ATL : TROPICAL DEPRESSION ERIKA (06L)

[tailgater]

The LLC is very evident in this Quickscat image.
http://manati.orbit.nesdis.noaa.gov/img ... ap?484,219

it is well SW of where you are looking, look again @13.8N 57W

[Dean4Storms]

If that QScat is accurate this system is one of the strangest laid out Tropical Waves that I can remember with the crest of the wave oriented from WSW to ENE and supporting 50kt winds?

[Derek Ortt]

I'd expect HWRF and GFDL to send that east through the weakness if the runs were extended. Those runs look to threaten Bermuda

[cycloneye]

The LLC is very evident in this Quickscat image.
http://manati.orbit.nesdis.noaa.gov/img ... ap?484,219

it is well SW of where you are looking look again @13.8N 57W

That pass was made yesterday afternoon.Look at the time down in purple.

[canes04]

The shear is almost gone, take a look at WV. By the time recon gets there the LLC should form under the convection.
Give this 12 to 24 hours to stack and we should see a strengthing system moving slowly wnw.
The Islands and EC coast need to monitor this closely.

Gatorcane, how can you give the all clear for FL, have you seen the latest model runs?

Good luck to all in the path of this one, it could be a major by weeks end.

[HURAKAN]

Best Track 12z:

AL, 94, 2009090112, , BEST, 0, 159N, 571W, 30, 1006

[Derek Ortt]

http://metofis.rsmas.miami.edu/~dortt/s ... 1_loop.gif

no, the shear is not letting up. Look at how far the upper trough digged into the Carib. The eastern edge and its SW flow is cutting right through the disturbance.

Edited by mf_dolphin

[cycloneye]

12 UTC Bam Models

WHXX01 KWBC 011244
CHGHUR
TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1244 UTC TUE SEP 1 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) 20090901 1200 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
090901 1200 090902 0000 090902 1200 090903 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 15.9N 57.1W 16.6N 58.8W 17.1N 60.4W 17.8N 61.7W
BAMD 15.9N 57.1W 16.6N 58.6W 17.2N 59.9W 17.6N 61.0W
BAMM 15.9N 57.1W 16.4N 58.6W 16.8N 59.9W 17.1N 61.0W
LBAR 15.9N 57.1W 16.8N 59.0W 17.5N 61.0W 18.2N 63.0W
SHIP 30KTS 32KTS 36KTS 44KTS
DSHP 30KTS 32KTS 36KTS 44KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
090903 1200 090904 1200 090905 1200 090906 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 18.2N 63.2W 19.1N 66.4W 19.9N 69.9W 20.4N 73.7W
BAMD 17.9N 62.1W 18.4N 64.4W 18.9N 66.7W 19.3N 69.2W
BAMM 17.3N 62.1W 17.6N 64.5W 18.0N 67.3W 18.3N 70.5W
LBAR 18.7N 65.1W 19.8N 68.7W 20.3N 71.0W 19.5N 72.0W
SHIP 51KTS 66KTS 70KTS 71KTS
DSHP 51KTS 66KTS 68KTS 56KTS

...INITIAL CONDITIONS...
LATCUR = 15.9N LONCUR = 57.1W DIRCUR = 285DEG SPDCUR = 12KT
LATM12 = 15.6N LONM12 = 54.9W DIRM12 = 285DEG SPDM12 = 12KT
LATM24 = 14.5N LONM24 = 52.3W
WNDCUR = 30KT RMAXWD = 90NM WNDM12 = 30KT
CENPRS = 1007MB OUTPRS = 1012MB OUTRAD = 150NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

[tailgater]

The LLC is very evident in this Quickscat image.
http://manati.orbit.nesdis.noaa.gov/img ... ap?484,219

it is well SW of where you are looking look again @13.8N 57W

That pass was made yesterday afternoon.Look at the time down in purple.

Opps I thought they posted the ascending and descending at the same time, Still Looks really stretched out to me

[wxman57]

This goes to show you how deceiving it can be to use only IR satellite imagery to determine if there's a circulation. Looked very impressive to me from home this morning, but when I got to the office and made that surface chart it was clear this was just a wave. That person writing the Crown Weather discussion appeared to be only looking at satellite imagery, and not wind data from surface obs and QS. Yes, it looks like a TD/TS, but it lacks one critical feature - a circulation.

A combination of visible satellite imagery, surface obs and recon (hopefully) will help us to determine if an LLC is forming today.

[Evil Jeremy]

The new BAMS end up taking 94L into the Islands. Also, in order for the new GFDL and HWRF to verify, 94L would need to be moving north right now, and it does not look to have a big northward component soon. Also, new CMC more west.

[otowntiger]

That Quickscat shows a really bizarre windfield. This is a weird one.

Looks like a classic open wave, which it probably is based on that center fix provided by WxMan57.

I don't think there's anything classic about this system. It is an odd one no doubt. But I do agree there is no closed circulation at this time, and it may not ever have one if Derek's observations about the effects of the trough continue to pan out.

[perk]

Ivanhater good job.

[HURAKAN]

I really hate these systems!

[wxman57]

Here's a 12Z analysis with some streamlines I drew into represent low-level flow. Crosshairs represent NHC 12Z best track position (15.9N/57.1W). Still has a good bit to go before becoming Erika. Hurricane threat to NE Caribbean has certainly diminished, as it does look like the heavier convection will pass north of the Caribbean. Plus, it's not even a TS yet. I still think it will most likely turn north to the east of the Bahamas, but we can't yet rule out a U.S. East Coast hit.

[Blown Away]

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE MELBOURNE FL
447 AM EDT TUE SEP 1 2009

SUN-TUE...DLM RIDGE INITIALLY IN PLACE BEGINS TO WEAKEN ACROSS FL
AND THE WRN ATLC AS MINOR SHORT WAVE ENERGY PUSHES EWD AND OFFSHORE
THE ERN CONUS. AM HAVING PROBLEMS WITH THE GFS SOLN BRINGING A WAVE
ALL THE WAY WWD INTO THE BAHAMAS. MUCH LIKE THE CASE WAS WITH BILL
...PREFER THE MORE LKLY ECM SOLN...AS THERE WILL LKLY BE MORE THAN
ENOUGH EROSION OF THE WRN PORTION OF THE BERMUDA RIDGE TO ALLOW THE
CTRL ATLC SYSTEM TO TURN NWD WELL EAST OF FL. NET RESULT IS A WEAK
ONSHORE FLOW/PRES PATTERN WITH SUFFICIENT MOISTURE FOR NEAR NORMAL
(CLIMO) POPS IN THE 30-40 PCT RANGE.

NWS Melbourne thoughts on 94L.

[SEASON_CANCELED]

Models are worthless at this point. There still is no storm, or storm center. All they do is show a general track which doesnt answer the question of wether it will impact the CONUS or not.

[jlauderdal]

This goes to show you how deceiving it can be to use only IR satellite imagery to determine if there's a circulation. Looked very impressive to me from home this morning, but when I got to the office and made that surface chart it was clear this was just a wave. That person writing the Crown Weather discussion appeared to be only looking at satellite imagery, and not wind data from surface obs and QS. Yes, it looks like a TD/TS, but it lacks one critical feature - a circulation.

A combination of visible satellite imagery, surface obs and recon (hopefully) will help us to determine if an LLC is forming today.

and this should be stickied for all the people that look at IR day after day and post that a system should be classified after looking at all the cool looking orange colors on IR, folks no LLC=no classification regardless of how impressive the sat presentation is

[Evil Jeremy]

I still think it will most likely turn north to the east of the Bahamas, but we can't yet rule out a U.S. East Coast hit.

What are you and Derek seeing that makes you think recurve?

[tailgater]

The real question is why isn't this forming a LLC? Shear ? It must be lower level shear? dry air ? speed of 850mb winds? energy?
Mid level shear would be my best guess