INVEST 91L -Discussions,Analysis and Imagery

[Aric Dunn]

Well, I may get blasted for this ... but I really am unimpressed with 91L tonight. There's still no signficant surface low from which convection is wrapping ... the upper low clearly still is influencing the outflow structure. All we have (which is what we had 2 days ago) is a lot of disorganized weather.

im impressed but also not so impressed.. the convection pattern is quite sad.. and need to move away from land otherwise its going to be very slow !!

[Dionne]

Sweet Jesus..PLEASE let it turn north and come to Louisiana. I would give anything to have this park on top of us for 2 or 3 days. This heat is unbearable.

yeah.......and maybe just hit a bit of SW Mississippi.......a nice rain and cooler temps.....I'm gonna go do my rain dance.....

[Aric Dunn]

this system looks far better than bret did when it formed (1999) bret. It had no convection 3 hours after being classified

That said, I decided NOT to issue any updates even if it is officially classified, as I do not believe it quite meets the criteria to be called a TD

agreed.. the convection really is not there .. but by definition i guess it could be .. lol

[Ed Mahmoud]

The GOES eclipse thread may explain why my floater hasn't updated since 2145Z

[Portastorm]

Well, I may get blasted for this ... but I really am unimpressed with 91L tonight. There's still no signficant surface low from which convection is wrapping ... the upper low clearly still is influencing the outflow structure. All we have (which is what we had 2 days ago) is a lot of disorganized weather.

im impressed but also not so impressed.. the convection pattern is quite sad.. and need to move away from land otherwise its going to be very slow !!

... and to be fair Aric, I went back and looked at your loops and I see what you mean about a circulation center. There seems to be several though and maybe that's the problem here.

[Ed Mahmoud]

The GOES eclipse thread may explain why my floater hasn't updated since 2145Z

or maybe not, just updated through 0015Z

[Ed Mahmoud]

Doesn't look impressive at all, even on IR2.

I suspect if a center ever does form, it will be Northeast of where low level swirl was back on visible imagery, in the stronger thunderstorms.

[Aric Dunn]

Well, I may get blasted for this ... but I really am unimpressed with 91L tonight. There's still no signficant surface low from which convection is wrapping ... the upper low clearly still is influencing the outflow structure. All we have (which is what we had 2 days ago) is a lot of disorganized weather.

im impressed but also not so impressed.. the convection pattern is quite sad.. and need to move away from land otherwise its going to be very slow !!

... and to be fair Aric, I went back and looked at your loops and I see what you mean about a circulation center. There seems to be several though and maybe that's the problem here.

agreed.. there probably is.. but the point being is that far north west would not be possible .. if you look at the loop you were looking at you would notice that.. that far NW has N to NE blowing thru it..

[weatherguru18]

I'm glad that I'm not the only one that thinks this thing is nothing more than a tease. The center is completely exposed. The ULL is out running the LLC. This *may* have a chance, but the center only has about 54 hours or so before "landfall." This will be a nice rainmaker though.

[tailgater]

That vortex near the Yucatan has little chance of becoming the dominant center....its being ripped apart by shear and is weakening.

how can you tell its weakening... ?? and its just LITTLE bigger than what I think of a vortex is

Well what im seeing is close to the northern coast of the Yucatan, while convection is firing North of the Yucatan channel. The area where that Low is doesn't have the best vorticity and doesn't have the best upper air dynamics. I'd look for the center to establish itself just N of the yucatan channel where convection is firing.

http://cimss.ssec.wisc.edu/tropic/real- ... 8vor4.html

http://cimss.ssec.wisc.edu/tropic/real- ... 8vor3.html

None of these maps suggest that a center is going to form that close to the coast, but further NNE.

Take a look at this loops showing good mid and upper organization or at least getting better than that surface circ. near the coast which moved little all day, maybe a little SW. IMHO if this system gets going it would have to relocate near the mid-level rotation
http://www.ssd.noaa.gov/goes/flt/t2/loop-jsl.html

http://www.ssd.noaa.gov/goes/flt/t2/loop-ir2.html

[teal61]

I'm glad that I'm not the only one that thinks this thing is nothing more than a tease. The center is completely exposed. The ULL is out running the LLC. This *may* have a chance, but the center only has about 54 hours or so before "landfall." This will be a nice rainmaker though.

I believe that to have a better shot at developing, the upper low does need to outrun the llcc.

[wxman57]

well i disagree. i personally watched the the 1km visible for a while and couple that with the radar loops i have made, it puts the center closer to the coast, you could clearly see a small tight center! and i know the difference between upper level sirus clouds verses low level .. so dont want to hear that ..

Why am I not surprised? You seem to look for arguments wherever you can find them. Perhaps the center was down south in your earlier radar images, but I think it's clearly moved or relocated to the northwest since then. I re-animated your image with much shorter time steps and you have your circle where the center may have been a few hours ago. I saw it down there too before sunset, but it appears to be accelerating off to the northwest now as the upper low moves out to the west. I captured your last image and drew a yellow circle near where the radar indicates the LLC. It's hard to pick it out with small showers forming and dissipating giving the illusion of movement in some parts of the circulation.



If you take a look at the heavy shower on the NE side of your blue circle in the last few frames of the loop, you can clearly see it's moving NW-NNW not to the W-WNW as it would if the LLC was as you've drawn it. It's a feeder band moving toward the center off to the northwest of your location. In the end, it makes zero difference which location is the center, as there's no significant convection firing yet, and the general path would be the same.

[Aric Dunn]

That vortex near the Yucatan has little chance of becoming the dominant center....its being ripped apart by shear and is weakening.

how can you tell its weakening... ?? and its just LITTLE bigger than what I think of a vortex is

Well what im seeing is close to the northern coast of the Yucatan, while convection is firing North of the Yucatan channel. The area where that Low is doesn't have the best vorticity and doesn't have the best upper air dynamics. I'd look for the center to establish itself just N of the yucatan channel where convection is firing.

http://cimss.ssec.wisc.edu/tropic/real- ... 8vor4.html

http://cimss.ssec.wisc.edu/tropic/real- ... 8vor3.html

None of these maps suggest that a center is going to form that close to the coast, but further NNE.

Take a look at this loops showing good mid and upper organization or at least getting better than that surface circ. near the coast which moved little all day, maybe a little SW. IMHO if this system gets going it would have to relocate near the mid-level rotation
http://www.ssd.noaa.gov/goes/flt/t2/loop-jsl.html

http://www.ssd.noaa.gov/goes/flt/t2/loop-ir2.html[/quote]

yeah been watching further north for something to relocate ... but as of yet cant see anything .. but like i said before you said it either needs to move north or reform away from the coast..

the upper low is moving away and will only improve the environment as time goes by

[Aric Dunn]

well i disagree. i personally watched the the 1km visible for a while and couple that with the radar loops i have made, it puts the center closer to the coast, you could clearly see a small tight center! and i know the difference between upper level sirus clouds verses low level .. so dont want to hear that ..

Why am I not surprised? You seem to look for arguments wherever you can find them. Perhaps the center was down south in your earlier radar images, but I think it's clearly moved or relocated to the northwest since then. I re-animated your image with much shorter time steps and you have your circle where the center may have been a few hours ago. I saw it down there too before sunset, but it appears to be accelerating off to the northwest now as the upper low moves out to the west. I captured your last image and drew a yellow circle near where the radar indicates the LLC. It's hard to pick it out with small showers forming and dissipating giving the illusion of movement in some parts of the circulation.



If you take a look at the heavy shower on the NE side of your blue circle in the last few frames of the loop, you can clearly see it's moving NW-NNW not to the W-WNW as it would if the LLC was as you've drawn it. It's a feeder band moving toward the center off to the northwest of your location. In the end, it makes zero difference which location is the center, as there's no significant convection firing yet, and the general path would be the same.

well unfornately your yellow circle has showers and storm moving SW thru yours.. im not sure if you have a loop . but when i get 9 more new images i will post another loop

[Steve]

How anyone can say something is organized or disorganized based off of IR is beyond me. Even >I< am not that good. Unless it is a very mature system with a CDO et al with spiraling bands, you just can't tell. Tomorrow's visibles will show us what we do or don't have to grow on the next day or two. JMO

Probably a couple of centers spinning around in there anyway.

>>Sweet Jesus..PLEASE let it turn north and come to Louisiana. I would give anything to have this park on top of us for 2 or 3 days. This heat is unbearable.

Wuss. The heat rules. I hated school as a kid and always equated heat with vacation. I don't care if it's 101 with 85% humidity. It's summer time baby.

Steve

[Normandy]

Aric look at the IR shots of the system right now....that LLC is producing ZERO convection and is being sheared heavily by the ULL.

If that becomes the dominant center this won't develop because its far too close to the ULL. Check out the convection firing over the Channel, thats the best area for a center to truly establish itself.

[KFDM Meteorologist]

0Z NAM Starting

http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_006l.gif

[HURAKAN]

Impressive.

TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
0102 UTC TUE AUG 14 2007

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 (AL912007) 20070814 0000 UTC

...00 HRS... ...12 HRS... ...24 HRS. .. ...36 HRS...
070814 0000 070814 1200 070815 0000 070815 1200

LAT LON LAT LON LAT LON LAT LON
BAMS 22.1N 87.7W 23.0N 89.8W 23.8N 91.8W 24.8N 94.2W
BAMD 22.1N 87.7W 23.3N 90.0W 24.5N 92.4W 25.6N 94.9W
BAMM 22.1N 87.7W 23.1N 90.0W 24.2N 92.4W 25.2N 95.1W
LBAR 22.1N 87.7W 22.7N 90.0W 23.6N 92.7W 24.7N 95.6W
SHIP 30KTS 37KTS 45KTS 53KTS
DSHP 30KTS 37KTS 45KTS 53KTS

...48 HRS... ...72 HRS... ...96 HRS. .. ..120 HRS...
070816 0000 070817 0000 070818 0000 070819 0000

LAT LON LAT LON LAT LON LAT LON
BAMS 25.9N 96.4W 27.9N 100.2W 29.6N 103.4W 30.9N 104.8W
BAMD 27.0N 97.5W 29.6N 101.2W 31.4N 103.0W 32.2N 101.3W
BAMM 26.6N 97.5W 28.8N 101.3W 30.3N 104.1W 30.9N 104.6W
LBAR 26.1N 98.5W 29.4N 102.9W 32.0N 104.2W 32.8N 103.1W
SHIP 58KTS 69KTS 74KTS 69KTS
DSHP 51KTS 29KTS 27KTS 27KTS

...INITIAL CONDITIONS...
LATCUR = 22.1N LONCUR = 87.7W DIRCUR = 285DEG SPDCUR = 9KT
LATM12 = 21.6N LONM12 = 85.9W DIRM12 = 291DEG SPDM12 = 10KT
LATM24 = 20.6N LONM24 = 83.8W
WNDCUR = 30KT RMAXWD = 75NM WNDM12 = 25KT
CENPRS = 1006MB OUTPRS = 1009MB OUTRAD = 130NM SDEPTH = M
RD34NE = 0NM RD34SE = 0NM RD34SW = 0NM RD34NW = 0NM

$$
NNNN

[Aric Dunn]

seriously .. im not arguing at all its a disscusion.. sorry if you think that..\

and to add to your yellow circle if you notice the band on the Ne side of my blue circle! its heading through your yellow circle as well

but honestly its not that big of a deal because like you and myself as well has others the center is and likely will move and or reform.


edit..
andi have about 30 images in loop on my computer which is much clearer wish i could post that loop

it has clearly moved..

[KFDM Meteorologist]

12 HR. NAM

http://www.nco.ncep.noaa.gov/pmb/nwprod ... p_012l.gif