霧峰追風者

  一級颶風  
編號：11 L
名稱：Leslie

  基本資料  
擾動編號日期：2018 年 09 月 23 日 02 時
命名日期　　：2018 年 09 月 23 日 23 時
撤編日期　　：2018 年 00 月 00 日 00 時
登陸地點　　：暫無

  巔峰時期資料  
近中心最強風速 ：80 kt
海平面最低氣壓 ：969 百帕

  過去路徑圖  

  擾動編號資料  
90L.INVEST.30kts-1003mb-32.0N-44.5W

NHC : 60%

2. A frontal non-tropical low pressure system is located about 1000
miles west-southwest of the Azores. Conditions are expected to
become conducive for this low to acquire subtropical or tropical
characteristics during the next day or so, and a subtropical or
tropical cyclone is likely to form by early next week while the low
meanders over the central Atlantic Ocean. For more information on
this system, see High Seas Forecasts issued by the National Weather
Service.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...70 percent.

以上資料來自：NHC、颱風論壇整理製作

t02436

NHC 15Z升格13L並直接命名Leslie，目前是35節的副熱帶風暴。

251
WTNT43 KNHC 231432
TCDAT3

Subtropical Storm Leslie Discussion Number   1
NWS National Hurricane Center Miami FL       AL132018
1100 AM AST Sun Sep 23 2018

The development of a subtropical storm that NHC and the global
models have been advertising for the past several days has
materialized, and based on satellite intensity classification from
TAFB and earlier ASCAT data, advisories on Subtropical Storm Leslie
have been initiated.

Leslie is still embedded within an upper-level low and strong winds
are removed from the center.  However, there is a chance as usual
that the subtropical cyclone could develop additional convection
near the center, and the transition to a tropical system during the
next day or so is not out of the question.  Global models do
indicate that a new low is going to form north of Leslie, and that
the subtropical cyclone will become absorbed by the new larger low.
This is the scenario depicted by NHC at this time.

Leslie is embedded within very light steering currents, and most
likely the cyclone will be meandering today and tomorrow.  After
that time, with the development of the new low to the north, Leslie
will likely move east until it becomes absorbed.

FORECAST POSITIONS AND MAX WINDS

INIT  23/1500Z 33.0N  46.5W   35 KT  40 MPH
12H  24/0000Z 33.2N  47.2W   40 KT  45 MPH
24H  24/1200Z 33.0N  47.5W   40 KT  45 MPH
36H  25/0000Z 33.0N  46.5W   40 KT  45 MPH
48H  25/1200Z 33.0N  45.0W   40 KT  45 MPH
72H  26/1200Z...ABSORBED BY LARGER LOW

$$
Forecaster Avila

霧峰追風者

併入鋒面系統裡，不過有機會72H後再次轉化副熱帶風暴。

676
WTNT43 KNHC 251439
TCDAT3

Post-Tropical Cyclone Leslie Discussion Number   9
NWS National Hurricane Center Miami FL       AL132018
1100 AM AST Tue Sep 25 2018

Leslie has become a post-tropical cyclone.  Conventional and
microwave satellite imagery show that Leslie's surface circulation
has become elongated along an intruding baroclinic zone indicated
by a recent 1158 UTC ASCAT-A pass.  Any deep convection appears to
be developing due to dynamic forcing.  A rather large stratocumulus
cloud shield and associated cooler, stable air is quickly advecting
into the area as well. The initial intensity is maintained at 30 kt
for this last advisory.

Leslie is forecast to strengthen during the next couple of days due
to baroclinic processes. The official forecast, based on the GFS and
European global models, and the SHIPS statistical intensity
guidance, shows an increase of the sustained winds to hurricane
force in 2 days, around the same period that the shear drops below
10 kt.  The non-tropical low is then forecast to move south of the
strong upper-level westerlies and detach from the frontal boundary.
According to the global models and the Florida State Cyclone Phase
forecast, Leslie should make a transition from a frontal system to
an asymmetric shallow warm-core seclusion.  Beyond day 3, guidance
suggests that Leslie will acquire subtropical characteristics and a
more symmetric, deepening warm-core low while meandering in weaker
steering currents.  The intensity forecast follows this scenario and
is based on the aforementioned global and statistical models.

Leslie is now moving eastward at a slightly faster forward motion,
about 10 kt.  A turn to the north is expected in 36 hours followed
by a slower westward motion as Leslie slips south of the
mid-latitude westerlies.  Through the remaining portion of the
forecast, Leslie should move at a slower speed generally westward
as a ridge builds to the north. NHC forecast is nudged toward the
TVCN consensus through 48 hours, then follows more closely to the
GFEX (GFS/ECMWF) consensus model.

This is the last advisory issued by the National Hurricane Center on
Leslie.  Additional information on this system can be found in High
Seas Forecasts issued by the National Weather Service, under AWIPS
header NFDHSFAT1, WMO header FZNT01 KWBC, and available on the Web
at https://ocean.weather.gov/shtml/NFDHSFAT1.shtml.

FORECAST POSITIONS AND MAX WINDS

INIT  25/1500Z 31.6N  44.4W   30 KT  35 MPH...POST-TROPICAL
12H  26/0000Z 32.1N  42.5W   40 KT  45 MPH...POST-TROP/EXTRATROP
24H  26/1200Z 33.6N  40.1W   50 KT  60 MPH...POST-TROP/EXTRATROP
36H  27/0000Z 35.6N  39.9W   60 KT  70 MPH...POST-TROP/EXTRATROP
48H  27/1200Z 36.1N  41.7W   65 KT  75 MPH...POST-TROP/EXTRATROP
72H  28/1200Z 35.5N  45.3W   60 KT  70 MPH...SUBTROPICAL STORM
96H  29/1200Z 34.6N  48.1W   55 KT  65 MPH...SUBTROPICAL STORM
120H  30/1200Z 34.4N  49.6W   50 KT  60 MPH...SUBTROPICAL STORM

$$
Forecaster Roberts

霧峰追風者

NHC 展望提升至20%，有機會再次轉暖。

3. Post-Tropical Cyclone Leslie is currently centered about 950 miles
southwest of the Azores Islands, and it is forecast to meander over
the central Atlantic for the next day or so.  By Thursday or
Friday, Leslie is expected to reacquire subtropical or tropical
characteristics while the cyclone moves slowly eastward to
east-northeastward over the north-central Atlantic. For more
information on this system, see High Seas Forecasts issued by the
National Weather Service.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...high...80 percent.

霧峰追風者

NHC 展望提升至70%。

1. Post-Tropical Cyclone Leslie, located over the central Atlantic
Ocean several hundred miles west-southwest of the Azores, has
intensified into a potent non-tropical low with hurricane-force
winds.  The associated shower activity is becoming more organized,
and the low is showing signs of taking on more subtropical
characteristics.  Leslie is expected to again become a subtropical
storm, or possibly a tropical storm, on Thursday or Friday while it
moves west-southwestward at about 10 mph over the north-central
Atlantic.  For more information on this system, see High Seas
Forecasts issued by the National Weather Service.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

t02436

AL, 13, 2018092712,   , BEST,   0, 369N,  425W,  65,  970, EX,

NHC展望提升到90%

1. Post-Tropical Cyclone Leslie, located over the central Atlantic
Ocean several hundred miles west of the Azores, remains a powerful
non-tropical low with hurricane-force winds.  The associated shower
activity is gradually becoming more organized, and Leslie is
expected to again become a subtropical storm, or possibly a tropical
storm, later today or Friday while it moves west-southwestward at
about 10 mph over the north-central Atlantic.  For more information
on this system, see High Seas Forecasts issued by the National
Weather Service.
* Formation chance through 48 hours...high...90 percent.
* Formation chance through 5 days...high...90 percent.

超廣的風場






奇葩的路徑

霧峰追風者

二次轉暖，預計72H轉為熱帶風暴，巔峰上望70KT。

020
WTNT43 KNHC 290252
TCDAT3

Subtropical Storm Leslie Discussion Number  11
NWS National Hurricane Center Miami FL       AL132018
1100 PM AST Fri Sep 28 2018

Convective banding has been consolidating to the south of Leslie's
center since the afternoon, but recent scatterometer data indicate
that the maximum winds have decreased to 40 kt and the area of
gale-force winds has decreased in size.  The convective structure
suggests that Leslie may be taking on some tropical characteristics,
but since wave vapor imagery still shows the cyclone embedded within
a complex deep-layer low, Leslie is still being designated as
subtropical.

Leslie is moving west-southwestward, or 255 degrees at 10 kt.
Leslie is entrenched between several mid-tropospheric highs located
to its east and west, and these features are expected to push
Leslie slowly southwestward for the next 3 days.  The track
guidance is tightly clustered during this period, and the NHC
forecast is very similar to the previous one.  After day 3, Leslie
is likely to meander on days 4 and 5 in weak steering, and the
updated official forecast has been adjusted southward and eastward
at the end of the forecast period to account for the latest model
solutions.

Global model fields indicate that Leslie has migrated to the
northwest of its parent upper-level low, which is putting it under
a regime of moderate north-northeasterly shear.  For the next 48
hours, this shear is expected to continue, and phase-space diagrams
suggest that Leslie will be straddling the line between shallow and
deep warm core.  As a result, only modest strengthening is
anticipated during this period, and the official forecast maintains
Leslie as a subtropical storm through 48 hours.  However, the
transition to a tropical storm could occur any time during the next
day or two.  After 48 hours, Leslie should definitely be deep warm
core, and more significant strengthening is expected, with the
cyclone forecast to reach hurricane intensity by day 4.  This
scenario is shown by the various intensity models, and the NHC
intensity forecast is very close to the HFIP Corrected Consensus
aid and the Florida State Superensemble.  If the statistical-
dynamical models are correct, Leslie could be stronger by the end of
the forecast period than is indicated in the NHC forecast.

Large swells generated by Leslie when it was a stronger
extratropical low have already reached Bermuda, will soon reach the
Lesser and Greater Antilles, and should reach portions of the east
coast of the United States later this weekend.  These swells could
cause life-threatening surf and rip currents.


FORECAST POSITIONS AND MAX WINDS

INIT  29/0300Z 35.7N  49.4W   40 KT  45 MPH
12H  29/1200Z 34.9N  50.8W   45 KT  50 MPH
24H  30/0000Z 34.0N  52.0W   45 KT  50 MPH
36H  30/1200Z 33.5N  53.0W   50 KT  60 MPH
48H  01/0000Z 33.1N  53.9W   50 KT  60 MPH
72H  02/0000Z 32.2N  55.4W   60 KT  70 MPH...TROPICAL CYCLONE
96H  03/0000Z 30.5N  56.0W   65 KT  75 MPH
120H  04/0000Z 31.5N  56.5W   70 KT  80 MPH

$$
Forecaster Berg

t02436

南落即將結束，也準備站上颶風強度，看來還要在大西洋飄一陣子...

104
WTNT43 KNHC 021433
TCDAT3

Tropical Storm Leslie Discussion Number  25
NWS National Hurricane Center Miami FL       AL132018
1100 AM AST Tue Oct 02 2018

Leslie has generally changed little during the past several hours.
The storm continues to have a ragged banded eye feature with
multiple mesovortices within it.  Deep convection is most organized
in a curved band that currently wraps from the northeast to
southwest quadrant of the storm.  The initial intensity is held at
55 kt, which is near the high end of the satellite estimates.
Although the storm has not strengthened much during the past day or
so, it still has an opportunity to intensify while it moves over
slightly higher SSTs and remains in favorable atmospheric conditions
during the next day or two.  Beyond a couple of days, slow weakening
seems likely as Leslie heads over SSTs cooler than 26 deg C and into
a slightly drier environment.  The NHC intensity forecast is the
same as the previous one, and it is in good agreement with the HCCA
and IVCN consensus aids.  This intensity forecast lies between the
aggressive statistical-dynamical models and the lower HMON and
COAMPS-TC models that keep Leslie below hurricane strength.

The tropical storm continues to lose latitude, with the latest
initial motion estimate being 215/7.  A continued slow south to
south-southwest motion is forecast during the next 24 hours as the
system moves in the flow on the east side of a mid-level high.
After that time, the combination of a shortwave trough to the west
and an amplifying mid-level ridge to the southeast should cause
Leslie to move northward to north-northeastward late this week.  By
the weekend, the models suggest that Leslie should turn eastward
when it moves in the mid-latitude westerlies.  The NHC track
forecast is nudged to the west to come into better agreement with
the latest models.

Large swells generated by Leslie are expected to increase tomorrow
and Thursday across the southeastern coast of the United States,
Bermuda, the Bahamas, and the Greater and Lesser Antilles.  These
swells will also begin to increase near the coasts of New England
and Atlantic Canada by the end of the week.  Please consult products
from your local weather office as these conditions could cause
life-threatening surf and rip currents.

FORECAST POSITIONS AND MAX WINDS

INIT  02/1500Z 30.9N  56.1W   55 KT  65 MPH
12H  03/0000Z 30.1N  56.4W   60 KT  70 MPH
24H  03/1200Z 29.8N  56.6W   65 KT  75 MPH
36H  04/0000Z 30.5N  56.7W   70 KT  80 MPH
48H  04/1200Z 31.9N  56.5W   70 KT  80 MPH
72H  05/1200Z 35.9N  56.3W   60 KT  70 MPH
96H  06/1200Z 37.6N  54.2W   60 KT  70 MPH
120H  07/1200Z 37.3N  50.5W   55 KT  65 MPH

$$
Forecaster Cangialosi