2024 - tracking the tropics

[40/70 Benchmark]

1 hour ago, WxWatcher007 said:

Good stuff, @40/70 Benchmark. Our thoughts are aligned. If there is a legitimate inner core completed or near completion at the Yucatán Channel, I think it’ll be all systems go for a high end wind and surge system, even if an ERC levels things off later. 

If not, it may just slow walk its way along in terms of intensification until Thursday.

I do think this will end up a large system and will be much more resistant to shear and/or dry air as a result, with the increasing forward speed being a secondary factor in limiting any window for weakening. I think the floor is probably around 100mph and the ceiling is still fairly high, around 140mph.

Right now I think LF is probably around 120 imo. 

I think max intensity will he 125mph prior to landfall at 110mph...but will do Final on Thursday.

[dryslot]

Hmm

[ROOSTA]

Just had a shower pass through, one of those outer-outer spiral bands. .23" in one-minute.
This storm seems different than other events. It's a unique feeling with dews and temp in the upper 70's. The air you can wear.
 
In the 12yrs being here the highest wind experienced was 93mph. in Michael. Power was out for 6 days!   

[Patrick-02540]

A little hurricane history. 

From 1980 to 2020, there were 21 "major" hurricanes (Cat 3 or higher) that hit the US (5 in the 80s, 5 in 90s, 7 in the 00s, and 4 in the 10s).

That's 5.25 of them per decade. The average since 1850 is 5.6 per decade. So the last 4 decades have been slightly below average, but close enough that we can call it average.

The total number of hurricanes that hit the US during that period is 66, or 16.5 per decade. The average since 1850 is 17.7 per decade. Again, slightly below average, but close enough that I think we can call it statistically average.

[cardinalland]

3 hours ago, Patrick-02540 said:

A little hurricane history. 

From 1980 to 2020, there were 21 "major" hurricanes (Cat 3 or higher) that hit the US (5 in the 80s, 5 in 90s, 7 in the 00s, and 4 in the 10s).

That's 5.25 of them per decade. The average since 1850 is 5.6 per decade. So the last 4 decades have been slightly below average, but close enough that we can call it average.

The total number of hurricanes that hit the US during that period is 66, or 16.5 per decade. The average since 1850 is 17.7 per decade. Again, slightly below average, but close enough that I think we can call it statistically average.

meanwhile in the 2020s, we’ve already had 13 hurricane landfalls and 5 major hurricane landfalls… yowza!

[ineedsnow]

6z GFS please

[Snowcrazed71]

1 hour ago, ineedsnow said:

6z GFS please

Are you asking to see it, are you saying show something really good

[40/70 Benchmark]

 

Intensifying Hurricane Helene's Devastation of Florida Coast Imminent

Intensification through Landfall Around Midnight Likely

The situation:

Hurricane Helene is centered near latitude 25.5 N and longitude 85.5 W, which is about 290 miles south of  Apalachicola, FL. Maximum sustained winds are currently about 105 mph sustained with a minimum central pressure of 960mb as of 11am EDT.

 

 

*Preparation to protect life and property from around Tampa Bay up the coast to Apalachee Bay should be complete and if they are not, focus on the life portion of this message and disregard property. Surge will begin inundating areas on the coast this evening well in advance of landfall.*

Track Forecast:

The forecast track philosophy from First Call on Tuesday is unchanged and of high confidence. The system will continue in a general north northeast heading until landfall on the northeastern Gulf coast of Florida later this evening.

 

 

It is very possible that there may be some subtle nuances to the track that will have large ramifications on lives in individual locales, but this is why everyone was instructed to prepare as if they are a certainty to be ground zero, so to speak. The belief that guidance is currently erroneously too far to the west is one prominent example of this.

 

 

 

However, this will not be able to be definitively known for several hours, which will be too late for any adjustments from those impacted.

The reason for this anticipated late correction from guidance is from experience with respect to model errors during the interaction of powerful hurricanes with mid latitude troughs, which is being validated to some degree by short term trends. As precarious as the track nuances are at this point, the forecast for the precise landfall intensity is several magnitudes more tedious due to this intricate interaction with two Goliaths of the atmosphere in Helene and the approaching trough.

 

 

 

 

 

Intensity Forecast:

Thus far the track and intensity forecast from First Call on Tuesday has been very accurate in that it brushed the eastern tip of the Yucatan and has continued to at a deliberate pace of intensification since.

While it has become much better organized in general, the system still has some structural inconsistencies present.

 

 

Although it has developed an organized central dense overcast, it remains in the process of closing off the eye wall, which is a red flag for truly exotic levels of intensification over the next several hours. However, the system is organized enough to continue to avail of absolute rocket fuel from the perspective of oceanic heat potential as it is currently traversing the loop current.

 

 

The balance of the forecast between now and landfall is convoluted and heavily reliant the precise manner of interaction with the incoming trough. Conditions are not ideal, so any category 5 delusions from some of the twitter juggernauts should have been adequately medicated by this point. The system will soon be departing the loop current, which is not a substantial limiting factor given that the sea should remain adequately warm of sufficient depth. However, there will be increasing wind shear over the northeast Gulf of Mexico due to the influence of said trough.

 

 

As the graphic above elucidates, the environment will not be as hostile as the shear graphic implies due to the fact that said shear will be parallel to the north northeast movement of the storm. It will also be aiding in the evacuation of outflow aloft by way of fairly strong diffluence, which act to negate the negative influence of the shear as well. This is the assortment of dynamics that are referred to by "precise interaction with the trough" and these factors acting to negate the influence of the shear are illustrated quite will in the shear trend graphic below.

 

 

 

Notice how a decrease in shear is denoted by guidance along the modeled path of the storm by the dashed lines. This is a reflection of the aforementioned processes at play. One additional factor at play aiding in the sustainment of an environment sufficient to maintain a major hurricane all the way to the coast is an adequate mid level moisture supply, as dry air is slow to be entrained into the circulation during trough interaction.

 

 

In summary, the interaction between Helene and the upper level trough is such that the impact of significant shear prior to landfall will be largely negated by the fact that is is parallel to the storm's moment, in addition to ventilation aloft via divergent flow accentuating outflow to the NNE. The system's sheer size and fast rate of movement will also act to limit the impact of said deleterious atmospheric influences as well, since smaller systems are more prone to atmospheric imperfections and the fast rate of movement limited exposure prior to landfall. However, the residual structural inconsistencies coupled with the cyclone's rather large size and the fact that shear does in fact exist will result in an imperfect environment that will only allow for slow to perhaps more moderately paced intensification once mid latitude upper support commences for the next 12 hours of so prior to landfall. Thus the intensity forecast is increased slightly from First Call to reflect the absence of a significant weakening trend prior to landfall.

 

Final Call:

 

FIRST CALL: ISSUED 2:45PM EDT TUESDAY 9/24:

[Typhoon Tip]

1 hour ago, 40/70 Benchmark said:

 

Intensifying Hurricane Helene's Devastation of Florida Coast Imminent

Intensification through Landfall Around Midnight Likely

The situation:

Hurricane Helene is centered near latitude 25.5 N and longitude 85.5 W, which is about 290 miles south of  Apalachicola, FL. Maximum sustained winds are currently about 105 mph sustained with a minimum central pressure of 960mb as of 11am EDT.

 

 

*Preparation to protect life and property from around Tampa Bay up the coast to Apalachee Bay should be complete and if they are not, focus on the life portion of this message and disregard property. Surge will begin inundating areas on the coast this evening well in advance of landfall.*

Track Forecast:

The forecast track philosophy from First Call on Tuesday is unchanged and of high confidence. The system will continue in a general north northeast heading until landfall on the northeastern Gulf coast of Florida later this evening.

 

 

It is very possible that there may be some subtle nuances to the track that will have large ramifications on lives in individual locales, but this is why everyone was instructed to prepare as if they are a certainty to be ground zero, so to speak. The belief that guidance is currently erroneously too far to the west is one prominent example of this.

 

 

 

However, this will not be able to be definitively known for several hours, which will be too late for any adjustments from those impacted.

The reason for this anticipated late correction from guidance is from experience with respect to model errors during the interaction of powerful hurricanes with mid latitude troughs, which is being validated to some degree by short term trends. As precarious as the track nuances are at this point, the forecast for the precise landfall intensity is several magnitudes more tedious due to this intricate interaction with two Goliaths of the atmosphere in Helene and the approaching trough.

 

 

 

 

 

Intensity Forecast:

Thus far the track and intensity forecast from First Call on Tuesday has been very accurate in that it brushed the eastern tip of the Yucatan and has continued to at a deliberate pace of intensification since.

While it has become much better organized in general, the system still has some structural inconsistencies present.

 

 

Although it has developed an organized central dense overcast, it remains in the process of closing off the eye wall, which is a red flag for truly exotic levels of intensification over the next several hours. However, the system is organized enough to continue to avail of absolute rocket fuel from the perspective of oceanic heat potential as it is currently traversing the loop current.

 

 

The balance of the forecast between now and landfall is convoluted and heavily reliant the precise manner of interaction with the incoming trough. Conditions are not ideal, so any category 5 delusions from some of the twitter juggernauts should have been adequately medicated by this point. The system will soon be departing the loop current, which is not a substantial limiting factor given that the sea should remain adequately warm of sufficient depth. However, there will be increasing wind shear over the northeast Gulf of Mexico due to the influence of said trough.

 

 

As the graphic above elucidates, the environment will not be as hostile as the shear graphic implies due to the fact that said shear will be parallel to the north northeast movement of the storm. It will also be aiding in the evacuation of outflow aloft by way of fairly strong diffluence, which act to negate the negative influence of the shear as well. This is the assortment of dynamics that are referred to by "precise interaction with the trough" and these factors acting to negate the influence of the shear are illustrated quite will in the shear trend graphic below.

 

 

 

Notice how a decrease in shear is denoted by guidance along the modeled path of the storm by the dashed lines. This is a reflection of the aforementioned processes at play. One additional factor at play aiding in the sustainment of an environment sufficient to maintain a major hurricane all the way to the coast is an adequate mid level moisture supply, as dry air is slow to be entrained into the circulation during trough interaction.

 

 

In summary, the interaction between Helene and the upper level trough is such that the impact of significant shear prior to landfall will be largely negated by the fact that is is parallel to the storm's moment, in addition to ventilation aloft via divergent flow accentuating outflow to the NNE. The system's sheer size and fast rate of movement will also act to limit the impact of said deleterious atmospheric influences as well, since smaller systems are more prone to atmospheric imperfections and the fast rate of movement limited exposure prior to landfall. However, the residual structural inconsistencies coupled with the cyclone's rather large size and the fact that shear does in fact exist will result in an imperfect environment that will only allow for slow to perhaps more moderately paced intensification once mid latitude upper support commences for the next 12 hours of so prior to landfall. Thus the intensity forecast is increased slightly from First Call to reflect the absence of a significant weakening trend prior to landfall.

 

Final Call:

 

FIRST CALL: ISSUED 2:45PM EDT TUESDAY 9/24:

fwiw,

2:25 PM EDT Thu Sep 26
Location: 26.7°N 84.9°W
Moving: NNE at 16 mph
Min pressure: 959 mb
Max sustained: 120 mph

[weathafella]

Bookbinder one of the authors of the latest NHC disco.  Is that Evan Bookbinder who was at NWS FO in MO somewhere and a poster here back in the day and on irc way back 25 years ago?

[wxeyeNH]

Finally RI  946-947mb as of 6pm

[WxWatcher007]

Sky is the limit

[Torch Tiger]

damn :/.

[Torch Tiger]

I thought the static/intensification phase would be earlier than it was

[mreaves]

My brother is in Thomasville, GA, about 30 miles north of Tallahassee. He’s not sure what to expect. He’s hoping it wobbles east a bit so they don’t get the NE quadrant. His biggest worry is the several large pines in his yard. 

[Chrisrotary12]

Steinahatchee is a magnet!

[Go Kart Mozart]

37 minutes ago, mreaves said:

My brother is in Thomasville, GA, about 30 miles north of Tallahassee. He’s not sure what to expect. He’s hoping it wobbles east a bit so they don’t get the NE quadrant. His biggest worry is the several large pines in his yard. 

Not many families have sibs in Thomasville and Barre.  I hope he ends up unscathed!

[Ginx snewx]

2 hours ago, weathafella said:

Bookbinder one of the authors of the latest NHC disco.  Is that Evan Bookbinder who was at NWS FO in MO somewhere and a poster here back in the day and on irc way back 25 years ago?

I think so Jer

[dendrite]

[Typhoon Tip]

140 mph

[Ginx snewx]

Tallahassee looking like it may get nw eyewall

[Typhoon Tip]

long range rad looks like concentric eyewalls

[Ginx snewx]

12 minutes ago, dendrite said:

Beast mode.

[drstuess]

Issac popping a pinhole eye way out in the middle of nowhere.

Sent from my SM-S901U using Tapatalk

[powderfreak]

1 hour ago, dendrite said:

Imagine being under a 0.5 degree base level velocity scan of 170mph?

With thunder and lightning, along with torrential rain?

[Torch Tiger]

oof

[dryslot]

Rural, Perry/Fish Creek landfall.

[40/70 Benchmark]

1 minute ago, 40/70 Benchmark said:

Not bad...had that spot pegged on Tuesday First Call...will do the full post mortem tomorrow night.

It was obvious most guidance was erroneously west, as was NHC.

 

 

[mreaves]

8 minutes ago, 40/70 Benchmark said:

 

That landfall should put my brother on the west side of the storm. Still have extreme wind warnings for Thomas County, GA east though. The weather channel has someone in Valdosta, about 45 miles east of him.  

[weathafella]

38 minutes ago, 40/70 Benchmark said:

 

Seeing Apalachacola National Forest conjures an image from Deliverance…