09L.Helene 達C4即將登陸美國今年最強颶風

alu · 2024-9-23 03:58

基本資料
編號　　　　：97 L
擾動編號日期：2024 年 09 月 23 日 02 時
撤編日期　　：2024 年 09 月 00 日 00 時
AL, 97, 2024092218, , BEST, 0, 153N, 832W, 20, 1007, DB, 34, NEQ

Tropical Weather Outlook Text EspañolTropical Weather Discussion
ZCZC MIATWOAT ALL
TTAA00 KNHC DDHHMM

Tropical Weather Outlook
NWS National Hurricane Center Miami FL
200 PM EDT Sun Sep 22 2024

For the North Atlantic...Caribbean Sea and the Gulf of Mexico:

2. Northwestern Caribbean Sea and Gulf of Mexico:
Disorganized showers and thunderstorms located over the northwestern
Caribbean Sea and portions of Central America are associated with a
broad area of low pressure. Environmental conditions appear
favorable for development of this system, and a tropical depression
or tropical storm is likely to form during the next few days while
moving northward across the northwestern Caribbean Sea and Gulf of
Mexico. Regardless of development, this disturbance is expected to
produce heavy rains over portions of Central America during the next
several days. Interests in the northwestern Caribbean, Yucatan
Peninsula of Mexico, and western Cuba should closely monitor the
progress of this feature. Later this week, the system is forecast to
move generally northward across the Gulf of Mexico, and interests
along the northern and northeastern Gulf Coast should also monitor
the progress of this system.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 7 days...high...80 percent.

goes16_ir_97L_202409221835_lat15.3-lon-83.2.jpg

goes16_ir_97L_202409221835_lat15.3-lon-83.2.jpg

krichard2011 · 2024-9-23 23:19

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

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

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krichard2011 · 2024-9-25 14:22

NHC 昨日升格命名 Helene
後續上看C3

000
WTNT44 KNHC 250256
TCDAT4
Tropical Storm Helene Discussion Number 7
NWS National Hurricane Center Miami FL AL092024
1000 PM CDT Tue Sep 24 2024
Helene continues to become better organized with increased
convective banding features and an overall more symmetrical-looking
cloud pattern. The convection is very deep with cloud tops to -80
deg C or colder. Doppler velocity data from a NOAA Hurricane
Hunter aircraft indicate no significant vertical tilt of the
vortex in the low- to mid-troposphere. This suggests that the
vertical wind shear is low. Earlier flight-level wind data from the
aircraft indicate the the maximum winds are near 50 kt, although
this may be conservative.
Although the storm has been wobbling over the past few hours,
center fixes from the NOAA Hurricane Hunter aircraft indicate a
generally west-northwestward motion at around 300/9 kt. Helene
should turn northwestward soon as a high pressure area over Florida
shifts eastward, with the tropical cyclone center passing near the
northeastern Yucatan Peninsula tomorrow morning. Meanwhile, a
mid-tropospheric trough is digging over the Lower Mississippi
Valley. This evolution of the steering flow should cause Helene to
turn northward with an increase in forward speed during the next day
or so. An accelerating northward to north-northeastward motion over
the eastern Gulf of Mexico should take the system to the
northeastern Gulf of Mexico coast in about 48 hours. After
landfall, Helene should curve cyclonically around a mid-level low
over the south-central United States. The official forecast is very
similar to the previous one and is on top of the latest corrected
consensus track guidance.
Over the next couple of days, Helene will be moving through an
environment of low vertical wind shear, ample environmental
moisture, and over waters of high oceanic heat content. Thus,
significant strengthening is anticipated before landfall on the
northeast Gulf coast. The NHC intensity forecast explicitly shows
steady to rapid intensification (RI) of 25 kt for the next 24 hours
and 30 kt for the 24- to 48-hour forecast interval. This is in
general agreement with the SHIPS RI indices.
Helene is predicted to grow to a very large size in the NHC
forecast. Therefore 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 it crosses the coast will likely result in farther
inland penetration of strong winds over parts of the southeastern
United States after landfall.
KEY MESSAGES:
1. Helene is forecast to intensify and be near hurricane strength
when it passes near the northeastern coast of the Yucatan
Peninsula on Wednesday, where a Hurricane Warning is in effect.
2. Helene is expected to rapidly intensify and grow in size over the
eastern Gulf of Mexico. 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 levels are
expected along the coast of the Florida Big Bend. Residents in
those areas should follow advice given by local officials and
evacuate if told to do so.
3. Damaging hurricane-force winds are expected along portions of
coast of the Florida Big Bend, where a Hurricane Warning is now in
effect. Preparations to protect life and property should be
complete by early Thursday since tropical storm conditions are
expected to begin within this area on Thursday.
4. Tropical Storm Helene will bring heavy rain to portions of the
western Caribbean with potentially significant flooding across
western Cuba and the northeastern Yucatan Peninsula. Considerable
flash and urban flooding is expected across portions of Florida, the
Southeast, southern Appalachians, and the 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 25/0300Z 19.9N 85.5W 50 KT 60 MPH
12H 25/1200Z 21.1N 86.3W 65 KT 75 MPH
24H 26/0000Z 22.7N 86.4W 75 KT 85 MPH
36H 26/1200Z 25.4N 85.5W 90 KT 105 MPH
48H 27/0000Z 29.5N 84.2W 105 KT 120 MPH
60H 27/1200Z 34.0N 84.5W 30 KT 35 MPH
72H 28/0000Z 36.5N 86.5W 20 KT 25 MPH...POST-TROP/INLAND
96H 29/0000Z 37.0N 89.0W 20 KT 25 MPH...POST-TROP/INLAND
120H 30/0000Z...DISSIPATED
$$
Forecaster Pasch

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kingchard2011 · 2024-9-25 23:43

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