Atlantic Tropical Wave/disturbance Thread 2009

[Cookie]

its getting to that time of year where the first signs start to appear so this thread is for discuss any tropical waves and disturbances in the atlantic

[Iceberg]

A quick update some very very heavy shear north of 10N.

ITCZ is south of the Equator still and the start of the season looks awhile off yet.

[Cookie]

thanks for the update mate

[Cookie]

we're off first tropical wave of 2009

TROPICAL WEATHER DISCUSSION

NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL

205 PM EDT WED MAY 13 2009

TROPICAL WEATHER DISCUSSION FOR NORTH AMERICA...CENTRAL

AMERICA...GULF OF MEXICO...CARIBBEAN SEA...NORTHERN SECTIONS

OF SOUTH AMERICA...AND ATLANTIC OCEAN TO THE AFRICAN COAST

FROM THE EQUATOR TO 32N. THE FOLLOWING INFORMATION IS BASED

ON SATELLITE IMAGERY...METEOROLOGICAL ANALYSIS...WEATHER

OBSERVATIONS...AND RADAR.

BASED ON 1200 UTC SURFACE ANALYSIS AND SATELLITE IMAGERY

THROUGH 1715 UTC.

...TROPICAL WAVES...

THE FIRST ANALYZED TROPICAL WAVE OF 2009 HAS BEEN ADDED TO THE

13/1200 UTC MAP ALONG 17W/18W MOVING W NEAR 15 KT. RECENT

TIME-HEIGHT ANALYSES FROM BAMAKO INDICATE MEAN SFC-650 MB WINDS

VEERED FROM NE TO SE IN CONJUNCTION WITH AN ORGANIZED AREA OF

DEEP MOIST CONVECTION THAT MOVED OFF THE AFRICAN COAST DURING

THE LAST DAY. THIS WIND SHIFT AT BAMAKO OCCURRED ON MAY 12 2009.

TIME-HEIGHT ANALYSES FROM BAMAKO ALSO INDICATE LOW-TO-MID LEVEL

MOISTURE MAXIMIZED AFTER THE PASSAGE OF THE TROPICAL WAVE.

ALSO...THE WAVE COINCIDES WITH A WESTWARD-MOVING DEEP LAYER

MOISTURE MAXIMUM AS INDICATED IN THE MIMIC TPW PRODUCT FROM

CIMSS. METSAT-9 VISIBLE SATELLITE IMAGERY INDICATES CONTINUED

LOW-LEVEL CYCLONIC TURNING...THOUGH RECENT QUIKSCAT IMAGERY

INDICATES THAT CURVATURE VORTICITY HAS DIMINISHED NEAR THE WAVE

AS IT BECOMES ABSORBED IN STRONGER NORTHERLY FLOW. DESPITE THE

TEMPORARY LOSS IN CURVATURE VORTICITY AT THE SURFACE...REGIONAL

VARIATIONS IN WIND SPEED AT THE SURFACE ARE MAINTAINING POSITIVE

SURFACE VORTICITY NEAR THE WAVE. MUCH OF THE CONVECTION

ASSOCIATED WITH THE WAVE HAS DIMINISHED...WITH SCATTERED

MODERATE CONVECTION FROM 1N-7N BETWEEN 14W-22W.

[Cookie]

The 2009 Atlantic hurricane season may get off to an early start. For the past two days, most of our reliable hurricane forecast models have been predicting the possibility of a subtropical depression forming near Florida or Western Cuba Monday - Thursday next week. An area of disturbed weather associated with a mid- to upper-level trough of low pressure near eastern Cuba and the southeastern Bahama Islands is predicted to slide west-northwest over the next few days. Wind shear over this low, current a prohibitively high 40 knots, is expected to relax to just 10 knots by Monday in the region surrounding Florida. This may allow a disturbance with a surface warm core to develop, according to phase space analyses from Florida State. However, since the upper atmosphere will still be cold, any development of this system will likely be subtropical in nature. If a subtropical storm does form, it may be fairly dry, like Subtropical Storm Andrea of May 2007. This storm ended up fanning fires in Florida, instead of putting them out. Water vapor loops show plenty of dry, continental air in the region, and it will take many days for the atmosphere to moisten enough to support formation of a subtropical depression.

Figure 1. Water vapor image showing moisture from a weak mid- to upper-level low of low pressure over the southeastern Bahama Islands, surrounded by a large area of dry air, and sandwiched between the polar and subtropical jet stream. Image credit: NOAA/SSD.

The GFS and NOGAPS models predict a subtropical depression could form by Tuesday, while the ECMWF shows development later in the week. The latest UKMET model forecast puts development Wednesday or Thursday near Haiti. The area of predicted development is sandwiched in a relatively narrow band of low wind shear between two branches of the jet stream. This is not a typical set-up for formation of a May tropical cyclone. With so much shear and dry air around, I put the probability of a subtropical depression forming next week at about 10%. Any developing system will also have to contend with the arrival Tuesday of a strong upper-level low pressure system that is expected to drop down over the northern Gulf of Mexico. The eventual track of any depression that forms is highly uncertain, and the models support tracks up the U.S. East Coast towards South Carolina, or up the west coast of Florida in the Gulf of Mexico.

http://www.wunderground.com/blog/JeffMaste...l?entrynum=1219

[Tn9]

http://www.wunderground.com/blog/JeffMaste...l?entrynum=1219

Lets hope so,i hope its an very active season,i dont mean that in a nasty way,as we know the suffering they cause,but they are fascinating to track and forecast,they are like a living entity.

[Somerset Squall]

I don't reckon anything will develop in the area. The environment is very hostile and even Mr Masters himself has now backed down.

[Cookie]

I don't reckon anything will develop in the area. The environment is very hostile and even Mr Masters himself has now backed down.

I don't often disagree with you, ( but I will most likely be wrong)

shear isn't looking that bad and ocean temps are looking good. I think their may be a slight chance of a possible disturbance happing. A lot of models are saying that might, yes like always it is a long way out.

Edited May 15, 2009 by cookie

[Cookie]

or am I just clutching as straws?

:lol:

[Cookie]

things seem to have changed again, this is looking nothing more then a rain brining system.

[Somerset Squall]

I don't often disagree with you, ( but I will most likely be wrong)

shear isn't looking that bad and ocean temps are looking good. I think their may be a slight chance of a possible disturbance happing. A lot of models are saying that might, yes like always it is a long way out.

Yes, sea temps aren't bad but shear is around about 30kts, which doesn't mean it will definitely stop development but will seriously hinder any potential. In addition, the air is quite dry which may further supress the convection needed for a subtropical cyclone to form. But I could be wrong too , and as we all know, Mother Nature does what she wants!

[Somerset Squall]

There is more potential with this system than the other one. There is a strong circulation and the low has become detached from the jet meaning it may meander in subtropical waters rather than zipping to the northeast. There is a small chance of the low gradually aquiring subtropical characteristics, Andrea did the same thing in 2007, though addmittedly the waters were a bit warmer.

Just a side note, but wouldn't this have been better off in the Atlantic tropical wave/disturbance thread?

[Cookie]

yeah I should have both of these threads in their, I will see about getting them moved.

[Cookie]

models really seem to be on board with some sort of development and possible invest 48 hrs or so.

[Somerset Squall]

The models are chopping and changing a lot at the moment, as can be expected. There is a lot of uncertainty what will happen- there isn't really anything out there yet but scattered convection in the Caribbean, and at best, the conditions are marginal. I'd like to see the shear lessen first before I become more confident of possible development.

[M'Lady]

Just a side note, but wouldn't this have been better off in the Atlantic tropical wave/disturbance thread?

yeah I should have both of these threads in their, I will see about getting them moved.

And, as if by magic, it is done.

[Cookie]

thanks again :lol:

seem from the GOM system that we could have according from accuweather the first named system by the end of the week.

Edited May 17, 2009 by cookie

[Iceberg]

Well spotted fokes.

METO took a particular shine to this yesterday.

" GLOBAL MODEL DATA TIME 12UTC 17.05.2009

NEW TROPICAL STORM FORECAST TO DEVELOP AFTER 36 HOURS

FORECAST POSITION AT T+ 36 : 25.9N 79.8W

VERIFYING TIME POSITION STRENGTH TENDENCY

-------------- -------- -------- --------

00UTC 19.05.2009 25.9N 79.8W WEAK

12UTC 19.05.2009 25.9N 79.0W MODERATE INTENSIFYING RAPIDLY

00UTC 20.05.2009 26.5N 79.4W MODERATE INTENSIFYING SLIGHTLY

12UTC 20.05.2009 27.9N 80.3W MODERATE WEAKENING SLIGHTLY

00UTC 21.05.2009 26.5N 83.5W MODERATE WEAKENING SLIGHTLY

12UTC 21.05.2009 26.7N 83.5W MODERATE LITTLE CHANGE

00UTC 22.05.2009 27.2N 84.2W WEAK WEAKENING SLIGHTLY

12UTC 22.05.2009 28.1N 84.7W WEAK WEAKENING SLIGHTLY

00UTC 23.05.2009 29.0N 85.8W MODERATE INTENSIFYING SLIGHTLY

12UTC 23.05.2009 30.0N 87.9W MODERATE INTENSIFYING SLIGHTLY

THIS INFORMATION IS PROVIDED AS GUIDANCE FOR TROPICAL CYCLONE

RSMCS. IT REQUIRES INTERPRETATION BY TROPICAL CYCLONE SPECIALISTS

AND SHOULD NOT BE CONSIDERED AS A FINAL PRODUCT

MET OFFICE, EXETER, UK

"

Shear is due to weaken a bit but still to nearly 30Kt. SST's are also very marginal at around the 27C mark around it's track.

Talking about track, the globals take it across florida, either middle Florida or south. Then along and up into LA. The tropical models have yet to initial it, even ships !.

Still with all this though, the system looks to have some shape and could be very close to Invest status which could come this morning.

My view is that the globals could be right, but conditions for it to develop are certainly marginal and a good dose of luck would be needed.

[Iceberg]

This has now been upped to Invest 90L.

Do we have a different thread for invests.?.

Little information out atm, Shear is still strong and greatly effecting the system. Circulation is there. The track is still via Meto over Florida and into LA. GFS takes it further north and there is no more sea after a Florida hit.

It will be interesting to see what Ships et al make of it.

Personally I am not too convinced of anything much a TD at best maybe.

[Somerset Squall]

This has now been upped to Invest 90L.

Do we have a different thread for invests.?.

Yes, here:

http://www.netweather.tv/forum/index.php?showtopic=54620

[Iceberg]

Cheers must have been blind.

[Somerset Squall]

Cheers must have been blind.

It was quite far down the page! I think I started it a little prematurely

An early start to the season again perhaps. The NHC have taken a little interest in it. We shall see.

[Cookie]

well im chuffed that we got an invest out of it, never gave up and it didn't prove me wrong.

[Somerset Squall]

The extratropical low that absorbed invest 90L has dumped in excess of 20 inches of rainfall in some parts of Florida, causing some road closures and flooding. There is quite a strong circulation with the low which is now located in the eastern GOM. The system is still very much extratropical at the moment but as it moves towards the Gulf coast waters will be around 26-27C, so there is a small risk of a subtropical or tropical depression forming prior to landfall, providing shear becomes low enough and the air profile a little moister. Just a small risk however, but there could be another invest out of this.

[Cookie]

I think we may have an invest with this one sooner rather then later. next 24 to 36 hrs at a guess?