Helene 即將登陸

強度也進一步來到C4 115KT 氣壓 942hPa
由於已經相當靠近陸地
強度推測已達巔峰
但仍是將會是今年美國登陸最強颶風

1. 076
   
2. WTNT44 KNHC 262043
   
3. TCDAT4
   
4. 
   
5. Hurricane Helene Discussion Number  14
   
6. NWS National Hurricane Center Miami FL       AL092024
   
7. 500 PM EDT Thu Sep 26 2024
   
8. 
   
9. Helene has rapidly intensified today while nearing landfall in the
   
10. Florida Big Bend.  Doppler radar and aircraft data indicate that the
    
11. eyewall is now completely closed and the eye has become more
    
12. circular and is clearing out.  The aircraft data also indicated
    
13. that the inner core has contracted significantly today while the
    
14. tropical-storm-force winds have expanded.  Based on all of the data,
    
15. the initial intensity is set at 110 kt.  The latest minimum pressure
    
16. based on the aircraft data is around 951 mb. Tropical-storm-force
    
17. winds are occurring across portions of west-central and southwestern
    
18. Florida, and conditions are expected to deteriorate rapidly in the
    
19. hurricane warning area during the next several hours.  It should be
    
20. emphasized that Helene is at the upper bound of hurricanes in
    
21. terms of storm size and impacts are and will occur well away
    
22. from the center.
    
23. 
    
24. The large hurricane is now accelerating north-northeastward, with
    
25. the latest initial motion estimated to be 025/20 kt.  This general
    
26. motion is expected to continue, taking the core of the major
    
27. hurricane to the Florida Big Bend later this evening.  After
    
28. landfall, a turn to the north over Georgia is expected late tonight
    
29. and early Friday, followed by a slowdown or a complete stall over
    
30. the Tennessee Valley late Friday and Saturday when Helene merges
    
31. with a mid- to upper-level low.
    
32. 
    
33. The hurricane has intensified by 30 kt since sunrise and given the
    
34. conducive environmental conditions and contracting inner core, it
    
35. seems likely that Helene will be at or very near category 4 strength
    
36. when it makes landfall in the Florida Big Bend this evening.
    
37. The fast forward speed when Helene moves inland will result in a
    
38. far inland penetration of strong winds over parts of the
    
39. southeastern United States, including strong gusts over the higher
    
40. terrain of the southern Appalachians.  Accordingly, a
    
41. higher-than-normal gust factor is indicated in the official forecast
    
42. while Helene is inland.
    
43. 
    
44. KEY MESSAGES:
    
45. 
    
46. 1. A catastrophic and deadly storm surge will occur along portions
    
47. of the Florida Big Bend coast, where inundation could reach as high
    
48. as 20 feet above ground level, along with destructive waves.  If
    
49. you live in this area and were told to evacuate by local officials,
    
50. your opportunity to do so is almost over.  There is also a danger
    
51. of life-threatening storm surge along the remainder of the west
    
52. coast of the Florida Peninsula.  
    
53. 
    
54. 2. Potentially catastrophic hurricane-force winds are expected
    
55. within the eyewall of Helene and will spread inland over portions
    
56. of northern Florida and southern Georgia when Helene makes landfall
    
57. in the Florida Big Bend region this evening.  Persons in these
    
58. areas should be prepared to take shelter in the interior portion of
    
59. a well-built structure and remain sheltered until after hazardous
    
60. conditions pass. You may need to remain sheltered after the storm
    
61. due to downed trees and power lines, as well as flooding, in the
    
62. area.
    
63. 
    
64. 3. Damaging wind gusts will penetrate well inland over portions of
    
65. Georgia and the Carolinas  tonight, particularly over the higher
    
66. terrain of the southern Appalachians. Residents in these areas
    
67. should be prepared for the possibility of long-duration power
    
68. outages.  If you use a generator after the storm, be sure it is
    
69. placed outside at least 20 feet away from doors, windows, and
    
70. garages to avoid deadly carbon monoxide poisoning.
    
71. 
    
72. 4. Catastrophic and life-threatening flash and urban flooding,
    
73. including numerous significant landslides, is expected across
    
74. portions of the southern Appalachians through Friday. Considerable
    
75. to locally catastrophic flash and urban flooding is likely for
    
76. northwestern and northern Florida and the Southeast through Friday.
    
77. Widespread significant river flooding and isolated major river
    
78. flooding are likely.
    
79. 
    
80. 
    
81. FORECAST POSITIONS AND MAX WINDS
    
82. 
    
83. INIT  26/2100Z 27.9N  84.6W  110 KT 125 MPH
    
84. 12H  27/0600Z 31.5N  83.7W   90 KT 105 MPH...INLAND
    
85. 24H  27/1800Z 35.8N  85.0W   40 KT  45 MPH...POST-TROP/EXTRATROP
    
86. 36H  28/0600Z 37.0N  86.5W   30 KT  35 MPH...POST-TROP/EXTRATROP
    
87. 48H  28/1800Z 37.1N  87.0W   25 KT  30 MPH...POST-TROP/EXTRATROP
    
88. 60H  29/0600Z 37.1N  87.3W   20 KT  25 MPH...POST-TROP/EXTRATROP
    
89. 72H  29/1800Z...DISSIPATED
    
90. 
    
91. $$
    
92. Forecaster Cangialosi

複製代碼

NHC 升格C1
上看110KT

000
WTNT44 KNHC 251457
TCDAT4

Hurricane Helene Discussion Number   9
NWS National Hurricane Center Miami FL       AL092024
1000 AM CDT Wed Sep 25 2024

Air Force Reserve and NOAA Hurricane Hunter aircraft have been
investigating Helene, with each plane recently measuring peak
flight-level winds of 81 kt and 78 kt, respectively.  Helene has
therefore become a hurricane with an estimated intensity of 70 kt.  
Dropsonde data also indicate that the pressure has fallen to about
979 mb.  Radar data from Mexico and Cuba, as well as reconnaissance
reports, indicate that Helene has formed a partial, elliptical
eyewall that is open on the east side.

Helene has turned north-northwestward (330/9 kt) and is expected to
turn northward and north-northeastward later today and tonight,
bringing the center to the coast of the Florida Big Bend Thursday
evening. After landfall, Helene is expected to interact with a
deep-layer trough over the Lower Mississippi Valley and swing back
to the northwest and stall near the Tennessee Valley late Friday
into the weekend.  The track guidance remains tightly clustered,
and the NHC forecast is generally just an update of the previous
prediction. It is still too soon at this point to be overly focused
on an exact landfall location and time, since NHC track forecasts
can be off by an average of 60 nm at the 36-hour forecast time.

Helene is expected to move through/over an environment of
relatively low shear, strong upper-level divergence, and sea
surface temperatures of 29-31 degrees Celsius, all of which should
foster additional strengthening.  Rapid Intensification (RI)
indices indicate a high chance of RI during the next 24 hours, and
as a result the NHC intensity forecast shows Helene becoming a
major hurricane by Thursday morning.  There is still some
uncertainty on exactly how strong Helene will get, and upward
adjustments to the forecast intensity could be required in
subsequent advisories if Helene rapidly intensifies more than
forecast.  Regardless, 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 likely extend
well away from the center and outside the forecast cone,
particularly on the east side.  In addition, the fast forward speed
while Helene crosses the coast will likely result in farther inland
penetration of strong winds over parts of the southeastern United
States after landfall, including strong gusts over higher terrain
of the southern Appalachians.


KEY MESSAGES:

1. Hurricane and tropical storm conditions are expected over
northeastern portions of the Yucatan Peninsula of Mexico today where
Tropical Storm and Hurricane Warnings are in effect.  Tropical storm
conditions are occurring over portions of western Cuba within the
Tropical Storm Warning area, and hurricane conditions are possible
today within the Hurricane Watch area.

2. Due to the large size of Helene, there is a danger of
life-threatening storm surge along the entire west coast of the
Florida Peninsula and Florida Big Bend.  The highest inundation of
greater than 10 ft is expected along the Florida Big Bend coast.
Residents in those areas should follow advice given by local
officials and evacuate if told to do so.

3. Devastating hurricane-force winds are expected across portions
of northern Florida and southern Georgia where the core of Helene
moves inland.  Preparations to protect life and property should be
completed by early Thursday since tropical storm conditions are
expected to begin within these areas on Thursday.  Because of
Helene’s expected fast forward speed, damaging and life-threatening
wind gusts, are expected to penetrate well inland over portions of
the southeastern United States, including in the higher terrain of
the southern Appalachians.  

4. 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.
Considerable and potentially life-threatening flash and urban
flooding is expected across portions of northwestern and northern
Florida, the Southeast, southern Appalachians, and the Upper
Tennessee Valley Wednesday through Friday. This includes the risk of
landslides across the southern Appalachians. Widespread minor to
moderate river flooding is likely, and isolated major river flooding
is possible.


FORECAST POSITIONS AND MAX WINDS

INIT  25/1500Z 21.6N  86.3W   70 KT  80 MPH
12H  26/0000Z 23.0N  86.4W   85 KT 100 MPH
24H  26/1200Z 25.7N  85.7W  105 KT 120 MPH
36H  27/0000Z 29.7N  84.6W  110 KT 125 MPH
48H  27/1200Z 34.3N  85.0W   50 KT  60 MPH...INLAND
60H  28/0000Z 36.6N  86.9W   30 KT  35 MPH...POST-TROP/INLAND
72H  28/1200Z 36.9N  87.8W   20 KT  25 MPH...POST-TROP/INLAND
96H  29/1200Z 36.6N  87.9W   15 KT  15 MPH...POST-TROP/INLAND
120H  30/1200Z...DISSIPATED

$$
Forecaster Berg

NHC 昨日升格命名 Helene
後續上看C3

1. 000
   
2. WTNT44 KNHC 250256
   
3. TCDAT4
   
4. 
   
5. Tropical Storm Helene Discussion Number   7
   
6. NWS National Hurricane Center Miami FL       AL092024
   
7. 1000 PM CDT Tue Sep 24 2024
   
8. 
   
9. Helene continues to become better organized with increased
   
10. convective banding features and an overall more symmetrical-looking
    
11. cloud pattern.  The convection is very deep with cloud tops to -80
    
12. deg C or colder.  Doppler velocity data from a NOAA Hurricane
    
13. Hunter aircraft indicate no significant vertical tilt of the
    
14. vortex in the low- to mid-troposphere.  This suggests that the
    
15. vertical wind shear is low.  Earlier flight-level wind data from the
    
16. aircraft indicate the the maximum winds are near 50 kt, although
    
17. this may be conservative.
    
18. 
    
19. Although the storm has been wobbling over the past few hours,
    
20. center fixes from the NOAA Hurricane Hunter aircraft indicate a
    
21. generally west-northwestward motion at around 300/9 kt.  Helene
    
22. should turn northwestward soon as a high pressure area over Florida
    
23. shifts eastward, with the tropical cyclone center passing near the
    
24. northeastern Yucatan Peninsula tomorrow morning.  Meanwhile, a
    
25. mid-tropospheric trough is digging over the Lower Mississippi
    
26. Valley.  This evolution of the steering flow should cause Helene to
    
27. turn northward with an increase in forward speed during the next day
    
28. or so.  An accelerating northward to north-northeastward motion over
    
29. the eastern Gulf of Mexico should take the system to the
    
30. northeastern Gulf of Mexico coast in about 48 hours.  After
    
31. landfall, Helene should curve cyclonically around a mid-level low
    
32. over the south-central United States.  The official forecast is very
    
33. similar to the previous one and is on top of the latest corrected
    
34. consensus track guidance.
    
35. 
    
36. Over the next couple of days, Helene will be moving through an
    
37. environment of low vertical wind shear, ample environmental
    
38. moisture, and over waters of high oceanic heat content. Thus,
    
39. significant strengthening is anticipated before landfall on the
    
40. northeast Gulf coast.  The NHC intensity forecast explicitly shows
    
41. steady to rapid intensification (RI) of 25 kt for the next 24 hours
    
42. and 30 kt for the 24- to 48-hour forecast interval.  This is in
    
43. general agreement with the SHIPS RI indices.
    
44. 
    
45. Helene is predicted to grow to a very large size in the NHC
    
46. forecast.  Therefore storm surge, wind, and rainfall impacts will
    
47. likely extend well away from the center and outside the forecast
    
48. cone, particularly on the east side.  In addition, the fast forward
    
49. speed while it crosses the coast will likely result in farther
    
50. inland penetration of strong winds over parts of the southeastern
    
51. United States after landfall.
    
52. 
    
53. 
    
54. KEY MESSAGES:
    
55. 
    
56. 1. Helene is forecast to intensify and be near hurricane strength
    
57. when it passes near the northeastern coast of the Yucatan
    
58. Peninsula on Wednesday, where a Hurricane Warning is in effect.
    
59. 
    
60. 2. Helene is expected to rapidly intensify and grow in size over the
    
61. eastern Gulf of Mexico.  There is a danger of life-threatening storm
    
62. surge along the entire west coast of the Florida Peninsula and
    
63. Florida Big Bend.  The highest inundation levels are
    
64. expected along the coast of the Florida Big Bend.  Residents in
    
65. those areas should follow advice given by local officials and
    
66. evacuate if told to do so.
    
67. 
    
68. 3. Damaging hurricane-force winds are expected along portions of
    
69. coast of the Florida Big Bend, where a Hurricane Warning is now in
    
70. effect.  Preparations to protect life and property should be
    
71. complete by early Thursday since tropical storm conditions are
    
72. expected to begin within this area on Thursday.
    
73. 
    
74. 4. Tropical Storm Helene will bring heavy rain to portions of the
    
75. western Caribbean with potentially significant flooding across
    
76. western Cuba and the northeastern Yucatan Peninsula.  Considerable
    
77. flash and urban flooding is expected across portions of Florida, the
    
78. Southeast, southern Appalachians, and the Tennessee Valley Wednesday
    
79. through Friday.  This includes the risk of landslides across the
    
80. southern Appalachians.  Widespread minor to moderate river flooding
    
81. is likely, and isolated major river flooding is possible.
    
82. 
    
83. 
    
84. FORECAST POSITIONS AND MAX WINDS
    
85. 
    
86. INIT  25/0300Z 19.9N  85.5W   50 KT  60 MPH
    
87. 12H  25/1200Z 21.1N  86.3W   65 KT  75 MPH
    
88. 24H  26/0000Z 22.7N  86.4W   75 KT  85 MPH
    
89. 36H  26/1200Z 25.4N  85.5W   90 KT 105 MPH
    
90. 48H  27/0000Z 29.5N  84.2W  105 KT 120 MPH
    
91. 60H  27/1200Z 34.0N  84.5W   30 KT  35 MPH
    
92. 72H  28/0000Z 36.5N  86.5W   20 KT  25 MPH...POST-TROP/INLAND
    
93. 96H  29/0000Z 37.0N  89.0W   20 KT  25 MPH...POST-TROP/INLAND
    
94. 120H  30/0000Z...DISSIPATED
    
95. 
    
96. $$
    
97. Forecaster Pasch

複製代碼

NHC 認定潛在熱帶氣旋 並編號09L
並且將在當地時間下午進行颱風飛機實測

1. 000
   
2. WTNT44 KNHC 231500
   
3. TCDAT4
   
4. 
   
5. Potential Tropical Cyclone Nine Discussion Number   1
   
6. NWS National Hurricane Center Miami FL       AL092024
   
7. 1100 AM EDT Mon Sep 23 2024
   
8. 
   
9. A broad area of low pressure over the northwestern Caribbean Sea
   
10. continues to produce disorganized showers and thunderstorms. While
    
11. some mid-level rotation is evident in visible satellite images,
    
12. surface observations and visible satellite images suggest the
    
13. low-level circulation remains broad and farther to the southwest.
    
14. Nonetheless, the system has a high chance of tropical cyclone
    
15. formation during the next day or two, and it is likely to bring
    
16. tropical storm conditions to land areas within the next 36 to
    
17. 48 hours. Therefore, the NHC is initiating Potential Tropical
    
18. Cyclone advisories for this disturbance.
    
19. 
    
20. The initial motion is quite uncertain given the current lack of
    
21. organization, but the best estimate is northward at about 5 kt. A
    
22. gradual turn toward the northwest is expected during the next day or
    
23. so, with the center passing through the Yucatan Channel and into the
    
24. southern Gulf of Mexico. Thereafter, the system is forecast to
    
25. accelerate northward across the eastern Gulf of Mexico within the
    
26. flow between a digging deep-layer trough over the central United
    
27. States and a ridge over the western Atlantic. This motion should
    
28. bring the center of the system toward the northeastern Gulf Coast on
    
29. Thursday. The track guidance agrees reasonably well on this
    
30. scenario, and the initial NHC forecast lies near the simple and
    
31. corrected consensus aids. Since the disturbance currently lacks a
    
32. well-defined center, users are reminded that the average forecast
    
33. track uncertainty is larger in these situations, and future track
    
34. adjustments may be required. Given the large size of the
    
35. tropical-storm-force wind field and fast forward speed that is
    
36. forecast, storm surge, wind, and rainfall impacts will likely extend
    
37. well away from the center, particularly to the east of the system.
    
38. 
    
39. While the system is currently broad and not well organized, the
    
40. models suggest a more well-defined center should develop during the
    
41. next day or so. Once the system becomes better organized and
    
42. develops an inner core, the environmental and oceanic conditions
    
43. appear favorable for significant strengthening. In fact, the DTOPS
    
44. statistical guidance shows a 95 percent chance of a 65-kt increase
    
45. in intensity during the next 72 h, and the hurricane regional models
    
46. highlight the potential for strengthening to major hurricane
    
47. intensity. Thus, the NHC forecast shows significant strengthening
    
48. while the system moves across the eastern Gulf of Mexico, with a
    
49. 95-kt intensity in 72 h. While this forecast is aggressive, it lies
    
50. near or slightly below the consensus aids, and future adjustments
    
51. may be necessary.  An Air Force Reserve reconnaissance aircraft is
    
52. scheduled to investigate the system this afternoon.
    
53. 
    
54. Based on the NHC forecast, Tropical Storm Warnings and Hurricane
    
55. Watches have been issued for portions of western Cuba the Yucatan
    
56. Peninsula of Mexico. Interests along the northeastern Gulf Coast,
    
57. including the Florida Panhandle and portions of the Florida west
    
58. coast should monitor the progress of this system.
    
59. 
    
60. 
    
61. KEY MESSAGES:
    
62. 
    
63. 1. The disturbance is forecast to strengthen and be near hurricane
    
64. strength when it reaches the far northwestern Caribbean Sea Tuesday
    
65. night. Tropical storm conditions are expected over portions of
    
66. western Cuba and the northeastern coast of the Yucatan Peninsula
    
67. with hurricane conditions possible.
    
68. 
    
69. 2. The system is expected to intensify while it moves northward
    
70. over the eastern Gulf of Mexico, and it could be a major hurricane
    
71. when it reaches the northeastern Gulf Coast on Thursday. There is an
    
72. increasing risk of life-threatening storm surge and damaging
    
73. hurricane-force winds along portions of the northern and
    
74. northeastern Gulf Coast, including the Florida Panhandle and
    
75. portions of the Florida west coast. Although it is too soon to
    
76. specify the exact location and magnitude of impacts, residents in
    
77. these areas should monitor the latest forecast updates and ensure
    
78. that they have their hurricane plan in place.
    
79. 
    
80. 3. Potential Tropical Cyclone Nine will bring heavy rain to portions
    
81. of the western Caribbean which may lead to flooding and possible
    
82. mudslides in western Cuba.
    
83. 
    
84. 
    
85. FORECAST POSITIONS AND MAX WINDS
    
86. 
    
87. INIT  23/1500Z 17.6N  82.0W   25 KT  30 MPH...POTENTIAL TROP CYCLONE
    
88. 12H  24/0000Z 18.6N  82.4W   30 KT  35 MPH...TROPICAL CYCLONE
    
89. 24H  24/1200Z 19.5N  83.7W   40 KT  45 MPH
    
90. 36H  25/0000Z 20.6N  85.1W   50 KT  60 MPH
    
91. 48H  25/1200Z 22.1N  86.0W   65 KT  75 MPH
    
92. 60H  26/0000Z 24.2N  86.0W   85 KT 100 MPH
    
93. 72H  26/1200Z 27.1N  85.1W   95 KT 110 MPH
    
94. 96H  27/1200Z 34.0N  83.0W   35 KT  40 MPH...INLAND
    
95. 120H  28/1200Z 38.5N  87.0W   20 KT  25 MPH...POST-TROPICAL
    
96. 
    
97. $$
    
98. Forecaster Reinhart

複製代碼