Tropical Depression Twenty-One Special Advisory Number 1
NWS National Hurricane Center Miami FL AL212020
900 AM CVT Mon Sep 14 2020
...NEW TROPICAL DEPRESSION FORMS OVER THE FAR EASTERN TROPICAL
ATLANTIC...
...EXPECTED TO BE SHORT-LIVED...
SUMMARY OF 900 AM CVT...1000 UTC...INFORMATION
----------------------------------------------
LOCATION...18.5N 28.3W
ABOUT 330 MI...535 KM WNW OF THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...N OR 355 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
DISCUSSION AND OUTLOOK
----------------------
At 900 AM CVT (1000 UTC), the center of newly formed Tropical
Depression Twenty-One was located near latitude 18.5 North,
longitude 28.3 West. The depression is moving toward the north near
6 mph (9 km/h) and this motion is forecast to continue into this
afternoon, followed by a turn toward the northwest tonight, with a
west-northwestward motion expected on Tuesday and Wednesday.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Some slight strengthening could occur today and tonight, and the
depression could briefly become a tropical storm during that time.
Weakening is expected to begin by Tuesday night, if not sooner, and
continue into Wednesday and Thursday.
The estimated minimum central pressure is 1009 mb (29.80 inches).
HAZARDS AFFECTING LAND
----------------------
None.
NEXT ADVISORY
-------------
Next complete advisory at 200 PM CVT.
$$
Forecaster Stewart/Beven
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
BULLETIN
Tropical Storm Vicky Advisory Number 2
NWS National Hurricane Center Miami FL AL212020
200 PM CVT Mon Sep 14 2020
...DEPRESSION BECOMES THE TWENTIETH NAMED STORM OF THE 2020
ATLANTIC HURRICANE SEASON...
...VICKY IS EXPECTED TO BE SHORT-LIVED...
SUMMARY OF 200 PM CVT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...18.7N 28.5W
ABOUT 350 MI...565 KM WNW OF THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
DISCUSSION AND OUTLOOK
----------------------
At 200 PM CVT (1500 UTC), the center of Tropical Storm Vicky was
located near latitude 18.7 North, longitude 28.5 West. Vicky is
moving toward the northwest near 6 mph (9 km/h) and this motion is
forecast to continue into this afternoon. A turn toward the
northwest is forecast tonight, with a west-northwestward motion
expected on Tuesday and Wednesday.
Maximum sustained winds have increased to near 45 mph (75 km/h)
with higher gusts. Little change in strength is expected during
the next day or so. Weakening is expected to begin by Tuesday
night and Vicky is forecast to degenerate to a remnant low on
Thursday.
Tropical-storm-force winds extend outward up to 105 miles (165 km)
from the center.
The estimated minimum central pressure is 1002 mb (29.59 inches).
HAZARDS AFFECTING LAND
----------------------
None.
NEXT ADVISORY
-------------
Next complete advisory at 800 PM CVT.
$$
Forecaster Roberts
Tropical Storm Vicky Discussion Number 2
NWS National Hurricane Center Miami FL AL212020
200 PM CVT Mon Sep 14 2020
A METOP A/B ASCAT scatterometer pass over the cyclone showed a large
swath of winds in the northeast quadrant on the order of 35 to 39
kt. Deep convection in that region of the cyclone continues to
increase as well as near the center of circulation. Accordingly,
the initial intensity is raised to 40 kt, making this the twentieth
named storm of the season. This should be a short-lived tropical
cyclone, however, as increasing southwesterly shear is expected to
quickly weaken Vicky to a depression in a couple days, and the
system is expected to degenerate to a remnant low Thursday. This
scenario is based on a combination of the global models and the
ECMWF and FV3 SHIPS statistical-dynamical intensity models.
The initial motion estimate is an uncertain 325/05 kt. The cyclone
is forecast to move northwestward with some increase in forward
speed during the next 24 hours within the low to mid-level steering
flow produced by the eastern end of the African monsoon trough. By
Tuesday night, Vicky should turn west-northwestward to westward
along the southern periphery of a subtropical ridge over the
eastern Atlantic. The official track forecast is close to the
various consensus aids and is just to the north of the previous
advisory beyond 36 hours.
FORECAST POSITIONS AND MAX WINDS
INIT 14/1500Z 18.7N 28.5W 40 KT 45 MPH
12H 15/0000Z 19.6N 29.3W 40 KT 45 MPH
24H 15/1200Z 20.6N 30.5W 35 KT 40 MPH
36H 16/0000Z 21.6N 32.4W 35 KT 40 MPH
48H 16/1200Z 22.2N 34.6W 30 KT 35 MPH
60H 17/0000Z 22.7N 36.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 17/1200Z 23.0N 39.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 18/1200Z 23.1N 42.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 19/1200Z...DISSIPATED
$$
Forecaster Roberts
BULLETIN
Tropical Storm Vicky Advisory Number 3
NWS National Hurricane Center Miami FL AL212020
800 PM CVT Mon Sep 14 2020
...VICKY EXPECTED TO WEAKEN OVERNIGHT...
SUMMARY OF 800 PM CVT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...19.3N 29.5W
ABOUT 430 MI...690 KM WNW OF THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
DISCUSSION AND OUTLOOK
----------------------
At 800 PM CVT (2100 UTC), the center of Tropical Storm Vicky was
located near latitude 19.3 North, longitude 29.5 West. Vicky is
moving toward the northwest near 7 mph (11 km/h). A continued
northwestward motion is expected through early Tuesday, followed by
a gradual turn toward the west by Wednesday.
Maximum sustained winds are near 45 mph (75 km/h) with higher gusts.
Gradual weakening is anticipated, and Vicky is forecast to become a
remnant low during the next day or two.
Tropical-storm-force winds extend outward up to 105 miles (165 km)
from the center.
The estimated minimum central pressure is 1002 mb (29.59 inches).
HAZARDS AFFECTING LAND
----------------------
None.
NEXT ADVISORY
-------------
Next complete advisory at 200 AM CVT.
$$
Forecaster Zelinsky
Tropical Storm Vicky Discussion Number 3
NWS National Hurricane Center Miami FL AL212020
800 PM CVT Mon Sep 14 2020
Vicky is severely sheared by strong upper-level westerly winds. The
initial intensity is held at 40 kt based on earlier ASCAT data, but
it is entirely possible the cyclone has weakened since this morning
and all recent intensity estimates are lower. The shear is the main
factor in Vicky's forecast; it is expected to increase substantially
(up to 60 kt in 24 h in GFS-SHIPS diagnostics) and should cause the
cyclone to weaken. The NHC forecast now shows Vicky becoming a
remnant low in 36 hours, and it would not be surprising if it
happens sooner than that given the very hostile environment. After
Vicky loses all of its convection, the dynamical models suggest that
it will take a couple more days for the remnant low to spin down and
open into a trough.
Vicky's movement has been somewhat erratic since it formed, but a
long-term motion estimate is 325/6 kt. A continued northwestward
motion is forecast for the next 12 to 24 hours, followed by a turn
toward the west as Vicky weakens and is increasingly steered by
low-level easterly winds. The NHC track forecast is based on the
TVCN and HCCA consensus aids and is practically on top of the
previous forecast.
FORECAST POSITIONS AND MAX WINDS
INIT 14/2100Z 19.3N 29.5W 40 KT 45 MPH
12H 15/0600Z 20.1N 30.3W 35 KT 40 MPH
24H 15/1800Z 21.2N 31.9W 35 KT 40 MPH
36H 16/0600Z 22.0N 33.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 16/1800Z 22.5N 35.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 17/0600Z 22.9N 38.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 17/1800Z 23.0N 39.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 18/1800Z 23.1N 43.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 19/1800Z...DISSIPATED
$$
Forecaster Zelinsky
NWS National Hurricane Center Miami FL AL212020
900 AM CVT Mon Sep 14 2020
...NEW TROPICAL DEPRESSION FORMS OVER THE FAR EASTERN TROPICAL
ATLANTIC...
...EXPECTED TO BE SHORT-LIVED...
SUMMARY OF 900 AM CVT...1000 UTC...INFORMATION
----------------------------------------------
LOCATION...18.5N 28.3W
ABOUT 330 MI...535 KM WNW OF THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...35 MPH...55 KM/H
PRESENT MOVEMENT...N OR 355 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1009 MB...29.80 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
DISCUSSION AND OUTLOOK
----------------------
At 900 AM CVT (1000 UTC), the center of newly formed Tropical
Depression Twenty-One was located near latitude 18.5 North,
longitude 28.3 West. The depression is moving toward the north near
6 mph (9 km/h) and this motion is forecast to continue into this
afternoon, followed by a turn toward the northwest tonight, with a
west-northwestward motion expected on Tuesday and Wednesday.
Maximum sustained winds are near 35 mph (55 km/h) with higher gusts.
Some slight strengthening could occur today and tonight, and the
depression could briefly become a tropical storm during that time.
Weakening is expected to begin by Tuesday night, if not sooner, and
continue into Wednesday and Thursday.
The estimated minimum central pressure is 1009 mb (29.80 inches).
HAZARDS AFFECTING LAND
----------------------
None.
NEXT ADVISORY
-------------
Next complete advisory at 200 PM CVT.
$$
Forecaster Stewart/Beven
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
BULLETIN
Tropical Storm Vicky Advisory Number 2
NWS National Hurricane Center Miami FL AL212020
200 PM CVT Mon Sep 14 2020
...DEPRESSION BECOMES THE TWENTIETH NAMED STORM OF THE 2020
ATLANTIC HURRICANE SEASON...
...VICKY IS EXPECTED TO BE SHORT-LIVED...
SUMMARY OF 200 PM CVT...1500 UTC...INFORMATION
----------------------------------------------
LOCATION...18.7N 28.5W
ABOUT 350 MI...565 KM WNW OF THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 6 MPH...9 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
DISCUSSION AND OUTLOOK
----------------------
At 200 PM CVT (1500 UTC), the center of Tropical Storm Vicky was
located near latitude 18.7 North, longitude 28.5 West. Vicky is
moving toward the northwest near 6 mph (9 km/h) and this motion is
forecast to continue into this afternoon. A turn toward the
northwest is forecast tonight, with a west-northwestward motion
expected on Tuesday and Wednesday.
Maximum sustained winds have increased to near 45 mph (75 km/h)
with higher gusts. Little change in strength is expected during
the next day or so. Weakening is expected to begin by Tuesday
night and Vicky is forecast to degenerate to a remnant low on
Thursday.
Tropical-storm-force winds extend outward up to 105 miles (165 km)
from the center.
The estimated minimum central pressure is 1002 mb (29.59 inches).
HAZARDS AFFECTING LAND
----------------------
None.
NEXT ADVISORY
-------------
Next complete advisory at 800 PM CVT.
$$
Forecaster Roberts
Tropical Storm Vicky Discussion Number 2
NWS National Hurricane Center Miami FL AL212020
200 PM CVT Mon Sep 14 2020
A METOP A/B ASCAT scatterometer pass over the cyclone showed a large
swath of winds in the northeast quadrant on the order of 35 to 39
kt. Deep convection in that region of the cyclone continues to
increase as well as near the center of circulation. Accordingly,
the initial intensity is raised to 40 kt, making this the twentieth
named storm of the season. This should be a short-lived tropical
cyclone, however, as increasing southwesterly shear is expected to
quickly weaken Vicky to a depression in a couple days, and the
system is expected to degenerate to a remnant low Thursday. This
scenario is based on a combination of the global models and the
ECMWF and FV3 SHIPS statistical-dynamical intensity models.
The initial motion estimate is an uncertain 325/05 kt. The cyclone
is forecast to move northwestward with some increase in forward
speed during the next 24 hours within the low to mid-level steering
flow produced by the eastern end of the African monsoon trough. By
Tuesday night, Vicky should turn west-northwestward to westward
along the southern periphery of a subtropical ridge over the
eastern Atlantic. The official track forecast is close to the
various consensus aids and is just to the north of the previous
advisory beyond 36 hours.
FORECAST POSITIONS AND MAX WINDS
INIT 14/1500Z 18.7N 28.5W 40 KT 45 MPH
12H 15/0000Z 19.6N 29.3W 40 KT 45 MPH
24H 15/1200Z 20.6N 30.5W 35 KT 40 MPH
36H 16/0000Z 21.6N 32.4W 35 KT 40 MPH
48H 16/1200Z 22.2N 34.6W 30 KT 35 MPH
60H 17/0000Z 22.7N 36.8W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 17/1200Z 23.0N 39.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 18/1200Z 23.1N 42.2W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 19/1200Z...DISSIPATED
$$
Forecaster Roberts
BULLETIN
Tropical Storm Vicky Advisory Number 3
NWS National Hurricane Center Miami FL AL212020
800 PM CVT Mon Sep 14 2020
...VICKY EXPECTED TO WEAKEN OVERNIGHT...
SUMMARY OF 800 PM CVT...2100 UTC...INFORMATION
----------------------------------------------
LOCATION...19.3N 29.5W
ABOUT 430 MI...690 KM WNW OF THE CABO VERDE ISLANDS
MAXIMUM SUSTAINED WINDS...45 MPH...75 KM/H
PRESENT MOVEMENT...NW OR 325 DEGREES AT 7 MPH...11 KM/H
MINIMUM CENTRAL PRESSURE...1002 MB...29.59 INCHES
WATCHES AND WARNINGS
--------------------
There are no coastal watches or warnings in effect.
DISCUSSION AND OUTLOOK
----------------------
At 800 PM CVT (2100 UTC), the center of Tropical Storm Vicky was
located near latitude 19.3 North, longitude 29.5 West. Vicky is
moving toward the northwest near 7 mph (11 km/h). A continued
northwestward motion is expected through early Tuesday, followed by
a gradual turn toward the west by Wednesday.
Maximum sustained winds are near 45 mph (75 km/h) with higher gusts.
Gradual weakening is anticipated, and Vicky is forecast to become a
remnant low during the next day or two.
Tropical-storm-force winds extend outward up to 105 miles (165 km)
from the center.
The estimated minimum central pressure is 1002 mb (29.59 inches).
HAZARDS AFFECTING LAND
----------------------
None.
NEXT ADVISORY
-------------
Next complete advisory at 200 AM CVT.
$$
Forecaster Zelinsky
Tropical Storm Vicky Discussion Number 3
NWS National Hurricane Center Miami FL AL212020
800 PM CVT Mon Sep 14 2020
Vicky is severely sheared by strong upper-level westerly winds. The
initial intensity is held at 40 kt based on earlier ASCAT data, but
it is entirely possible the cyclone has weakened since this morning
and all recent intensity estimates are lower. The shear is the main
factor in Vicky's forecast; it is expected to increase substantially
(up to 60 kt in 24 h in GFS-SHIPS diagnostics) and should cause the
cyclone to weaken. The NHC forecast now shows Vicky becoming a
remnant low in 36 hours, and it would not be surprising if it
happens sooner than that given the very hostile environment. After
Vicky loses all of its convection, the dynamical models suggest that
it will take a couple more days for the remnant low to spin down and
open into a trough.
Vicky's movement has been somewhat erratic since it formed, but a
long-term motion estimate is 325/6 kt. A continued northwestward
motion is forecast for the next 12 to 24 hours, followed by a turn
toward the west as Vicky weakens and is increasingly steered by
low-level easterly winds. The NHC track forecast is based on the
TVCN and HCCA consensus aids and is practically on top of the
previous forecast.
FORECAST POSITIONS AND MAX WINDS
INIT 14/2100Z 19.3N 29.5W 40 KT 45 MPH
12H 15/0600Z 20.1N 30.3W 35 KT 40 MPH
24H 15/1800Z 21.2N 31.9W 35 KT 40 MPH
36H 16/0600Z 22.0N 33.8W 30 KT 35 MPH...POST-TROP/REMNT LOW
48H 16/1800Z 22.5N 35.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
60H 17/0600Z 22.9N 38.0W 25 KT 30 MPH...POST-TROP/REMNT LOW
72H 17/1800Z 23.0N 39.9W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 18/1800Z 23.1N 43.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 19/1800Z...DISSIPATED
$$
Forecaster Zelinsky
