Major Hurricane Helene

[PackGrad05]

3 minutes ago, WxWatcher007 said:

The west trend has continued on the globals, with the 06z Euro and 06z GEFS ticking west. More in line with the spaghetti models.

The GEFS ensemble mean is pretty much identical to previous runs...  the members have just tightened around the mean.  

[Windspeed]

And there it is. Is this the real turn to the northeast happening? Would be significantly earlier than models showed...

Radar suggests a more northerly motion has commenced as well in the past few hours.

[beanskip]

6 minutes ago, wxeyeNH said:

Didn't Michael  that wiped out Mexico Beach go over Tallahassee?  That was a Cat 5.  Just to the east of the eye is the worst and I don't remember if it went west of the city.  This will be scary because unlike Michael it will be dark.

No. Michael missed Tallahassee by almost 100 miles and Michael was a much tighter storm. Bad impacts, for sure -- much like Hermine. But nothing like this. 

[jbenedet]

6 minutes ago, wxeyeNH said:

Didn't Michael  that wiped out Mexico Beach go over Tallahassee?  That was a Cat 5.  Just to the east of the eye is the worst and I don't remember if it went west of the city.  This will be scary because unlike Michael it will be dark.

It was about 100 miles west of Tallahassee. The rainfall threat with Michael was much lower than is with Helene. That’s why the natural disaster risk is overall higher imo.

We are also going to see a stronger storm (higher wind and overall rainfall) further inland due to the UL vort phasing and PRE. So I think the power outage risk is higher generally for a much larger area.

[WxWatcher007]

11 minutes ago, cptcatz said:

And there it is. Is this the real turn to the northeast happening? Would be significantly earlier than models showed...

I’d wait to see more longer term motion/center fixes. 

9 minutes ago, PackGrad05 said:

The GEFS ensemble mean is pretty much identical to previous runs...  the members have just tightened around the mean.  

That’s a better way to characterize it, thanks. Here’s the illustration for others. Will try to add those in future posts.

18z yesterday 

 

00z

 

06z

[hawkeye_wx]

The latest dropsonde pressure is still 981 mb, so it has plateaued for now.  Radar and satellite show a bit of a dry slot has wrapped up the east and north sides of the core.  I think at least a couple models hinted at this happening this morning.

[WxWatcher007]

We have our first VDM with data on a nascent eyewall trying to form, along with FL winds slightly above 64kt. 

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 25th day of the month at 13:54Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF99-5309
Storm Name: Helene
Storm Number & Year: 09 in 2024 (flight in the North Atlantic basin)
Mission Number: 11
Observation Number: 11 ( See all messages of this type for this mission. )

A. Time of Center Fix: 25th day of the month at 13:12:50Z
B. Center Fix Coordinates: 21.33N 86.16W
B. Center Fix Location: 46 statute miles (74 km) to the ENE (75°) from Cancún, Quintana Roo, Mexico.
C. Minimum Height at Standard Level: 2,941m (9,649ft) at 700mb
D. Minimum Sea Level Pressure: 982mb (29.00 inHg)
E. Dropsonde Surface Wind at Center: From 360° at 22kts (From the N at 25mph)
F. Eye Character: Open from the northeast to the southeast
G. Eye Shape: Elliptical (oval shaped)
G. Orientation of Major Axis in Elliptical Eye: 360° to 180° (N to S)
G. Length of Major Axis in Elliptical Eye: 50 nautical miles (58 statute miles)
G. Length of Minor Axis in Elliptical Eye: 30 nautical miles (35 statute miles)
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 47kts (54.1mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 46 nautical miles (53 statute miles) to the NE (36°) of center fix at 13:00:00Z
J. Maximum Flight Level Wind Inbound: From 128° at 51kts (From the SE at 58.7mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 94 nautical miles (108 statute miles) to the NE (42°) of center fix at 12:46:30Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 60kts (69.0mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 29 nautical miles (33 statute miles) to the SSW (204°) of center fix at 13:21:30Z
N. Maximum Flight Level Wind Outbound: From 284° at 68kts (From the WNW at 78.3mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 39 nautical miles (45 statute miles) to the SSW (205°) of center fix at 13:24:30Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 10°C (50°F) at a pressure alt. of 3,049m (10,003ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 16°C (61°F) at a pressure alt. of 3,049m (10,003ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 6°C (43°F)
R. Sea Surface Temp (collected at same location as temp inside eye): Not Available
S. Fix Determined By: Penetration, Radar, Wind, Pressure and Temperature
S. Fix Level: 700mb
T. Navigational Fix Accuracy: 0.02 nautical miles
T. Meteorological Accuracy: 2 nautical miles

Remarks Section:
 

Maximum Flight Level Wind: 68kts (~ 78.3mph) which was observed 39 nautical miles (45 statute miles) to the SSW (205°) from the flight level center at 13:24:30Z

[NorthHillsWx]

Tallahassee is going to get smoked and the further west this goes the odds increase that the peak surge will hit a populated beach town. Things are in motion right now that are leading up to a historic and devastating hurricane. Only saving grace is the broad circulation may keep peak winds down just a bit but that will not affect surge potential or inland wind threat one bit. Very disheartening to see the satellite look this morning and know this thing is about to go over the loop current 

[gymengineer]

>75 kt flight level wind on this pass. That may be enough for the upgrade. 

[kat5hurricane]

26 minutes ago, wxeyeNH said:

Didn't Michael  that wiped out Mexico Beach go over Tallahassee?  That was a Cat 5.  Just to the east of the eye is the worst and I don't remember if it went west of the city.  This will be scary because unlike Michael it will be dark.

And it's a much larger storm than Michael which will have far reaching effects. Michael had large impacts over a much smaller region so Tallahassee was largely spared.

[Weather Mike]

3 minutes ago, NorthHillsWx said:

Tallahassee is going to get smoked and the further west this goes the odds increase that the peak surge will hit a populated beach town. Things are in motion right now that are leading up to a historic and devastating hurricane. Only saving grace is the broad circulation may keep peak winds down just a bit but that will not affect surge potential or inland wind threat one bit. Very disheartening to see the satellite look this morning and know this thing is about to go over the loop current 

I think we need time to see if this goes more west. It appears to me on radar its now heading north and soon NE so maybe in time we shift things back a little east. Time will tell later today,  

[Amped]

5 minutes ago, jbenedet said:

It was about 100 miles west of Tallahassee. The rainfall threat with Michael was much lower than is with Helene. That’s why the natural disaster risk is overall higher imo.

We are also going to see a stronger storm (higher wind and overall rainfall) further inland due to the UL vort phasing and PRE. So I think the power outage risk is higher generally for a much larger area.

There is an inverted troff on the NW side of this storm as it makes landfall. That may produce a more onshore wind trajectory to the west of the track than you'd typically expect.

[MattPetrulli]

Just now, gymengineer said:

>75 kt flight level wind on this pass. That may be enough for the upgrade. 

78 knot FL would support a 65 knot even 70 knot upgrade. 

[dan11295]

Once the core gets a bit further away from the Yucatan and cycles out any dry air at least steady intensification will likely commence.

[beanskip]

So I know the NAM is pretty worthless for tropical systems, but it is, I think, noteworthy that it slowed down landfall by what looks like 6-8 hours on the 12z run vs. 6z. 

[Normandy]

Top of the morning folks.  We definitely got a rapidly intensifying cyclone (and a gigantic one at that the windfield is huge).  Seems like my initial just north of Tampa call is going to be too far east, but man the intensity call is right on.  This one is gonna smack the panhandle hard and the large size of it might bring big winds well Inland into Georgia.  Enjoy tracking this one everyone 

[MattPetrulli]

81 knot FL on last pass. We got a hurricane more than likely.

[CoastalWx]

Needs to get away from the Yucatan for more rapid strengthening. Later today and tonight.

[NorthHillsWx]

Hurricane upgrade incoming at 11

[Radtechwxman]

27 minutes ago, hawkeye_wx said:

The latest dropsonde pressure is still 981 mb, so it has plateaued for now.  Radar and satellite show a bit of a dry slot has wrapped up the east and north sides of the core.  I think at least a couple models hinted at this happening this morning.

Wonder if that will get into the core and impact organization a while since core is still kind of open and not completely closed off yet

[40/70 Benchmark]

5 minutes ago, CoastalWx said:

Needs to get away from the Yucatan for more rapid strengthening. Later today and tonight.

Especially tomorrow as that incoming trough enhances diffluence.

[cardinalland]

47 minutes ago, cptcatz said:

And there it is. Is this the real turn to the northeast happening? Would be significantly earlier than models showed...

i imagine a CAG system like this one will continue to wobble quite a bit as it coalesces

[CoastalWx]

The land friction will probably cause some issues with wobbling etc for a few hours. 

[Radtechwxman]

And there it is. Hurricane Helene. 80mph 979mb. Forecasting 125 mph landfall now. I think cat 4 is a decent if not good possibility. 

[NeonPeon]

Can someone clarify something for the uneducated.

The storm seems to have some dry air entrainment, but the general discussion has been that this was not likely to be an issue with this storm. Is what I'm seeing on satellite as dry air just subsidence from a storm that is lopsided, with an asymmetrical core? Are they one in the same?

[beanskip]

29 minutes ago, beanskip said:

So I know the NAM is pretty worthless for tropical systems, but it is, I think, noteworthy that it slowed down landfall by what looks like 6-8 hours on the 12z run vs. 6z. 

12Z ICON 2-3 hours slower as well.

Obviously, timing is a point of interest, but this is also more hours over warm Gulf waters. 

[schoeppeya]

3 minutes ago, NeonPeon said:

Can someone clarify something for the uneducated.

The storm seems to have some dry air entrainment, but the general discussion has been that this was not likely to be an issue with this storm. Is what I'm seeing on satellite as dry air just subsidence from a storm that is lopsided, with an asymmetrical core? Are they one in the same?

My guess is we are probably just seeing some structural changes and it may try and clear out an eye before the pressure starts falling again. Even when storms are going through RI we see periods where the pressure drops pause while the storms "consolidates" before the next wave of intensification. 

[BoulderWX]

10 minutes ago, Radtechwxman said:

And there it is. Hurricane Helene. 80mph 979mb. Forecasting 125 mph landfall now. I think cat 4 is a decent if not good possibility. 

Yup, horrible look for TLH with the center projected to pass just to the east. 

[NorthHillsWx]

As for dry air intrusion- this is totally normal for any developing hurricane. With the lack of shear at present, and the extremely vigorous convection the system is generating, I expect it to be easy to mix out as the core develops. This is a CLASSIC look of a storm primed to go. There is no inhibiting factor at present to prevent steady to rapid intensification. This is on schedule and to be honest that is a terrifying satellite look at this stage

[Windspeed]

[mention=9730]WxWatcher007[/mention] [mention=17109]NorthHillsWx[/mention] That dry slot you both were mentioning earlier seems to have been pulled into the developing core. Granted, I'm not sure how thorough the echoes are on the La Bajada radar, but perhaps this will help to keep Helene in check a bit longer until it can gain some separation away from the Yucatán landmass. Pretty much looking for anything to stunt or delay RI, which will make time an issue for Helene to reach MPI.