ATL: Tropical Depression Fay

[Tampa Bay Hurricane]

ECMWF (See animation in the models thread) has this hitting
Florida as a hurricane on the southeast Coast and then riding along
the west coast to the panhandle.

[HURAKAN]

[storms in NC]

I really wouldn't go by the spaghetti models till it has a closed center. After that it would give a better out look JMO

As far is it not developing at this time. It is like making a cake it has to have all the ingredient to develop and in a day or two it will be a cake. Like someone said with surprises with it. JMO

[DESTRUCTION5]

I find that new EURO interesting because it is now calling for Dev north of DR...When it did not before..

[HURAKAN]

[Tampa Bay Hurricane]

It is slowly developing. It will pulse on and off, but eventually
convection will build around the center, so a Tropical Depression
within 48-72 hours is what I foresee. It is again, very slow to
develop. Yesterday I said it would be a tropical depression today,
but it is developing much more slowly than I thought, so it may
be another few days before a depression forms. Once the depression
forms, the track would be a dangerous one for Florida, according
to the ECMWF.

[Tampa Bay Hurricane]

This image shows that convection is certainly gradually
building, and we are looking at a developing system. The
convection is building arund the center on the west and east
sides and attempting to surround the center. Thunderstorm
activity is increasing around 92L.

[HURAKAN]

This image shows that convection is certainly gradually
building, and we are looking at a developing system. The
convection is building arund the center on the west and east
sides and attempting to surround the center. Thunderstorm
activity is increasing around 92L.

But you can also see in the loop how it's being sheared.

Loop: http://www.ssd.noaa.gov/goes/flt/t1/loop-vis.html

[Tampa Bay Hurricane]

This image shows that convection is certainly gradually
building, and we are looking at a developing system. The
convection is building arund the center on the west and east
sides and attempting to surround the center. Thunderstorm
activity is increasing around 92L.

But you can also see in the loop how it's being sheared.

Loop: http://www.ssd.noaa.gov/goes/flt/t1/loop-vis.html

True...but I think in a couple of days that shear will be gone once 92L
is further west. But thank you for pointing that out. It is a factor
to watch closely.

[MiamiensisWx]

I think it is extremely prudent to not "write it off." As previously mentioned, the wave axis has entered the shear zone (strongest UL winds) from the upper low to the north. In other words, the fact that the thunderstorms are sheared via strong divergence should have been anticipated. The system is currently encountering the worst conditions, which will continue during the next ~24-28 hours. Shear will likely decrease after this time frame, as the system enters the west side of the shear zone and an upper level anticyclone builds at 300 mb. There are also several reasons for concerns down the line in the Bahamas and southern Florida. This system will survive the hostile conditions over the next 24 hours.

1. LL 850 mb vorticity has been quite strong near the northern end of the wave axis (http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8sht.html). This would eventually favor the formation of a surface low in the region of best LL convergence and ascent. The bolded portion is important: with an increasingly unstable boundary layer, thunderstorms would develop and result in the development of a LLC. Note that the ascent provided by the UL divergence (shear) is partially contributing to convection developing in the vicinity of the strongest 850 mb vorticity. The fact that the vorticity has been persistent is disconcerting, and it will certainly remain as the system moves WNW across the NE Caribbean toward the islands of the Bahamas.

2. The wave axis is still present. In other words, even if most of the thunderstorms dissipate, the wave axis will still remain as it moves WNW across the NE Caribbean toward the Bahamas. The associated LL convergence line will be present, so additional thunderstorms can develop down the line, depending on other synoptic/thermodynamic factors as well. TCs can eventually develop if the wave axis/convergence line eventually enters more conducive conditions.

3. Most of the models (depicting a TC) have remained consistent: they do NOT develop the TC until the system is NW of Puerto Rico. This would coincide with the more conducive upper air regime. Additionally, WV data indicates the TUTT to the west is continuing to progress westward. As the upper low north of 92L moves slowly NE and the system (92L) passes the shear zone beyond ~24-28 hours, we will observe the gradual evolution of the aforementioned 300 mb anticyclone.

[MiamiensisWx]

I think it is extremely prudent to not "write it off." As previously mentioned, the wave axis has entered the shear zone (strongest UL winds) from the upper low to the north. In other words, the fact that the thunderstorms are sheared via strong divergence should have been anticipated. The system is currently encountering the worst conditions, which will continue during the next ~24-28 hours. Shear will likely decrease after this time frame, as the system enters the west side of the shear zone and an upper level anticyclone builds at 300 mb. There are also several reasons for concerns down the line in the Bahamas and southern Florida. This system will survive the hostile conditions over the next 24 hours.

1. LL 850 mb vorticity has been quite strong near the northern end of the wave axis (http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8sht.html). This would eventually favor the formation of a surface low in the region of best LL convergence and ascent. The bolded portion is important: with an increasingly unstable boundary layer, thunderstorms would develop and result in the development of a LLC. Note that the ascent provided by the UL divergence (shear) is partially contributing to convection developing in the vicinity of the strongest 850 mb vorticity. The fact that the vorticity has been persistent is disconcerting, and it will certainly remain as the system moves WNW across the NE Caribbean toward the islands of the Bahamas.

2. The wave axis is still present. In other words, even if most of the thunderstorms dissipate, the wave axis will still remain as it moves WNW across the NE Caribbean toward the Bahamas. The associated LL convergence line will be present, so additional thunderstorms can develop down the line, depending on other synoptic/thermodynamic factors as well. TCs can eventually develop if the wave axis/convergence line eventually enters more conducive conditions.

3. Most of the models (depicting a TC) have remained consistent: they do NOT develop the TC until the system is NW of Puerto Rico. This would coincide with the more conducive upper air regime. Additionally, WV data indicates the TUTT to the west is continuing to progress westward. As the upper low north of 92L moves slowly NE and the system (92L) passes the shear zone beyond ~24-28 hours, we will observe the gradual evolution of the aforementioned 300 mb anticyclone.

In the short term, the wave axis will definitely affect the NE Caribbean (Leewards/Puerto Rico), with thunderstorms producing isolated precip over the islands.

My original prognosis that did not support a "miss" for the islands should have been heeded, though I don't anticipate development prior to reaching the Leewards and Puerto Rico.

[Tampa Bay Hurricane]

Excellent analysis Miami. I am learning a lot from your
writings.

I agree Miami I am also seeing similar observations
and have similar expectations for significant development
after 48 hours once it moves out of these shear conditions.

DO NOT write this off folks. It is in unfavorable conditions
FOR NOW, but conditions improve for development after 48
hours from here.

[storms in NC]

[img][/img]

[alan1961]

This thing is causing some head scratching, that MLC hours ago that looked like it dissappeared must of left some sort of eddy behind which is convecting again..not dead yet

[MiamiensisWx]

http://www.nco.ncep.noaa.gov/pmb/nwprod/analysis/carib/gfs/06/images/gfs_300_030l.gif

Note the building H3 anticyclone around ~30 hours...

[cycloneye]

[Cyclone1]

Convection is refiring at a pretty decent clip.

[canegrl04]

94L all over again.This thing will fight to hold on untill it gets past DR and then BOOM

[storms in NC]

I think that the center is where that burst of dark red is. I was just looking at the loop to see if I could see any thing and that is where I seen it at.

[cycloneye]

Another pic that covers Eastern and Central Caribbean: