ATL: HELENE - Post-Tropical - Discussion

[wx98]

Mentioned a couple hours ago on the pre-invest thread:

“Look for probs in the 48-hour TWO to start coming up with each update. Florida Panhandle to Big Bend is looking like the most likely landfall point, probably by Thursday. It will be rather quick, so it may be difficult to get people to pay adequate attention until it’s late in the game. I’d expect PTC advisories to start tomorrow, unless it’s able to quickly close off by then and go straight to a TD/TS.”

They went ahead and upped from 10 to 40% at 18z.

I also mentioned that the 12z GFS and ECMWF both have landfall within 50 miles of each other (Panama to Apalachicola) Thursday evening around 7 pm CDT.

Also, the WPC QPF has “landfall” around Panama at the same time Thursday evening, based on the orientation of the rainfall output.

[kevin]

I shared yesterday's version in the previous thread, but thought it would be helpful to post today's version as well. I've never seen MPIs in the GOM comparable to this. Basically everything supports sub-900 mbar as the maximum theoretical potential. I guess it's the flip side of the underwhelming season so far: whatever eventually forms will have nuclear fuel-like SSTs to work with. Average North Atlantic SSTs have also surpassed 2023 again in recent days to become the record highest for this time of the year.

[Category5Kaiju]

Slightly off-topic here, but it's looking ever-so more likely that this storm is going to ultimately nab the name "Helene;" although not an I name, "Helene" has had a very strong run historically, with all four of its hurricane versions reaching the cusp of Category 3 status or higher (two Category 4s). At least based on history and superstition alone, should this version become a hurricane....watch out.

[StPeteMike]

Besides the close proximity to the Honduras/Nicaragua landmass, what else is there that could prevent TD status earlier than forecasted? Even Michael strengthened while being almost right on shore of Honduras.

[Fancy1002]

If that storm that hit North Carolina had been given the name, Helene, Then this would’ve been the I storm. The national hurricane center got lucky.

[CrazyC83]

If that storm that hit North Carolina had been given the name, Helene, Then this would’ve been the I storm. The national hurricane center got lucky.

Unless the 0/50 storm can get its act fast and fool us into becoming Helene...

[TomballEd]

From pre-invest thread:

Re: Low pressure developing over the western Caribbean Sea (40/80)
#1300 Unread postby wx98 » Sun Sep 22, 2024 1:29 pm

WPC QPF indicates a possible/probable Panama City area landfall Thursday afternoon/evening.

I can't find WPC model diagnostic discussions, but they used to assign weighting, sometimes discounting some model, to create an ensemble QPF forecast. Without a center, the data isn't complete, but QPF can serve as a super ensemble. Landfall just W of the heaviest rain. Looking at actual ensembles, this could be a Mississippi Valley rainfall event as the remnants seem to get captured by a trough.

[Jr0d]

At least now the hurricane models can start running, however I do t expect them to be helpful for at least another 24 hours as their input data is currently sub par and the current center is I'll defined.

It does seem to be currently further south so it may get a little more time over water.

I do think by Tuesday, the overall attitude West Central Florida to the Panhandle will be a bit hectic, probably even some panic especially if this goes from a depression to hurricane quickly as I believe it will.

[cycloneye]

At the NHC site, they have key messages for this disturbance. Maybe PTC comming very soon?

[CrazyC83]

At the NHC site, they have key messages for this disturbance. Maybe PTC comming very soon?

https://i.imgur.com/cqxtICG.png

That would likely be tomorrow sometime if not already a TC. The Cuba and Yucatan watches will likely be needed tomorrow. Tuesday looks to be the critical day - I think by the 4 pm advisory then will require a Hurricane Watch and Storm Surge Watch for the Gulf Coast wherever the projected track at that point is.

[CrazyC83]

As I mentioned in the Models thread, what is really needed now are additional balloon launches in the trough area, combined with sending the G-IV for a mission tomorrow in the Gulf as well. We are 48 hours away from the time that watches are needed, and we still are in dark territory right now.

[robbielyn]

As I mentioned in the Models thread, what is really needed now are additional balloon launches in the trough area, combined with sending the G-IV for a mission tomorrow in the Gulf as well. We are 48 hours away from the time that watches are needed, and we still are in dark territory right now.

Yeah a lot of people don’t even know about it yet.

[FLpanhandle91]

Fort Walton Beach here and I believe that panic across the panhandle starts tomorrow evening. I am going to be booking a hotel north and west potentially tonight as I live right on the water.

[3090]

As much as I would love to have this avoid the Tampa Bay region, I have to feel for the people of Big Bend to Pensacola if it heads in that direction. They would need at least a 500 year break of storms after everything they have gone through.

What about folks not in that area that may get the landfall?

[aspen]

As I mentioned in the Models thread, what is really needed now are additional balloon launches in the trough area, combined with sending the G-IV for a mission tomorrow in the Gulf as well. We are 48 hours away from the time that watches are needed, and we still are in dark territory right now.

Yeah a lot of people don’t even know about it yet.

Hopefully the NHC initiates PTC advisories on this by tomorrow morning at the latest. This could be a fairly substantial hit, and it’s only 4-5 days away. Cuba and the Yucatan will also need advisories soon.

[TomballEd]

As I mentioned in the Models thread, what is really needed now are additional balloon launches in the trough area, combined with sending the G-IV for a mission tomorrow in the Gulf as well. We are 48 hours away from the time that watches are needed, and we still are in dark territory right now.

Has NHC requested 6 hour soundings from stations near the Gulf?

[3090]

As I mentioned in the Models thread, what is really needed now are additional balloon launches in the trough area, combined with sending the G-IV for a mission tomorrow in the Gulf as well. We are 48 hours away from the time that watches are needed, and we still are in dark territory right now.

It is very unnerving ATM.

[wx98]

From pre-invest thread:

Re: Low pressure developing over the western Caribbean Sea (40/80)
#1300 Unread postby wx98 » Sun Sep 22, 2024 1:29 pm

WPC QPF indicates a possible/probable Panama City area landfall Thursday afternoon/evening.

I can't find WPC model diagnostic discussions, but they used to assign weighting, sometimes discounting some model, to create an ensemble QPF forecast. Without a center, the data isn't complete, but QPF can serve as a super ensemble. Landfall just W of the heaviest rain. Looking at actual ensembles, this could be a Mississippi Valley rainfall event as the remnants seem to get captured by a trough.

https://imagizer.imageshack.com/img924/5922/Eba5ZE.gif

I was referring to the 6-hourly QPF forecasts, which currently shows the progression of the low coming inland in 6 hour frames.

[wx98]

At the NHC site, they have key messages for this disturbance. Maybe PTC comming very soon?

https://i.imgur.com/cqxtICG.png

PTC designation will likely be tomorrow morning, either 9z or 15z, depending on trends.

[wx98]

As I mentioned in the Models thread, what is really needed now are additional balloon launches in the trough area, combined with sending the G-IV for a mission tomorrow in the Gulf as well. We are 48 hours away from the time that watches are needed, and we still are in dark territory right now.

I’d say NWS offices will start specials tomorrow or Tuesday.