ATL: ALBERTO - Post-Tropical

[Steve]

Nam barely makes it passed the central gulf before turning W to wsw and is quite a bit stronger..

Yeah, it's only out to 84 hours, so it's hard to tell if a loop is commencing or if it's following ICON's lead in just jetting off to the west.

Edit to say that yeah, real strong ridging off the SW Atlantic at 84 hours. Intensifying and at about 995mb, and a semi-strong tropical storm look to it on the pressure anomaly presentation.

Pressure Anomaly
https://www.tropicaltidbits.com/analysi ... 2412&fh=84

Also, here's the 250mb winds showing the split of the shear (presumably due to the influence of an upper low as noted by someone earlier).
https://www.tropicaltidbits.com/analysi ... 2412&fh=84

[SoupBone]

You're saying you wouldn't rule out Texas?

Aric, what indicators are you seeing that would not rule out a Texas impact?

Stronger ridging building in. and no long wave trough to pick it up. the ICON model and others have hinted at the idea. however, if it were to happen it would likely only be a weak low pressure.

Thanks, man. So a Texas impact would likely be much less in terms of moisture impact if that were to verify?

[cycloneye]

[Aric Dunn]

Nam barely makes it passed the central gulf before turning W to wsw and is quite a bit stronger..

Yeah, it's only out to 84 hours, so it's hard to tell if a loop is commencing or if it's following ICON's lead in just jetting off to the west.

Speaking of which.. 12z ICON is running

[Aric Dunn]

Aric, what indicators are you seeing that would not rule out a Texas impact?

Stronger ridging building in. and no long wave trough to pick it up. the ICON model and others have hinted at the idea. however, if it were to happen it would likely only be a weak low pressure.

Thanks, man. So a Texas impact would likely be much less in terms of moisture impact if that were to verify?

as of right now it would seem that way. way to far out.

[Aric Dunn]

There is one thing to note.. all the models have been extending 90l life time in the same spot. just 2 day ago the models had this starting to move north today.. now the models are saying it will essentially be in the same location for another 48 hours. this also is probably why the models are showing a slightly stronger system too.

[txwatcher91]

I am not canceling my outdoor plans here in SE Florida the storm will be too far away from this part of the state.

May want to rethink that, the moisture field on this storm will be HUGE covering hundreds of miles. 3km nam through 60 hours is dropping a good amount of rain on SE FL. Multiple bands appear to rotate through during the day Saturday...

[psyclone]

Well it would seem that based on trends the steady rains should remain west of peninsular florida so hopefully we can salvage our holiday weekend to some degree. with a stout southeast wind we should still see plenty of convection converging on the west coast though...so duck and cover space will be a requirement. Doesn't look like our low is in any hurry to move and the convection is firing over lots of deep warm water in the Yucatan channel

it's a lopsided system that's broad so it may not be the case - we could still see heavy rains along the Fl west coast perhaps 30-50 miles inland - we'll see. It could be a redo of Debbie in 2012.

https://www.washingtonpost.com/blogs/capital-weather-gang/post/tropical-storm-debby-generates-incredible-rainfall-over-north-florida/2012/06/26/gJQAnzJP4V_blog.html?utm_term=.068c92777281

Full disclosure...I'll confess to the possibility of subconscious -removed-. I'm sick of rain and want to hit the beach. Having said that I'm not expecting a Debby redux here which for me unleashed an astonishing 15" of rain on me in a day...before it was even classified! In my nearly 2 decades of living here it remains the king flooding event...by far. I suppose a more modest version remains possible but I'm leaning on (hoping) a more westerly track with the best rains west of 85 longitude. As always deep convection over the Yucatan channel headed for the loop current = eventual trouble for someone.. so we watch with interest

[Icybubba]

Due to the nature of pre-season storms, it's not a huge concern where this landfalls, the east side will get most of the rain

[ronjon]

90L looks to be experiencing heavy shear still but convection is on the increase over its east half - low pressure looks to be near the coast near Cozumel now.

http://rammb.cira.colostate.edu/ramsdis/online/loop.asp?data_folder=tropical/tropical_ge_4km_visir2_floater_2&width=640&height=480&number_of_images_to_display=12

[Shell Mound]

Current mesoanalysis indicates that the low-level centre and the cutoff low are already becoming vertically stacked, albeit slowly. Another key is that the mid-level ridging to the north has trended stronger than originally forecast. This means that the ongoing convection near the northeastern tip of the Yucatán Peninsula only serves to warm up the column, which would actually tend to weaken the cutoff low, and through feedback also enhance the mid-level ridge. Since the subtropical jet is also verifying stronger than forecast, the combination of a weaker, more co-located cutoff low and stronger mid-level ridging would both enhance low-level convergence and via convection increase outflow to the north. All these factors would favour a stronger potential tropical cyclone, and even tend to favour a tropical rather than subtropical system, probably quite similar in structure to last year's Cindy. Thus a strong tropical storm or even a low-end hurricane over the Gulf is becoming increasingly plausible. Trends suggest that the greatest threat for a landfall exists between Mobile, AL, and Panama City, FL.

[Steve]

ICON is filling in. At 69H (valid 4am CDT Sunday morning), the left hook is taking place. ICON has it coming off the Yucatan on a NNE heading before what apparently is the influence of Atlantic ridging.
https://www.tropicaltidbits.com/analysi ... 2412&fh=69

[Icybubba]

90L looks to be experiencing heavy shear still but convection is on the increase over its east half - low pressure looks to be near the coast near Cozumel now.

http://rammb.cira.colostate.edu/ramsdis/online/loop.asp?data_folder=tropical/tropical_ge_4km_visir2_floater_2&width=640&height=480&number_of_images_to_display=12

Here is the shear chart, the Gulf is beginning to expirence a lowering in wind shear http://tropic.ssec.wisc.edu/real-time/w ... oom=&time=

[ronjon]

Look at all the dry mid-level air coming off mexico and Tx into 90L. The trough in the central GOM also seems to be sinking south.

http://rammb.cira.colostate.edu/ramsdis/online/loop.asp?data_folder=tropical/tropical_ge_14km_wv&width=640&height=480&number_of_images_to_display=24

[stormlover2013]

https://www.tropicaltidbits.com/analysi ... 2412&fh=96

[ronjon]

Nam barely makes it passed the central gulf before turning W to wsw and is quite a bit stronger..

LOL - I wonder why we're using NAM for tropical systems too! Wasn't yesterdays runs having it heading for the NE GOM?

[Aric Dunn]

ICON pretty much dropping 90 feet of rain on New Orleans lol

[Aric Dunn]

Nam barely makes it passed the central gulf before turning W to wsw and is quite a bit stronger..

LOL - I wonder why we're using NAM for tropical systems too! Wasn't yesterdays runs having it heading for the NE GOM?

IT has been doing quite a bit better the last couple years. and since this system is involved with a baroclinic system the NAM is quite useful

[stormlover2013]

I am using NAM for upper level pattern

[Steve]

Nam barely makes it passed the central gulf before turning W to wsw and is quite a bit stronger..

LOL - I wonder why we're using NAM for tropical systems too! Wasn't yesterdays runs having it heading for the NE GOM?

You'd have to go back to the archives, but it proved to be of value during Harvey (even around 20N which it's supposed to suck in and where it's basically outside of resolution). We were all kind of laughing at what it was depicting. But it led the way on depicting structure and intensity. It also got it caught up in the pattern (though not the exact track) when I think the GFS was marching it across S TX for a few runs.

Also, it comes out ahead of all the other models, so why not?