ATL: HERMINE - Post-Tropical - Discussion

[caneman]

As the past several days, there are still several weak circulations embedded in the system as it moves slowly to the west, but the large ULL is moving along with it - hard to see anything else coming from 99L for now if at all.

If the ULL were not there that'd be another matter and perhaps the models would be right this time, but not with the present environment.

http://www.goes.noaa.gov/HURRLOOPS/huwvloop.html

A little wishful thinking there Frank. Believe that will soon eject out. I'm looking for development tonight or tomorrow morning. We'll see.

[Frank2]

Maybe, but when I worked in the business as a young adult, the rule was ULL's prevent tropical cyclone formation. The system is now moving beneath a large ULL - my guess the NHC will expand on this in the 8 a.m. (perhaps lowering the numbers)...

[caneman]

They can and do prevent development but I believe that Ull is expected to eject out. Looks to be getting squashed now. Needs to make it around Key West. Time will tell. I wouldn't be surprised either way. Not sure I remember a year where models have been so unreliable.

[jlauderdal]

Also just as I suspected the Euro has followed suit. that upper low does not look like it will dive any further south as the uppler low over the western gulf is not moving much. which should force this upper low to turn back to the nw giving the system a good shot.

I still think it is too early to be looking 2 days past this system as bad as that sounds.

We have already been burned once looking 5 days out. I still rather wait until we get a storm and how far south and west in tracks into the Gulf

good thinking on your part..although modeling has settled down in the search term. multiple outcomes that are being generated in the longer term and none of the models can be favored

side note: nhc is liking the system coming off and it has model support to make it across 0/50...unlike our friend 99l this one should be easier for the models to handle as it will have an LLC early on in its life

[Blinhart]

http://radar.weather.gov/ridge/lite/N0Z/BYX_loop.gif

Looking at this radar looks like a circulation is about to hit the Keys.

[GCANE]

Air appears to be more stable than this time yesterday.
Theta E ridge has pulled away somewhat, runs basically thru Tampa Bay at 357.
CAPE = 3000 in the Straits.
Vorticity is down from 6, yesterday afternoon, to currently 3 centered at 24.0N 79.7W.
HOWEVER, there is a nicely structured warm core at 1C, centered at about 10km, with no inversion.
Yesterday around noon, there was a 2C inversion at 1km and it fell apart late in the day.

[Blinhart]

Air appears to be more stable than this time yesterday.
Theta E ridge has pulled away somewhat, runs basically thru Tampa Bay at 357.
CAPE = 3000 in the Straits.
Vorticity is down from 6, yesterday afternoon, to currently 3 centered at 24.0N 79.7W.
HOWEVER, there is a nicely structured warm core at 1C, centered at about 10km, with no inversion.
Yesterday around noon, there was a 2C inversion at 1km and it fell apart late in the day.

For us people that don't understand all this scientific information, what does that mean?

[GCANE]

From Storm Predicition Center Mesoanalysis
Winds aloft, just west of the current convection.
300mb: NNW 10knts
500mb: NNE 10knts with a defined vorticity
700mb: ENE 15knts with a wave appearance
825mb: ENE 15knts wave
950mb: NE 15knts wave

[Blinhart]

From Storm Predicition Center Mesoanalysis
Winds aloft, just west of the current convection.
300mb: NNW 10knts
500mb: NNE 10knts with a defined vorticity
700mb: ENE 15knts with a wave appearance
825mb: ENE 15knts wave
950mb: NE 15knts wave

So it isn't stacked is what you are trying to say?

[GCANE]

Air appears to be more stable than this time yesterday.
Theta E ridge has pulled away somewhat, runs basically thru Tampa Bay at 357.
CAPE = 3000 in the Straits.
Vorticity is down from 6, yesterday afternoon, to currently 3 centered at 24.0N 79.7W.
HOWEVER, there is a nicely structured warm core at 1C, centered at about 10km, with no inversion.
Yesterday around noon, there was a 2C inversion at 1km and it fell apart late in the day.

For us people that don't understand all this scientific information, what does that mean?

Its a comparison to yesterday.
Air was more unstable which caused the hot towers to fire.
They in turn increased vorticity later in the day (cyclonic turning in the mid atmosphere) and helped to build the warm core.
That warm core however had a high temperature block at about 1km altitude that kept surface moisture from lifting up into the atmosphere and fire off convection as a typical topical low would do.

So IMHO currently, I would not expect to see strong towers fire around sunrise.
But, if the current warm core holds up and clears the straits, it could begin to pick up heat out of the ocean and develop as a tropical low.
Currently, it is showing no temperature block.
The winds at 300mb need to relax abit so that ventilation can develop if and when strong convection gets going.

[Blinhart]

Air appears to be more stable than this time yesterday.
Theta E ridge has pulled away somewhat, runs basically thru Tampa Bay at 357.
CAPE = 3000 in the Straits.
Vorticity is down from 6, yesterday afternoon, to currently 3 centered at 24.0N 79.7W.
HOWEVER, there is a nicely structured warm core at 1C, centered at about 10km, with no inversion.
Yesterday around noon, there was a 2C inversion at 1km and it fell apart late in the day.

For us people that don't understand all this scientific information, what does that mean?

Its a comparison to yesterday.
Air was more unstable which caused the hot towers to fire.
They in turn increased vorticity later in the day (cyclonic turning in the mid atmosphere) and helped to build the warm core.
That warm core however had a high temperature block at about 1km altitude that kept surface moisture from lifting up into the atmosphere and fire off convection as a typical topical low would do.

So IMHO currently, I would not expect to see strong towers fire around sunrise.
But, if the current warm core holds up and clears the straits, it could begin to pick up heat out of the ocean and develop as a tropical low.
Currently, it is showing no temperature block.
The winds at 300mb need to relax abit so that ventilation can develop if and when strong convection gets going.

Thank you very much

[GCANE]

From Storm Predicition Center Mesoanalysis
Winds aloft, just west of the current convection.
300mb: NNW 10knts
500mb: NNE 10knts with a defined vorticity
700mb: ENE 15knts with a wave appearance
825mb: ENE 15knts wave
950mb: NE 15knts wave

So it isn't stacked is what you are trying to say?

Its not all that bad IMHO.
The 300mb winds is causing some shear.
Some really strong, sustained convection could clear that out if it happens.

[Alyono]

development chances are increasing rapidly. May be close to 90% now

[Nimbus]

http://radar.weather.gov/ridge/lite/N0Z/BYX_loop.gif

Looking at this radar looks like a circulation is about to hit the Keys.

The center is showing on radar close to the north coast of Cuba but that may be a misleading signature from mid level vorticity above 40,000 feet.

The Earth is not flat.

[Alyono]

http://radar.weather.gov/ridge/lite/N0Z/BYX_loop.gif

Looking at this radar looks like a circulation is about to hit the Keys.

The center is showing on radar close to the north coast of Cuba but that may be a misleading signature from mid level vorticity above 40,000 feet.

The Earth is not flat.

not sure. That radar center aligns with the ASCAT center

[GCANE]

I am going to be watching cloud cover over south FL this afternoon.
Air is juiced and if it remains relatively clear, I expect to see another round of heavy pop-up storms to develop.
They should push right into 99L which should be close to the Keys at that time.
Might add some fuel to the fire.

[Nimbus]

http://radar.weather.gov/ridge/lite/N0Z/BYX_loop.gif

Looking at this radar looks like a circulation is about to hit the Keys.

The center is showing on radar close to the north coast of Cuba but that may be a misleading signature from mid level vorticity above 40,000 feet.

The Earth is not flat.

No west winds over Cuba on the ASCAT but if those radar echoes are from above 40,000

not sure. That radar center aligns with the ASCAT center

edit: On the ASCAT there are wind barbs facing south that are located much further west along the northern Cuban coastline meaning the LLC is still elongated East to west and the radar echoes show mid level vorticity further east just SW of Andros Island.

[GCANE]

Checking RAP 300mb forecast 18 hrs out and putting 99L in the Keys; winds don't look too bad.
Closest feature is the ULL in the north GOM just offshore of the TX/LA coast.
From what I can tell from current WV image, its not all that bad with a lot of moisture in it.

[La Sirena]

development chances are increasing rapidly. May be close to 90% now

Development....today? Or is this once it hits the GOM?

[Alyono]

development chances are increasing rapidly. May be close to 90% now

Development....today? Or is this once it hits the GOM?

overall development chances