Cat 4 Hurricane Helene | 140mph 938mb | Landfall Big Bend/Perry

[StretchCT]

Having gotten 12 inches of rain in 8 hours a few weeks back, I can't imagine getting double that. 

The Nam3k is extreme, though. it's gotten some extreme events before. Some of the other models and their top rainfall totals (*is still raining). Most of these are in the Blue Ridge/Smokey Mt area

UKMET 17        ICON 17.5

GEM 15.5         Graphcast 7

GFS 15             AIFS 12

Euro 17             NAM 15.5

RAP 17.5.          RGEM 15

HRRR 23.          ARW 21*

NSSL 15*           RFFS 16.5.   NBM 17.5

 

[StretchCT]

Sonde data so far

General path of the centers.

Wider view - the red are 50-60kt and the yellow orange are 60+.  They extend very far from the center. West to east line is 230 miles. But the strongest winds are NOT around the center meaning this is still an immature system.  The size could keep it weaker.  

 

Edited September 26 by StretchCT

[Sentinel]

7 minutes ago, StretchCT said:

Having gotten 12 inches of rain in 8 hours a few weeks back, I can't imagine getting double that. 

The Nam3k is extreme, though. it's gotten some extreme events before. Some of the other models and their top rainfall totals (*is still raining). Most of these are in the Blue Ridge/Smokey Mt area

UKMET 17        ICON 17.5

GEM 15.5         Graphcast 7

GFS 15             AIFS 12

Euro 17             NAM 15.5

RAP 17.5.          RGEM 15

HRRR 23.          ARW 21*

NSSL 15*           RFFS 16.5.   NBM 17.5

 

 

[Sentinel]

 

[StretchCT]

9 minutes ago, Sentinel said:

 

The only reason I miss Twitter is the weather info on there.  Threads isn't there yet, but it's coming along. 

[StretchCT]

The last vortex message from mission 13 had an elliptical eye 25 miles by 15 miles

Spoiler

Product: NOAA Vortex Message (URNT12 KWBC)
Transmitted: 26th day of the month at 1:43Z
Agency: National Oceanic and Atmospheric Administration (NOAA)
Aircraft: Lockheed WP-3D Orion (Reg. Num. N42RF)
Storm Name: Helene
Storm Number & Year: 09 in 2024 (flight in the North Atlantic basin)
Mission Number: 13
Observation Number: 17

A. Time of Center Fix: 26th day of the month at 1:11:06Z
B. Center Fix Coordinates: 22.88N 86.70W
B. Center Fix Location: 119 statute miles (192 km) to the N (5°) from Cancún, Quintana Roo, Mexico.
C. Minimum Height at Standard Level: Not Available
D. Minimum Sea Level Pressure: 973mb (28.74 inHg)
E. Dropsonde Surface Wind at Center: From 205° at 7kts (From the SSW at 8mph)
F. Eye Character: Open in the southeast
G. Eye Shape: Elliptical (oval shaped)
G. Orientation of Major Axis in Elliptical Eye: 80° to 260° (E to W)
G. Length of Major Axis in Elliptical Eye: 25 nautical miles (29 statute miles)
G. Length of Minor Axis in Elliptical Eye: 15 nautical miles (17 statute miles)
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: Not Available
I. Location & Time of the Estimated Maximum Surface Wind Inbound (Undecoded): NA
J. Maximum Flight Level Wind Inbound: From 296° at 68kts (From the WNW at 78.3mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 56 nautical miles (64 statute miles) to the SSW (210°) of center fix at 0:56:52Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: Not Available
M. Location & Time of the Estimated Maximum Surface Wind Outbound (Undecoded): NA
N. Maximum Flight Level Wind Outbound: From 138° at 66kts (From the SE at 76.0mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 51 nautical miles (59 statute miles) to the NNE (31°) of center fix at 1:23:35Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 17°C (63°F) at a pressure alt. of 2,441m (8,009ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 19°C (66°F) at a pressure alt. of 2,446m (8,025ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 16°C (61°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: Other - Not surface, 1500ft, 925mb, 850mb, 700mb, 500mb, 400mb, 300mb or 200mb
T. Navigational Fix Accuracy: 0.01 nautical miles
T. Meteorological Accuracy: 1 nautical mile

Remarks Section:
 

Maximum Flight Level Wind: 70kts (~ 80.6mph) which was observed 43 nautical miles (49 statute miles) to the E (85°) from the flight level center at 23:49:42Z

Mission 12 reported a circular eye 10nm wide about 20 minutes later. 

Spoiler

Product: Air Force Vortex Message (URNT12 KNHC)
Transmitted: 26th day of the month at 2:09Z
Agency: United States Air Force
Aircraft: Lockheed WC-130J Hercules with reg. number AF97-5303
Storm Name: Helene
Storm Number & Year: 09 in 2024 (flight in the North Atlantic basin)
Mission Number: 12
Observation Number: 26

A. Time of Center Fix: 26th day of the month at 1:31:30Z
B. Center Fix Coordinates: 22.90N 86.73W
B. Center Fix Location: 120 statute miles (194 km) to the N (4°) from Cancún, Quintana Roo, Mexico.
C. Minimum Height at Standard Level: 2,869m (9,413ft) at 700mb
D. Minimum Sea Level Pressure: 972mb (28.71 inHg)
E. Dropsonde Surface Wind at Center (Undecoded): NA
F. Eye Character: Open in the east-northeast
G. Eye Shape & Diameter: Circular with a diameter of 10 nautical miles (12 statute miles)
H. Estimated (by SFMR or visually) Maximum Surface Wind Inbound: 51kts (58.7mph)
I. Location & Time of the Estimated Maximum Surface Wind Inbound: 17 nautical miles (20 statute miles) to the SW (228°) of center fix at 1:26:30Z
J. Maximum Flight Level Wind Inbound: From 308° at 61kts (From the NW at 70.2mph)
K. Location & Time of the Maximum Flight Level Wind Inbound: 57 nautical miles (66 statute miles) to the SW (226°) of center fix at 1:06:00Z
L. Estimated (by SFMR or visually) Maximum Surface Wind Outbound: 57kts (65.6mph)
M. Location & Time of the Estimated Maximum Surface Wind Outbound: 44 nautical miles (51 statute miles) to the NE (48°) of center fix at 1:44:00Z
N. Maximum Flight Level Wind Outbound: From 139° at 67kts (From the SE at 77.1mph)
O. Location & Time of the Maximum Flight Level Wind Outbound: 55 nautical miles (63 statute miles) to the NE (48°) of center fix at 1:47:00Z
P. Maximum Flight Level Temp & Pressure Altitude Outside Eye: 12°C (54°F) at a pressure alt. of 3,052m (10,013ft)
Q. Maximum Flight Level Temp & Pressure Altitude Inside Eye: 15°C (59°F) at a pressure alt. of 3,045m (9,990ft)
R. Dewpoint Temp (collected at same location as temp inside eye): 13°C (55°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: 1.5 nautical miles

Remarks Section - Remarks That Were Decoded...
 

Maximum Flight Level Wind: 68kts (~ 78.3mph) which was observed 50 nautical miles (58 statute miles) to the SE (129°) from the flight level center at 23:51:30Z

Remarks Section - Additional Remarks...

 

 

LAST WIND 03006KT AT 014 METERS

 

[StretchCT]

Looking at the 18z hurricane model runs.  HRWF had the storm at 963 earlier this evening.  HMON 960.  HAFS A at 972. HAFS B at 969.  

HAFS B takes the storm from 965 at 3z to 942 at 12z.

HAFS A takes the storm from 970 at 3z to 951 at 12z. 

Spoiler

 

 

[StretchCT]

Disco notes: well organized, ragged eye, but not a well defined core and broad windfield. Call is for it to reach Cat 4, but noted HAFS A&B are even higher. 

Spoiler

Hurricane Helene Discussion Number  11
NWS National Hurricane Center Miami FL       AL092024
1000 PM CDT Wed Sep 25 2024

Satellite images show that Helene has a well-organized appearance, 
with numerous convective banding features.  A ragged-looking eye 
feature is also apparent.  However, reports from both Air Force and 
a NOAA Hurricane Hunter aircraft investigating the system suggest 
that the it lacks a well-defined inner core with a somewhat broad 
maximum wind field for now.  The central pressure has dropped a 
little to around 972 mb.  Given the slowly falling central 
pressure, the intensity is maintained at 75 kt for this advisory.  
Helene's structure and intensity will continue to be closely 
monitored by Hurricane Hunter aircraft tonight and Thursday.

The hurricane continues moving northward with an estimated initial
motion of 360/08 kt.  For the next couple of days, the steering
scenario for this system remains basically unchanged from the
earlier advisory.  The flow between a mid-tropospheric trough over
the east-central United States and a ridge over the western
Atlantic should result in Helene accelerating northward to
north-northeastward during the next 24 to 36 hours. This motion 
will bring the center of Helene to the northeastern Gulf of Mexico 
coast in about 24 hours.  The official track forecast through 
landfall is very similar to the previous NHC prediction and remains 
close to the corrected consensus guidance. After landfall, the 
trough to the northwest of the tropical cyclone becomes a cutoff 
low, and Helene should turn leftward as it rotates around the low.  
In 3-4 days, the system should become a shallow extratropical 
cyclone within weaker steering currents.

Helene should be in an atmospheric and oceanic environment over the
eastern Gulf of Mexico that will be very conducive for 
strengthening.  The system is expected to traverse the Loop Current, 
which has especially high oceanic heat content.  This, along with 
fairly low vertical wind shear and a moist mid- to lower- 
tropospheric air mass, should likely result in rapid 
intensification before landfall.  The official forecast continues
to call for the hurricane to reach category 4 status tomorrow.  It 
should be noted that the HAFS-A and HAFS-B regional hurricane models 
show even more intensification than indicated here.

Helene is forecast to be a large major hurricane when it reaches the
Big Bend coast of Florida.   As a result, storm surge, wind, and
rainfall impacts will extend well away from the center and outside
the forecast cone, particularly on the east side.  In addition, the
fast forward speed when Helene moves inland will result in a far
inland penetration of strong winds over parts of the southeastern
United States, including strong gusts over higher terrain of the
southern Appalachians.  A higher-than-normal gust factor is 
indicated in the official forecast while Helene is inland.


KEY MESSAGES:

1. A catastrophic and deadly storm surge is likely along portions
of the Florida Big Bend coast, where inundation could reach as high
as 20 feet above ground level, along with destructive waves.  There
is also a danger of life-threatening storm surge along the remainder
of the west coast of the Florida Peninsula.  Residents in those
areas should follow advice given by local officials and evacuate if
told to do so.

2. Potentially catastrophic hurricane-force winds are expected
within the eyewall of Helene when it makes landfall in the Florida
Big Bend region late Thursday.  Preparations to protect life and
property should be completed by early Thursday before tropical
storm conditions arrive.  Damaging and life-threatening
hurricane-force winds, especially in gusts, will penetrate well
inland over portions of northern Florida and southern Georgia late
Thursday and Thursday night where Hurricane Warnings are in effect.
Strong wind gusts are also likely farther north across portions of
northern Georgia and the Carolinas, particularly over the higher
terrain of the southern Appalachians.

3. Catastrophic and life-threatening flash and urban flooding, 
including numerous landslides, is expected across portions of the 
southern Appalachians through Friday. Considerable to locally 
catastrophic flash and urban flooding is likely for northwestern and 
northern Florida and the Southeast through Friday. Widespread minor 
to moderate river flooding and isolated major river flooding are 
likely.

4. Tropical storm conditions are expected over portions of western
Cuba within the Tropical Storm Warning area.  Hurricane Helene will 
bring heavy rain to portions of the western Caribbean with 
potentially significant flooding across western Cuba and the 
northeastern Yucatan Peninsula into early Thursday.


FORECAST POSITIONS AND MAX WINDS

INIT  26/0300Z 23.1N  86.6W   75 KT  85 MPH
 12H  26/1200Z 25.4N  86.1W   95 KT 110 MPH
 24H  27/0000Z 29.5N  84.5W  115 KT 130 MPH
 36H  27/1200Z 34.3N  84.7W   50 KT  60 MPH...INLAND
 48H  28/0000Z 36.7N  87.1W   30 KT  35 MPH...POST-TROP/EXTRATROP
 60H  28/1200Z 36.8N  88.5W   25 KT  30 MPH...POST-TROP/EXTRATROP
 72H  29/0000Z 36.7N  87.0W   20 KT  25 MPH...POST-TROP/EXTRATROP
 96H  30/0000Z 36.7N  84.9W   15 KT  15 MPH...POST-TROP/EXTRATROP
120H  01/0000Z...DISSIPATED

FORECAST POSITIONS AND MAX WINDS

INIT  25/2100Z 22.5N  86.6W   75 KT  85 MPH
 12H  26/0600Z 24.1N  86.2W   95 KT 110 MPH
 24H  26/1800Z 27.4N  85.2W  115 KT 130 MPH
 36H  27/0600Z 32.1N  84.6W   70 KT  80 MPH...INLAND
 48H  27/1800Z 36.1N  86.0W   35 KT  40 MPH...POST-TROP/EXTRATROP
 60H  28/0600Z 37.1N  88.1W   25 KT  30 MPH...POST-TROP/EXTRATROP
 72H  28/1800Z 36.8N  88.7W   20 KT  25 MPH...POST-TROP/EXTRATROP
 96H  29/1800Z 37.0N  88.0W   15 KT  15 MPH...POST-TROP/EXTRATROP
120H  30/1800Z...DISSIPATED

[StretchCT]

Watching the convection circle around the south side of the eye.

 

 

[StretchCT]

[tool483]

Sea is def angry at the southern most point

https://www.youtube.com/watch?v=10L3vvNt4sE

[StretchCT]

And we’re off…

RawT just spiked to 5.8 which is over 100kts. Tiny eye.  



 

[Burr]

Continued development of the inner core.  What a difference a day makes.

 

[1816]

I'm getting the sense that this storm is abnormally "heavy"  

Of course the sheer size but it seems to have just such a vast amount of moisture and clouds/bands that it has to rotate. 

Of course it's had the dry air and structure problems but it feels like one of those huge industrial machines. They take a ton of energy and time to get going up to speed but once they get going there's so much momentum. Helene feels like it's just getting turned on and up to speed. 

[Undertakerson2.0]

Suggests that Helene is able to shove the shear aside. 

[Undertakerson2.0]

It's deepening and check out how it's firing hard on the E flank and pulling 60kts + much more to the center. 

Helene will be all the "buzz" as it goes deeper in short order. 

Edited September 26 by Undertakerson2.0

[Undertakerson2.0]

Hmmm - 6z GFS comes ashore as a 967mb storm - that is some 9mb weaker than the 00z run (956mb)

 

Edited September 26 by Undertakerson2.0

[FortySixAnd32]

9 hours ago, StormfanaticInd said:

May have to be concerned with strong wind gust in the Ohio Valley 🤔 

Football Friday Night will be interesting....

[FortySixAnd32]

8 hours ago, Sentinel said:

 

 

[MaineJay]

1 hour ago, Undertakerson2.0 said:

Suggests that Helene is able to shove the shear aside. 

Not to mention there are instances where a little shear actually facilitates RI

[Wtkidz]

Just for fun. The 06z NAM 

[Undertakerson2.0]

Not mentioned in the update is that, at peak winds of 115 mph, it appears as though Cat4 is off the table. 

[Undertakerson2.0]

[Jon Snow]

7 hours ago, StretchCT said:

I have family in panama city and tampa area.  Thinking I should start making room for house guests.

[Wtkidz]

18 minutes ago, Jon Snow said:

I have family in panama city and tampa area.  Thinking I should start making room for house guests.

Yes and they may be able to come up by boat.