ATL: IAN - Post-Tropical - Discussion

[underthwx]

98L looks a bit disheveled this morning. Doubt a TD forms till 98L reaches the central Caribbean......MGC

Agree. It needs to gain latitude and seems to be battling outflow shear from Fiona. Being so far south there is less Coriolis effect to help it organize.

Also, if I'm not mistaken, 98L is moving at 15-20 mph forward speed?

[Poonwalker]

98L looks a bit disheveled this morning. Doubt a TD forms till 98L reaches the central Caribbean......MGC

Agree. It needs to gain latitude and seems to be battling outflow shear from Fiona. Being so far south there is less Coriolis effect to help it organize.

Also, if I'm not mistaken, 98L is moving at 15-20 mph forward speed?

Hard to compute speed but it does look like the wave itself is moving quickly in that range, it's going to have some form of land interaction with South America soon, but .. the funny thing is .. if the general low pressure stays just off the coast the land interaction could help it tighten up.

[underthwx]

This is an excerpt from 7:01 AM Discussion NWS Lake Charles..."Guidance has been coming into better agreement on the development
of a tropical cyclone in the caribbean over the next few days that
will then likely move into the gulf of Mexico early next week. NHC
presently gives this disturbance a 70 percent chance of development
over the next 48 hours and a 90 percent chance over the next five
days. There remains a very large spread in the ensembles regarding
the eventual track and intensity of this cyclone beyond that point
which is not unusual for a system that has yet to actually develop
and at this time range. The aforementioned shortwave will likely
have some, if not a significant impact on the eventual track of any
potential cyclone. With that in mind, while it is important to
recognize a potential threat to the gulf coast next week, it`s too
soon to draw any scientifically valid conclusions regarding a
specific track or impacts at any location along the gulf coast.
Interests along the gulf coast should continue to monitor the
development of this disturbance over the coming week."

[Iceresistance]

NWS-Mobile/Pensacola on Invest 98L


https://s5.gifyu.com/images/NWS-Mobile-AL-and-Pensacola-FL-on-Invest-98L.png

An area of disturbed weather in the tropical Atlantic will move west into the Caribbean Sea over the next few days. This system presently poses no threat to the Gulf of Mexico through the end of the week, but may enter the Gulf of Mexico next week. We will continue to monitor the progress of this system and provide updates as needed. For more information, visit The National Hurricane Center Webpage.

[Iceresistance]

Multiple National Weather Services are watching 98L closely, all forecast discussions are in the long range.

NWS-New Orleans

At this point, Invest 98L that is forecast to move into the
Caribbean over the next few days, is not expected to have any impact
on the local forecast package through the end of the long term
forecast period next Tuesday, no matter what solution ends up being
accurate. We`re still in the heart of hurricane season, so
monitoring the forecast remains prudent.

NWS-Tallahassee

In the tropics, Invest 98L, located to the east of the Windward
Islands, has a high chance of development during the next 2 days
and also during the next 5 days. This system bears watching
heading into next week. Stay up to date with the latest outlooks
regarding the tropics by visiting the National Hurricane Center
website at www.hurricanes.gov.

NWS-Tampa Bay

High pressure will then
try to build in from the east early next week as a potential
tropical cyclone moves north into the Gulf of Mexico. The exact
location and strength of this system remain unknown, so continue
to monitor the situation and keep up with the latest NHC
forecasts.

[Iceresistance]

NWS-Miami

For the early portion of next week, uncertainty remains higher than
normal for this portion of the forecast period as attention shifts to
the tropics where a tropical disturbance currently is pushing westward
through the Caribbean Sea. While it remains too early to speculate the
exact details regarding this disturbance, winds across the area will
veer more to the southeast and draw in deep tropical moisture to
the region during this time frame. This will continue to increase
the chances of showers and thunderstorms across South Florida for
early next week regardless of potential development of the tropical
disturbance. This will continue to be monitored as the week progresses.

[Sciencerocks]

[AutoPenalti]

 https://twitter.com/RyanMaue/status/1572576202413707267

[Nimbus]

Sharpening wave south of Barbados.
Dry air in circulation evident with many outflow boundaries.
Would have been better for the CONUS if it was a little better organized but you could wishcast it to stay weak all the way to Mexico.

[Tireman4]

Nothing from HGX..

LONG TERM...
(Friday through Tuesday)
Issued at 317 AM CDT Wed Sep 21 2022

Near record breaking heat is still in the forecast for Thursday
through Saturday as the area remains under the influence of
mid/upper level ridging. Still looking for high temperatures in the
upper 90s to around 100 to the north through west of the I-59/69
corridor and in the low to mid 90s closer to the coast. The ridge
begins to break down on Saturday resulting in slightly lower
afternoon highs, but the anticipated values in the mid to upper 90s
inland and even around 90 at the coast will still be close to
records for that day. A building ridge out west and a trough out
east will help to bring a cold front into and through the area on
Monday. Before the front`s arrival, Sunday will be another warm day
(highs ranging from around 90 at the coast to the mid/upper 90s
inland). After the front`s passage on Monday (still anticipating
highs ranging from around 90 at the coast to the mid 90s inland
along with low shower and thunderstorm chances mainly near and to
the south of the I-10 corridor), expect a notable change come
Tuesday and Wednesday as a drier airmass (dew points in the 40s/50s)
filters into the area. If all goes right, low temperatures on
Wednesday night will be in the low to mid 60s for much of the inland
areas with even an upper 50 not out of the question around and to
the north of the Huntsville area.

[underthwx]

https://twitter.com/RyanMaue/status/1572576202413707267

Auto.....looking at this weather map you shared, it depicts 98L located at the western portion of Cuba. And what looks like to me is a frontal boundary above 98L? Based on this map, would this indicate a potential track across the Southern Florida peninsula, or potentially just East of Florida potentially? Hypothetically speaking of course.

[AutoPenalti]

https://twitter.com/RyanMaue/status/1572576202413707267

Auto.....looking at this weather map you shared, it depicts 98L located at the western portion of Cuba. And what to me is a frontal boundary above 98L? Based on this map, would this indicate a potential track across the Southern Florida peninsula, or potentially just East of Florida potentially? Hypothetically speaking of course.

It's dependent on the location of that trough, how fast it lifts off and the exact location of 98L at that timeframe.

Based on that image though, I would bet on a FL peninsula impact. We won't know until Sunday or Monday.

[underthwx]

https://twitter.com/RyanMaue/status/1572576202413707267

Auto.....looking at this weather map you shared, it depicts 98L located at the western portion of Cuba. And what to me is a frontal boundary above 98L? Based on this map, would this indicate a potential track across the Southern Florida peninsula, or potentially just East of Florida potentially? Hypothetically speaking of course.

It's dependent on the location of that trough, how fast it lifts off and the exact location at that timeframe.

Based on that image though, I would bet on a FL peninsula impact. We won't know until Sunday or Monday.

Agree with you there Auto, thanks for your reply

[AutoPenalti]

 https://twitter.com/webberweather/status/1572598639918485505

[wxman57]

If I was a hurricane forecaster (which I am), I'd put my money on the FL Peninsula for now. Models are often too far west in this type of setup.

[underthwx]

If I was a hurricane forecaster (which I am), I'd put my money on the FL Peninsula for now. Models are often too far west in this type of setup.

Good enough for me....just seems to make the most sense, given all the facts thus far. Definitely bears watching if I'm a resident of that region.

[DESTRUCTION5]

Both the GFS and Euro show significant trough interaction when it gets north of Cuba. That almost looks certain. How strong it is and the degree of turn to the NE and when will be huge for possible impacts.

Even east of FL at this point is not out of the question.

[otowntiger]

If I was a hurricane forecaster (which I am), I'd put my money on the FL Peninsula for now. Models are often too far west in this type of setup.

Good enough for me....just seems to make the most sense, given all the facts thus far. Definitely bears watching if I'm a resident of that region.

thanks 57, and

[wxman57]

There is always a fine line between an approaching trof will enhance outflow (Lily becoming a Cat 4 off LA coast in 2002) or it will produce wind shear (Lily 2002, as it neared landfall and was weakened considerably). Too early to tell which will affect this potential hurricane. Heck, this might not be Hermine. That low around 12N/33W looks like it could be a TS today. Haven't seen an ASCAT to determine if it has an LLC.

[DestinHurricane]

This smells like a potentially dangerous setup here. If think gets as strong as models forecast, you've either got a very large Northern Gulf storm like Ivan or Kat, which would obviously be extremely dangerous anywhere along that cost. But looking at this setup, a due N moving storm around the FL peninsula is possible. With as broad as this looks like it'll be, thats not great. If it stays offshore the W coast, West Coast is gonna get RAKED by surge. If it moves up Florida just E of center, Dade, Broward, and PBC potentially all get the eyewall of a major. The, relatively speaking, least devastating track would be close to Irma's where more of the core gets burried in the swamps. Doesn't say much though, because thats still plenty bad. Looking at ensembles, looks like its not gonna cut NE like wilma, but rather due N. I'm fairly sure that depends on the orientation of the trough, a neutrally titled one would bring this due N here?