Strong wave near Leeward Islands - Is Invest 97L

[Blown Away]

IMO, the TUTT is retreating and looks like it is weakening and I don't see the winds screaming to the NE like they were a few days ago. The convection is really blowing up E of the Northern islands and it does have a curvature look to it.

[bvigal]

Does anybody see any sign of a broad low?

NHC mentions it, but doesn't put it on surface map - it's too broad to nail down. But there are some indicators.
Looking at the buoy reports last 24hrs that are all south of 15N as this passed by, looks like any low at least north of 15N. I thought this ship report might be a clue. But it might have been a strong squall.

ID T1 TIME LAT LON WDIR WSPD GST WVHT PRES PTDY ATMP WTMP DEWP
SHIP S 0600 15.50 -57.90 320 42.0 - - - 29.92 -0.04 81.5 - 75.9

Now that I've posted it, let me also state again for 2010 caveat about these type of reports:
Ships don't return gust column information, so PLEASE don't anyone read this and think it means 42kt sustained winds!! I look at 500mi radius of ship reports every day for over 8 years, comparing to nearby airports, buoys, satellite estimates, and captains who call me with first-hand reports. Ship reports in this part of the world are usually not sustained averages, they are peaks. The big cruise ships might do them, but then they are 200ft above the water, so equally inflated compared to airports. We have these airports in Caribbean, many right off the beach, and when the wind is blowing from a direction where there's no land blocking and nothing sticking up for miles upwind, they will always return a much lower reading than a ship nearby in open seas. Same for buoys. That's because they average the winds. Ship reports come from a variety of programs, some are private sailboats, some are local inter-island freighters. Always take ship reports with a "grain of salt", and verify with additional data, if possible.

[OURAGAN]

Finally we will not get too much rain in Guadeloupe for the moment, occording radar of Guadeloupe, the rain is north of our area:

[Gustywind]

Here is the translation from this weather alert (yellow code) at 930 AM:

Synopsis and observations:
An area of showers and tstorms (twave) is concerning the Lesser Antilles. The most active part is located on the East Atlantic, at 100 kilometers east of the Nothern Leewards (St Marteen and St Barth).

Forecasts:
Tstorms, accompanied with strong showers and sometimes gustywinds, will spread on the area of St Marteen and St Barth and could concerned these two islands, and for a pretty long period, at least tommorow night.

Summary:
The risk is moderate;
The impact expected is moderate.

[b]Validity-Duration:[/b]
From Sunday 18th- Monday 19th at least
Next weather forecast: tonight at approximetaly 6 PM.

Stay tuned.

[Gustywind]

Here is the translation from this weather alert (yellow code) at 930 AM:

Synopsis and observations:
An area of showers and tstorms (twave) is concerning the Lesser Antilles. The most active part is located on the East Atlantic, at 100 kilometers east of the Nothern Leewards (St Marteen and St Barth).

Forecasts:
Tstorms, accompanied with strong showers and sometimes gustywinds, will spread on the area of St Marteen and St Barth and could concerned these two islands, and for a pretty long period, at least tommorow night.

Summary:
The risk is moderate;
The impact expected is moderate.

[b]Validity-Duration:[/b]
From Sunday 18th- Monday 19th at least
Next weather forecast: tonight at approximetaly 6 PM.

Stay tuned.

For those who want to improve their french during the holidays . http://www.meteo.fr/temps/domtom/antill ... ivi_in.pdf
It's the best moment to begin, why not

[Gustywind]

Finally we will not get too much rain in Guadeloupe for the moment, occording radar of Guadeloupe, the rain is north of our area:

Absolutely Ouragan, that's relatively good news for us but the southern portion of this bulk seems to pop steadily and some isolated and tenacious showers are concerning the northern tip of the island near Anse-Bertrand. Given the overall trend looks like for the moment (next 2 or 4 hours) that we should not deal with much rain... hopefully . The moist air behing should allow for mini burst this afternoon and tonight, let's wait and see. Whereas we should continue to monitor this system, we always know all the gimmicks of these twaves in July.

[srainhoutx]

OURAGAN and Gustywind I removed the link to the Guadalupe Radar as it was causing a log in and password pop up to occur.

[bvigal]

Thanks for the translation, as it seems Guadeloupe has been the center of much of the shower activity crossing the Leewards this season! Those of us in PR/VI pay close attention to Guadeloupe, because we usually get what you do a few hours later!

For those who want to improve their french during the holidays . http://www.meteo.fr/temps/domtom/antill ... ivi_in.pdf
It's the best moment to begin, why not

Gusty, I want to improve my French! (Spanish, too) I'd rather set up inter-island visiting program, where interested persons visit each other and immerse in the language they want to learn. With my 4 years of French in high school a few centuries ago, it wouldn't take me long to learn to hear and speak it again. Reading/writing might take longer...

[floridasun78]

next few day will tell

[wxman57]

It still the NAM I don't believe that model unless the system is already developed. That model cries wolf all summer long usually.

And then i STILL don't believe it.

It's going to take a few days for the disturbance to consolidate and have a shot at developing. What gets my attention is the tremendous amount of moisture available across the Caribbean now. It's far greater than pre-Alex (I'll just post the loop links here):

pre-Alex:
http://cimss.ssec.wisc.edu/tropic/real- ... anim72.gif

Current:
http://cimss.ssec.wisc.edu/tropic/real- ... t72hrs.gif

Both GFS and Euro build a ridge over the SE U.S. in 3 days. However, both weaken it rather quickly. This could allow for an increasing risk to the northern Gulf coast vs. NE Mexico/south TX (should it develop).

Caribbean definitely seems primed for development. We'll just have to watch and wait now...

[cycloneye]

Here is this mornings take about the wave by Dr Jeff Masters.

Posted by: JeffMasters, 1:57 PM GMT on July 18, 2010

A tropical wave near 18N, 60W is entering the northernmost Lesser Antilles Islands and is generating some disorganized heavy thunderstorm activity. This wave is under about 20 knots of wind shear, due to strong upper-level westerly winds. The strong upper-level winds are associated with the counter-clockwise flow of air around an upper-level cold-cored low pressure system a few hundred miles north of Puerto Rico. As the wave progresses west to west-northwest through Tuesday, thunderstorm activity will increase, due to interaction with the upper low. The rains from these thunderstorms will bring the threat of flooding to Puerto Rico on Monday, the Dominican Republic on Tuesday, and Haiti on Wednesday. The upper low will also bring high wind shear of 20 - 30 knots over the the wave on Monday and Tuesday. No development of the wave is likely until at least Thursday, when it will be over the eastern Bahamas and eastern Cuba. At that time, shear is expected to drop below 20 knots, and the wave has the potential to develop. However, none of the reliable computer models is calling for tropical cyclone development over the next seven days. I expect that this wave will eventually enter the Gulf of Mexico early next week. NHC is giving the wave a 10% chance of developing into a tropical depression by Tuesday.

[srainhoutx]

And then i STILL don't believe it.

We would be in TS/Hurricane conditions this morning in TX if the NAM had been correct with the current GOM wave. Now back on Topic.

[cycloneye]

wxman57, when you expect this to be tagged as Invest?

[bvigal]

Good morning, wxman! I was wanting to ask what you think about this TUTT, NWS/SJU says we'll feel the effects for a couple more days, but it does look weaker and farther north. Do you think it will continue to move away, and if not, any indication of how long before it fizzles?

[wxman57]

wxman57, when you expect this to be tagged as Invest?

Almost did it again - clicked edit on your post.

I'd definitely expect it to get some attention soon, invest-wise. No reason not to. Invests aren't reserved only for those systems that are likely to develop in the near-term. An invest just gives the NHC the opportunity to look more closely at it to see where some of the models might take it should it develop. Absolutely no harm in doing that.

[KWT]

Looking ar the Vis.imagery there is some weak turning close to the convection, itsd not closed though and its certainly very elongated as well from the looks of things.

ULL shifting orientation right now which maybe the first sign its going to lift out from the region a little.

The convection though is interesting and needs to be watched, esp if the shear does decrease down the line, if the circulation can tighten and it the system can stay away from the Islands in the whole its going to have a shot at developing.

If it keeps going invest could well occur today IMO.

[Gustywind]

Thanks for the translation, as it seems Guadeloupe has been the center of much of the shower activity crossing the Leewards this season! Those of us in PR/VI pay close attention to Guadeloupe, because we usually get what you do a few hours later!

For those who want to improve their french during the holidays . http://www.meteo.fr/temps/domtom/antill ... ivi_in.pdf
It's the best moment to begin, why not

Gusty, I want to improve my French! (Spanish, too) I'd rather set up inter-island visiting program, where interested persons visit each other and immerse in the language they want to learn. With my 4 years of French in high school a few centuries ago, it wouldn't take me long to learn to hear and speak it again. Reading/writing might take longer...

You're definitely right my BVIGAL, nice analysis as usual! Yeah "curiously" Guadeloupe has been the center of much of the shower activity... hoping that it's pure hazardous thing Yeah we're linked Guadeloupe from PR BVI with the trajectory of these systems. Glad to see that you were a excellent pupil but always a nice too in 2010 So i will post more french text from Meteo-France if you are interrested ! I appreciate franckly your post!

[Vortex]

Question of the day? If this system spins up an LLC will it be just north, south, or over the Greater antilles...GFS says just north while Canadian runs the length of the Greater antilles. To be determined but all models agree on copius anmounts of rainfall associated with this system so flash flooding and mudslides seem to be a given...

[Vortex]

In all liklihood, whether or not this system tracks through the Bahamas, Greater Antilles, or just South(Carribean) it will find itself in the Gulf in 5-7 days...Model consensus is strong that ridging to the north should keep it W/WNW for some time.

[KWT]

Indeed Vortex, I was thinking earlier this could take a Georges type path, just to the north or south of the Islands and this one has a shot, if it goes over the islands then the only real shot of development will likely be in the Gulf...I think whilst early days the Para GFS isn't far off.