老農民版夜神月

  熱帶風暴  
編號：21 L
名稱：Vicky

  基本資料  
擾動編號日期：2020 年 09 月 12 日 20 時
命名日期　　：2020 年 09 月 14 日 23 時
撤編日期　　：2020 年 09 月 18 日 03 時
登陸地點　　：無

  巔峰時期資料  
近中心最強風速 ：40  kt( TS )
海平面最低氣壓 ：1002 百帕
  擾動編號資料    
97L.INVEST.15kts.1007mb.13N.20W


  NHC：30％

3. Another area of disturbed weather, associated with a tropical wave,
is located near the Cabo Verde Islands.  Environmental conditions
support some development during the next few days, and a tropical
depression could form over the far eastern tropical Atlantic early
next week while the system moves slowly westward. By mid-week,
upper-level winds could become less conducive for development.
* Formation chance through 48 hours...low...30 percent.
* Formation chance through 5 days...medium...60 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Medium,40%/60%

3. Showers and thunderstorms located near the Cabo Verde Islands are
associated with a broad area of low pressure that has developed
along a tropical wave.  Environmental conditions support some
additional development during the next few days, and a tropical
depression could form over the far eastern tropical Atlantic early
next week while the system moves slowly west-northwestward. By
mid-week, upper-level winds could become less conducive for
development.
* Formation chance through 48 hours...medium...40 percent.
* Formation chance through 5 days...medium...60 percent.

老農民版夜神月

FWC-N 發布TCFA
NHC展望提升至70%

WTNT21 KNGU 131600
SUBJ/TROPICAL CYCLONE FORMATION ALERT (97L)//
RMKS/
1. FORMATION OF A SIGNIFICANT TROPICAL CYCLONE IS POSSIBLE WITHIN
100 NM EITHER SIDE OF A LINE FROM 16.7N 27.0W TO 20.5N 27.7W
WITHIN THE NEXT 24 HOURS. AVAILABLE DATA DOES NOT JUSTIFY
ISSUANCE OF NUMBERED TROPICAL CYCLONE WARNINGS AT THIS TIME.
WINDS IN THE AREA ARE ESTIMATED TO BE 20 TO 25 KNOTS. SYNOPTIC
DATA AND RADAR DATA AT 130600Z INDICATE THAT A CIRCULATION CENTER
IS LOCATED NEAR 16.9N 26.8W. THE SYSTEM IS MOVING 348 DEGREES AT
10 KNOTS.
2.A LARGE AREA OF SHOWERS AND THUNDERSTORMS ASSOCIATED
WITH AN ELONGATED AREA OF LOW PRESSURE WEST OF THE CABO VERDE
ISLANDS HAS BECOME BETTER ORGANIZED. ENVIRONMENTAL CONDITIONS ARE
CONDUCIVE FOR FURTHER DEVELOPMENT, AND A TROPICAL DEPRESSION IS
LIKELY TO FORM WITHIN THE NEXT DAY OR SO WHILE THE SYSTEM MOVES
NORTH-NORTHWESTWARD AT 10 KNOTS IN THE EASTERN PORTION OF THE
TROPICAL ATLANTIC.
3. THIS ALERT WILL BE REISSUED, UPGRADED TO WARNING OR
CANCELLED BY 141600Z.//

2. Satellite-derived wind data from this morning indicated that the
circulation associated with an area of low pressur located a
couple of hundred miles west-northwest of the Cabo Verde Islands
remains elongated.  However, environmental conditions are conducive
for a short-lived tropical depression to form over the next day or
so while the low moves north-northwestward at 5 to 10 mph.  
Development is not expected by Tuesday when the system is forecast
to encounter strong upper-level winds and move over colder waters.
* Formation chance through 48 hours...high...70 percent.
* Formation chance through 5 days...high...70 percent.

老農民版夜神月

09Z升格21L,預測將短暫成為TS

WTNT41 KNHC 140950
TCDAT1

Tropical Depression Twenty-One Special Discussion Number   1
NWS National Hurricane Center Miami FL       AL212020
900 AM CVT Mon Sep 14 2020

First-light visible satellite imagery indicates that the low
pressure system that moved off the coast of Africa a few days ago
has continued to become better organized overnight. Scatterometer
surface wind data from around 13/2200 UTC indicated that the
circulation had become better defined, and that surface winds of
25-28 kt existed in the southwestern quadrant. Since then, deep
convection has increased, and it is presumed that the surface winds
and circulation definition have increased in response, which
justifies the initiation of advisories on TD-21.

The initial motion estimate is an uncertain 355/05 kt. The cyclone
is forecast to gradually move northward today and northwestward
tonight as the depression moves around the eastern end of the
eastern Atlantic/west African monsoon trough. By Tuesday night and
continuing into Wednesday and Thursday, a west-northwestward to
westward motion along the southern periphery of a deep-layer ridge
is expected. The NHC track forecast lies down the middle of the
surprisingly tightly packed guidance envelope, and is similar to
the consensus model TVCA.

The depression is expected to be short-lived as a tropical cyclone.
Having said that, there is a narrow window of opportunity today and
tonight for the cyclone to strengthen into a tropical storm before
strong westerly shear in excess of 30 kt is forecast to induce rapid
weakening on Tuesday. The cyclone is expected to degenerate into a
remnant low by Tuesday night, and then dissipate over water on
Friday, if not sooner.

FORECAST POSITIONS AND MAX WINDS

INIT  14/1000Z 18.5N  28.3W   30 KT  35 MPH
12H  14/1800Z 19.6N  28.6W   35 KT  40 MPH
24H  15/0600Z 20.5N  29.6W   30 KT  35 MPH
36H  15/1800Z 21.3N  30.9W   25 KT  30 MPH
48H  16/0600Z 21.9N  32.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
60H  16/1800Z 22.4N  34.8W   20 KT  25 MPH...POST-TROP/REMNT LOW
72H  17/0600Z 22.8N  36.9W   20 KT  25 MPH...POST-TROP/REMNT LOW
96H  18/0600Z 23.4N  41.0W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  19/0600Z...DISSIPATED

$$
Forecaster Stewart/Beven

t02436

北大連發，15Z命名Vicky。

197
WTNT41 KNHC 141440
TCDAT1

Tropical Storm Vicky Discussion Number   2
NWS National Hurricane Center Miami FL       AL212020
200 PM CVT Mon Sep 14 2020

A METOP A/B ASCAT scatterometer pass over the cyclone showed a large
swath of winds in the northeast quadrant on the order of 35 to 39
kt.  Deep convection in that region of the cyclone continues to
increase as well as near the center of circulation.  Accordingly,
the initial intensity is raised to 40 kt, making this the twentieth
named storm of the season.  This should be a short-lived tropical
cyclone, however, as increasing southwesterly shear is expected to
quickly weaken Vicky to a depression in a couple days, and the
system is expected to degenerate to a remnant low Thursday.  This
scenario is based on a combination of the global models and the
ECMWF and FV3 SHIPS statistical-dynamical intensity models.

The initial motion estimate is an uncertain 325/05 kt. The cyclone
is forecast to move northwestward with some increase in forward
speed during the next 24 hours within the low to mid-level steering
flow produced by the eastern end of the African monsoon trough.  By
Tuesday night, Vicky should turn west-northwestward to westward
along the southern periphery of a subtropical ridge over the
eastern Atlantic. The official track forecast is close to the
various consensus aids and is just to the north of the previous
advisory beyond 36 hours.

FORECAST POSITIONS AND MAX WINDS

INIT  14/1500Z 18.7N  28.5W   40 KT  45 MPH
12H  15/0000Z 19.6N  29.3W   40 KT  45 MPH
24H  15/1200Z 20.6N  30.5W   35 KT  40 MPH
36H  16/0000Z 21.6N  32.4W   35 KT  40 MPH
48H  16/1200Z 22.2N  34.6W   30 KT  35 MPH
60H  17/0000Z 22.7N  36.8W   25 KT  30 MPH...POST-TROP/REMNT LOW
72H  17/1200Z 23.0N  39.0W   25 KT  30 MPH...POST-TROP/REMNT LOW
96H  18/1200Z 23.1N  42.2W   20 KT  25 MPH...POST-TROP/REMNT LOW
120H  19/1200Z...DISSIPATED

$$
Forecaster Roberts

老農民版夜神月

今年的大西洋真的誇張,最快命名風暴紀錄瘋狂刷新中
而光是這種非洲波氣旋都不知道有多少顆了...

老農民版夜神月

於21Z退化為殘餘低氣壓，NHC對其發出最終報

921
WTNT41 KNHC 172039
TCDAT1

Post-Tropical Cyclone Vicky Discussion Number  15
NWS National Hurricane Center Miami FL       AL212020
500 PM AST Thu Sep 17 2020

There has not been any organized deep convection near the center of
Vicky in more than 12 hours as very strong vertical wind shear
continues to take a toll on the cyclone.  Vicky has become a swirl
of low clouds and no longer meets the definition of a tropical
cyclone.  Therefore, the system is being declared a remnant low and
this will be the last NHC advisory on Vicky.  The Dvorak CI-number
from TAFB suggests that the intensity of the system has fallen to 25
kt, which is the basis for the advisory wind speed. Very strong
vertical wind shear associated with outflow from Hurricane Teddy is
expected to continue to cause the remnant low to weaken, and the
system is expected to degenerate into a trough of low pressure in 24
to 36 hours.  The official forecast follows suit and calls for
dissipation by early Saturday.

Vicky is now moving west-southwestward or 250/10 kt. The remnant low
should remain on a west-southwestward heading while it is steered
by the low-level northeasterly trade wind flow over the next day or
so. The latest NHC track forecast is near the various consensus
aids and in the middle of the tightly clustered dynamical models.

This is the last NHC advisory on Vicky. Additional information on
the remnant low can be found in High Seas Forecasts issued by the
National Weather Service, under AWIPS header NFDHSFAT1, WMO header
FZNT01 KWBC, and online at ocean.weather.gov/shtml/NFDHSFAT1.php

FORECAST POSITIONS AND MAX WINDS

INIT  17/2100Z 21.1N  39.1W   25 KT  30 MPH...POST-TROPICAL
12H  18/0600Z 20.6N  40.4W   25 KT  30 MPH...POST-TROP/REMNT LOW
24H  18/1800Z 19.9N  42.1W   20 KT  25 MPH...POST-TROP/REMNT LOW
36H  19/0600Z...DISSIPATED

$$
Forecaster Brown