ATL: ARLENE - Post-Tropical - Discussion

[cycloneye]

 https://twitter.com/EricBlake12/status/854113147019563008

[CrazyC83]

From Alicia Bentley's webpage.

I thought it was fun to track the PV anomaly from a central US cyclone last week march across the SE US and into the SW Atlantic before interacting with the midlatitude cyclone over the north-central Atlantic.

http://i.imgur.com/LBgRD9f.gif

Has there ever been (in the satellite era) a tropical or subtropical cyclone who had origins in the polar vortex?

[wxman57]

From Alicia Bentley's webpage.

I thought it was fun to track the PV anomaly from a central US cyclone last week march across the SE US and into the SW Atlantic before interacting with the midlatitude cyclone over the north-central Atlantic.

http://i.imgur.com/LBgRD9f.gif

Has there ever been (in the satellite era) a tropical or subtropical cyclone who had origins in the polar vortex?

It's not really a Polar vortex, it's just an upper-level low pressure system. It's not that uncommon that a TC will develop beneath an upper-level low like this. Currently, a number of the NHC forecasters are in New Orleans for the National Hurricane Conference (that's where I am). I wonder if that might mean that the NHC will be less inclined to issue advisories on a subtropical low in the middle of nowhere. I don't think it has much chance of being named. There isn't much time before it moves off to the north and merges with an approaching front.

[Hypercane_Kyle]

Building convection. Let's see if 91L can sustain it.

[cycloneye]

Popcorn.At least is trying.

[TheStormExpert]

Tweets from JB concerning Invest 91L.

 https://twitter.com/bigjoebastardi/status/854297198514851840




 https://twitter.com/bigjoebastardi/status/854297402873978880

[cycloneye]

Nice loop from GOES-16.

 https://twitter.com/MichaelRLowry/status/854334178036527107

[TheStormExpert]

Gaining more convection as it drifts SE into slightly warmer waters.

[cycloneye]

Stays at 30%.

Special Tropical Weather Outlook
NWS National Hurricane Center Miami FL
130 PM EDT Tue Apr 18 2017

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

A non-tropical low pressure system is located over the central
Atlantic about midway between Bermuda and the Azores Islands. This
low is producing disorganized cloudiness and showers, and an area of
gusty winds to the west of the center. This system has the
opportunity to become a subtropical cyclone over the next 24 hours
before it becomes absorbed by a larger extratropical cyclone. The
next Special Tropical Weather Outlook will be issued by 2 PM EDT
Wednesday. For additional information on this system, please
see High Seas Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...low...30 percent
* Formation chance through 5 days...low...30 percent

High Seas Forecasts issued by the National Weather Service can be
found under AWIPS header NFDHSFAT1, WMO header FZNT01 KWBC, and on
the Web at http://www.opc.ncep.noaa.gov/shtml/NFDHSFAT1.shtml.

$$
Forecaster Avila

[RL3AO]

91L is starting to look a bit better this afternoon. Might make a run at being named after all.

[gatorcane]

yeah quite impressive for being so far north and time of year

[weathaguyry]

Yeah, if that convection can wrap around a little bit to the west side, it should be named.

[Kazmit]

Definitely looks better than yesterday with that convection. Although if it wants to be named it will have to do it within 24 hours (per the NHC) before it gets absorbed. The chances are still 30%/30%, but I think it should be at least 50%/50%...
I agree that it has a shot if the convection wraps around fully.

[Kazmit]

18z... models show it curving and then heading NW. What an unusual track.

[cycloneye]

Building convection.

[1900hurricane]

From Alicia Bentley's webpage.

I thought it was fun to track the PV anomaly from a central US cyclone last week march across the SE US and into the SW Atlantic before interacting with the midlatitude cyclone over the north-central Atlantic.

http://i.imgur.com/LBgRD9f.gif

Has there ever been (in the satellite era) a tropical or subtropical cyclone who had origins in the polar vortex?

Little late here, but PV in this scenario is not "Polar Vortex," but rather "Potential Vorticity."

[RL3AO]

From Alicia Bentley's webpage.

I thought it was fun to track the PV anomaly from a central US cyclone last week march across the SE US and into the SW Atlantic before interacting with the midlatitude cyclone over the north-central Atlantic.

http://i.imgur.com/LBgRD9f.gif

Has there ever been (in the satellite era) a tropical or subtropical cyclone who had origins in the polar vortex?

Little late here, but PV in this scenario is not "Polar Vortex," but rather "Potential Vorticity."

Thanks for pointing that out. I didn't even correlate those two lol.

[weathaguyry]

Wow! That's a pretty nice little area of convection around the center!

[wxman57]

Only 24 hours until it merges with another system to its north (tomorrow late afternoon). Center is completely exposed and convection-free. Chances of it being named are slim to none. NHC forecasters here at the National Hurricane Conference aren't even mentioning it.

[TropicalAnalystwx13]

This is without a doubt a subtropical cyclone. It's not even ambiguous.

That is not an exposed center, it's an eye-like feature.