SUBTROPICAL CYCLONE INFORMATION.

ATLANTIC OBJECTIVE AIDS FOR

DISTURBANCE INVEST (AL942009) 20090830 1800 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090830 1800 090831 0600 090831 1800 090901 0600

LAT LON LAT LON LAT LON LAT LON
BAMS 12.1N 47.5W 13.7N 49.9W 15.2N 52.2W 16.3N 54.0W
BAMD 12.1N 47.5W 13.2N 49.8W 14.2N 51.8W 14.9N 53.5W
BAMM 12.1N 47.5W 13.2N 49.8W 14.2N 51.8W 14.9N 53.5W
LBAR 12.1N 47.5W 13.2N 49.6W 14.3N 51.8W 15.0N 53.9W
SHIP 25KTS 31KTS 39KTS 48KTS
DSHP 25KTS 31KTS 39KTS 48KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090901 1800 090902 1800 090903 1800 090904 1800

LAT LON LAT LON LAT LON LAT LON
BAMS 17.2N 55.4W 18.2N 58.0W 19.0N 60.4W 20.0N 63.3W
BAMD 15.3N 55.0W 15.6N 58.0W 16.2N 61.4W 17.3N 64.8W
BAMM 15.3N 54.9W 15.6N 57.4W 16.1N 60.3W 16.7N 63.6W
LBAR 15.5N 55.8W 15.9N 59.6W 17.0N 63.3W 18.5N 66.4W
SHIP 56KTS 74KTS 84KTS 90KTS
DSHP 56KTS 74KTS 84KTS 90KTS

...INITIAL CONDITIONS...
LATCUR = 12.1N LONCUR = 47.5W DIRCUR = 290DEG SPDCUR = 12KT
LATM12 = 11.2N LONM12 = 45.1W DIRM12 = 290DEG SPDM12 = 15KT
LATM24 = 10.6N LONM24 = 42.0W
WNDCUR = 25KT RMAXWD = 60NM WNDM12 = 25KT
CENPRS = 1007MB OUTPRS = 1011MB OUTRAD = 150NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

[KWT]

Yeah just a touch to the north of the SSD position cycloneye. Still not really gaining much latitude, shear wall is quite obvious on the WV but the further south if stays the less this shear should be...and it should be noted the models are pretty awful forecasting it.

[x-y-no]

12Z ECMWF takes it as a weak low into the leeward islands and opens it up into a wave as it crosses Puerto Rico, then carries that wave WNW just north of Hispaniola and Cuba ...

5 day:



Note the mid-level ridging over the wave.


7 day:



Ridging still there, extending over Florida, but weakening.

[KWT]

Ridging looks good enough on the ECM to send it into Florida, however we have a long way to go with this yet and if it does develop it'll probably head a little more to the north west of where the ECM has.

[Evil Jeremy]

According to the extended Miami Forecast Discussion. Florida is safe from soon to be Erika.
http://www.wunderground.com/DisplayDisc ... Lauderdale

Very premature statement. Its unlikely that it will effect us right now, but things always change in the tropics.

[Typhoon_Willie]

Looks like we will have to wait and see what happens here. A lot of time to watch it. Looks interesting though.