Tropical Storm Vicky

Post Tropical Vicky Track 1700 Hours September 17 2020
Post Tropical Vicky Track 1700 Hours September 17 2020

Tropical Storm Vicky Wind Speed FieldTropical Storm VickyNWS National Hurricane Center Miami FL 500 PM AST Thu Sep 17, 2020 (see Thurs video below)

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.

FORECAST POSITIONS AND MAX WINDS

INIT  17/2100Z 21.1N  39.1W   25 KT  30 MPH - Post Tropical (WSW Cape Verde Islands)
 12H  18/0600Z 20.6N  40.4W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 24H  18/1800Z 19.9N  42.1W   20 KT  25 MPH - Low (WSW Cape Verde Islands)
 36H  19/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Thu Sep 17, 2020 

Vicky is feeling the affects of very strong upper-level winds associated with the outflow of Hurricane Teddy. These winds have caused the remaining convection to be stripped well away from the center, and recent ASCAT data indicates that Vicky has weakened to a tropical depression. The ASCAT data support a peak wind speed of 30 kt. Vertical wind shear of 40-50 kt is forecast to continue plaguing Vicky, and the cyclone should continue to weaken and become a remnant low later today. The global models indicate that the circulation will open up into a trough within 36 to 48 hours, and the official forecast calls for dissipation within that time period.

Now that Vicky has become a vertically shallow cyclone, it has turned south of due west and is moving 260/12 kt. Vicky or its remnants should turn west-southwestward later today as it is steered by the low-level northeasterly flow. The latest NHC track forecast is in best agreement with the HFIP corrected consensus model.

FORECAST POSITIONS AND MAX WINDS

INIT  17/1500Z 21.4N  38.2W   30 KT  35 MPH - Depression (WSW Cape Verde Islands)
 12H  18/0000Z 21.0N  39.6W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 24H  18/1200Z 20.4N  41.3W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 36H  19/0000Z 19.6N  43.0W   20 KT  25 MPH - Low (WSW Cape Verde Islands)
 48H  19/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM AST Wed Sep 16, 2020 

A layer of cirrus clouds are covering the center of Vicky, but those clouds are associated with outflow from Hurricane Teddy. A combination of outflow from Teddy and an upper-level low to the north of Vicky is causing very strong westerly winds across the top of the struggling tropical storm. As a result, Vicky is producing minimal convection that is displaced to the east of the center. Recent ASCAT data indicated that the maximum winds are still near 35 kt, but Vicky’s wind field is becoming smaller and the system is on the overall decline. There is no indication that the shear will decrease and Vicky should weaken as a result. The NHC forecast calls for Vicky to become a remnant low within 24 hours (if not sooner) and dissipate in a few days.

Vicky is still heading generally westward. The tropical storm will likely continue westward through tomorrow morning, and then turn west-southwestward in the low-level tradewind flow after that for as long as it lasts. There is little spread in the track guidance and the NHC forecast is essentially the same as the multi-model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  17/0300Z 21.6N  35.8W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Islands)
 12H  17/1200Z 21.6N  37.1W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Islands)
 24H  18/0000Z 21.0N  39.0W   30 KT  35 MPH - Low (WSW Cape Verde Islands)
 36H  18/1200Z 20.2N  40.6W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 48H  19/0000Z 19.4N  42.3W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 60H  19/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM AST Wed Sep 16, 2020 

There’s been little change in Vicky’s cloud pattern this afternoon. What’s left of the deep convection associated with Vicky is displaced well to the east of the center. Cirrus clouds produced by the outflow of Hurricane Teddy, located nearly 1000 miles to the west-southwest of Vicky, are obscuring the sheared surface circulation. The initial intensity is held at 35 kt for this advisory in deference to the earlier scatterometer pass and due to the fact that the cloud pattern has remained unchanged.

The UW-CIMSS SAT-Wind/shear products and water vapor imagery reveal an interesting upper wind pattern consisting of an upper low just to the west of Vicky and a narrow upper-tropospheric ridge to the south of the cyclone. These upper-level features are temporarily creating a very diffluent pattern which appears to be offsetting the blistering westerly shear a bit. In any event, Vicky is still forecast to gradually lose strength and degenerate to a remnant low on Friday, which is in best agreement with the global models and the statistical-dynamical intensity aids.

The initial motion estimate is more westward, or 270/08. Vicky should continue moving westward for the next day or two before turning west-southwestward in the low-level tradewind flow. The new NHC track forecast is south of the previous one and is close to the HCCA and TCVA multi-model consensus guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  16/2100Z 21.5N  35.7W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Islands)
 12H  17/0600Z 21.6N  37.0W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Islands)
 24H  17/1800Z 21.3N  38.9W   30 KT  35 MPH - Depression (WSW Cape Verde Islands)
 36H  18/0600Z 20.6N  40.7W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 48H  18/1800Z 19.8N  42.3W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 60H  19/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Wed Sep 16, 2020 

Hostile vertical shear of 50 to 60 kt has finally taken a toll on Vicky. A 1227 UTC ASCAT-B overpass showed peak winds of 35 kt north of the center, and that is the basis for the advisory intensity. The strong shear is expected to continue while Vicky moves over marginal 26-27C SSTs, so additional weakening is forecast. Vicky should become a tropical depression in around 24 hours before weakening to a remnant low in about 2 days, with dissipation expected by day 3. However, the timing of when organized deep convection will finally cease is difficult to determine, so its is possible Vicky could weaken faster than indicated here or hang on a bit longer. The initial motion estimate is more westward, or 270/08.

Vicky should continue moving westward for the next day or two before turning west-southwestward in the low-level flow. The new NHC track forecast is south of the previous one and is close to the new multi-model consensus aids. The ASCAT data were also used to modify the initial 34-kt wind radii.

FORECAST POSITIONS AND MAX WINDS

INIT  16/1500Z 21.5N  34.7W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Islands)
 12H  17/0000Z 21.6N  36.0W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Islands)
 24H  17/1200Z 21.7N  37.7W   30 KT  35 MPH - Depression (WSW Cape Verde Islands)
 36H  18/0000Z 21.5N  39.5W   30 KT  35 MPH - Depression (WSW Cape Verde Islands)
 48H  18/1200Z 21.0N  41.1W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 60H  19/0000Z 20.5N  42.8W   20 KT  25 MPH - Low (WSW Cape Verde Islands)
 72H  19/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM AST Tue Sep 15, 2020 

Vicky provided a surprise this evening, with scatterometer data showing a solid 45-kt in the northwestern quadrant of the storm. You would never guess it from the satellite images, which show a very sheared system that would at best support an 30-35 kt intensity, as indicated by the latest Dvorak estimates. The initial wind speed is set to 45 kt, higher than the last time but not really a true strengthening since conventional satellite data was a bit deceptive earlier. Despite Vicky holding its own, models are still showing the strong shear persisting, which should eventually cause weakening. The cyclone is likely to last longer than previously anticipated though with some upper-level divergence counteracting the effects of the shear, but Vicky is forecast gradually lose strength and decay in a remnant low in a couple of days, similar to the consensus guidance.

The storm continues to more west-northwestward, a little to the left of previous, at 290/10. Vicky should gradually turn westward tomorrow and west-southwestward later this week as it becomes a shallower cyclone. The new forecast is quite similar to the previous one, leaning on the northern side of the well-clustered guidance envelope since Vicky is persisting as a deeper cyclone for the moment. The only small change is to add a 72-hour forecast point as the remnants could linger for a while longer.

FORECAST POSITIONS AND MAX WINDS

INIT  16/0300Z 21.6N  33.1W   45 KT  50 MPH - Tropical Storm (WSW Cape Verde Islands)
 12H  16/1200Z 22.0N  34.5W   40 KT  45 MPH - Tropical Storm (WSW Cape Verde Islands)
 24H  17/0000Z 22.3N  36.3W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Islands)
 36H  17/1200Z 22.4N  38.0W   30 KT  35 MPH - Depression (WSW Cape Verde Islands)
 48H  18/0000Z 22.3N  39.7W   30 KT  35 MPH - Low (WSW Cape Verde Islands)
 60H  18/1200Z 22.0N  41.5W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 72H  19/0000Z 21.5N  43.5W   20 KT  25 MPH - Low (WSW Cape Verde Islands)
 96H  20/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM AST Tue Sep 15, 2020 

Vicky continues to be blasted by around 50 kt of westerly shear, with deep convection being continually removed from the center. Overall the coverage and intensity of the deep convection has decreased since this morning, and the initial intensity has been set to 40 kt based on a blend of the latest Dvorak estimates (30-35 kt) and SATCON (45 kt). The high shear is expected to persist, and that in combination with marginal SSTs should result in weakening, and Vicky is expected to become a remnant low in around 36 hours, with dissipation expected in about 3 days. The new NHC intensity forecast is close to HCCA and the IVCN consensus aids.

The initial motion estimate is a bit faster toward the west-northwest or 300/10. Vicky should continue west-northwestward for the next 12 to 24 hours and then turn westward in the low-level flow before dissipation. The new NHC track forecast is similar to the previous one, near the middle of the guidance envelope, and has been adjusted a bit slower toward the latest consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT  15/2100Z 21.2N  32.1W   40 KT  45 MPH - Tropical Storm (WSW Cape Verde Islands)
 12H  16/0600Z 21.6N  33.4W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Islands)
 24H  16/1800Z 22.1N  35.2W   30 KT  35 MPH - Depression (WSW Cape Verde Islands)
 36H  17/0600Z 22.4N  37.0W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 48H  17/1800Z 22.4N  38.7W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 60H  18/0600Z 22.2N  40.4W   20 KT  25 MPH - Low (WSW Cape Verde Islands)
 72H  18/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 200 AM CVT Tue Sep 15, 2020

Vicky continues to be highly sheared due to strong upper- tropospheric flow associated with a nearby trough, and its associated deep convection is confined to a small cluster to the northeast of the center. An ASCAT overpass from a few hours ago showed an area of winds to just over 40 kt over the northern semicircle and, based on sampling limitations, the current intensity has been adjusted to 45 kt. The storm is not likely to maintain its intensity, since the dynamical guidance indicates that the shear over the cyclone will become even stronger during the next day or so. Therefore steady weakening is anticipated, and Vicky is likely to become a remnant low in about 36 hours. The official intensity forecast is near or slightly below the latest model consensus.

Center fixes give a slow northwestward motion, or 315/6 kt. A narrow and weak low- to mid-level ridge to the north of Vicky should result in a northwestward to west-northwestward motion into early Wednesday. Thereafter, when the system will have probably have lost most of its deep convection, the shallow cyclone is likely to move mainly westward following the low-level environmental winds. The official track forecast is close to previous one and about in the middle of the guidance suite.

FORECAST POSITIONS AND MAX WINDS

INIT  15/0300Z 19.5N  29.9W   45 KT  50 MPH - Tropical Storm (WSW Cape Verde Islands)
 12H  15/1200Z 20.5N  31.0W   40 KT  45 MPH - Tropical Storm (WSW Cape Verde Islands)
 24H  16/0000Z 21.4N  32.7W   35 KT  40 MPH - Tropical Storm (WSW Cape Verde Islands)
 36H  16/1200Z 22.0N  34.8W   30 KT  35 MPH - Low (WSW Cape Verde Islands)
 48H  17/0000Z 22.3N  37.0W   30 KT  35 MPH - Low (WSW Cape Verde Islands)
 60H  17/1200Z 22.5N  39.0W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 72H  18/0000Z 22.5N  41.0W   25 KT  30 MPH - Low (WSW Cape Verde Islands)
 96H  19/0000Z 22.5N  44.5W   20 KT  25 MPH - Low (WSW Cape Verde Islands)
120H  20/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 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 - Tropical Storm (WNW Cape Verde Islands)
 12H  15/0600Z 20.1N  30.3W   35 KT  40 MPH - Tropical Storm (WNW Cape Verde Islands)
 24H  15/1800Z 21.2N  31.9W   35 KT  40 MPH - Tropical Storm (WNW Cape Verde Islands)
 36H  16/0600Z 22.0N  33.8W   30 KT  35 MPH - Low (WNW Cape Verde Islands)
 48H  16/1800Z 22.5N  35.9W   25 KT  30 MPH - Low (WNW Cape Verde Islands)
 60H  17/0600Z 22.9N  38.0W   25 KT  30 MPH - Low (WNW Cape Verde Islands)
 72H  17/1800Z 23.0N  39.9W   25 KT  30 MPH - Low (WNW Cape Verde Islands)
 96H  18/1800Z 23.1N  43.5W   20 KT  25 MPH - Low (WNW Cape Verde Islands)
120H  19/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 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 - Tropical Storm (WNW Cape Verde Islands)
 12H  15/0000Z 19.6N  29.3W   40 KT  45 MPH - Tropical Storm (WNW Cape Verde Islands)
 24H  15/1200Z 20.6N  30.5W   35 KT  40 MPH - Tropical Storm (WNW Cape Verde Islands)
 36H  16/0000Z 21.6N  32.4W   35 KT  40 MPH - Tropical Storm (WNW Cape Verde Islands)
 48H  16/1200Z 22.2N  34.6W   30 KT  35 MPH - Depression (WNW Cape Verde Islands)
 60H  17/0000Z 22.7N  36.8W   25 KT  30 MPH - Low (WNW Cape Verde Islands)
 72H  17/1200Z 23.0N  39.0W   25 KT  30 MPH - Low (WNW Cape Verde Islands)
 96H  18/1200Z 23.1N  42.2W   20 KT  25 MPH - Low (WNW Cape Verde Islands)

NWS National Hurricane Center Miami FL 800 PM EDT Sun Sep 13, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Hurricane Paulette, located over the western Atlantic, on Tropical Depression Rene, located over the central Atlantic, on Tropical Storm Sally, centered over the northeastern Gulf of Mexico, and on Tropical Depression Twenty, located over the east-central tropical Atlantic.

  • 1. A weak area of low pressure over the west-central Gulf of Mexico continues to produce limited shower activity. Any development of this system is expected to be slow to occur while it moves southwestward and then southward at 5 to 10 mph over the western Gulf of Mexico during the next few days. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…20 percent.
  • 2. An elongated area of low pressure located a couple of hundred miles west-northwest of the Cabo Verde Islands continues to produce an area of showers and thunderstorms. Environmental conditions are conducive for a short-lived tropical depression to form on Monday 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.
  • 3. A tropical wave is forecast to move off the west coast of Africa on Monday. Some slow development of the system is possible by the middle or late part of the week as the wave moves westward at about 10 mph over the far eastern tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 200 PM EDT Sun Sep 13, 2020

For the North Atlantic…Caribbean Sea and the Gulf of Mexico:

The National Hurricane Center is issuing advisories on Hurricane Paulette, located over the western Atlantic, on Tropical Depression Rene, located over the central Atlantic, on Tropical Storm Sally, centered over the northeastern Gulf of Mexico, and on Tropical Depression Twenty, located over the eastern tropical Atlantic.

  • 1. A surface trough over the west-central Gulf of Mexico continues to produce limited shower activity. Any development of this system is expected to be slow to occur while it moves southwestward and then southward at 5 to 10 mph over the western Gulf of Mexico during the next few days. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…20 percent.
  • 2. Satellite-derived wind data from this morning indicated that the circulation associated with an area of low pressure 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.
  • 3. A tropical wave is forecast to move off the west coast of Africa on Monday. Some gradual development of the system is possible by the middle of the week as the wave moves westward at about 10 mph over the far eastern tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

If this system is named, it will become Tropical Storm Vicky.

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