Invest 94L,Near Windwards-Discussions

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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#141 Postby SouthFloridawx » Tue Aug 28, 2007 1:21 pm

Jeff Masters blog...

A tropical wave midway between Africa and the Lesser Antilles (labeled "invest 94L" by NHC this morning) has become a little better organized this morning, and does have the potential to develop into a tropical depression later this week. Wind shear is a favorable 5-10 knots over 94L, and shear should not be a problem for it over the next few days. The system is not well-organized, with a sloppy, elongated circulation, as seen on last night's QuikSCAT pass. This morning's QuikSCAT pass missed the storm. The system does have a major impediment to development--the presence of a large, dusty area of dry air surrounding its north side (Figure 1). Water vapor satellite loops of the region don't show any significant moistening of the region around 94L occurring, and this will have to happen before the system can develop into a tropical depression. If the storm can develop a better-organized circulation, it will be able to pump more moisture into the surrounding atmosphere and help itself out. Current visible satellite loops shows that this is not happening at present--the thunderstorm activity associated with 94L is rather weak.

None of the reliable computer models develop 94L. The system should track through the Lesser Antilles Islands on Friday, bringing gusty winds and heavy rain. I expect that the earliest 94L could become a tropical depression would be Thursday, and it is unlikely the Lesser Antilles would experience anything worse than a 50 mph tropical storm. It is more likely that 94L will still be a tropical disturbance when it passes through the Lesser Antilles.


http://www.wunderground.com/blog/JeffMa ... amp=200708
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#142 Postby Nimbus » Tue Aug 28, 2007 1:22 pm

In the shorter term the 6Z GFS was showing a weakness in the ridge that pulled 94L north of the islands. As MW explained the GFDL and derived products may not be tuned to peak season development so the fact that the 12Z run of the GFDL dissipates the storm may not be Accurate. There is no model consensus that is for sure.
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#143 Postby gatorcane » Tue Aug 28, 2007 1:28 pm

Check out the wind shear tendency. This graphic shows the winds are continuing to lighten ahead of our system :eek:

Image
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#144 Postby Ed Mahmoud » Tue Aug 28, 2007 1:29 pm

Although the GFDL loses this system, if you look at the rainfall and pressure fields in the outer grid, the GFDL tracks this as a healthy wave to near Hispaniola in 120 hours, then seems to weaken it some by 126 hours.
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#145 Postby 'CaneFreak » Tue Aug 28, 2007 1:38 pm

For what its worth, the HWRF keeps it a relatively weak system, but does bring it up to TS status in a couple of days and sends it towards Luis in the PR area in 5 days or so....

http://moe.met.fsu.edu/cgi-bin/hwrftc2. ... =Animation
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#146 Postby gatorcane » Tue Aug 28, 2007 1:42 pm

remember all -

Models are not going to initialize well until the system consolidates. But we should expect a W to even WSW movement over the next couple of days as the subtropical ridge to the north builds and moves west in tandem with the wave.

Keep in mind it is not uncommon for systems here to move like this for several days then start to move more WNW or even NW once they sense any kind of weakness. So we shouldn't be set on a Dean like path either.
Last edited by gatorcane on Tue Aug 28, 2007 1:43 pm, edited 1 time in total.
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#147 Postby wxman57 » Tue Aug 28, 2007 1:42 pm

I suggest looking at a long-term WV loop of the Atlantic. Note the fairly strong ridge (and dry air) just north of 94L. The setup as far as steering currents is very similar to Dean, but with less moisture available. Remember that the global models were clueless with Dean, trying to slow it down and turn it right every single run. But Dean kept moving rapidly westward and models shifted westward with time. I can see the same thing happening with 94L, but conditions aloft aren't as ideal as they were with Dean. 94L will probably take longer to organize, and it may keep up the rapid westward motion for quite a while.
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#148 Postby gatorcane » Tue Aug 28, 2007 1:47 pm

wxman57 wrote:I suggest looking at a long-term WV loop of the Atlantic. Note the fairly strong ridge (and dry air) just north of 94L. The setup as far as steering currents is very similar to Dean, but with less moisture available. Remember that the global models were clueless with Dean, trying to slow it down and turn it right every single run. But Dean kept moving rapidly westward and models shifted westward with time. I can see the same thing happening with 94L, but conditions aloft aren't as ideal as they were with Dean. 94L will probably take longer to organize, and it may keep up the rapid westward motion for quite a while.


I will find it hard to believe it will follow a path similar to Dean in the long-term. The chance of back-to-back paths like that to me is small. I agree it will move west and probably through the Caribbean but the chance of no weakness at all if it moves all the way through the Caribbean is very small.

There are already signs of short waves trying to break the ridge over the Southern CONUS and all the global models are showing a break in the subtropical ridge at 144 hours.
Last edited by gatorcane on Tue Aug 28, 2007 1:50 pm, edited 1 time in total.
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#149 Postby 'CaneFreak » Tue Aug 28, 2007 1:49 pm

its also funny to note wxman57 that even though there is that dry air to the north of the system...where is most of the convection at this present moment???? on the northern perifery (spelling?) of the circulation!!!! I agree with you though...it is going to take some time and I expect a w to wnw motion for quite a while due to the current synoptic setup in the low levels. btw...has anyone done a center fix lately? can't seem to find it at the present moment..
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#150 Postby Derek Ortt » Tue Aug 28, 2007 1:54 pm

I do not see a WNW track until this reaches 70W... this has a very good chance of becoming a south American storm
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#151 Postby ConvergenceZone » Tue Aug 28, 2007 1:55 pm

gatorcane wrote:
wxman57 wrote:I suggest looking at a long-term WV loop of the Atlantic. Note the fairly strong ridge (and dry air) just north of 94L. The setup as far as steering currents is very similar to Dean, but with less moisture available. Remember that the global models were clueless with Dean, trying to slow it down and turn it right every single run. But Dean kept moving rapidly westward and models shifted westward with time. I can see the same thing happening with 94L, but conditions aloft aren't as ideal as they were with Dean. 94L will probably take longer to organize, and it may keep up the rapid westward motion for quite a while.


I will find it hard to believe it will follow a path similar to Dean in the long-term. The chance of back-to-back paths like that to me is small. I agree it will move west and probably through the Caribbean but the chance of no weakness at all if it moves all the way through the Caribbean is very small.

There are already signs of short waves trying to break the ridge over the Southern CONUS and all the global models are showing a break in the subtropical ridge at 144 hours.


I'm thinking that what WXMAN means regrding "similar to dean" is the direct up until it gets towards the gulf(if it does), then it will probably start bending more North. We got pretty lucky with Dean not finding a weakness in the ridge, that doesn't happen too often. I doubt we'll be so lucky the next time.
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#152 Postby skysummit » Tue Aug 28, 2007 2:04 pm

18z...

Code: Select all

TROPICAL CYCLONE GUIDANCE MESSAGE
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
1902 UTC TUE AUG 28 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 (AL942007) 20070828 1800 UTC
 
        ...00 HRS...   ...12 HRS...   ...24 HRS. ..   ...36 HRS...
        070828  1800   070829  0600   070829  1800   070830  0600
 
         LAT    LON     LAT    LON     LAT    LON     LAT    LON
BAMS    10.5N  41.5W   10.9N  44.3W   11.7N  47.2W   12.5N  49.7W
BAMD    10.5N  41.5W   10.5N  44.2W   10.3N  46.8W   10.0N  49.3W
BAMM    10.5N  41.5W   10.5N  44.2W   10.7N  47.0W   10.7N  49.6W
LBAR    10.5N  41.5W   10.6N  44.4W   10.8N  47.3W   10.6N  50.2W
SHIP        25KTS          30KTS          36KTS          43KTS
DSHP        25KTS          30KTS          36KTS          43KTS
 
        ...48 HRS...   ...72 HRS...   ...96 HRS. ..   ..120 HRS...
        070830  1800   070831  1800   070901  1800   070902  1800
 
         LAT    LON     LAT    LON     LAT    LON     LAT    LON
BAMS    13.5N  52.4W   15.2N  57.7W   15.9N  62.8W   16.5N  68.6W
BAMD     9.6N  51.8W    9.6N  57.2W   10.0N  63.5W   10.7N  70.1W
BAMM    10.7N  52.2W   11.1N  58.0W   11.5N  64.2W   12.1N  70.6W
LBAR    10.6N  53.1W   10.8N  58.8W   11.1N  64.2W   10.9N  65.8W
SHIP        49KTS          62KTS          73KTS          82KTS
DSHP        49KTS          62KTS          73KTS          80KTS
 
         ...INITIAL CONDITIONS...
LATCUR =  10.5N LONCUR =  41.5W DIRCUR = 270DEG SPDCUR =  18KT
LATM12 =  10.5N LONM12 =  38.0W DIRM12 = 272DEG SPDM12 =  19KT
LATM24 =  10.5N LONM24 =  32.5W
WNDCUR =   25KT RMAXWD =   40NM WNDM12 =   25KT
CENPRS = 1009MB OUTPRS = 1010MB OUTRAD =  120NM SDEPTH =   M
RD34NE =    0NM RD34SE =    0NM RD34SW =    0NM RD34NW =   0NM
 
$$
NNNN
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#153 Postby cycloneye » Tue Aug 28, 2007 2:06 pm

Image
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#154 Postby wxman57 » Tue Aug 28, 2007 2:11 pm

12Z Euro is in. Though it doesn't develop any surface low, it keeps that very strong 500mb ridge just north of where the disturbance will be through 168 hours, even strengthens the ridge. Very similar setup to that of Dean. Would make a NW turn difficult. This system could just stay on a 270-280 degree track for 5+ days at 17-18 kts. Any model indicating a NW turn in the eastern Caribbean may not be analyzing/predicting the ridge to its north very well.
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#155 Postby windstorm99 » Tue Aug 28, 2007 2:27 pm

Image
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#156 Postby wxman57 » Tue Aug 28, 2007 2:31 pm

Here you go, I plotted the 12Z European in 1/2 mb increments and added 500mb heights in 10 meter increments for Friday through Tuesday. On the map, I indicated where the disturbance might be assuming it's moving at 17-18 kts each day. If the European is right about the ridge, a westerly track is most likely.

Friday:
http://myweb.cableone.net/nolasue/eurofri.gif

Saturday:
http://myweb.cableone.net/nolasue/eurosat.gif

Sunday:
http://myweb.cableone.net/nolasue/eurosun.gif

Monday:
http://myweb.cableone.net/nolasue/euromon.gif

Tuesday:
http://myweb.cableone.net/nolasue/eurotue.gif
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Re: Invest 94L in Central Atlantic-Discussions-Analysis-Imagery

#157 Postby windstorm99 » Tue Aug 28, 2007 2:34 pm

wxman57 wrote:Here you go, I plotted the 12Z European in 1/2 mb increments and added 500mb heights in 10 meter increments for Friday through Tuesday. On the map, I indicated where the disturbance might be assuming it's moving at 17-18 kts each day. If the European is right about the ridge, a westerly track is most likely.

Friday:
http://myweb.cableone.net/nolasue/eurofri.gif

Saturday:
http://myweb.cableone.net/nolasue/eurosat.gif

Sunday:
http://myweb.cableone.net/nolasue/eurosun.gif

Monday:
http://myweb.cableone.net/nolasue/euromon.gif

Tuesday:
http://myweb.cableone.net/nolasue/eurotue.gif


Doesn't look like a U.S. threat if we go with the lastest EURO.
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#158 Postby fci » Tue Aug 28, 2007 2:35 pm

Getting an error when I try each of the links.

EDIT:
Not anymore!
Thanks for fixing.
Last edited by fci on Tue Aug 28, 2007 2:37 pm, edited 1 time in total.
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Re:

#159 Postby wxman57 » Tue Aug 28, 2007 2:36 pm

fci wrote:Getting an error when I try each of the links.


I was uploading new images with a blue "H" identifying the ridge. Try now.
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#160 Postby RL3AO » Tue Aug 28, 2007 2:37 pm

Woah woah woah. I go to bed reading on here that this wave is dead and this season is a flop and a joke. 12 hours later...

:lol:
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