Tropical Storm Nadine

Tropical Storm Nadine Track 2300 Hours October 12 2018
Tropical Storm Nadine Track 2300 Hours October 12 2018

NWS National Hurricane Center Miami FL 1100 PM AST Fri Oct 12 2018

Tropical Storm Nadine  (see 3 videos below) – ASCAT data indicate that Nadine no longer has a closed circulation nor a well-defined center. This is also confirmed by low cloud motions from GOES-16. Thus Nadine has degenerated into an open wave, and this is the last advisory on this system. The initial wind speed is reduced to 30 kt to match the value from the scatterometer. Strong shear should cause the remnants to slowly weaken as the system moves quickly westward beneath the Atlantic subtropical ridge.

FORECAST POSITIONS AND MAX WINDS

INIT  13/0300Z 16.0N  39.5W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)

NWS National Hurricane Center Miami FL 1100 AM AST Fri Oct 12 2018

Tropical Storm Nadine Strong southwesterly shear has caused the center of Nadine to become well removed from the deep convection this morning. Although Dvorak satellite intensity estimates were T3.0 (45 kt) at 1200 UTC, the center has become further removed from the convection since that time, and the initial wind speed has been reduced to 40 kt for this advisory. The strong southwesterly shear is expected to persist over Nadine through the weekend, which should result in steady weakening and dissipation of the system by Sunday, if not sooner.

Nadine took a northwestward jog overnight, but now appears to have resumed a west-northwestward heading at about 7 kt. As the storm weakens and becomes a shallower system it should turn westward and accelerate within the low-level trade wind flow. The more northward initial position has required a northward adjustment in the NHC track forecast, but the new forecast again takes Nadine westward until dissipation occurs.

FORECAST POSITIONS AND MAX WINDS

INIT  12/1500Z 16.0N  36.2W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  13/0000Z 16.1N  37.9W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  13/1200Z 16.3N  40.6W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  14/0000Z 16.5N  43.6W   25 KT  30 MPH - Sub- tropical Storm (WSW Mindelo, Cape Verde)
 48H  14/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM AST Thu Oct 11 2018

Tropical Storm Nadine continues to be strongly sheared. A brief burst of deep convection occurred near the center of the cyclone a few hours ago, but the center has since become exposed once again. The initial intensity has been decreased to 45 kt based primary on the latest TAFB and SAB Dvorak fixes. Additional weakening is likely over the next day or so while Nadine remains strongly sheared. The regional and global models now show Nadine degenerating into a trough of low pressure within 48 h, and this is reflected in the new NHC forecast.

The tropical storm is moving west-northwestward with an initial speed of 7 kt. The models are in good agreement that Nadine will continue on a similar heading and speed for the next 24 h or so, before turning toward the west as it weakens. The NHC forecast has been nudged to the southwest at most forecast points, and is generally near the HFIP Corrected Consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  11/2100Z 14.5N  34.9W   45 KT  50 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  12/0600Z 14.9N  36.0W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  12/1800Z 15.5N  37.7W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  13/0600Z 15.7N  40.0W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 48H  13/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Thu Oct 11 2018

Tropical Storm Nadine  is strongly sheared and the low-level center of the tropical storm is now completely exposed, nearly 50 n mi to the southwest of the nearest deep convection. Satellite intensity estimates have decreased since last night, so the intensity has been lowered to 50 kt. This value is still on the high side of the available intensity estimates, but Nadine’s intensity has generally been near the top of the intensity estimates for the past few days.

Steady weakening is still anticipated because the shear is forecast by all models to increase further during the next day or two. By 72 h, if not sooner, all of the dynamical models forecast that Nadine will have lost its deep convection and degenerated into a trough of low pressure. No significant changes were made to the NHC intensity forecast.

Nadine is still moving northwestward at 7 kt. Since Nadine’s surface circulation has become completely exposed and the vortex is likely becoming very shallow, a quicker turn toward the west-northwest and west is now shown in the official track forecast. The track forecast has therefore been adjusted toward the southwest at most forecast times, but is still close to HCCA and TVCN through the short forecast period.

FORECAST POSITIONS AND MAX WINDS

INIT  11/1500Z 14.1N  34.0W   50 KT  60 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  12/0000Z 14.8N  34.9W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  12/1200Z 15.5N  36.3W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  13/0000Z 15.9N  38.0W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 48H  13/1200Z 16.2N  40.2W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 72H  14/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM AST Wed Oct 10 2018

Tropical Storm Nadine  – Another burst of deep convection has formed near the center of Nadine, which is typical in sheared tropical cyclones. A recent ASCAT pass indicated several believable 50-55 kt winds, so the initial intensity is held at 55 kt for this advisory. The shear is only forecast to increase over the next couple of days, which should lead to weakening, especially by Friday. All of the dynamical models indicate that Nadine will degenerate into a trough of low pressure over the weekend, and no significant changes were made to the previous forecast.

Nadine continues to move northwestward due to a ridge near the Cabo Verde Islands. This general course is forecast for the next day or so until Nadine become a more shallow system, which should cause the cyclone to turn toward the west-northwest. The previous interpolated forecast came in basically on top of the new consensus and corrected-consensus guidance, so the new track forecast is very close to the previous NHC prediction.

FORECAST POSITIONS AND MAX WINDS

INIT  11/0300Z 13.6N  32.7W   55 KT  65 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  11/1200Z 14.3N  33.4W   50 KT  60 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  12/0000Z 15.3N  34.5W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  12/1200Z 16.0N  36.0W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 48H  13/0000Z 16.5N  37.5W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 72H  14/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM AST Wed Oct 10 2018

Tropical Storm Nadine  – The exposed low-level center of Nadine is now peeking out from beneath its upper cloud canopy. The initial intensity has been held at 55 kt out of respect for earlier ASCAT data, but it is possible that some weakening has occurred since this morning. Strong westerly wind shear will likely prevent Nadine from becoming any better organized going forward, so the official intensity forecast now calls for steady weakening for the next 2 days. All of the dynamical models indicate that Nadine will degenerate into a trough of low pressure within the next 72 h, and the NHC forecast now shows dissipation occuring by that point.

Nadine is moving steadily northwestward with an initial motion of 315/7 kt. As long as Nadine remains a tropical cyclone, it should stay on a similar heading, and the models are in generally good agreement on its track. The NHC track forecast has been adjusted a little to the southwest, and is generally close to the TVCX and HCCA consensus aids at all times. From 48 h onward, the cyclone or its remnant trough will likely be entirely separated from its convection and turn westward in low-level easterly flow.

FORECAST POSITIONS AND MAX WINDS

INIT  10/2100Z 13.1N  32.2W   55 KT  65 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  11/0600Z 13.8N  32.9W   50 KT  60 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  11/1800Z 14.8N  34.0W   45 KT  50 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  12/0600Z 15.7N  35.1W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 48H  12/1800Z 16.2N  36.8W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 72H  13/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Wed Oct 10 2018

Tropical Storm Nadine  Several microwave overpasses after 0600 UTC indicated that Nadine very quickly developed a well-defined mid-level eye overnight. This signature is typically associated with strengthening tropical cyclones. Although more recent visible imagery indicates that strong shear has since caused the cyclone to become tilted with height, a pair of ASCAT passes around 1200 UTC indicated maximum winds of 45-50 kt. Given the small size of the tropical storm, the ASCAT likely under-sampled the true maximum, so the initial intensity has been raised to 55 kt. Due to limitations in our ability to observe the intensity of small tropical storms far from land, it should be noted that this estimate is fairly uncertain.

Since the tropical storm appears to have become more tilted since last night, further strengthening is not likely. Shear analysis from UW-CIMSS shows that Nadine is moving into a region of 20-30 kt of westerly shear, and SHIPS diagnostics indicate that the shear could increase to near 40 kt in another couple of days. All of the intensity guidance indicates that Nadine will weaken quickly by tomorrow, and it could become a depression by 72 h. Dissipation will likely follow shortly after, as shown by nearly all of the global and regional models.

The aforementioned ASCAT passes were very helpful in locating the center of Nadine at 1200 UTC, and the tropical storm is moving northwestward, or 325/6 kt. A northwestward to north-northwestward motion at a similar forward speed is anticipated for the next day or two. By Friday, a turn toward the west will likely begin as the low-level circulation of Nadine becomes separated from its convection and turns westward in the low-level easterlies. Nadine is essentially on the track of the previous NHC forecast, and no significant changes to the track forecast were required.

FORECAST POSITIONS AND MAX WINDS

INIT  10/1500Z 12.6N  31.6W   55 KT  65 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  11/0000Z 13.5N  32.1W   55 KT  65 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  11/1200Z 14.6N  32.9W   50 KT  60 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  12/0000Z 15.7N  33.9W   45 KT  50 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 48H  12/1200Z 16.5N  35.2W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 72H  13/1200Z 17.5N  39.1W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 96H  14/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 AM AST Wed Oct 10 2018

Tropical Storm Nadine continues to gradually strengthen. Microwave images indicate that the storm is beginning to develop an inner core with a concentrated area of deep convection noted in infrared satellite imagery. The initial intensity is raised to 45 kt, in agreement with 3.0/45 kt Dvorak classifications from TAFB and SAB. Nadine has about another day to strengthen while it remains in favorable atmospheric conditions of low wind shear and high moisture, and over warm waters. The NHC intensity forecast follows the HCCA and IVCN guidance and brings Nadine to 55 kt during that time period. Thereafter, the global models all show a sharp increase in southwesterly shear and that should end the opportunity for strengthening and cause weakening. The combination of strong shear, drier air, and slightly cooler SSTs should cause the cyclone to open into a trough in 3 to 4 days, or perhaps even sooner.

The compact storm is moving north-northwestward at 6 kt, and the center is a little to the right of the previous forecast track. A continued northwest to north-northwest motion is expected during the next couple of days while Nadine moves toward a trough over the east-central Atlantic, the same trough that Leslie is embedded in. After that time, the weak and shallow system should turn to the left until dissipation. The NHC track forecast has been adjusted a little to the right of the previous one due to the more northward initial motion and position.

FORECAST POSITIONS AND MAX WINDS

INIT  10/0900Z 12.1N  31.1W   45 KT  50 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  10/1800Z 12.8N  31.7W   50 KT  60 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  11/0600Z 13.9N  32.5W   55 KT  65 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  11/1800Z 15.1N  33.4W   45 KT  50 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 48H  12/0600Z 16.0N  34.7W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 72H  13/0600Z 17.3N  38.3W   25 KT  30 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 96H  14/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM AST Tue Oct 09 2018

Tropical Storm Nadine is a sheared tropical cyclone this afternoon with the center partially exposed on the southwestern side of an increasing area of convection. Dvorak estimates are unchanged since earlier, so the initial wind speed remains 35 kt. The shear is forecast to remain low enough to support strengthening during the next day or so, along with sufficiently warm waters. However, Nadine should encounter a large upper trough after that time, which should cause weakening to begin on Thursday. Later on, cooler SSTs and strong shear are expected to cause Nadine to degenerate into a trough of low pressure by the weekend. Model guidance is in fair agreement on this scenario, and the new NHC prediction is close to the previous one and the model consensus.

Satellite imagery today shows that Nadine has turned rightward and is moving 300/7. A northwestward track should begin overnight and continue for the next few days due to steering from a mid-level ridge near the Cabo Verde Islands. A westward turn is expected beyond day 3 as Nadine becomes a shallow system and dissipates. The track forecast isn’t super confident because it is somewhat dependent on the intensity. For example, a stronger cyclone like the GFS shows would have the potential to move more toward the north- northwest as it attempts to remain a vertically coherent system. Since Nadine isn’t expected to get very strong, the official forecast will stay near or just south of the model consensus, which results in no significant change to the previous track forecast.

FORECAST POSITIONS AND MAX WINDS

INIT  09/2100Z 10.9N  30.6W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  10/0600Z 11.6N  31.5W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  10/1800Z 12.6N  32.5W   45 KT  50 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  11/0600Z 13.7N  33.4W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 48H  11/1800Z 15.0N  34.7W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 72H  12/1800Z 17.0N  37.5W   25 KT  30 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 96H  13/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Tue Oct 09 2018

Tropical Storm Nadine –  The cloud pattern of the cyclone features a curved band that wraps around the eastern and southern parts of the circulation. Dvorak estimates from TAFB and SAB are both T2.5/35 kt, and that is used for the initial intensity, making the system a tropical storm. The environment appears conducive for some additional strengthening during the next 24 hours or so, with SSTs above 28C and generally light to moderate westerly shear. After that time, the shear increases to 25-30 kt and SSTs along the forecast track fall below 27C by 72 hours. These factors should result in weakening, and all of the global models show the cyclone dissipating in 4 to 5 days. The NHC forecast follows these trends and is close to the various consensus aids through the forecast period.

Based on geostationary imagery and a 0815Z SSMIS pass, the initial motion estimate is a somewhat uncertain 285/08, with Nadine currently situated south of a narrow mid-level ridge. The ridge will weaken as a mid/upper-level trough that Leslie is embedded in digs southward along 40W longitude. This pattern will cause Nadine to turn more northwestward by 24 hours. By 96 hours, a weakening Nadine should bend back to the west as a shallow system. The new NHC track forecast is a bit to the right of the previous one due to the new initial position, and lies near HCCA through 48 hours and closer to the TVCA multi-model consensus after that time.

FORECAST POSITIONS AND MAX WINDS

INIT  09/1500Z 10.5N  30.0W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  10/0000Z 11.1N  31.0W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  10/1200Z 11.9N  32.1W   45 KT  50 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  11/0000Z 13.0N  33.0W   45 KT  50 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 48H  11/1200Z 14.3N  34.1W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 72H  12/1200Z 16.7N  36.6W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 96H  13/1200Z 18.0N  40.0W   25 KT  30 MPH - Tropical Storm (WSW Mindelo, Cape Verde)

NWS National Hurricane Center Miami FL 600 AM AST Tue Oct 09 2018

Tropical Storm Nadine – Geostationary satellite and recent microwave data indicate that the low pressure system over the eastern Atlantic Ocean has developed sufficently organized deep convection and a well-defined center of circulation to be considered a tropical depression, the fifteenth one of the 2018 Atlantic hurricane season. The initial intensity is set at 30 kt, in agreement with Dvorak 2.0/30 kt classifications from both TAFB and SAB. The depression is expected to strengthen a little during the next 36 to 48 hours while it remains in favorable oceanic and atmospheric conditions. Thereafter, a significant increase in west-southwesterly shear, drier air, and slightly cooler SSTs should cause weakening. The global models all show the depression opening up into a trough by day 5, and the official forecast predicts dissipation accordingly.

The initial motion is uncertain since the system just formed a well-defined center, but my best guess is 285/10 kt. The depression is expected to turn northwestward tonight and continue in that general direction on Wednesday and Thursday as it moves toward a broad trough over the central Atlantic, the same one that Leslie is embedded in. After that time, when the system weakens and becomes shallow, a turn back to the left is forecast. The models are in fair agreement, and the NHC track forecast lies near the middle of the guidance envelope.

FORECAST POSITIONS AND MAX WINDS

INIT  09/1000Z 10.3N  29.7W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 12H  09/1800Z 10.6N  30.8W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 24H  10/0600Z 11.3N  32.1W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 36H  10/1800Z 12.4N  33.0W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 48H  11/0600Z 13.6N  34.0W   40 KT  45 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 72H  12/0600Z 16.1N  36.0W   35 KT  40 MPH - Tropical Storm (WSW Mindelo, Cape Verde)
 96H  13/0600Z 17.5N  39.5W   30 KT  35 MPH - Tropical Storm (WSW Mindelo, Cape Verde)

NWS National Hurricane Center Miami FL 200 PM EDT Mon Oct 8 2018

For the North Atlantic…Caribbean Sea and the Gulf of Mexico: The National Hurricane Center is issuing advisories on Hurricane Michael, located near the western tip of Cuba, and on Tropical Storm Leslie, located over the central Atlantic Ocean.

Showers and thunderstorms associated  with a tropical wave located several hundred miles southwest of the Cabo Verde Islands continue to show signs of organization. However, recent satellite data indicate that the system currently lacks a well-defined surface circulation. Environmental conditions are expected to be conducive for development during the next few days, and a tropical depression could form while the system moves generally west-northwestward. By late this week, strong upper-level winds are expected to limit further development of the disturbance.

* Formation chance through 48 hours…medium…50 percent. * Formation chance through 5 days…medium…60 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Mon Oct 8 2018

Tropical Storm Nadine forming – For the North Atlantic…Caribbean Sea and the Gulf of Mexico: The National Hurricane Center is issuing advisories on Tropical Storm Michael, located over the northwestern Caribbean Sea, and on Tropical Storm Leslie, located over the central Atlantic Ocean.

Shower and thunderstorm activity has become more concentrated since last night, and a tropical depression could form during next few days while it moves west-northwestward. By late this week, however, upper-level winds are expected to become unfavorable for development. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium…50 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Sun Oct 7 2018

If this sysytem is nmaed, it will be Tropical Storm Nadine.

For the North Atlantic…Caribbean Sea and the Gulf of Mexico: The National Hurricane Center is issuing advisories on Tropical Storm Michael, located over the northwestern Caribbean Sea, and on Tropical Storm Leslie, located over the central Atlantic Ocean.

2. An area of disturbed weather associated with a tropical wave has formed a few hundred miles south of the Cabo Verde Islands. Conditions appear to be favorable for some development during the next few days as the system moves westward across the tropical Atlantic. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…30 percent.

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