INVEST 99L near Leewards,comments,sat pics,etc #4

[senorpepr]

Looks like the LLC(Yes it is one)has become even more developed which now you can clearly see. Also convection has been firing up...The thing hurting the system is northwestly shear of 20 knots...Which is pushing the convection off. On the last few frames it shows convection is starting to fire over the LLC. This LLC looks very good right now...Would not at all be suprized if this was upgraded to a 1.5/2.0t later today. With it about ready to go through the islands the nhc needs to watch this.

You have a sharp NE-Sw orientated CUSP...you do not have a LLC. Get out the vis-a-vis and write on the monitor and the cusp will come alive...and you will see there are no eastward moving cloud elements. The LLC does not look that good because it isn't there in ground-relative terms. Stop following the center with your eyes. Grab a marker and analyze the elements.

It's a cusp. NE-SW and sharp...close to being closed but not yet.

AFM, it's refreshing to hear people, including mets, refer to the good ol' cusp. Maybe analysts tend to skip over the cusp stage in cyclone development.

[x-y-no]

Looks like the LLC(Yes it is one)has become even more developed which now you can clearly see. Also convection has been firing up...The thing hurting the system is northwestly shear of 20 knots...Which is pushing the convection off. On the last few frames it shows convection is starting to fire over the LLC. This LLC looks very good right now...Would not at all be suprized if this was upgraded to a 1.5/2.0t later today. With it about ready to go through the islands the nhc needs to watch this.

You have a sharp NE-Sw orientated CUSP...you do not have a LLC. Get out the vis-a-vis and write on the monitor and the cusp will come alive...and you will see there are no eastward moving cloud elements. The LLC does not look that good because it isn't there in ground-relative terms. Stop following the center with your eyes. Grab a marker and analyze the elements.

It's a cusp. NE-SW and sharp...close to being closed but not yet.

Well, as I said in the last thread, between 17:15 and 18:15 gmt I thought I was seeing a slight SW flow near 15.1N 57.6W. But high clouds are now covering the area, so I'm not confident about it having been the real thing.

Given that uncertainty, I don't see any reason to rush to call it a TD. If it's going to develop significantly, then soon enough it'll be clear rather than ambiguous.

EDIT: I don't care to draw on my screen, so I just hold a card with regular markings on it against the screen in the area I'm interested in.

[NONAME]

Bouy 41100 is show a preasure of between 1012-1013Mb the bouy located 6NM away from 99L. it has a wind of 6Kt and a preasure tendance of around 2Mbs the bouy is located at 15.90n 57.90w and the wind direction is 50°.

http://www.ndbc.noaa.gov/radial_search. ... t=A&time=3

[Air Force Met]

Looking really close, I see exactly what AFM is talking about. To the untrained eye, it's like a trick of the eyes. It looks like a closed low, but it's not..not quite yet. Thanks AFM for pointing that out.

In streamline analysis we call it a CUSP. The wave axis will run down the center of the CUSP...the sharper the wave axis...the sharper the CUSP. The vorticity center will sit in the middle of the CUSP where the divergent streamline changes to a convergent one.

[WindRunner]

I'm not sounding an alarm or anything, but if you look at the vis loop you might just notice a couple of (barely) eastward moving clouds in the last 5 or so frames (ending at 18:45Z image) that are getting pulled under the new convective flareup over the center. Then again, I might have been staring at that loop too long . . .

[x-y-no]

Bouy 41100 is show a preasure of between 1012-1013Mb located 6NM away from it it has a wind of 6Kt and a preasure tendance of around 2Mbs the bouy is located at 15.90n 57.90w and the wind direction is 50°.

That's the trouble with these hyperactive threads ... see page 2.

[wxman57]

Just breaking in with a new GARP image of satellite/sfc obs. One of the two small eddies passed very close to the buoy in the past hour. Lowest pressure is probably around 1012mb. Wind is now fairly light and variable at the buoy:

http://www.ndbc.noaa.gov/station_page.php?station=41100

Here's the surface plot with satellite:
http://myweb.cableone.net/nolasue/99Li.gif

I put an "X" over two small eddies that appear to be rotating to the southwest. The larger red arrow indicates general motion.

Still looks not much different from this morning. Convection may be decreasing a bit, and according to this brand new McIDAS image, the two small eddies are not as apparent on high-res shots now as they were an hour ago.

http://myweb.cableone.net/nolasue/99Lj.gif

Looks like no well-defined LLC.

Ok, carry on....

[Air Force Met]

AFM, it's refreshing to hear people, including mets, refer to the good ol' cusp. Maybe analysts tend to skip over the cusp stage in cyclone development.

Well...I have two things to thank for that:

1) METSAT school...and
2) Tropical Metorology course at Keelser...in which I steamlined my fanny off using satellite imagery and a bunch of charts with a few wind barbs on it.

The CUSP is all important and is the final step before it closes off. Whether it takes the next step is up to it.

[AJC3]

Looks like the LLC(Yes it is one)has become even more developed which now you can clearly see. Also convection has been firing up...The thing hurting the system is northwestly shear of 20 knots...Which is pushing the convection off. On the last few frames it shows convection is starting to fire over the LLC. This LLC looks very good right now...Would not at all be suprized if this was upgraded to a 1.5/2.0t later today. With it about ready to go through the islands the nhc needs to watch this.

You have a sharp NE-Sw orientated CUSP...you do not have a LLC. Get out the vis-a-vis and write on the monitor and the cusp will come alive...and you will see there are no eastward moving cloud elements. The LLC does not look that good because it isn't there in ground-relative terms. Stop following the center with your eyes. Grab a marker and analyze the elements.

It's a cusp. NE-SW and sharp...close to being closed but not yet.

Well, as I said in the last thread, between 17:15 and 18:15 gmt I thought I was seeing a slight SW flow near 15.1N 57.6W. But high clouds are now covering the area, so I'm not confident about it having been the real thing.

Given that uncertainty, I don't see any reason to rush to call it a TD. If it's going to develop significantly, then soon enough it'll be clear rather than ambiguous.

<insert forecast disclaimer here>


I think regardless of which side of the fence one falls on, this system is getting closer to closing a wind center. It looks as though the system will get far enough west of the developing TUTT low to it's north so that the northerly shear will decrease some, but not completely. Eventually the GFS shows the TUTT low "chasing" this system WNW toward the SE U.S. coast.

The air mass out ahead of it is not nearly as dry as what it is embedded in now, so I'd expect a slow increase in convection. Since the system is gaining latitude, it should slow it's forward speed soon. I think this system will close off and become a depression within 24 hours.

[benny]

Light NW winds from a buoy... you cusp people
http://www.ndbc.noaa.gov/station_page.php?station=41100

[x-y-no]

Bouy 41100 - 20:00 GMT

pressure 1011.8mb

wind NW at < 2 knots

[Air Force Met]

I'm not sounding an alarm or anything, but if you look at the vis loop you might just notice a couple of (barely) eastward moving clouds in the last 5 or so frames (ending at 18:45Z image) that are getting pulled under the new convective flareup over the center. Then again, I might have been staring at that loop too long . . .

No offense...but I'm looking at a better sat loop than the SSD page.

[NDG]

Buoy 41100 now showing a light NW wind, pressure continuing to drop to below 1012 MB.

Wind Direction (WDIR): NW ( 320 deg true )
Wind Speed (WSPD): 1.0 m/s
Wave Height (WVHT): 2.2 m
Dominant Wave Period (DPD): 7 sec
Atmospheric Pressure (PRES): 1011.8 mb
Pressure Tendency (PTDY): -2.4 mb ( Falling )
Air Temperature (ATMP): 27.0 °C
Water Temperature (WTMP): 28.4 °C

[Matt-hurricanewatcher]

I'm not sounding an alarm or anything, but if you look at the vis loop you might just notice a couple of (barely) eastward moving clouds in the last 5 or so frames (ending at 18:45Z image) that are getting pulled under the new convective flareup over the center. Then again, I might have been staring at that loop too long . . .

This may not be 100 percent closed but I seen eastly's to.

[Air Force Met]

I think regardless of which side of the fence one falls on, this system is getting closer to closing a wind center. It looks as though the system will get far enough west of the developing TUTT low to it's north so that the northerly shear will decrease some, but not completely. Eventually the GFS shows the TUTT low "chasing" this system WNW toward the SE U.S. coast.

The air mass out ahead of it is not nearly as dry as what it is embedded in now, so I'd expect a slow increase in convection. Since the system is gaining latitude, it should slow it's forward speed soon. I think this system will close off and become a depression within 24 hours.

Now that is an assessment I can agree with. It's getting close. The CUSP phase is the last phase before it closes off...especially with it being so sharp.

[Trugunzn]

looking more and mor eimpressive

[shaggy]

2 knts are you kiddin me 2 knts is it and this is suppose to be a forming TD? Anyone thinking this is a TD needs to remember there are winds that are required to reach 30mph before it can go TD so let me know when it gains another 28mph!

[Brent]

I think this is going to develop afterall...

[Scorpion]

No, it just needs an LLC. Windspeed is not considered.

[all_we_know_is_FALLING]

I think the NHC should NOT declare this a TD until later tonight. See if it continues to remain somewhat organized.