Possible development east of Lesser Antilles,model runs here

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Tampa_God
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Re: Possible development off W Africa during next several days

#221 Postby Tampa_God » Fri Jul 11, 2008 5:46 pm

I don't know, it looks like the convection near 8 N and 33 W has a more favorable chance at developing than this wave, even with it's location.
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Re: GFS,CMC,EURO,UKMET,NOGAPS spawn New Low in E Atlantic

#222 Postby cycloneye » Fri Jul 11, 2008 5:51 pm

18z GFS tracks low thru NE Caribbean towards Bahamas.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml
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Re: GFS,CMC,EURO,UKMET,NOGAPS spawn New Low in E Atlantic

#223 Postby Tampa_God » Fri Jul 11, 2008 6:01 pm

cycloneye wrote:18z GFS tracks low thru NE Caribbean towards Bahamas.

http://www.nco.ncep.noaa.gov/pmb/nwprod ... loop.shtml

I would agree with GFS until they break up the high and allow this heading North. I just don't see the High breaking down any time soon.
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Re: GFS,CMC,EURO,UKMET,NOGAPS spawn New Low in E Atlantic

#224 Postby cycloneye » Fri Jul 11, 2008 6:08 pm

I posted the text earlier,but here is the graphic from 12z UKMET that has a Moderate TS.I put the red line as distance from where I am.

Image
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Re: GFS,CMC,EURO,UKMET,NOGAPS spawn New Low in E Atlantic

#225 Postby Tampa_God » Fri Jul 11, 2008 6:15 pm

cycloneye wrote:I posted the text earlier,but here is the graphic from 12z UKMET that has a Moderate TS.I put the red line as distance from where I am.

Image

Is that still Bertha in the same area though?

Interesting that pretty much everyone has this heading north of the Lesser Antilles. If so, the islands have been pretty lucky so far.
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Re: GFS,CMC,EURO,UKMET,NOGAPS spawn New Low in E Atlantic

#226 Postby cycloneye » Fri Jul 11, 2008 6:24 pm

Here are the last four runs of GFS.

Image
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#227 Postby HURAKAN » Fri Jul 11, 2008 6:25 pm

Interesting the system next to the Carolinas. The path looks similar to Arthur 2002 and/or Alex 2004.
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Re:

#228 Postby Thunder44 » Fri Jul 11, 2008 6:37 pm

HURAKAN wrote:Interesting the system next to the Carolinas. The path looks similar to Arthur 2002 and/or Alex 2004.


Nice to see some interest in it. Upton, the local NWS office for this area, seemed to be a little bit concerned about in their discussion about it this afternoon:

THE FORECAST BECOMES TRICKY ON SUNDAY WITH MODEL GUIDANCE INDICATING
A POSSIBLE WARM CORE LOW OFF THE CAROLINA COAST THIS WEEKEND. SOME
OF THE GUIDANCE (GFS) HAS THE LOW WEAKENING AND DISSIPATING...WHILE
OTHER SOLUTIONS (NAM/ECMWF) HAVE THE LOW WEAKENING AND GETTING
CAUGHT UP IN A COLD FRONT WHICH IS EXPECTED TO MOVE THROUGH THE AREA
MONDAY. THE CANADIAN MODEL HAS THE LOW...HOWEVER IT DOES NOT BRING
THE SYSTEM UP THE COAST. CONFIDENCE IS NOT VERY HIGH ON WHAT WILL
HAPPEN WITH THIS SYSTEM AND WE WILL HAVE TO CONTINUE TO WATCH THIS
SYSTEM.

MEANWHILE AN UPPER TROUGH/COLD FRONT WILL APPROACH FROM THE WEST.
BOTH THE GFS AND NAM HAVE SLOWED DOWN ITS TIMING OF THE FRONT. FOR
NOW...THE FRONT IS EXPECTED TO APPROACH SUNDAY NIGHT AND SLOWLY MOVE
THROUGH THE AREA DURING THE DAY ON MONDAY. THE TIMING OF THE FRONT
COULD IMPACT WHAT...IF ANY OCCURS WITH THE LOW OFF THE CAROLINA
COAST. EITHER WAY...MONDAY LOOKS LIKE A WET DAY WITH THE FRONT
MOVING ACROSS THE AREA.


http://www.crh.noaa.gov/product.php?sit ... hlight=off
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Re: Possible development off W Africa during next several days

#229 Postby MiamiensisWx » Fri Jul 11, 2008 7:22 pm

I still continue to maintain my original position that tropical cyclogenesis is a real possibility. I expect additional convection to develop as the tropical wave axis and associated low level convergence moves west and transects the low level 850 mb vorticity off the coast. A broad and weak area of low pressure is already present in the vicinity as well. The strongest mid level circulation is located further north near the Cape Verde islands, but that should change as the surface low develops further south over the next few days. With an unstable boundary layer in place closer to the region between 10-12 N and 20-30W over the best oceanic heat content/SSTs, ascent of parcels should be enhanced. Additionally, this is juxtaposed over the same region in which the broad low pressure area is present and the wave axis is intersecting the substantive 850 mb low level vorticity, as mentioned in the first two sentences of this post. This should aid the development of a surface low in the vicinity over the next few days. Subsidence and capping from the SAL is minimal in the immediate vicinity and across areas to the west, and several models (including the operational GFS, several ensembles, and Euro) remain consistent with a weaker Azores ridge and few signs of a significant 700 mb temp inversion spreading west over the next several days. In other words, all signs indicate minimal convective inhibition, including analysis of the current thermodynamic environment. Overall, based on my analysis of the environment and current evolution, I strongly suspect that the operational GFS, several GFS ensembles, and Euro were "picking up" on tropical cyclogenesis west and south of the Cape Verde islands over the next several days.

If development will take place, it (and the intensity trend of the possible system) will largely hinge on the evolution of the upper low that is currently in the eastern subtropical Atlantic near 45 W. The strength, movement, and location of the upper low will be crucial as it transitions to a cutoff low at H5 by the middle of the upcoming week. It will also depend on the respective track of the surface low across the tropical MDR region. If the surface low tracks north of ~12 N (closer to the upper low), the upper level divergence may result in greater ascent for additional development of convection and prove to be beneficial for thunderstorms' outflow. However, if the surface low tracks further south, the divergence from upper low may merely induce shear over the system and negate more rapid development. If the upper low is stronger and deeper as it transitions to a H5 cutoff low, the surface low's position in the MDR may not result in significant differences, as it would still be affected by the shear. However, even if the surface low does face greater shear via a southerly path, it would likely not prevent gradual intensification and organization.

Overall, I believe this one has a decent shot for development. It is far too early to focus on any potential "impact" or track; firstly, we need a defined LLC and development. However, it should be closely watched over the next several days and upcoming week.
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Re: Possible development off W Africa during next several days

#230 Postby MiamiensisWx » Fri Jul 11, 2008 7:48 pm

Additional convection is developing in the vicinity south of the Cape Verde islands:

http://oiswww.eumetsat.org/IPPS/html/DerivedProducts/MSG2/MPE/WESTERNAFRICA/index.htm

18Z operational GFS continues to advertise the development of a surface low near 30 hours:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/00/images/gfs_ten_030l.gif
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#231 Postby HURAKAN » Fri Jul 11, 2008 8:41 pm

Image

Could the next wave be "our wave."?
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Re:

#232 Postby MiamiensisWx » Fri Jul 11, 2008 8:50 pm

HURAKAN wrote:Could the next wave be "our wave."?

I personally don't believe that's the case. Note that the Euro and operational GFS develop a surface low between 24-32 W at a similar latitude between 24-48 hours. The wave axis inland over Africa will not move quickly to reach the specified vicinity within this time frame (next few days). Therefore, it seems plausible that both models are developing a surface low via the current wave axis that is currently located just W of the African coastline.
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Re: Possible development off W Africa during next several days

#233 Postby MiamiensisWx » Fri Jul 11, 2008 9:15 pm

New wave axis may be introduced SSE of the Cape Verde islands soon:

http://www.opc.ncep.noaa.gov/UA/Atl_Tropics.gif

Satellite data and surface observations indicates its presence.
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Re: Possible development off W Africa during next several days

#234 Postby MiamiensisWx » Fri Jul 11, 2008 10:27 pm

It is significant that several of the "reliable" global models indicate tropical cyclogenesis within the same latitude/longitude region between ~24-48 hours.

Naval Oceanographic model (NOGAPS) indicates development of surface low near 30 hours:

https://www.fnmoc.navy.mil/wxmap_cgi/cgi-bin/wxmap_single.cgi?area=ngp_atlantic&dtg=2008071118&prod=sfc10m&tau=030

Euro develops surface low in identical vicinity between 24-48 hours:

http://raleighwx.easternuswx.com/models/euro/00zeurotropical850mbVortSLP024.gif

http://raleighwx.easternuswx.com/models/euro/00zeurotropical850mbVortSLP048.gif

Operational GFS is nearly indistinguishable from NOGAPS and Euro around 30 hours out; check the surface reflection:

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/00/images/gfs_ten_030l.gif

The mean (average!) of the recent 18Z GFS ensembles also indicates the presence of a surface low in the same vicinity near 36 hours:

http://raleighwx.easternuswx.com/models/gfsensemble/18zgfsensemble500mbHGHTtropical036.gif

All of these models have also been consistent for multiple runs. I'm often skeptical of models depicting tropical cyclogenesis in situations where the synoptics and environment clearly do not support it; however, as I previously mentioned, the environment is clearly supportive and conducive for possible development as well.

Who wants to discount the data and state that this system unequivocably won't develop?
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Re: Possible development off W Africa during next several days

#235 Postby cycloneye » Fri Jul 11, 2008 10:41 pm

The big question is from where will develop the system that the global models show? From what is in the water now or from something that is still inside Africa?

Image
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Re: Possible development off W Africa during next several days

#236 Postby MiamiensisWx » Fri Jul 11, 2008 10:42 pm

cycloneye wrote:The big question is from where will develop the system that the global models show? From what is in the water now or from something that is still inside Africa?

It's the wave axis over the open waters off W Africa. It's currently SSE of the Cape Verde islands, and it will likely be introduced in the upcoming TAFB surface analysis.
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Re: GFS,CMC,EURO,UKMET,NOGAPS spawn New Low in E Atlantic

#237 Postby cycloneye » Fri Jul 11, 2008 11:07 pm

00z GFS rolling in:

78 hours= http://www.nco.ncep.noaa.gov/pmb/nwprod ... _078l.gif= Low latitud low around 40w.

96 hours= http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_096l.gif Low passes 40w still at low latitud.
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Re: GFS,CMC,EURO,UKMET,NOGAPS spawn New Low in E Atlantic

#238 Postby tailgater » Fri Jul 11, 2008 11:11 pm

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Re: GFS,CMC,EURO,UKMET,NOGAPS spawn New Low in E Atlantic

#239 Postby boca » Fri Jul 11, 2008 11:13 pm

Their is also a flare up around 11n and 46w on ir.

http://www.ssd.noaa.gov/goes/east/catl/avn-l.jpg
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Re: GFS,CMC,EURO,UKMET,NOGAPS spawn New Low in E Atlantic

#240 Postby cycloneye » Fri Jul 11, 2008 11:15 pm

108 hours= http://www.nco.ncep.noaa.gov/pmb/nwprod ... n_108l.gif Low continues at low latitud around 45w.
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