ATL: HELENE - Models

[caneman]

Latest 18Z GEFS ensembles, with a slight SE shift from the 12Z and east of the NHC track:
https://i.postimg.cc/Y2JmDJTR/gfs-ememb-lowlocs-watl-fh0-36.gif

I've noticed the same in previous storms. I'm not questioning the NHC'S ability but I am asking does that mean they've discounted these other models for one reason or another? Legit question.

I'm not sure, you could ask them. They still use the Florida State Super ensemble as far as I know, and it's skill blending various models has shown to be higher than individual models.

How could I really ask them? Are you being serious? It's just a curious question. Maybe they are relying on the FSU model. I have zero clue and just curious. I just don't know if sometimes they rely on one some models more than others for one reason or another. Maybe things have changed but I remember not so long ago when the Euro spoke people listened as an example. Wanting to learn and certainly not wanting to challenge them as they are almost always spot on. Maybe they are so skilled that they have more knowledge than models?

[Bocadude85]

Latest 18Z GEFS ensembles, with a slight SE shift from the 12Z and east of the NHC track:
https://i.postimg.cc/Y2JmDJTR/gfs-ememb-lowlocs-watl-fh0-36.gif

Something to watch will be at which latitude Helene crosses east of longitude 86. The farther west models don’t show her crossing this until 25-26N.

[Steve]

I've noticed the same in previous storms. I'm not questioning the NHC'S ability but I am asking does that mean they've discounted these other models for one reason or another? Legit question.

I'm not sure, you could ask them. They still use the Florida State Super ensemble as far as I know, and it's skill blending various models has shown to be higher than individual models.

How could I really ask them? Are you being serious? It's just a curious question. Maybe they are relying on the FSU model. I have zero clue and just curious. I just don't know if sometimes they rely on one some models more than others for one reason or another. Maybe things have changed but I remember not so long ago when the Euro spoke people listened as an example. Wanting to learn and certainly not wanting to challenge them as they are almost always spot on. Maybe they are so skilled that they have more knowledge than models?

Send them an email or letter?

[tolakram]

I'm not sure, you could ask them. They still use the Florida State Super ensemble as far as I know, and it's skill blending various models has shown to be higher than individual models.

How could I really ask them? Are you being serious? It's just a curious question. Maybe they are relying on the FSU model. I have zero clue and just curious. I just don't know if sometimes they rely on one some models more than others for one reason or another. Maybe things have changed but I remember not so long ago when the Euro spoke people listened as an example. Wanting to learn and certainly not wanting to challenge them as they are almost always spot on. Maybe they are so skilled that they have more knowledge than models?

Send them an email or letter?

I forget who from here last asked them a question but I remember that they answered.

[caneman]

I'm not sure, you could ask them. They still use the Florida State Super ensemble as far as I know, and it's skill blending various models has shown to be higher than individual models.

How could I really ask them? Are you being serious? It's just a curious question. Maybe they are relying on the FSU model. I have zero clue and just curious. I just don't know if sometimes they rely on one some models more than others for one reason or another. Maybe things have changed but I remember not so long ago when the Euro spoke people listened as an example. Wanting to learn and certainly not wanting to challenge them as they are almost always spot on. Maybe they are so skilled that they have more knowledge than models?

Send them an email or letter?

You seriously can do that?

[caneman]

How could I really ask them? Are you being serious? It's just a curious question. Maybe they are relying on the FSU model. I have zero clue and just curious. I just don't know if sometimes they rely on one some models more than others for one reason or another. Maybe things have changed but I remember not so long ago when the Euro spoke people listened as an example. Wanting to learn and certainly not wanting to challenge them as they are almost always spot on. Maybe they are so skilled that they have more knowledge than models?

Send them an email or letter?

I forget who from here last asked them a question but I remember that they answered.

Ok. Cool. My scientific part of my brain begs for an answer. Like things have to make sense. Lol

[MetsIslesNoles]

Anybody know why so many tv stations and social media account seem to be pushing the GRAF model. (What even is that?)

[Slughitter3]

Send them an email or letter?

I forget who from here last asked them a question but I remember that they answered.

Ok. Cool. My scientific part of my brain begs for an answer. Like things have to make sense. Lol

There's a good chance they'll answer you via social media as well. I've had some success with that method in the past.

Sent from my SM-S928U using Tapatalk

[jlauderdal]

Anybody know why so many tv stations and social media account seem to be pushing the GRAF model. (What even is that?)

They are paying for access so they are going to use it and some of their competitors in the media are unhappy about it because its to the east.

[caneman]

Anybody know why so many tv stations and social media account seem to be pushing the GRAF model. (What even is that?)

Where is it calling for landfall?

[ronjon]

Latest 18Z GEFS ensembles, with a slight SE shift from the 12Z and east of the NHC track:
https://i.postimg.cc/Y2JmDJTR/gfs-ememb-lowlocs-watl-fh0-36.gif

I've noticed the same in previous storms. I'm not questioning the NHC'S ability but I am asking does that mean they've discounted these other models for one reason or another? Legit question and would like a knowledgeable persons answer and not guess work.

Gatorcane makes a good point. And your observations Caneman are valid. Believe NHC had consistently tracked west for Debby which made landfall in Steinhachee. Now its way too early to say one way or the other how Helene will landfall. I had forgot NHC utilizes UKMET and the ensembles in addition to the big two: Euro and GFS. In any case, think we're in real time tracking mode now and specifically watching if the storm follows that NE track the first 24 hrs that GFS is projecting to maybe get a better handle on ultimate landfall.

[aspen]

18z hurricane models still show recovery over the next 6-12 hours and RI until landfall. Helene looks pretty roughed-up now — 2024’s Gulf dry air strikes again — but the chances for a Cat 4 landfall remain.

[Steve]

Anybody know why so many tv stations and social media account seem to be pushing the GRAF model. (What even is that?)

It’s been a while since I read it but I think the weather company was some weather tech nerds who partnered with IBM and possibly NVDA technology to put together a physics oriented modeling solution that incorporated AI. I don’t think it’s an exclusively radar derived product your local weather station might have - like vipir or whatever. This is their words and not an independent 3rd party analysis. So it’s biased. But it’s interesting. And it’s also had some pretty decent successes over the last couple years and some head scratchers as well.

https://www.weathercompany.com/global-h ... recasting/

Here’s when it came out in 2018 with Weather Underground describing what it was supposed to be.

https://www.wunderground.com/cat6/IBM-I ... ting-Model

[gatorcane]

The GFS at hour 24 shifted right but the landfall is still similar. It also shifted slightly right between the 12Z and 6Z. We may see a more NE track for some period of time tomorrow across the EGOM before it veers a bit more NNE. Again, the NHC isn't showing this but the GFS and ECMWF are both showing a period of time where it moves more NE than NNE, maybe it ends up a bit closer to the west coast of Florida as a result:

[Poonwalker]

Sometimes NHC will explain their track decision in their discussions. They will give weight to models based on the previous trends. They are also privy to exactly what is being fed into these prior to the runs.

[Travorum]

The GFS at hour 24 shifted right but the landfall is still similar. It also shifted slightly right between the 12Z and 6Z. We may see a more NE track for some period of time tomorrow across the EGOM before it veers a bit more NNE. Again, the NHC isn't showing this but the GFS and ECMWF are both showing a period of time where it moves more NE than NNE, maybe it ends up a bit closer to the west coast of Florida as a result:

https://i.postimg.cc/bwdTGLmW/gfs-mslp-pcpn-watl-fh24-trend.gif

I'm not well versed in reading the steering currents, but it looks to me like on the 18z GFS the high pressure east of Florida doesn't build as far west in the short run, which allows the initial motion of Helene to head more to the northeast. After that, the ULL over the US builds more further to the southeast than in previous runs which pulls Helene further to the north. The overall effect of this ends up being that the more easterly trajectory through 24 hours is counteracted by the more northerly pull after that, and therefore the final landfall location doesn't change significantly.

A notable result of this, like you said, is that while the landfall location doesn't change significantly, the trajectory leading up to landfall reaches much closer to the west coast of Florida, possibly resulting in greater storm surge.

[gatorcane]

It's the NAM, but even it has shifted east, a bit closer to the west coast of Florida:

[redingtonbeach]

It's the NAM, but even it has shifted east, a bit closer to the west coast of Florida:
https://i.postimg.cc/BbLDgZz0/nam-mslp-pcpn-watl-fh21-trend.gif

Like the NAM for track, especially the conus NAM.

[CycloysisNegative]

What I noticed is there is a difference in the placement of the cutoff low between 12z/18z model runs. It’s further NW, not by a ton, but by around the same margin of the eastward shift. I would imagine being further away, its influence would decrease.

[TampaWxLurker]

These models showing a right nudge are interesting. Maybe the start of a trend. Let's see if it can thread the needle.

Head just slightly east of track, not far enough for major rises in predicted surge for the Tampa Bay area, but just far enough east that it ends up coming onshore where Tallahassee ends up on the western side and doesn't get the worst of it. Coming onshore in the vicinity of the mouth of the Aucillla River.