ATL: Tropical Depression Dolly

[DESTRUCTION5]

Somethings "seems" a little off with this. The UKMET isn't developing it at all, there is some very dry air to the NW and although the banding is decent, the QSCAT signature isn't very impressive even for a tropical wave.

Perhaps there is something slightly off with the thermodynamic environment that is keeping this from really getting going.

Still waiting for one of those circular convective bubbles to push up near the middle of the broad low. I am sure the NHC is waiting for some deeper thunderstorms to redevelop before even considering an upgrade at this time.

MW

This is a name I like to see...Glad to see you MW...

[Ed Mahmoud]

Somethings "seems" a little off with this. The UKMET isn't developing it at all, there is some very dry air to the NW and although the banding is decent, the QSCAT signature isn't very impressive even for a tropical wave.

Perhaps there is something slightly off with the thermodynamic environment that is keeping this from really getting going.

Still waiting for one of those circular convective bubbles to push up near the middle of the broad low. I am sure the NHC is waiting for some deeper thunderstorms to redevelop before even considering an upgrade at this time.

MW

This reminds me of some of the recent East Pac invests/depressions, that take a day or two to separate from the ITCZ. But this seems to be headed in the right direction, organization wise. It does have dry air ahead of it, although the dry air seems to be shrinking Westward ahead of it.

The UK Met hasn't blown my socks off this season.

The longer it takes to break free, the less time it has to gain strength before the islands, and I'm sure our friends like Gustywind would prefer a tropical storm to a hurricane, so hopefully this works out.

[HurricaneHunter914]

Question. How does low level convergence form over a system?

[Ivanhater]

Hmm..Looks like this will take the Caribbean train...I cant wait til this forms (if it forms), so we can get a better handle on ut and the models have an actual system to base off of...

[Ed Mahmoud]

NOUS42 KNHC 141400
WEATHER RECONNAISSANCE FLIGHTS
CARCAH, NATIONAL HURRICANE CENTER, MIAMI, FL.
1000 AM EDT MON 14 JULY 2008
SUBJECT: TROPICAL CYCLONE PLAN OF THE DAY (TCPOD)
VALID 15/1100Z TO 16/1100Z JULY 2008
TCPOD NUMBER.....08-044

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY: LOW LEVEL INVEST FOR
16/1800Z NEAR 13.0N AND 54.0W AND BEGIN 6 HRLY FIXES
IF SYSTENM (sic) DEVELOPS AT 17/0600Z, ALSO A GIV MISSION
FOR 17/0000Z.
II. PACIFIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY.....NEGATIVE.
WVW

[Gustywind]

000
FXCA62 TJSJ 141007
AFDSJU

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN JUAN PR
607 AM AST MON JUL 14 2008

THE GFS HAS BECOME POSITIVELY SCHIZOPHRENIC FOR OUR AREA LATER
THIS WEEK...AS THE 18Z AND 00Z RUNS COULD HARDLY BE MORE
DIFFERENT. ALTHOUGH BOTH RUNS SCARCELY DIFFERED WITH RESPECT TO
TIMING...THE 18Z RUN DEVELOPED A STRONG TROPICAL STORM OR
HURRICANE AND PULLED IT DIRECTLY SOUTH OF THE LOCAL AREA...WHILE
THE LATEST 00Z RUN SHOWED HARDLY ANY CIRCULATION AT ALL IN A
RELATIVELY STRONG TROPICAL WAVE. HOW THIS ACTUALLY TURNS OUT WILL
DEPEND ON HOW WELL CONVECTION NEAR 40 WEST CAN ORGANIZE. AND...ONCE
IT DOES...THE MODEL WILL LIKELY PULL TOGETHER ITS BIFURCATED
FORECAST. THOSE WHO HAVE NOT COMPLETED THEIR EARLY SEASON
HURRICANE PREPARATIONS SHOULD DO SO IMMEDIATELY AS THE SYSTEM IS
ALREADY SHOWING SIGNS OF CYCLONIC TURNING. AVERAGE WEATHER WITH
SCATTERED SHOWERS AND THUNDERSTORMS FOLLOWS THIS SYSTEM REGARDLESS
OF ITS STRENGTH.
Leewards from Guadeloupe to Puerto Rico keep watching it...

Sometime back in the mid to late '80s, a tropical wave passed over Barbados with gusts in excess of 55 mph (well above the tropical storm threshold). So even if 94L remained a wave, it could still pack a punch.[/quote
You're right Abajan agree with you, whereas it seems that a wave in 2003 or 2004 brang the same values in Marie Galante and" les Saintes " in Guadeloupe they report gusts to 60 kts, so we can't ignore and underestimated the power of a simple wave or organized or not and a storm or cane. To sum up all residents should continue to monitor the tropics activity especially with 94L, and maybe TD 3...should it verifies first !

[KWT]

Yep Ed I noticed that as well I think the wave that went on to be Boris was also very streched out and that one took a while to get going but it doesn't seem all that far away from being a depression depsite having a lack of any real deep convection with it. Still we will what happens over the next 24hrs I guess!

Mike, derek was saying ealrier its because there is a real lack of low level convergence but who knows?

[PTrackerLA]

Until yesterday afternoon when deep convection developed near the "center", the general consensus was that this would be slow to organize and probably not be a depression until Tuesday. This is what I'm seeing now, a slowly developing system and with convection likely increasing later today I believe we're still headed for a depression by tomorrow IMO.

[KWT]

I. ATLANTIC REQUIREMENTS
1. NEGATIVE RECONNAISSANCE REQUIREMENTS.
2. OUTLOOK FOR SUCCEEDING DAY: LOW LEVEL INVEST FOR
16/1800Z NEAR 13.0N AND 54.0W AND BEGIN 6 HRLY FIXES
IF SYSTENM (sic) DEVELOPS AT 17/0600Z, ALSO A GIV MISSION
FOR 17/0000Z.

Ah recon, I was wondering if we was going to get recon for this invest as long as it doesn't completely decay by that time we should see our first recon on Wednesday, also 6hr fixes after that as well so they are taking this seriously.

[Blown Away]

Convection starting to pop on the N side, broad low around 12N/42.5W. I think TD is on the way.

http://www.ssd.noaa.gov/goes/flt/t2/loop-avn.html

[Ed Mahmoud]

Question. How does low level convergence form over a system?

Something makes winds come together/converge near the center, causing air to rise. Upper divergence can lower pressur enear the surface, allowing air to converge.

While the South American heat low causes divergence in the Eastern Caribbean, and speeds up the low level winds, when they reach the Western Caribbean and start feeling the affects of land, they slow down, causing a piling up of air and convergence.

Anything that causes air to slow causes convergence, like onshore flow in the early morning that experiences an increase in friction due to land will slow down just offshore, and form the morning showers along the coast that happen in SE Texas in the Summer months sometimes.


Anyway, it is kind of a feedback, if there is upper divergence, and enough convergence for thunderstorms, eventually the thunderstorms evacuate enough air from the surface that are then dispersed aloft, lowering pressure, and creating more convergence.



Note, this is not the textbook answer, because I don't know what the textbook answer is.

Nobody asks questions about mobility ratios, or the movement of multiphase fluid in anisotropic and hetereogeneous media. Which is good, because I barely understood in college, and now am clueless on what I am actually a professional.

[Weatherfreak14]

Convection starting to pop on the N side, broad low around 12N/42.5W. I think TD is on the way.

http://www.ssd.noaa.gov/goes/flt/t2/loop-avn.html

If only that can get wrapped around enough and stay with it.... It might have a chance for 11pm adv tonight or 11am tommrow.

[KWT]

Yep blown away at least that new convection should keep this low going for a little while longer until it gets better organised.

PTrackerLA, indeed just need to watch to see if any strong convective bursts develop near the center.

[HurricaneHunter914]

Question. How does low level convergence form over a system?

Something makes winds come together/converge near the center, causing air to rise. Upper divergence can lower pressur enear the surface, allowing air to converge.

While the South American heat low causes divergence in the Eastern Caribbean, and speeds up the low level winds, when they reach the Western Caribbean and start feeling the affects of land, they slow down, causing a piling up of air and convergence.

Anything that causes air to slow causes convergence, like onshore flow in the early morning that experiences an increase in friction due to land will slow down just offshore, and form the morning showers along the coast that happen in SE Texas in the Summer months sometimes.


Anyway, it is kind of a feedback, if there is upper divergence, and enough convergence for thunderstorms, eventually the thunderstorms evacuate enough air from the surface that are then dispersed aloft, lowering pressure, and creating more convergence.



Note, this is not the textbook answer, because I don't know what the textbook answer is.

Nobody asks questions about mobility ratios, or the movement of multiphase fluid in anisotropic and hetereogeneous media. Which is good, because I barely understood in college, and now am clueless on what I am actually a professional.

Thanks Ed, that helped me alot.

[Sanibel]

The center of circulation seems stronger than Chris, so this could have more of a chance. If we think of Bertha's strong circulation and what that lead to that would give development a better chance, but 94L is further south into the July Caribbean synoptic. 94L's history is seeing the convection jump to the center from the south, so maybe it will do it again today? Can't say for sure because it all depends on the conditions that are currently keeping the convection down. I suspect the Atlantic ridge has been pushed down on top of 94L making subsidence. This would also force a west-ish track. This would mean if 94L's circulation is strong it should outlast it, but then it has to deal with Caribbean transition. SST's climb tomorrow to the west.

[senorpepr]

Mike, derek was saying ealrier its because there is a real lack of low level convergence but who knows?

Derek is probably onto something there...

[cheezyWXguy]

The center of circulation seems stronger than Chris, so this could have more of a chance. If we think of Bertha's strong circulation and what that lead to that would give development a better chance, but 94L is further south into the July Caribbean synoptic. 94L's history is seeing the convection jump to the center from the south, so maybe it will do it again today? Can't say for sure because it all depends on the conditions that are currently keeping the convection down. I suspect the Atlantic ridge has been pushed down on top of 94L making subsidence. This would also force a west-ish track. This would mean if 94L's circulation is strong it should outlast it, but then it has to deal with Caribbean transition. SST's climb tomorrow to the west.

Stop comparing this to Chris...Its not in the same area, likely not even forecast to move into that area, and atmospheric conditions are way more favorable for development. The only reason this isnt a td now is because of lack of low level convergence, which I can see is already beginning to come back. Its not like this system is being blasted with 30kts of mid-level shear.

[gatorcane]

[Sanibel]

Stop comparing this to Chris...Its not in the same area

I compared it to Chris because it is a good comparison to a storm that takes good form on satellite when weak but then suddenly thins out. I also qualified it in plain writing that this has a better circulation. Though I agree Chris was in an unfavorable spot for 2006 and 2007. I'd be more interested in what you thought about the ridge above possibly being pushed down on to it creating subsidence?


The key here is whether it reconvects or not.

[KWT]

Yep senorpepr ther eis certainly a lack of it, thats probably why it has a rather odd look right now with a nearly clear circulation and convection to the north and south of it.

as for the comprasion to Chris, I don't think its al lthat valid, though I will never forget the way that storm got hammer blowed by shear and in one night it went from look good to being totally naked, it was so swift!