老農民版夜神月

  熱帶風暴  
編號：11 E
名稱：Kevin

  基本資料  
擾動編號日期：2021 年 08 月 07 日 02 時
命名日期　　：2021 年 08 月 08 日 05 時
撤編日期　　：2021 年 08 月 13 日 14 時
登陸地點　　：無

  巔峰時期資料  
近中心最強風速 ：45  kt ( TS )
海平面最低氣壓 ：999 百帕

  擾動編號資料  
92E.INVEST.15kts.1006mb.14N.103W

NHC：20%

1. A large area of disorganized showers and thunderstorms is located
a few hundred miles south of the coast of southwestern Mexico.  
Environmental conditions are forecast to be conducive for
additional gradual development, and a tropical depression is likely
to form early next week while the system moves west-northwestward at
about 10 mph, parallel to and offshore of the coast of southwestern
Mexico.
* Formation chance through 48 hours...low...20 percent.
* Formation chance through 5 days...high...70 percent.

以上資料來自：NHC、颱風論壇整理製作

老農民版夜神月

NHC展望提升至40%,Medium

1. Showers and thunderstorms are beginning to show some signs of
organization in association with a broad area of low pressure
located a couple of hundred miles south of the coast of southwestern
Mexico. Environmental conditions are conducive for additional
development, and a tropical depression is expected to form late
this weekend or early next week while the system moves
west-northwestward at about 10 mph.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...high...90 percent.

老農民版夜神月

NHC升格TD11E,首報上望75節

000
WTPZ41 KNHC 071451
TCDEP1

Tropical Depression Eleven-E Discussion Number   1
NWS National Hurricane Center Miami FL       EP112021
1000 AM CDT Sat Aug 07 2021

Last night's METOP-A/B scatterometer overpasses indicated that the
area of low pressure located a couple hundred miles south-southwest
of Manzanillo, Mexico had become a little better defined, and
since that time, the system has developed sufficient organized
convection to be designated as a tropical depression.  The initial
intensity is estimated to be 30 kt and is in agreement with the
satellite intensity estimates from TAFB and SAB.

Modest northeasterly shear, warm sea surface temperatures and
a moist surrounding low- to mid-level environment support steady
strengthening during the next few days, and the depression
is forecast to become a tropical storm by tonight.  The Statistical
SHIPS (GFS/ECMWF), and the HCCA/IVCN multi-model intensity aids,
all show that the cyclone will become a hurricane in about 48
hours, and the NHC forecast follows suit.  The intensity forecast
resembles the HCCA and IVCN intensity consensus models, and is just
below the Decay SHIPS guidance.

The initial motion is estimated to be westward, or 275/8 kt.  The
depression is being steered by a mid-tropospheric ridge stretching
westward over the subtropical eastern Pacific from high pressure
located over the northern Gulf of Mexico.  A general westward motion
with a similar forward speed is expected through early next week.  
Through the remaining portion of the forecast, a turn toward the
west-northwest to northwest is expected due to a growing weakness in
the aforementioned ridge.  The official forecast is based on the
TVCN multi-model consensus and lies between the GFS and ECMWF global
models solutions.



FORECAST POSITIONS AND MAX WINDS

INIT  07/1500Z 15.9N 105.5W   30 KT  35 MPH
12H  08/0000Z 15.9N 106.8W   40 KT  45 MPH
24H  08/1200Z 15.9N 108.4W   45 KT  50 MPH
36H  09/0000Z 15.9N 109.7W   55 KT  65 MPH
48H  09/1200Z 16.2N 111.1W   65 KT  75 MPH
60H  10/0000Z 16.8N 112.3W   70 KT  80 MPH
72H  10/1200Z 18.0N 113.7W   70 KT  80 MPH
96H  11/1200Z 19.9N 117.3W   65 KT  75 MPH
120H  12/1200Z 21.7N 121.4W   50 KT  60 MPH

$$
Forecaster Roberts

老農民版夜神月

NHC升格TS,命名Kevin

000
WTPZ41 KNHC 072038
TCDEP1

Tropical Storm Kevin Discussion Number   2
NWS National Hurricane Center Miami FL       EP112021
300 PM MDT Sat Aug 07 2021

Visible satellite imagery has continued to show an improvement in
the cloud pattern of the tropical cyclone today. Banding has
increased over the western and southern portions of the circulation
while a small CDO has developed near the center.  Scatterometer data
from around 1700 UTC revealed an area of 30-kt winds to the
northwest of the center, but with the continued increase in
organization and Dvorak T-numbers of T2.5 from both TAFB and SAB the
initial wind speed has been increased to 35 kt. Kevin becomes the
eleventh named storm in the eastern Pacific basin during the 2021
season, which is running about a month ahead of schedule as the
eleventh named storm typically does not form until early-to-mid
September.

Kevin is located within an environment of low-to-moderate shear,
warm sea surface temperatures, and a moist atmosphere.  These
conditions are expected to support steady strengthening over the
next few days, and the cyclone is expected to become a hurricane
in about 36 hours.  There is some spread in the intensity guidance
with the statistical guidance on the more aggressive side as
compared to some of the dynamical models.  The NHC wind speed
forecast lies a little above the various consensus models but
slightly below the SHIPS guidance.

The storm is moving westward or 270/9 kt. A mid-tropospheric ridge
that extends across the subtropical eastern Pacific is forecast to
steer Kevin generally westward during the next 36 hours. After that
time, a cut-off low west of the Baja peninsula is expected to erode
the western portion of the ridge causing Kevin to turn west-
northwestward to northwestward through the remainder of the forecast
period. The GFS, which depicts an unrealistic elongation of the
system's low-level vorticity in about 48 hours, shows a much
sharper northward or northwestward motion from 48-72 hours. Less
weight was placed on that solution with the NHC track remaining
closer to the bulk of the guidance and the various consensus aids.  
The latest track forecast is similar to, but a little slower than
previous advisory.


FORECAST POSITIONS AND MAX WINDS

INIT  07/2100Z 15.8N 106.8W   35 KT  40 MPH
12H  08/0600Z 15.8N 108.1W   45 KT  50 MPH
24H  08/1800Z 15.7N 109.4W   55 KT  65 MPH
36H  09/0600Z 15.7N 110.5W   65 KT  75 MPH
48H  09/1800Z 16.2N 111.5W   70 KT  80 MPH
60H  10/0600Z 17.3N 112.7W   75 KT  85 MPH
72H  10/1800Z 18.2N 114.0W   75 KT  85 MPH
96H  11/1800Z 19.9N 117.6W   65 KT  75 MPH
120H  12/1800Z 21.9N 122.2W   50 KT  60 MPH

$$
Forecaster Brown

老農民版夜神月

發展不如預期,NHC大幅調低上望

466
WTPZ41 KNHC 091434
TCDEP1

Tropical Storm Kevin Discussion Number   9
NWS National Hurricane Center Miami FL       EP112021
900 AM MDT Mon Aug 09 2021

Kevin has been successfully battling moderate northeasterly wind
shear overnight, as a large convective mass with cloud tops colder
than -80 degrees C has persisted for several hours over the center
and southwestern portion of the cyclone's large circulation. The
latest Dvorak intensity estimates have a large spread, ranging from
55 kt from TAFB to 35 kt from the UW-CIMSS ADT. A mean of 45 kt from
these values suggest that the storm's initial intensity remains the
same as 6 h ago, which seems reasonable as the overall appearance of
Kevin has changed little this morning.

The storm is moving to the west-northwest at 300/07 kt along the
southwestern periphery of a mid-level ridge. This steering pattern
is forecast by all of the forecast models to remain in tact for the
next several days, resulting in a continued west-northwestward
motion. The only notable change in the track guidance was a slight
shift to the north, and the latest NHC track forecast lies in
between the previous one and the tightly clustered track guidance.

The favorable thermodynamic environment and warm water have allowed
Kevin to maintain deep convection despite the vertical wind shear.
With the large amount of convection occurring near and over the
center of the cyclone, it is possible for some slight strengthening
to occur in the short-term, despite wind shear persisting over the
next couple of days. By 48 hours, Kevin will begin to move over
decreasing SSTs and into a more stable atmospheric environment.
These unfavorable thermodynamic conditions should cause the cyclone
to begin weakening. By 96 hours, the system is forecast to be over
water temperatures of less than 23 degrees C, which should result in
the cyclone degenerating into a remnant low. The latest NHC
intensity forecast was decreased slightly from the previous one, and
is in good agreement with the various intensity consensus models.


FORECAST POSITIONS AND MAX WINDS

INIT  09/1500Z 16.6N 111.5W   45 KT  50 MPH
12H  10/0000Z 17.3N 112.5W   50 KT  60 MPH
24H  10/1200Z 18.1N 114.1W   50 KT  60 MPH
36H  11/0000Z 18.9N 115.6W   50 KT  60 MPH
48H  11/1200Z 19.7N 117.1W   50 KT  60 MPH
60H  12/0000Z 20.6N 119.0W   45 KT  50 MPH
72H  12/1200Z 21.4N 121.0W   40 KT  45 MPH
96H  13/1200Z 23.0N 125.6W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  14/1200Z 24.5N 130.6W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Latto

老農民版夜神月

NHC不再認為能夠增強,將逐漸減弱消亡

000
WTPZ41 KNHC 110236
TCDEP1

Tropical Storm Kevin Discussion Number  15
NWS National Hurricane Center Miami FL       EP112021
800 PM PDT Tue Aug 10 2021

Tracking the center of Kevin this evening has been a challenge, as
multiple low-level swirls appear to be rotating cyclonically around
a broader mean circulation. The deeper convection remains mostly
south of the estimated circulation center, though some cooler cloud
tops did attempt to build northward, following a mesovortex seen
on visible satellite imagery. Subjective Dvorak intensity estimates
from SAB and TAFB at 0000 UTC were T2.5/35 kt and T3.0/45 kt,
respectively, and the latest UW-CIMSS SATCON estimate was hovering
between these values at 42 kt. The initial intensity is held at 45
kt for this advisory, favoring the higher intensity estimates given
the earlier ASCAT data.

The initial motion is estimated at 315/7 kt, attempting to follow
the mean center that has several mesovorticies rotating
around. A general northwest to west-northwestward motion is
expected to continue over the next several days as the large
cyclone is steered by a deep-layer ridge located to its northeast.
The latest track guidance was a bit more poleward compared to the
previous cycle, and the latest NHC track forecast has been shifted
a bit more poleward in the short term, choosing to remain close to
the track guidance consensus.

Moderate to strong northeasterly wind shear continues to keep
Kevin's deepest convection downshear in the southern semicircle of
the large circulation envelope. Over the next 24 hours, Kevin will
also be crossing a sharp sea-surface temperature (SST) gradient,
with sub 26 C SSTs not far away to the north. As the
cyclone moves over these progressively cooler waters, gradual
weakening should commence. Simulated IR brightness temperature data
from both the GFS and ECMWF suggest that Kevin will lose its
remaining organized convection by 48-60 hours, and the latest NHC
intensity forecast shows Kevin becoming a remnant low by that time.


FORECAST POSITIONS AND MAX WINDS

INIT  11/0300Z 19.5N 115.4W   45 KT  50 MPH
12H  11/1200Z 20.7N 116.5W   40 KT  45 MPH
24H  12/0000Z 21.9N 118.3W   35 KT  40 MPH
36H  12/1200Z 23.0N 120.3W   30 KT  35 MPH
48H  13/0000Z 24.0N 122.5W   25 KT  30 MPH
60H  13/1200Z 25.1N 124.7W   25 KT  30 MPH...POST-TROP/REMNT LOW
72H  14/0000Z 26.3N 126.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
96H  15/0000Z 28.4N 130.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  16/0000Z...DISSIPATED

$$
Forecaster Papin/Stewart

老農民版夜神月

NHC判定已減弱為殘餘低氣壓

000
WTPZ41 KNHC 121431
TCDEP1

Post-Tropical Cyclone Kevin Discussion Number  21
NWS National Hurricane Center Miami FL       EP112021
800 AM PDT Thu Aug 12 2021

A little bit of convection continues to persist about 200 n mi to
the southwest of Kevin's center, but at that distance, it is not
considered organized in relation to the cyclone.  In fact, Kevin has
had this structure for a good 18 hours or so, and it has
therefore degenerated into a remnant low.  Based on last evening's
ASCAT passes, it is assumed that winds as high as 30 kt are still
occurring within the circulation.  However, the center will be
moving over waters colder than 23 degrees Celsius very soon, so a
gradual decrease in the winds is expected over the next couple of
days.  Dissipation of the remnant low in expected in about 3 days.

Kevin is moving toward the west-northwest, or 300/12 kt.  The
remnant low is expected to move along the southwestern periphery of
a low- to mid-level ridge centered over the United States and
Mexico, which should cause a west-northwestward or northwestward
motion until dissipation.  There is very little spread in the track
guidance, and this last NHC track forecast is just an update of
the previous one.

This is the last advisory being issued for Kevin.  For additional
information on the remnant low please see High Seas Forecasts
issued by the National Weather Service under AWIPS header NFDHSFEPI
and WMO header FZPN02 KWBC.

FORECAST POSITIONS AND MAX WINDS

INIT  12/1500Z 23.2N 120.6W   30 KT  35 MPH...POST-TROP/REMNT LOW
12H  13/0000Z 24.2N 122.5W   25 KT  30 MPH...POST-TROP/REMNT LOW
24H  13/1200Z 25.5N 124.9W   25 KT  30 MPH...POST-TROP/REMNT LOW
36H  14/0000Z 27.0N 126.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
48H  14/1200Z 28.7N 128.6W   20 KT  25 MPH...POST-TROP/REMNT LOW
60H  15/0000Z 30.2N 129.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
72H  15/1200Z...DISSIPATED

$$
Forecaster Berg