老農民版夜神月

  四級颶風  
編號：12 E
名稱：Linda

  基本資料  
擾動編號日期：2021 年 08 月 08 日 21 時
命名日期　　：2021 年 08 月 11 日 05 時
進入中太日期：2021 年 08 月 20 日 11 時
撤編日期　　：2021 年 08 月 25 日 14 時
登陸地點　　：無

  巔峰時期資料  
近中心最強風速 ：
國家颶風中心(NHC)：115 kt ( Cat.4 )
中太平洋颶風中心(CPHC)：40 kt ( TS )
海平面最低氣壓 ：950 百帕

  擾動編號資料  
93E.INVEST.15kts.1009mb.13N.100W

NHC：50%

1. A broad area of low pressure is producing some disorganized shower
activity a few hundred miles offshore of the coasts of southern
Mexico, Guatemala, and El Salvador.  Environmental conditions are
expected to be conducive for development of this system, and a
tropical depression is likely to form during the early or middle
portions of the week.  This system is expected to move westward to
west-northwestward at about 10 mph during the next several days,
parallel to and offshore of the coast of southern Mexico.
* Formation chance through 48 hours...medium...50 percent.
* Formation chance through 5 days...high...80 percent.

以上資料來自：NHC、CPHC、颱風論壇整理製作

老農民版夜神月

NHC展望提升至60%,如無意外JTWC稍晚會發布TCFA

1. A broad area of low pressure located a few hundred miles south of
the Gulf of Tehuantepec continues to produce disorganized showers
and thunderstorms. Environmental conditions are conducive for
development of this disturbance, and a tropical depression is
expected to form during the next two or three days.  This system is
forecast to move westward to west-northwestward at about 10 mph
during the next several days, parallel to and offshore of the coast
of southern Mexico.
* Formation chance through 48 hours...medium...60 percent.
* Formation chance through 5 days...high...90 percent.

老農民版夜神月

JTWC發布TCFA

WTPN21 PHNC 090000
MSGID/GENADMIN/JOINT TYPHOON WRNCEN PEARL HARBOR HI//
SUBJ/TROPICAL CYCLONE FORMATION ALERT (INVEST 93E)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
120 NM EITHER SIDE OF A LINE FROM 10.9N 95.2W TO 12.9N 101.4W
WITHIN THE NEXT 12 TO 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 15 TO 20 KNOTS. METSAT
IMAGERY AT 090000Z INDICATES THAT A CIRCULATION CENTER IS LOCATED
NEAR 11.0N 95.5W. THE SYSTEM IS MOVING WEST-NORTHWESTWARD AT 12
KNOTS.
2. REMARKS: AN AREA OF CONVECTION (93E) HAS PERSISTED NEAR 11.0N
95.5W APPROXIMATELY 300 NM SOUTH SOUTHEAST OF PUNTA ESCONDITA,
MEXICO. ANIMATED MULTISPECTRAL SATELLITE IMAGERY (MSI) DEPICTS AN
AREA OF FLARING CONVECTION AND BROAD TURNING AROUND AN ILL-DEFINED
LOW LEVEL CIRCULATION (LLC). A 082257Z SSMIS 91GHZ SATELLITE IMAGE
REVEALS AREAS OF DEEP CONVECTION WITHOUT A CLEAR LLC. ANALYSES
INDICATE AN OVERALL FAVORABLE ENVIRONMENT FOR DEVELOPMENT
CHARACTERIZED BY EQUATORWARD OUTFLOW ALOFT, LOW TO MODERATE (10-20
KT) VERTICAL WIND SHEAR (VWS), AND WARM (29-30C) SEA SURFACE
TEMPERATURES. GLOBAL MODELS GENERALLY AGREE THAT INVEST 93E WILL
CONSOLDATE AND STRENGTHEN AS IT PROPAGATES NORTHWESTWARD. MAXIMUM
SUSTAINED SURFACE WINDS ARE ESTIMATED AT 15 TO 20 KNOTS. MINIMUM SEA
LEVEL PRESSURE IS ESTIMATED TO BE NEAR 1007 MB. THE POTENTIAL FOR
THE DEVELOPMENT OF A SIGNIFICANT TROPICAL CYCLONE WITHIN THE NEXT 24
HOURS IS HIGH.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR CANCELLED BY
100000Z.//
NNNN

老農民版夜神月

NHC展望提升至High,70%/90%

1. A broad area of low pressure located a few hundred miles south of
the Gulf of Tehuantepec continues to produce disorganized showers
and a few thunderstorms.  Environmental conditions are conducive for
development of this disturbance, and a tropical depression is
expected to form within the next couple of days.  This system is
forecast to move westward to west-northwestward at about 10 mph
through midweek, parallel to and offshore of the coast of southern
Mexico.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...90 percent.

老農民版夜神月

數值看好後期強度,有望成為今年東太第2個MH

Heigo

NHC升格TD12E,首報上望80節

000
WTPZ42 KNHC 100843
TCDEP2

Tropical Depression Twelve-E Discussion Number   1
NWS National Hurricane Center Miami FL       EP122021
400 AM CDT Tue Aug 10 2021

Over the past several hours, showers and thunderstorms have showed
increased signs of organization in association with an area of low
pressure located a few hundred miles south of Acapulco, Mexico. An
ASCAT-B pass around 0330 UTC revealed that the low has developed a
well-defined center and is producing 25 to 30-kt winds, with some
higher wind vectors flagged as rain contaminated within the deep
convection occurring to the south and west of the center. The system
has become sufficiently organized to be classified as a tropical
depression, and its initial intensity is set at 30 kt for this
advisory.

The estimated motion of the depression is west-northwest, or
290/7 kt. The system is expected to generally move
west-northwestward to westward over the next several days, as it is
steered by a ridge to its north and northeast. This track is roughly
parallel to, but well offshore of, the southwestern coast of
Mexico. The track guidance is in reasonably good agreement, and the
official NHC forecast lies near the center of the guidance envelope.

The depression is located in a moist, unstable environment with
ample oceanic heat content to fuel strengthening during the next few
days. However, moderate to strong northerly vertical wind shear will
likely prevent rapid intensification of this system in the short
term. Nonetheless, the intensity guidance unanimously supports
strengthening, and this system is likely to become a tropical storm
later today. Continued strengthening is forecast through the rest of
the week and into the weekend, and the cyclone could reach hurricane
strength by Thursday. The official NHC intensity forecast generally
follows the IVCN consensus aid and shows the system's intensity
peaking on days 4 and 5, when the wind shear is forecast to
diminish while the cyclone remains over warm SSTs.


FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 13.0N 100.8W   30 KT  35 MPH
12H  10/1800Z 13.7N 102.0W   40 KT  45 MPH
24H  11/0600Z 14.3N 103.6W   45 KT  50 MPH
36H  11/1800Z 14.5N 105.3W   50 KT  60 MPH
48H  12/0600Z 14.7N 106.5W   60 KT  70 MPH
60H  12/1800Z 15.3N 107.9W   65 KT  75 MPH
72H  13/0600Z 16.3N 109.4W   70 KT  80 MPH
96H  14/0600Z 18.2N 113.3W   80 KT  90 MPH
120H  15/0600Z 19.0N 117.5W   80 KT  90 MPH

$$
Forecaster Reinhart/Pasch

老農民版夜神月

NHC升格TS,並命名Linda,略微上調上望至C2,85KT

000
WTPZ42 KNHC 102049
TCDEP2

Tropical Storm Linda Discussion Number   3
NWS National Hurricane Center Miami FL       EP122021
400 PM CDT Tue Aug 10 2021

A recent ASCAT-B overpass revealed tropical-storm-force winds in
both the northern and southern semicircles of the cyclone, with
believable peak winds of 38 kt. Therefore, the depression has been
upgraded to a 40-kt tropical storm.

Moderate to strong northerly shear over Linda is keeping the bulk of
the deep convection confined to the southern portion of the
cyclone's circulation, resulting in a partially exposed low-level
center. This shear is forecast to persist over the storm for the
next day or so. Therefore, despite a moist, unstable environment
with ample oceanic heat content, only slow strengthening is expected
in the short term. If the shear decreases as anticipated, a
faster rate of intensification should occur for a couple of days.
The latest NHC intensity forecast is on the low end of the guidance
through 24-36 h due to the anticipated affects of the shear, and
then trends to near the various intensity consensus values
thereafter.

The estimated motion of Linda remains 295/9 kt. The cyclone is
expected to turn westward tonight as a ridge builds to its north,
and then resume a west-northwestward motion by later this week as it
begins to move along the southwestern periphery of this ridge. This
track is roughly parallel to, but well offshore of, the southwestern
coast of Mexico over the next couple of days. Thereafter, the
depression is forecast to move away from the coast of Mexico. The
latest NHC forecast track is little changed from the previous one,
and lies near the consensus track guidance.


FORECAST POSITIONS AND MAX WINDS

INIT  10/2100Z 14.4N 102.8W   40 KT  45 MPH
12H  11/0600Z 14.8N 104.0W   45 KT  50 MPH
24H  11/1800Z 15.0N 105.6W   50 KT  60 MPH
36H  12/0600Z 15.3N 106.9W   60 KT  70 MPH
48H  12/1800Z 16.0N 108.3W   70 KT  80 MPH
60H  13/0600Z 16.9N 110.0W   80 KT  90 MPH
72H  13/1800Z 17.8N 112.0W   85 KT 100 MPH
96H  14/1800Z 19.3N 116.0W   85 KT 100 MPH
120H  15/1800Z 20.0N 120.0W   75 KT  85 MPH

$$
Forecaster Latto

老農民版夜神月

NHC將定強調至TS上限,即將升格C1.並持續上調上望至90節

000
WTPZ42 KNHC 112041
TCDEP2

Tropical Storm Linda Discussion Number   7
NWS National Hurricane Center Miami FL       EP122021
300 PM MDT Wed Aug 11 2021

After the issuance of the previous advisory, Linda showed hints of
an eye in visible and infrared satellite imagery.  That feature
is no longer apparent, and it appears that some dry air has
infiltrated into the circulation.  That being said, earlier
microwave data indicated that the storm has a robust structure, and
new convection is developing near the center.  The latest Dvorak
T-numbers are T3.5 from TAFB and T4.0 from SAB, and as a result,
the initial intensity is raised to 60 kt.

Linda has been losing latitude for the past 12-18 hours, and the
initial motion is south of due west, or 260/8 kt.  The mid-level
ridge that is steering Linda extends over northern Mexico, reaching
as far as the Baja California peninsula.  With Linda approaching
the western edge of the ridge, it should begin to gain latitude
again soon and turn toward the west-northwest by 24 hours.  General
ridging should remain in control through the 5-day forecast period,
maintaining Linda on a west-northwestward or westward track with
minimal changes in speed.  There were no noteworthy changes to the
guidance on this cycle, and the updated NHC track forecast is very
close to the HCCA consensus aid and not too different from the
previous forecast.

As mentioned earlier today, the environment ahead of Linda consists
of a mix of positives and negatives for intensification.  
North-northeasterly shear of 15-20 kt is not expected to decrease
much in the coming days, which could allow some dry air to continue
penetrating into the circulation.  On the other hand, Linda's track
will keep it over warm 28 degree Celsius waters for several days,
and strong upper-level divergence should support deep convective
development for another couple of days.  Therefore, steady
strengthening is shown in the official forecast, which indicates a
slightly higher peak intensity compared to this morning's forecast.
An important note is that several dynamical and statistical models
are showing the intensity peaking near or at major hurricane
intensity in 2 to 3 days.  However, given the presence of the shear,
I'd prefer to keep the forecast on the conservative side and only
nudge the forecast up for now.  Future upward adjustments may
be required if Linda strengthens more in the short term than what is
shown in the official forecast.  Weakening should occur by days 4
and 5 due to Linda moving over cooler waters.


FORECAST POSITIONS AND MAX WINDS

INIT  11/2100Z 13.6N 106.2W   60 KT  70 MPH
12H  12/0600Z 13.8N 107.2W   70 KT  80 MPH
24H  12/1800Z 14.5N 109.0W   80 KT  90 MPH
36H  13/0600Z 15.4N 110.9W   85 KT 100 MPH
48H  13/1800Z 16.4N 112.9W   90 KT 105 MPH
60H  14/0600Z 17.4N 115.0W   90 KT 105 MPH
72H  14/1800Z 18.1N 117.0W   90 KT 105 MPH
96H  15/1800Z 18.7N 120.9W   80 KT  90 MPH
120H  16/1800Z 18.9N 124.6W   65 KT  75 MPH

$$
Forecaster Berg