霧峰追風者

  一級颶風  
編號：15 E
名稱：Miriam

  基本資料  
擾動編號日期：2018 年 08 月 26 日 02 時
命名日期　　：2018 年 08 月 26 日 23 時
　　　　　　　2018 年 08 月 30 日 11 時 - CPHC接續發報
撤編日期　　：2018 年 09 月 03 日 09 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)：65 kts
中太平洋颶風中心(CPHC)：85 kts
海平面最低氣壓：974 百帕

  過去路徑圖  
無

  擾動編號資料  
99E.INVEST.25kts-1009mb-12.1N-120.7W


NHC : 40%

1. An area of low pressure located just over 1000 miles southwest of
the southern tip of the Baja California peninsula appears to be
becoming a little better organized.  Although satellite data
indicate that a well-defined surface circulation has not yet formed,
environmental conditions appear conducive for additional
development, and a tropical depression is likely to form within the
next few days while the system moves westward around 10 mph.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...high...70 percent.

以上資料來自：NHC、CPHC、颱風論壇整理製作

霧峰追風者

NHC 升格15E，逐漸增強，後期將進入中太。

276
WTPZ45 KNHC 260842
TCDEP5

Tropical Depression Fifteen-E Discussion Number   1
NWS National Hurricane Center Miami FL       EP152018
200 AM PDT Sun Aug 26 2018

Various satellite data over the past several hours, including recent
ASCAT scatterometer surface-wind data, indicate that the
well-defined low pressure area located about 1000 nmi southwest of
the southern tip of the Baja California peninsula has become much
better organized, and has developed into a tropical depression. A
small CDO-like feature has formed over the well-defined center
depicted in the ASCAT data, and a recent burst of cold cloud tops of
-80C have also developed just west of the center. The initial
intensity of 30 kt is based on 0458Z and 0558Z ASCAT wind data,
which indicated winds of 28-30 kt were located 35-40 nmi west and
southwest of the low-level center.

The initial motion estimate is 280/10 kt. The depression is expected
to remain south of a strong deep-layer subtropical ridge for the
next 96 hours, resulting in a general westward motion at a slightly
faster forward speed. By day 5, the cyclone is forecast to move into
a break in the ridge created by a broad mid-/upper-level trough that
is forecast to dig southward out of the northern Pacific between
140W-145W longitude. The forecast track lies essentially down the
middle of the guidance envelope, which is just north of the
consensus model TVCE and the GFS model, but south of the ECMWF and
UKMET models. The HRWF and HMON models were not being available for
the TVCE consensus on this cycle, so some significant adjustments to
the track in the next advisory may be required.

The cyclone has a radius of maximum winds (RMW) of 35-40 nmi based
on the recent ASCAT data. The combination of the modest RMW, low
vertical wind shear of less than 10 kt, a very moist mid-level
environment, and sea-surface temperatures above 28 deg C, favors
steady intensification and even the possibility of rapid
strengthening. Since this is the first forecast, however, the
intensity forecast is on the conservative side and calls for a
climatological increase of one T-number or 20 kt every 24 h for the
next 48 hours, which is above all of the intensity guidance except
for the Navy COAMPS (CTCI) model. By 96-120 hours, the intensity is
leveled off due to possible entrainment of drier air and an increase
in southwesterly vertical wind shear.

FORECAST POSITIONS AND MAX WINDS

INIT  26/0900Z 13.3N 124.1W   30 KT  35 MPH
12H  26/1800Z 13.5N 126.0W   40 KT  45 MPH
24H  27/0600Z 13.7N 128.4W   50 KT  60 MPH
36H  27/1800Z 13.9N 130.6W   60 KT  70 MPH
48H  28/0600Z 14.1N 132.6W   70 KT  80 MPH
72H  29/0600Z 14.3N 136.6W   80 KT  90 MPH
96H  30/0600Z 14.9N 140.1W   90 KT 105 MPH
120H  31/0600Z 17.4N 141.9W   90 KT 105 MPH

$$
Forecaster Stewart

t02436

評價40節，命名Miriam，巔峰上望90節。

565
WTPZ45 KNHC 261438
TCDEP5

Tropical Storm Miriam Discussion Number   2
NWS National Hurricane Center Miami FL       EP152018
800 AM PDT Sun Aug 26 2018

Deep convection associated with the tropical cyclone has continued
to become better organized this morning, with a significant increase
in banding noted in conventional satellite imagery.  An earlier
AMSR2 microwave overpass also revealed the increase in banding, but
the low-level center was located near the northeastern portion of
the main convective mass.  A Dvorak satellite intensity estimate of
T2.5 (35 k) was the basis for the 1200 UTC synoptic intensity, but
with the continued increase in organization, the initial wind speed
for this advisory has been set to 40 kt.

Miriam is moving westward or 275/11 kt. The tropical storm should
remain on a general westward heading during the next few days while
it remains to the south of a deep-layer ridge.  The orientation of
the ridge may shift more west-southwestward within the next day or
so, which could steer the tropical storm on a track slightly south
of due west.  The bulk of the dynamical model guidance has shifted
southward, so the NHC forecast track has been adjusted accordingly
through the first 3 days.  After that time, a weakness in the
subtropical ridge between 140W-145W longitude is expected to cause
Miriam to turn northwestward, then north-northwestward by the end
of the forecast period.  The latter portion of the official forecast
is similar to the previous advisory and is in best agreement with
the HFIP corrected consensus model.

The environment ahead of Miriam is expected to remain favorable for
strengthening.  The tropical storm will be traversing SSTs of 27-28C
and within low vertical wind shear conditions.   The NHC intensity
forecast calls for steady intensification during the next few days
and is at the upper-end of the intensity guidance.  Although the
various rapid intensification prediction techniques are not
particularly bullish, perhaps due to the low initial intensity of
the cyclone, it would not be surprising if the tropical storm went
through a period of rapid intensification within the next couple of
days.  The NHC intensity forecast is closest to the more aggressive
HWRF and HMON dynamical models.


FORECAST POSITIONS AND MAX WINDS

INIT  26/1500Z 13.2N 125.3W   40 KT  45 MPH
12H  27/0000Z 13.3N 127.1W   50 KT  60 MPH
24H  27/1200Z 13.5N 129.4W   60 KT  70 MPH
36H  28/0000Z 13.5N 131.5W   70 KT  80 MPH
48H  28/1200Z 13.5N 133.6W   80 KT  90 MPH
72H  29/1200Z 13.5N 137.6W   85 KT 100 MPH
96H  30/1200Z 14.9N 140.5W   90 KT 105 MPH
120H  31/1200Z 18.5N 142.0W   85 KT 100 MPH

$$
Forecaster Brown

t02436

21Z升C1，03Z進中太，對夏威夷不會造成影響。

WTPA43 PHFO 300252
TCDCP3

Hurricane Miriam Discussion Number  16
NWS Central Pacific Hurricane Center Honolulu HI   EP152018
500 PM HST Wed Aug 29 2018

While cloud tops associated with Miriam were on general warming
trend since the previous advisory, a new burst of convection has
recently developed over the center, while organized convective
bands continue to wrap in to the center from the southeast.
Subjective Dvorak intensity estimates of 4.0/65 kt from SAB/HFO are
supported by UW-CIMSS ADT, and that will be the initial intensity
estimate for this advisory.

The initial motion estimate is a somewhat uncertain 280/7 kt, as
the low-level center has been difficult to identify. Miriam has
moved into an area of light steering flow between a mid-level ridge
centered over the southwestern U.S., and a mid- to upper-level low
centered northeast of Hawaii. The gradient between the low and the
ridge will result in a southerly steering flow that will take
Miriam toward the north the next couple of days. A turn toward the
northwest is expected to begin tonight, followed by a turn toward
the north on Thursday, with the dynamical models in good agreement
on this evolution. Increasing model spread persists after day 3,
with ECMWF taking a deeper cyclone much faster and farther
northward than the most of the guidance, with this solution taking
consensus members well to the right of the updated forecast track.
The official forecast continues to lean toward the GFS and its
ensemble solution, with Miriam turning west-northwestward toward the
end of the forecast period as a weak and shallow system primarily
steered by the low-level trade wind flow.

The forecast anticipates that Miriam will be in an environment
conducive for modest strengthening for the next 24 hours or so,
with shear near 10 kt and SSTs near 28C. The forecast track toward
the north will take Miriam over cooler waters thereafter, with SSTs
below 26C by 72 h. Southwesterly shear is expected to increase to
near 30 kt in 48 h and to 40 kt in 72 h, and Miriam is expected to
degenerate into a remnant low by day 4. The official intensity
forecast follows trends presented by the multi-model consensus and
SHIPS.


FORECAST POSITIONS AND MAX WINDS

INIT  30/0300Z 14.4N 140.6W   65 KT  75 MPH
12H  30/1200Z 14.8N 141.2W   70 KT  80 MPH
24H  31/0000Z 16.0N 141.6W   75 KT  85 MPH
36H  31/1200Z 17.7N 141.5W   65 KT  75 MPH
48H  01/0000Z 19.4N 141.6W   55 KT  65 MPH
72H  02/0000Z 22.0N 143.2W   40 KT  45 MPH
96H  03/0000Z 25.0N 147.0W   30 KT  35 MPH...POST-TROP/REMNT LOW
120H  04/0000Z 27.0N 151.5W   25 KT  30 MPH...POST-TROP/REMNT LOW

$$
Forecaster Birchard

t02436

剩下一個空殼，15Z降格TD，即將消散。

WTPA43 PHFO 021443
TCDCP3

Tropical Depression Miriam Discussion Number  30
NWS Central Pacific Hurricane Center Honolulu HI   EP152018
500 AM HST Sun Sep 02 2018

The center of Miriam has been completely devoid of deep
convection for almost 24 hours as nearly 50 kt of southwesterly
vertical wind shear has taken its toll on the system. The latest
subjective Dvorak current intensity estimates range from
unclassifiable by SAB to T1.5/25 kt by JTWC, and T2.0/30 kt by
PHFO. The most recent UW-CIMSS ADT yielded an estimated intensity
of 25 kt. Based on a blend of these estimates, the initial
intensity is lowered to 30 kt for this advisory.

The initial motion is 320 deg / 12 kt. A broad mid- to upper-level
trough to the northwest of Miriam will maintain the very strong
vertical wind shear during the next couple of days. Since Miriam
has transitioned to a shallow low-level cloud swirl, it is now
being steered more toward the northwest under the influence of
a deep subtropical ridge located to the northeast. This
northwestward motion will likely persist through Monday. The latest
forecast track is close to the previous advisory, and remains near
the middle of the guidance envelope and close to the consensus model
guidance, TVCE and HCCA. Under the hostile vertical wind shear and
decreasing SSTs, Miriam will continue weakening. The latest
intensity forecast weakens Miriam at a slightly slower rate than
almost all of the guidance, and is closest to the GFS output. Note
that Miriam is forecast to become a remnant low later today,
followed by dissipation late Monday.


FORECAST POSITIONS AND MAX WINDS

INIT  02/1500Z 26.1N 143.9W   30 KT  35 MPH
12H  03/0000Z 27.3N 145.3W   25 KT  30 MPH...POST-TROP/REMNT LOW
24H  03/1200Z 28.6N 147.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
36H  04/0000Z 29.7N 149.6W   25 KT  30 MPH...POST-TROP/REMNT LOW
48H  04/1200Z...DISSIPATED

$$
Forecaster Houston