ATL: ISAAC - Post-Tropical - Discussion

[wxGuy]

Easy to see the dry air Florence is struggling with on this one. You have a link to this particular view?

https://www.nhc.noaa.gov/satellite.php

pick your poison

[Gustywind]

Tropical Weather Discussion
NWS National Hurricane Center Miami FL
757 AM EDT Fri Sep 7 2018

Tropical Weather Discussion for North America, Central America
Gulf of Mexico, Caribbean Sea, northern sections of South
America, and Atlantic Ocean to the African coast from the
Equator to 32N. The following information is based on satellite
imagery, weather observations, radar and meteorological analysis.

Based on 0600 UTC surface analysis and satellite imagery through
1145 UTC.

...SPECIAL FEATURES...

A broad and elongated area of low pressure is centered several hundred miles west of the Cabo Verde Islands is denoted by a
tropical wave with its axis along 34W and extending from 04N to 20N. A 1008 mb low is on the wave axis near 14N35W.
This system is moving westward at about 10 to 15 kt. The associated shower and thunderstorm activity has increased some during the last couple
of hours. Latest satellite imagery shows scattered moderate to strong convection within 150 nm of the low mostly in the W
quadrant. Environmental conditions appear conducive for development, and a tropical depression is expected to form within
the next day or two while the system moves slowly westward across the tropical Atlantic. The chance of this system becoming a
tropical cyclone during the next 48 hours remains in the high range. Please read the latest NHC Tropical Weather Outlook under
AWIPS/WMO headers MIATWOAT/ABNT20 KNHC for more information.

[Gustywind]

Latest SSD...

07/1145 UTC 13.5N 35.6W T1.0/1.0 92L

[Gustywind]

Invest 92L
As of 12:00 UTC Sep 07, 2018:
https://www.tropicaltidbits.com/storminfo/

Location: 13.7°N 35.3°W
Maximum Winds: 25 kt Gusts: 35 kt
Minimum Central Pressure: 1007 mb
Environmental Pressure: 1010 mb
Radius of Circulation: 210 NM
Radius of Maximum Wind: 90 NM

[WAcyclone]

Looks like we may already have Helene. Definitely at least a TD though:

[CyclonicFury]

Definitely looks like a tropical cyclone this morning. I’d expect advisories to be initiated at 11am, most likely on a TD 8.

[abajan]

Looking great!

https://fotos.subefotos.com/38282390f63 ... 33de3o.gif

Excellent vorticity signature!

[abajan]

Yea, this will be upgraded at 11am.

https://i.imgur.com/jW1UgAy.jpg

Nope. No indication on the NHC site of an upgrade at 11 AM.

[Gustywind]

Yea, this will be upgraded at 11am.

https://i.imgur.com/jW1UgAy.jpg

Nope. No indication on the NHC site of an upgrade at 11 AM.

Yes. But looks like something is cooking nicely with all those elements we have seen today. Wait and see.

[Blinhart]

If this system had a potential of hitting land soon it would of already been named a PTC, but since it is days away from land that don't have to name it a PTC, they can wait until it has enough evidence to name it either a TD or a TS.

[Gustywind]

If this system had a potential of hitting land soon it would of already been named a PTC, but since it is days away from land that don't have to name it a PTC, they can wait until it has enough evidence to name it either a TD or a TS.

Right! That make sense, cannot be more agree my friend. Looks like they may put the trigger at 5 PM for 92L we will see.

[AJC3]

Either the upper level easterlies over 92L have strengthened over the past 2-3 hours, or the lower level steering flow has weakened considerably (I suspect it's mostly the latter). Whatever the case may be, 92L's formative CDO is now west of the LLCC, which is quickly becoming exposed.

[Gustywind]

In the left corner is featherweight #92L, whose ASCAT pass showed a stronger/tighter circulation and has more organized deep convection than yesterday. In the right corner (in the monsoon trough) is heavy weight Potential TC8 with lots of convection that may take time to organize

https://twitter.com/info_jfourni/status ... 3990178818

[OURAGAN]

1007 MB, 30 KNOTS at NRL, it will be a TD soon

[Gustywind]

1007 MB, 30 KNOTS at NRL, it will be a TD soon

Any link please Ouragan to share with us this info. Thanks.

[AJC3]

1007 MB, 30 KNOTS at NRL, it will be a TD soon

Any link please Ouragan to share with us this info. Thanks.

I'd be seriously surprised if it was, considering the low level center is completely exposed now. Rather than moving westward, it appears to have become quasi-stationary for the time being.

[Hammy]

Highly unlikely it'll be upgraded anytime soon (even though it'll likely reach tropical storm intensity well before then) as they've gotten stricter over the years with what qualifies, it seems unless there's convection directly over the center around advisory time, they won't initiate advisories.

[Gustywind]

Matter of hours... now? given the latest TWO...

223
ABNT20 KNHC 071739
TWOAT

Tropical Weather Outlook...Resent
NWS National Hurricane Center Miami FL
200 PM EDT Fri Sep 7 2018

Satellite data indicate that the circulation of a low pressure system located about 700 miles west of the Cabo Verde Islands
is well defined. However, the associated shower and thunderstorm activity has not been sufficiently organized to designate the
system as a tropical depression. Only a slight increase in organization would lead to the initiation of advisories on this
system, possibly as early as later today or tonight. This low is expected to move slowly westward across the tropical Atlantic Ocean
during the next several days.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 5 days...high...90 percent.

[OURAGAN]

TD Later Today or tonight according the NHC at 2 PM

[Gustywind]

Invest 92L
As of 18:00 UTC Sep 07, 2018:


Location: 13.6°N 34.9°W
Maximum Winds: 30 kt Gusts: 40 kt
Minimum Central Pressure: 1007 mb
Environmental Pressure: 1010 mb
Radius of Circulation: 210 NM
Radius of Maximum Wind: 60 NM