(Sub)Tropical development likely near the Bahamas: (Invest 90L thread is up)

[Aric Dunn]

Being this is starting as a mesoscale system.. looking at such models is not a bad idea..

here is the RGEM.. interesting track..

https://www.tropicaltidbits.comhttp://n ... ed/video13 analysis/models/?model=rgem&region=seus&pkg=ref_frzn&runtime=2020051406&fh=6


WRF as well

https://www.tropicaltidbits.com/analysi ... 1400&fh=48

[aspen]

All models agree on a TC developing in 48-60 hours, or sometime on Saturday. The GFS and NAVGEM are rather aggressive and forecast a strong (sub)tropical storm at peak intensity, in the 985-990 mbar range, suggesting peak winds could be around 50-60 kt. While the latest CMC run shows future Arthur turning into New England, all other models agree on a track parallel to the US coast before turning out to sea.

[Aric Dunn]

All models agree on a TC developing in 48-60 hours, or sometime on Saturday. The GFS and NAVGEM are rather aggressive and forecast a strong (sub)tropical storm at peak intensity, in the 985-990 mbar range, suggesting peak winds could be around 50-60 kt. While the latest CMC run shows future Arthur turning into New England, all other models agree on a track parallel to the US coast before turning out to sea.

yeah, however it is all dependent on that clipper system diving sse far enough and fast enough to keep this east of the coast.

[cycloneye]

[GCANE]

850mb vort is developing south of Cuba

[northjaxpro]

Being this is starting as a mesoscale system.. looking at such models is not a bad idea..

here is the RGEM.. interesting track..

https://www.tropicaltidbits.comhttp://n ... ed/video13 analysis/models/?model=rgem&region=seus&pkg=ref_frzn&runtime=2020051406&fh=6


WRF as well

https://www.tropicaltidbits.com/analysi ... 1400&fh=48

RGEM rides the cyclone due north parallel up the Florida East Coast over the next 60 hours. It is not too far fetched actually to see this solution come to light, but odds are not likely.

[SFLcane]

Most recent HRRR has most of the wx associated with the low missing mainland South Florida to the south.

[TheStormExpert]

Most recent HRRR has most of the wx associated with the low missing mainland South Florida to the south.

The NWS says where I’m at 1-2 inches of rain is possible, but I’d be surprised once again if we get half an inch.

[Aric Dunn]

Being this is starting as a mesoscale system.. looking at such models is not a bad idea..

here is the RGEM.. interesting track..

https://www.tropicaltidbits.comhttp://n ... ed/video13 analysis/models/?model=rgem&region=seus&pkg=ref_frzn&runtime=2020051406&fh=6


WRF as well

https://www.tropicaltidbits.com/analysi ... 1400&fh=48

RGEM rides the cyclone due north parallel up the Florida East Coast over the next 60 hours. It is not too far fetched actually to see this solution come to light, but odds are not likely.

in the short term it is completely dependent on the low level structure. take the global models, they all have a similar track angle to the mesoscale models but shifted east.. that is because of the secondary lobe of vorticity that develops in the central bahamas which ultimately takes over correct ??

well the mesoscale models are not showing any such elongation or secondary circ.. so if you erase that from the global models the track would be nearly identical to the mesoscale models in the short term..

in the long term. everything is dependent on the clipper looking system diving sse in a very strange way..

so we have to wait and see how the mesoscale fluctuations play out.

[SFLcane]

Most recent HRRR has most of the wx associated with the low missing mainland South Florida to the south.

The NWS says where I’m at 1-2 inches of rain is possible, but I’d be surprised once again if we get half an inch.

Maybe less then that.

[Aric Dunn]

hmmm... 06z euro has shift west in the short term..

closes off surface circ in 12 to 24 hours west of keywest.. vs yesterday by the same time it was east of key largo..

[northjaxpro]

Being this is starting as a mesoscale system.. looking at such models is not a bad idea..

here is the RGEM.. interesting track..

https://www.tropicaltidbits.comhttp://n ... ed/video13 analysis/models/?model=rgem&region=seus&pkg=ref_frzn&runtime=2020051406&fh=6


WRF as well

https://www.tropicaltidbits.com/analysi ... 1400&fh=48

RGEM rides the cyclone due north parallel up the Florida East Coast over the next 60 hours. It is not too far fetched actually to see this solution come to light, but odds are not likely.

in the short term it is completely dependent on the low level structure. take the global models, they all have a similar track angle to the mesoscale models but shifted east.. that is because of the secondary lobe of vorticity that develops in the central bahamas which ultimately takes over correct ??

well the mesoscale models are not showing any such elongation or secondary circ.. so if you erase that from the global models the track would be nearly identical to the mesoscale models in the short term..

in the long term. everything is dependent on the clipper looking system diving sse in a very strange way..

so we have to wait and see how the mesoscale fluctuations play out.

It is an intriguing and plausible theory you mention Aric. I do agree that currently.it is a mesoscale feature with its baroclinic nature in its formative stages. It will be interesting to see exactly where and when the strong convection will eventually fire up to spawn the Low Pressure area. This should occur within the next 30 hours but I would not be surprised this happens as early as tomorrow afternoon somewhere in the Florida Straits region. We wait and see.

[Aric Dunn]

hmmm... 06z euro has shift west in the short term..

closes off surface circ in 12 to 24 hours west of keywest.. vs yesterday by the same time it was east of key largo..

by 48 hours it is still on the SW florida coast.. possibly a hint of something trying to redevelop well well east... near the north east bahamas.

still this makes it slower more west. so far

[Aric Dunn]

RGEM rides the cyclone due north parallel up the Florida East Coast over the next 60 hours. It is not too far fetched actually to see this solution come to light, but odds are not likely.

in the short term it is completely dependent on the low level structure. take the global models, they all have a similar track angle to the mesoscale models but shifted east.. that is because of the secondary lobe of vorticity that develops in the central bahamas which ultimately takes over correct ??

well the mesoscale models are not showing any such elongation or secondary circ.. so if you erase that from the global models the track would be nearly identical to the mesoscale models in the short term..

in the long term. everything is dependent on the clipper looking system diving sse in a very strange way..

so we have to wait and see how the mesoscale fluctuations play out.

It is an intriguing and plausible theory you mention Aric. I do agree that currently.it is a mesoscale feature with its baroclinic nature in its formative stages. It will be interesting to see exactly where and when the strong convection will eventually fire up to spawn the Low Pressure area. This should occur within the next 30 hours but I would not be surprised this happens as early as tomorrow afternoon somewhere in the Florida Straits region. We wait and see.

Hey look the 06z euro is following the mesoscale models..

eastern vorticity tries to get going but fails this far..

[boca]

Looks like the rain will miss the northern sections of South Florida just to the east and the drought will continue unless something changes as far as sat goes.

[Nancy Smar]

An area of cloudiness and thunderstorms located over the Straits of
Florida is forecast to spread northeastward during the next day or
two. Environmental conditions are expected to become conducive for
development, and this system is likely to become a tropical or
subtropical depression or storm this weekend when it is located near
or north of the northwestern Bahamas. The system is forecast to
move generally northeastward over the western Atlantic early next
week. Regardless of development, the disturbance is expected to
bring locally heavy rainfall and gusty winds to portions of
southeastern Florida and the central and northwestern Bahamas over
the next couple of days. The next Special Tropical Weather Outlook
on this system will be issued by 3 PM EDT today, or earlier, if
necessary.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...high...70 percent.

[Aric Dunn]

tracks across SE florida. drifting/stall east of central flroida out to 90 hours.. that is quite a shift in the thinking..

it is weaker which may have allowed it miss that shortwave. too bad the 6z does not go past 90 hours..

[mitchell]

It's fascinating that preseason activity has become almost an expectation. Went most of the 80s, 90s, and early 00s with almost none.

[Aric Dunn]

annnnd of course with this new track .... total rainfall is jumped up quite a bit and expanded well into central flroida now..

[ScottNAtlanta]

From what I gather...this would be welcomed rain. Haven't you guys been in drought conditions?