Tropical Storm Victor

Tropical Depression Victor Track 1100 Hours October 4 2021
Tropical Depression Victor Track 1100 Hours October 4 2021

Tropical Storm Victor Wind Speed FieldTropical Storm Victor – NWS National Hurricane Center Miami FL 1100 AM AST Mon Oct 04, 2021 (see Monday video below)

Victor is no longer a tropical cyclone. A timely 1048 UTC ASCAT-A pass confirms that Victor does not have a closed surface circulation. Since the system has degenerated into a trough of low pressure over the central Atlantic, this will be the final NHC advisory on Victor.

An area of 20 to 22-kt scatterometer winds is noted well to the northeast of the trough axis, but these winds should diminish through tonight as the trough dampens and the remnants move west-northwestward. Hostile environmental conditions, including strong southerly shear and very dry mid-level air, will inhibit any redevelopment of this system.

FORECAST POSITIONS AND MAX WINDS

INIT  04/1500Z 18.8N  45.2W   25 KT  30 MPH - Low (ENE San Juan,Puerto Rico)
 12H  05/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM AST Sun Oct 03, 2021

In its battle against dry air and shear, Victor is far from its namesake. The depression continues to produce only minimal deep convection to the north. Furthermore, an ASCAT overpass near 2219 UTC casts doubt on whether Victor still has a closed and well-defined circulation, showing generally light winds south of the suspect center. However, no visible imagery is currently available to confirm the state of Victor’s surface center, so advisories will continue for now. ASCAT data showed winds a little above 25 kt to the northeast of Victor’s center, so the initial intensity is held at 30 kt for this advisory.

Victor is moving northwestward at a slightly faster speed (305/13 kt). Based on the ASCAT data and recent ProxyVis imagery, the center of Victor was relocated about 40 n mi south of previous estimates, which has resulted in a southern shift in the forecast track. That said, Victor is not expected to persist for much longer. The hostile surrounding environment will likely cause Victor to become a remnant low or dissipate on Monday. Victor, or its remnants, should move generally northwestward or west-northwestward until dissipation occurs within a day or so.

FORECAST POSITIONS AND MAX WINDS

INIT  04/0300Z 17.8N  43.0W   30 KT  35 MPH - Depression (WSW Praia,Cape Verde)
 12H  04/1200Z 18.8N  44.9W   25 KT  30 MPH - Post Tropical (ENE San Juan,Puerto Rico)
 24H  05/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM AST Sun Oct 03, 2021 

The convective structure of Victor has deteriorated this afternoon. Only small pulses of convection have been observed north of the center over the past several hours. Victor’s exposed low-level circulation is also becoming more diffuse, with multiple cloud swirls noted in visible satellite imagery. Hopefully, scatterometer data this evening will provide more information about whether Victor still possesses a closed and well-defined surface center. For now, Victor is held as a 30-kt tropical depression, which is consistent with earlier scatterometer winds and a blend of the data-T and current intensity Dvorak estimates from TAFB and SAB.

Victor is unlikely to remain a tropical cyclone for much longer. The dry mid-level environment and 20-25 kt of southwesterly vertical wind shear are expected to limit Victor’s ability to sustain deep, organized convection going forward. Even if another diurnal convective pulse occurs tonight, it should be quickly stripped away from the center by the moderate to strong shear. The official NHC forecast shows Victor becoming a remnant low on Monday, then opening up into a trough and dissipating soon thereafter. Victor is moving northwestward, or 315/11 kt. A northwestward or west-northwestward motion is expected to continue through dissipation as the depression is steered by a subtropical ridge to its northeast. The official NHC track forecast is essentially an update of the previous one.

FORECAST POSITIONS AND MAX WINDS

INIT  03/2100Z 17.1N  41.3W   30 KT  35 MPH - Depression (WSW Praia,Cape Verde)
 12H  04/0600Z 18.4N  42.9W   25 KT  30 MPH - Post Tropical (ENE San Juan,Puerto Rico)
 24H  04/1800Z 19.7N  45.1W   25 KT  30 MPH - Post Tropical (ESE St.George's,Bermuda)
 36H  05/0600Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Sun Oct 03, 2021 

Despite persistent southwesterly vertical wind shear, Victor has managed to maintain an area of deep convection to the northeast of its low-level center through the morning hours. The latest objective and subjective satellite estimates range from 30-35 kt. However, an ASCAT-A pass from 1110 UTC indicates the increasingly elongated center of Victor is about 45 n mi south of previous estimates, which puts the center farther away from the edge of the convective overcast. Although a few 35-kt ASCAT wind vectors are noted, these retrievals are collocated with the most intense convection and appear artificially high when compared to the surrounding 20 to 30-kt wind field. Thus, the initial intensity of Victor is held at 30 kt for this advisory.

The SHIPS guidance indicates 15-20 kt of vertical wind shear will persist over Victor today, with even stronger shear expected on Monday. Additionally, the dry mid-level environment that Victor is embedded within appears unfavorable for sustaining deep convection. Therefore, gradual weakening is expected early this week, and Victor is forecast to lose its convection and degenerate into a remnant low by late Monday. Another plausible scenario is that Victor’s low-level center continues to lose definition and the system opens up into a trough with the next couple of days. Either way, Victor does not appear to have much of a future. A subtropical ridge over the eastern Atlantic is steering Victor northwestward, or 310/10 kt. A northwestward motion is expected to continue through dissipation as Victor moves around the southwestern periphery of the subtropical ridge. Although the track reasoning has not changed, the official NHC forecast track lies to the left of the previous advisory due to the center relocation described above.

FORECAST POSITIONS AND MAX WINDS

INIT  03/1500Z 16.1N  40.3W   30 KT  35 MPH - Depression (WSW Praia,Cape Verde)
 12H  04/0000Z 17.6N  41.9W   30 KT  35 MPH - Depression (WSW Praia,Cape Verde)
 24H  04/1200Z 19.5N  43.9W   25 KT  30 MPH - Post Tropical (ENE San Juan,Puerto Rico)
 36H  05/0000Z 21.1N  45.9W   25 KT  30 MPH - Post Tropical (ESE St.George's,Bermuda)
 48H  05/1200Z 22.4N  48.0W   20 KT  25 MPH - Post Tropical (ESE St.George's,Bermuda)
 60H  06/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM AST Sat Oct 02, 2021

Victor remains a tropical cyclone this evening, with pulsing deep convection occuring primarily north of the well-defined low-level center. However, this convection lacks much organization and is continually being stripped away by around 20 kt of south-southwesterly vertical wind shear. Earlier this evening, there was an ASCAT-A pass valid at 2238 UTC which had peak wind retrievals of 25-30 kt to the northeast of the center. There was also a nearby moored ocean buoy that at 0000 UTC reported sustained winds of 28 kt with a pressure of 1006.7 mb also just northeast of Victor. The latest advisory intensity is thus being maintained at 30 kt but the minimum pressure was lowered a bit due to this in-situ buoy data. The 30 kt intensity also agrees with most recent TAFB Dvorak CI estimate from 0000 UTC.

Ultimately the combination of southwesterly vertical wind shear and the associated entrainment of dry air will prove victorious against Victor, with the depression forecast to gradually weaken during the forecast period. The latest NHC intensity forecast still shows Victor becoming a remnant low by tomorrow evening, though 27 to 28 C sea surface temperatures could still support sheared convective bursts to the north of the low center into early next week. Victor’s low-level wind field will also continue to spin down over the subsequent days, and the circulation is forecast to open up into a trough by Tuesday. The latest forecast is essentially unchanged from the previous one and is in good agreement with the consensus aids and deterministic model output.

The depression continues to move to the northwest at 310/12 kt though with the occasional tug poleward by the convection on its northern side. This northwestward motion is expected to continue as Victor remains embedded in the flow around a low-level subtropical anticyclone to its northeast. The NHC track forecast continues to be in general agreement with the track guidance consensus, maintaining Victor on a similar forward motion until the system opens up into a trough in 2-3 days.

FORECAST POSITIONS AND MAX WINDS

INIT  03/0300Z 14.8N  38.9W   30 KT  35 MPH - Depression (WSW Praia,Cape Verde)
 12H  03/1200Z 16.3N  40.5W   30 KT  35 MPH - Depression (WSW Praia,Cape Verde)
 24H  04/0000Z 18.4N  42.4W   30 KT  35 MPH - Post Tropical (ENE San Juan,Puerto Rico)
 36H  04/1200Z 20.3N  44.3W   25 KT  30 MPH - Post Tropical (ESE St.George's,Bermuda)
 48H  05/0000Z 21.8N  46.4W   25 KT  30 MPH - Post Tropical (ESE St.George's,Bermuda)
 60H  05/1200Z 23.2N  48.3W   20 KT  25 MPH - Post Tropical (ESE St.George's,Bermuda)
 72H  06/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM AST Sat Oct 02, 2021

Victor was about out of time as a tropical cyclone, but a recent burst of deep convection about 60 n mi northeast of its center saved it from being declared a remnant low this afternoon. The cyclone continues to struggle with dry air and strong southwesterly shear. Scatterometer overpasses missed Victor today, so the initial advisory intensity of 30 kt is based on the latest CI-value from the TAFB Dvorak estimate.

The depression is moving northwest, or 310/12 kt in the flow to the southwest of a subtropical ridge. This general motion is forecast to continue until Victor dissipates in a few days. The latest NHC track forecast is little changed from the previous one, and is near the various multimodel track consensus solutions.

Victor refused to succumb to the strong shear and dry air over the past 24 h. However, these hostile conditions are not forecast to abate over the cyclone for the foreseeable future. Therefore, the depression should struggle to maintain persistent deep convection, and the cyclone could degenerate to a remnant low at any time over the next couple of days. The global model guidance is in good agreement that Victor should gradually weaken early this week, and open into a tough of low pressure by Tuesday. The latest NHC intensity forecast is unchanged from the previous one, except for the timing of the system becoming a remnant low.

FORECAST POSITIONS AND MAX WINDS

INIT  02/2100Z 13.7N  38.0W   30 KT  35 MPH - Depression (WSW Praia,Cape Verde)
 12H  03/0600Z 14.9N  39.5W   30 KT  35 MPH - Depression (WSW Praia,Cape Verde)
 24H  03/1800Z 16.8N  41.6W   30 KT  35 MPH - Post Tropical (ENE San Juan,Puerto Rico)
 36H  04/0600Z 18.9N  43.5W   25 KT  30 MPH - Post Tropical (ESE St.George's,Bermuda)
 48H  04/1800Z 20.7N  45.5W   20 KT  25 MPH - Post Tropical (ESE St.George's,Bermuda)
 60H  05/0600Z 22.5N  47.3W   20 KT  25 MPH - Post Tropical (ESE St.George's,Bermuda)
 72H  05/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Sat Oct 02, 2021

Strong southwesterly shear and entrainment of dry air have taken their toll on Victor. The deep convection and the remnant mid-level core has been stripped away from the cyclone’s low-level circulation, and is now more than 250 n mi northeast of Victor’s center. The most recent UW-CIMMS shear analysis indicates the shear magnitude is about 30 kt over the center of the cyclone, and nearly 50 kt just to its north. The initial intensity is being lowered to 35 kt for this advisory based on the latest subjective Dvorak intensity estimate from TAFB. However, this value could be generous.

Victor’s vector is 305/10 kt. This motion is expected to continue until the system dissipates, as the cyclone is steered in the flow to the southwest of a subtropical ridge. The latest NHC track forecast is just slightly to the left of the previous one, and lies on the western side of the guidance envelope to accommodate the shallow nature of the circulation.

The strong shear is not forecast to abate over the cyclone for the foreseeable future and very dry, African dust-laden air lies in the path of Victor. Therefore, it is unlikely that organized deep convection will redevelop near the center of the cyclone. Because of this, Victor is now expected to become a remnant low by tonight. The remnant low is forecast by the global models to open into a trough in 60 h. Due to the quick weakening that has been observed, the latest NHC intensity forecast was lowered through the first 12 h, and then remains the same as the previous forecast beyond that time frame.

FORECAST POSITIONS AND MAX WINDS

INIT  02/1500Z 13.1N  37.2W   35 KT  40 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  03/0000Z 14.1N  38.7W   30 KT  35 MPH - Post Tropical (WSW Praia,Cape Verde)
 24H  03/1200Z 15.9N  40.8W   30 KT  35 MPH - Post Tropical (WSW Praia,Cape Verde)
 36H  04/0000Z 18.0N  42.8W   25 KT  30 MPH - Post Tropical (ENE San Juan,Puerto Rico)
 48H  04/1200Z 20.0N  44.6W   20 KT  25 MPH - Post Tropical (ESE St.George's,Bermuda)
 60H  05/0000Z 21.6N  46.7W   20 KT  25 MPH - Post Tropical (ESE St.George's,Bermuda)
 72H  05/1200Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 PM AST Fri Oct 01, 2021

The structure of Victor this evening continues to degrade with the low-level center becoming decoupled from the mid- to upper-level circulation associated with the deeper convection. While the tropical storm does continue to produce a region of deep convection with cloud tops colder than -70 C, this activity is organized in a linear band that is now more than 150 n mi northeast of the exposed low-level center as seen on Proxy-Vis satellite imagery. Both ASCAT-B/C clipped the western half of Victor’s circulation, showing peak winds of 40 kt on the far edge of the pass. In addition, the latest subjective and objective satellite intensity estimates have been falling this evening. The latest intensity for this advisory has been lowered to 50 kt this advisory, assuming the scatterometer data missed higher wind values to the northeast of Victor closer to the convection. However, given Victor’s current structure, this estimate may still be generous.

Now that the low-level cloud swirl is readily apparent on satellite imagery, it is somewhat easier to track Victor this evening, with the estimated motion still west-northwest at 290/11 kt. Because the cyclone is also becoming more vertically shallow, the primarily steering feature will be a large low-level subtropical ridge centered to the north, which should guide Victor on a general west-northwestward to northwestward heading for the next 2-3 days at a similar forward motion. The latest track guidance has shifted westward this cycle, likely in response to Victor being a weaker cyclone less coupled to the deep convection. The latest NHC track forecast was also shifted a bit west over the forecast period, staying closer to the consensus aids HCCA and TVCA, though it is worth nothing this is still not as far west as the latest GFS or ECMWF runs.

While the deep-layer 200-850 hPa vertical wind shear has not been prohibitively strong today (15-20 kt), more substantial mid-level shear underneath the outflow layer (25-30 kt) appears to be responsible for the current disheveled appearance of Victor. This shear is related to a large upper-level cutoff low upstream of the tropical storm. Even though the current shear is not expected to increase much more in the short-term, the mid-level environment over Victor is expected to continue drying as the existing shear will import very dry air upstream into the core of the cyclone. All of the guidance responds to these unfavorable conditions by gradually weakening Victor over the next few days, and the latest NHC intensity forecast has been lowered a bit more compared to the previous advisory. While pulses of deep convection are likely to continue north of Victor over the next several days, the circulation is expected to gradually lose definition, and the global and high-res regional hurricane models now open up the system into a trough between 72-96 hours. The latest NHC intensity forecast now follows suit, showing dissipation by 96 hours.

FORECAST POSITIONS AND MAX WINDS

INIT  02/0300Z 12.3N  35.3W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  02/1200Z 13.2N  36.9W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  03/0000Z 14.6N  38.7W   40 KT  45 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  03/1200Z 16.5N  40.6W   40 KT  45 MPH - Tropical Storm (WSW Praia,Cape Verde)
 48H  04/0000Z 18.5N  42.6W   35 KT  40 MPH - Tropical Storm (ENE San Juan,Puerto Rico)
 60H  04/1200Z 20.6N  44.7W   35 KT  40 MPH - Tropical Storm (ESE St.George's,Bermuda)
 72H  05/0000Z 22.2N  46.5W   30 KT  35 MPH - Post Tropical (ESE St.George's,Bermuda)
 96H  06/0000Z...DISSIPATED

NWS National Hurricane Center Miami FL 500 PM AST Fri Oct 01, 2021 

Victor is looking disorganized. Deep convection has decreased in organization and coverage this afternoon. No recent microwave imagery has been available to assess the structure of the storm, but visible images from MET-11 and GOES-17 suggest that the circulation of the tropical storm is still elongated southwest-to-northeast. The intensity estimate remains 55 kt for this advisory, but this is on the high end of the recent estimates and could be generous.

Compared to the large changes made this morning, almost no change was made to the official track forecast this afternoon. The model consensus has shifted substantially back to the right, and now lies very near the previous NHC forecast. Victor is forecast to turn northwestward tomorrow, and then continue on that heading through early next week, steered by ridging to the northeast. The new NHC forecast is very near the model consensus through the end of the forecast. Despite the recent agreement between the NHC forecast and the consensus, confidence in the forecast will remain low until we see better run-to-run consistency in the track model guidance.

Shear and dry air may already be taking a toll on Victor, and SHIPS diagnostics from the GFS and ECMWF suggest that the environment will get worse with time. All of the intensity models forecast that Victor will weaken over the next several days in response to the hostile environment, and this is reflected in the NHC forecast, which is heavily based on the IVCN multi-model consensus. By day 5, all of the dynamical models indicate that Victor will likely degenerate into a trough of low pressure, so dissipation is shown. Several models, including the HWRF, GFS, and ECMWF indicate dissipation could occur sooner than that.

FORECAST POSITIONS AND MAX WINDS

INIT  01/2100Z 12.0N  34.3W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  02/0600Z 12.7N  35.5W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  02/1800Z 13.9N  37.2W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  03/0600Z 15.6N  39.0W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 48H  03/1800Z 17.6N  40.9W   40 KT  45 MPH - Tropical Storm (WSW Praia,Cape Verde)
 60H  04/0600Z 19.7N  42.9W   40 KT  45 MPH - Tropical Storm (ENE San Juan,Puerto Rico)
 72H  04/1800Z 21.5N  44.5W   35 KT  40 MPH - Depression (ESE St.George's,Bermuda)
 96H  05/1800Z 24.5N  47.5W   30 KT  35 MPH - Post Tropical (ESE St.George's,Bermuda)
120H  06/1800Z...DISSIPATED

NWS National Hurricane Center Miami FL 1100 AM AST Fri Oct 01, 2021

Since the last advisory, Victor’s deep convection has become limited to the northern portion of its circulation. Convective outflow is limited to the south, which indicates that the changes in the structure of the tropical storm are due at least in part to southerly wind shear. Microwave and ASCAT data between 0800 and 1200 UTC also indicate that the center of Victor has become elongated, and may be trying to reform to the north, closer to the convection. Even with that reformation, an 1128 ASCAT-B overpass revealed that the center of Victor is located substantially south of previous estimates, which has necessitated a significant change to the track forecast.

With the new position, the initial motion estimate is now 295/13 kt. The tropical storm is still generally expected to turn northwestward over the weekend and then continue on that heading through early next week, steered by the southwest periphery of a mid-level ridge centered over the eastern Atlantic. Nearly all of the dynamical models are showing this turn occuring slightly later than earlier forecasts, which results in a track well to the west of the previous NHC forecast. Combined with the updated analysis of Victor’s position, the new NHC forecast has been shifted over 100 n mi to the southwest by day 4. However, this is still on the far east side of the guidance envelope so additional changes to the track forecast might be needed this afternoon.

The aforementioned ASCAT data showed peak winds near 50 kt, which supports an intensity of 55 kt, assuming a little undersampling due to the resolution of the instrument. The intensity analysis is also supported by the latest TAFB Dvorak estimate. Despite the large changes to the track forecast, no change of note was made to the intensity forecast. Increasing shear and a dry surrounding environment should cause Victor to weaken during the next few days. Some models even indicate it could dissipate before the end of the forecast period. The NHC forecast is based on the intensity model consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  01/1500Z 11.5N  33.5W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  02/0000Z 12.0N  34.8W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  02/1200Z 13.1N  36.4W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  03/0000Z 14.7N  38.1W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 48H  03/1200Z 16.6N  40.0W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 60H  04/0000Z 18.7N  42.1W   40 KT  45 MPH - Tropical Storm (ENE San Juan,Puerto Rico)
 72H  04/1200Z 20.6N  43.9W   35 KT  40 MPH - Tropical Storm (ESE St.George's,Bermuda)
 96H  05/1200Z 23.6N  46.5W   30 KT  35 MPH - Depression (ESE St.George's,Bermuda)
120H  06/1200Z 27.1N  46.9W   25 KT  30 MPH - Post Tropical (ESE St.George's,Bermuda)

NWS National Hurricane Center Miami FL 500 AM AST Fri Oct 01, 2021 

Infrared and microwave satellite imagery indicate that Victor has continued to become a little better organized, with a 0342Z AMSR2 overpass showing that a 75-percent-closed mid-level eye feature had formed. However, both data sources also revealed that a pronounced dry slot has formed in the southeastern quadrant. Upper-level outflow remains well established in all quadrants except to the south where it is somewhat restricted. Despite the slightly improved satellite signatures, subjective and objective intensity classifications have not changed since the previous advisory, so the intensity remains at 50 kt for this advisory.

The initial motion estimate is 305/13 kt. Victor has made a slight jog toward the northwest, but this is likely a temporary motion due to redevelopment of the center farther into the convective cloud shield. The cyclone should resume a west-northwestward motion later today and maintain that motion for another day or so as Victor moves along the southwestern periphery of a strong subtropical ridge situated over the east-central Atlantic. The latest model runs continue to show a broad mid- to upper-level low developing over the central Atlantic to the west of Victor in the 24-72-h forecast period, which will act to erode the western portion of the ridge and create a deep-layer southerly flow pattern across the cyclone. As a result, Victor is forecast to turn northwestward by the weekend and then move northward by early next week. Owing to a more robust mid-/upper-level low forecast to develop than previously expected, the latest NHC track guidance has made a significant westward shift by at least 100 nmi at 72 h and nearly 200 nmi on days 4 and 5. This westward shift is due to Victor now forecast to weaken faster and become more vertically shallow, with the dominant steering flow shifting to low-level easterlies. The new NHC track forecast has also been shifted westward, but not as far west as the tightly packed consensus models, all of which lie well to the east of the westernmost GFS solution.

Victor is expected to remain in a somewhat favorable environment for the next 18 h or so, which should allow for at least some slight strengthening to occur. Thereafter, however, southwesterly deep-layer vertical wind shear is forecast by the GFS and ECMWF models to increase to 20-25 kt in 24 hours and 30-35 kt by 72 h. These hostile shear conditions, in conjunction with a drier air mass, should result in gradual weakening during the 24-120-h period, with Victor becoming a remnant low on day 5. The new official intensity forecast is a little below the previous advisory, but it is above the consensus intensity models ICON, HCCA, and FSSE, due to the recent development of the aforementioned primitive eye feature.

FORECAST POSITIONS AND MAX WINDS

INIT  01/0900Z 11.7N  32.3W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  01/1800Z 12.4N  33.6W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  02/0600Z 13.4N  35.3W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  02/1800Z 14.9N  36.8W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
 48H  03/0600Z 16.7N  38.6W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 60H  03/1800Z 19.0N  40.5W   40 KT  45 MPH - Tropical Storm (WSW Praia,Cape Verde)
 72H  04/0600Z 21.0N  42.0W   35 KT  40 MPH - Tropical Storm (ENE San Juan,Puerto Rico)
 96H  05/0600Z 24.0N  44.0W   30 KT  35 MPH - Depression (ESE St.George's,Bermuda)
120H  06/0600Z 28.0N  45.0W   25 KT  30 MPH - Post Tropical (ESE St.George's,Bermuda)

NWS National Hurricane Center Miami FL 1100 PM AST Thu Sep 30, 2021

Satellite imagery shows that Victor has become a little better organized since the last advisory, with the convective banding becoming better defined near the center in the northeastern semicircle. Recent ASCAT data showed winds of 45-47 kt about 70 n mi north of the center, and based on the likelihood of some undersampling the initial intensity is increased to 50 kt. Although the scatterometer showed a stronger storm, the data suggested the system has not yet formed a well-defined inner core.

The initial motion is now 300/10 kt. Victor is expected to continue west-northwestward for another 24 h or so on the south side of a deep-layer ridge over the subtropical eastern Atlantic. After that time, a developing mid- to upper-level low over the central Atlantic is expected to erode the western portion of the ridge. As a result, Victor is expected to turn northwestward by the weekend and then northward by early next week when it is forecast to move in the flow between the ridge and the low. The guidance has changed little since the previous advisory, with the HWRF remaining a significant outlier to the east. Thus, the new forecast track is a little to the west of the various consensus aids that include the HWRF. The new forecast is basically an update of the previous forecast.

Victor should remain in a favorable environment for the next 24 h or so, and the intensity forecast shows more strengthening during that time, After that, the upper-level low should cause moderate to strong southwesterly shear over the storm, and by the end of the forecast period it will be moving into a drier air mass. This combination should cause Victor to steadily weaken after 24 h. The new NHC forecast has some adjustments from the previous forecast, and it now calls for the cyclone to decay to a remnant low by 120 h. The intensity forecast lies near the upper edge of the intensity guidance through 48-60 h, and thereafter is close to the intensity consensus.

FORECAST POSITIONS AND MAX WINDS

INIT  01/0300Z 10.6N  30.7W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  01/1200Z 11.3N  32.1W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  02/0000Z 12.4N  33.8W   60 KT  70 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  02/1200Z 13.9N  35.2W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 48H  03/0000Z 15.5N  36.8W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
 60H  03/1200Z 17.7N  38.7W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 72H  04/0000Z 20.2N  40.4W   40 KT  45 MPH - Tropical Storm (ENE San Juan,Puerto Rico)
 96H  05/0000Z 25.0N  43.0W   30 KT  35 MPH - Depression (ESE St.George's,Bermuda)
120H  06/0000Z 28.5N  43.0W   25 KT  30 MPH - Post Tropical (ESE St.George's,Bermuda)

NWS National Hurricane Center Miami FL 500 PM AST Thu Sep 30, 2021 

Victor has been relatively steady in strength during the past several hours. Satellite images continue to show that the storm has a large circulation with numerous curved bands surrounding the center. However, recent microwave images indicate that the cyclone has yet to develop a well-defined inner core, which is likely why the system has not strengthened much despite the favorable environmental conditions. The Dvorak classifications are again unchanged and range from 35 to 45 kt, and on this basis, the initial intensity is held at 40 kt.

Victor is still moving west-northwestward, or 290 degrees, at 12 kt. The storm is forecast to continue on that same general track for about another day as it remains on the south side of a deep-layer ridge over the subtropical eastern Atlantic. By late Friday, a mid- to upper-level low is expected to form over the central Atlantic, and that feature should erode the western portion of the ridge. As a result, Victor is expected to turn northwestward by the weekend and then northward by early next week when it is forecast to move in the flow between the ridge and the low. The GFS has shifted westward this cycle and is now not far from the ECMWF track. The new NHC forecast track is nudged westward toward a consensus of the GFS, ECMWF, UKMET, and HMON models. The standard consensus aids could be too far to the east since the latest run of the HWRF, which is a member of those models, is a significant outlier to the east.

As mentioned above, although the storm has been in favorable conditions for strengthening during the past day or so, it has not taken full advantage likely due to its broad structure. The favorable environment for Victor should persist for about another 24 hours, so gradual strengthening is possible during that time period. However, by the weekend, the models show Victor moving into a region of moderate to strong southwesterly shear and a progressively drier airmass. These negative factors for the storm along with slightly cooler SSTs should cause Victor to lose strength this weekend and early next week. In fact, some of the models suggest that Victor could dissipate by the end of the forecast period. The new NHC intensity forecast is again a little lower than the previous one, trending toward the HCCA, IVCN, and IVDR consensus aids.

FORECAST POSITIONS AND MAX WINDS

INIT  30/2100Z  9.9N  30.0W   40 KT  45 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  01/0600Z 10.6N  31.4W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  01/1800Z 11.6N  33.1W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  02/0600Z 12.9N  34.6W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
 48H  02/1800Z 14.5N  36.2W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 60H  03/0600Z 16.4N  38.0W   40 KT  45 MPH - Tropical Storm (WSW Praia,Cape Verde)
 72H  03/1800Z 18.9N  40.0W   35 KT  40 MPH - Tropical Storm (ENE San Juan,Puerto Rico)
 96H  04/1800Z 23.6N  42.7W   30 KT  35 MPH - Depression (ESE St.George's,Bermuda)
120H  05/1800Z 28.0N  42.9W   30 KT  35 MPH - Depression (ESE St.George's,Bermuda)

NWS National Hurricane Center Miami FL 800 AM CVT Thu Sep 30, 2021

Victor is gradually getting better organized. AMSR2 microwave data from 0300 UTC showed that the low-level circulation has become more defined, with most convective banding features located west and southwest of the center. Victor’s intensity is now estimated to be 40 kt based on Dvorak estimates of T3.0 and T2.5 from TAFB and SAB, respectively, and objective numbers from UW-CIMSS around 40 kt.

Victor’s vector is toward the west-northwest (290 degrees) at 11 kt, and this heading should continue for the next 36 hours while the storm is located to the south a deep-layer ridge located over the subtropical eastern and central Atlantic. In about 2 days, a mid- to upper-level low is forecast to develop over the central Atlantic, causing Victor to curve around the western periphery of the ridge, which gets shunted eastward between the Azores and the Canary Islands. The track models are in generally good agreement on this scenario, and most of them are clustered tightly among each other. Two notable exceptions, which are discounted at this time, are the HWRF and ECMWF models. The HWRF, which is stronger than the other models, is way off to the east, while the ECMWF lies off to the south and west, a tendency that we’ve observed recently with other storms in the deep tropics. The NHC track forecast is not changed much from the previous iteration and lies close to the GFS, HCCA, Florida State Superensemble, and TVCA solutions.

If the low-level circulation is in fact becoming better defined as shown by microwave imagery, Victor should be able to continue strengthening for the next couple of days in an environment of low vertical shear and over warm waters of roughly 28 degrees Celsius. The NHC intensity forecast is near the upper end of the guidance during this period and continues to show Victor reaching hurricane strength in about 36 hours. Once the aforementioned mid- to upper-level low forms, strong southerly to southwesterly deep-layer shear is expected to develop over Victor and induce a weakening trend in about 3 days. The intensity forecast has been lowered a bit during the latter part of the forecast period given the trends in the intensity models, but it is not as low as the HCCA and IVCN aids. Interestingly, many of the global models suggest that the shear could be so strong that Victor might weaken to a depression or even degenerate into a remnant low by day 5.

FORECAST POSITIONS AND MAX WINDS

INIT  30/0900Z  8.7N  27.3W   40 KT  45 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  30/1800Z  9.4N  28.8W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  01/0600Z 10.2N  30.6W   60 KT  70 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  01/1800Z 11.2N  32.3W   65 KT  75 MPH - Category 1 (WSW Praia,Cape Verde)
 48H  02/0600Z 12.6N  33.8W   65 KT  75 MPH - Category 1 (WSW Praia,Cape Verde)
 60H  02/1800Z 14.4N  35.3W   60 KT  70 MPH - Tropical Storm (WSW Praia,Cape Verde)
 72H  03/0600Z 16.6N  37.0W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 96H  04/0600Z 22.0N  40.2W   40 KT  45 MPH - Tropical Storm (ENE  San Juan,Puerto Rico)
120H  05/0600Z 27.3N  41.9W   35 KT  40 MPH - Tropical Storm (ESE St.George's,Bermuda)

NWS National Hurricane Center Miami FL 200 AM CVT Thu Sep 30, 2021

Victor has changed little in organization since the last advisory, with a large circulation and a complex of convective bands mainly in the northern semicircle. Satellite intensity estimates from TAFB and SAB remain at or near 35 kt, as do other objective intensity estimates. Thus, the initial intensity is still 35 kt, although the most recent ASCAT-A data suggests the possibility that this is a little generous.

The center has moved or re-formed a bit to the west during the past several hours, although the longer-term motion still seems to be to the west-northwest at 290/11 kt. Other than the more westerly initial position, there is little change to the forecast philosophy or the forecast track since the last advisory. Victor is forecast to move west-northwestward for the next 36 h or so as it is steered by the flow on the south side of a deep-layer ridge. By 48 h, the global models forecast the western periphery of the ridge to get eroded by to a mid- to upper-level low over the subtropical central Atlantic. This evolution should cause the cyclone to turn northwestward at that time, followed by a northward turn by the end of the forecast period. There remains a fair amount of spread in the timing and location of the northward turn with the GFS and HWRF still on the right side of the guidance envelope and the ECMWF showing the slowest and westernmost solution. The new forecast track is in the center of the guidance envelope and lies very close to the various consensus models.

For the next 36-48 h, Victor is expected to remain in an environment of warm sea surface temperatures and light vertical wind shear. This should allow steady strengthening, and rapid strengthening cannot be ruled out if the storm develops a better defined inner core. Based on a steady strengthening scenario, the new intensity forecast is identical to the previous one, taking Victor to hurricane intensity in 36 h with a peak intensity of 70 kt in 48 h. After that time, the aforementioned upper-level low is expected to cause significant shear over Victor while the cyclone moves into a drier air mass. This combination should cause the cyclone to weaken, and it is possible Victor could weaken faster than currently forecast after 60 hours. The new official intensity forecast lies near the upper edge of the intensity guidance.

FORECAST POSITIONS AND MAX WINDS

INIT  30/0300Z  8.4N  26.7W   35 KT  40 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  30/1200Z  8.9N  28.3W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  01/0000Z  9.7N  30.2W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  01/1200Z 10.6N  32.0W   65 KT  75 MPH - Category 1 (WSW Praia,Cape Verde)
 48H  02/0000Z 11.8N  33.5W   70 KT  80 MPH - Category 1 (WSW Praia,Cape Verde)
 60H  02/1200Z 13.4N  35.1W   70 KT  80 MPH - Category 1 (WSW Praia,Cape Verde)
 72H  03/0000Z 15.5N  36.7W   60 KT  70 MPH - Tropical Storm (WSW Praia,Cape Verde)
 96H  04/0000Z 20.5N  39.5W   45 KT  50 MPH - Tropical Storm (ENE San Juan,Puerto Rico)
120H  05/0000Z 26.0N  41.0W   40 KT  45 MPH - Tropical Storm (ESE St.George's,Bermuda)

NWS National Hurricane Center Miami FL 800 PM CVT Wed Sep 29, 2021

The cloud pattern continues to exhibit a large circulation with numerous curved bands surrounding the center. The strongest thunderstorms remain on the system’s west side. The latest Dvorak estimates from TAFB and SAB have both increased to 2.5/35 kt, and on that basis, the cyclone has been upgraded to a 35-kt tropical storm.

Victor is still on a west-northwest course at about 11 kt. There has been little change to the track forecast reasoning. The cyclone is expected to continue west-northwestward during the next couple of days as it remains steered by the flow on the south side of a deep-layer ridge. By late Friday, however, the models show the western periphery of the ridge being eroded due to a mid- to upper-level low over the subtropical central Atlantic. As a result, the cyclone should turn northwestward by Friday night and then northward late this weekend or early next week. There remains a fair amount of spread in the timing and location of the northward turn with the GFS and HWRF still on the right side of the guidance envelope and the ECMWF showing the slowest and westernmost solution. Overall, the consensus models have not changed much and neither has the official track forecast.

The storm is expected to remain in conducive environmental conditions for strengthening during the next couple of days. During that time period, Victor is forecast to move over 28-29 deg C waters while embedded within a moist airmass with very low wind shear (less than 10 kt). Rapid intensification sometimes occurs when conditions are this favorable, however, since the storm is broad and does not yet have an inner core, gradual strengthening seems more reasonable. The NHC forecast brings Victor to hurricane intensity in 36 hours. In a few days, however, the models show a pronounced increase in southwesterly shear and a notably drier atmosphere. These unfavorable conditions should end the opportunity for strengthening and promote a weakening trend. The NHC intensity forecast is similar to the previous one and remains near a blend of the HCCA, IVCN, and IVDR consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT  29/2100Z  8.3N  25.5W   35 KT  40 MPH - Tropical Storm (WSW Praia,Cape Verde)
 12H  30/0600Z  8.8N  26.9W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  30/1800Z  9.5N  28.9W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  01/0600Z 10.3N  30.8W   65 KT  75 MPH - Category 1 (WSW Praia,Cape Verde)
 48H  01/1800Z 11.4N  32.4W   70 KT  80 MPH - Category 1 (WSW Praia,Cape Verde)
 60H  02/0600Z 12.8N  34.1W   70 KT  80 MPH - Category 1 (WSW Praia,Cape Verde)
 72H  02/1800Z 14.7N  35.8W   60 KT  70 MPH - Tropical Storm (WSW Praia,Cape Verde)
 96H  03/1800Z 19.3N  38.9W   50 KT  60 MPH - Tropical Storm (WSW Praia,Cape Verde)
120H  04/1800Z 24.9N  40.9W   40 KT  45 MPH - Tropical Storm (ENE San Juan,Puerto Rico)

NWS National Hurricane Center Miami FL 200 PM CVT Wed Sep 29, 2021 

The area of low pressure located over the far eastern tropical Atlantic that NHC has been monitoring has now become a tropical depression, the twentieth tropical cyclone of the 2021 Atlantic hurricane season. Satellite images indicate that the system is producing a large area of showers and thunderstorms that have become fairly well organized around the center. An ASCAT-A pass from a few hours ago indicated that the system now has a well-defined circulation and that the radius of maximum wind is 30-40 n mi north of the center. The initial intensity is set at 30 kt based on the ASCAT data and the T2.0/30 kt Dvorak classifications from TAFB and SAB. The minimum pressure of 1007 mb is partially based on data from a ship report that passed near the depression.

Based on satellite fixes, the depression appears to be moving west-northwestward at about 12 kt. The system is currently located on the south side of a deep-layer ridge, and that feature should keep the cyclone on a west-northwest track during the next couple of days. After that time, the models show a mid- to upper-level low developing over the central tropical Atlantic, which erodes the western portion of the ridge. This change in the steering flow should cause the system to turn northwestward on Friday and then northward toward the end of the forecast period. Although the models generally agree on the evolution of the large-scale pattern, there are notable differences in the details, which leads to a fair amount of spread concerning when and where the turn to the north occurs. The GFS is farthest east while the ECMWF shows the westernmost solution. The NHC track forecast lies between those models and is near the TVCA multi-model consensus.

The depression is expected to remain in conducive environmental conditions for strengthening during the next 2 or 3 days. During that time period, the storm is forecast to move over 28-29 deg C waters while embedded within an airmass of high mid-level moisture and very low wind shear (less than 10 kt). Therefore, steady strengthening seems likely, and the NHC forecast brings the system to a tropical storm by tonight and a hurricane in a couple of days. Beyond a few days, however, the models show a pronounced increase in southwesterly shear and a notably drier atmosphere. These unfavorable conditions should end the opportunity for strengthening and promote a weakening trend. The NHC intensity forecast is a near a blend of the HCCA, IVCN, and IVDR consensus models.

FORECAST POSITIONS AND MAX WINDS

INIT  29/1500Z  8.3N  24.6W   30 KT  35 MPH - Depression (WSW Praia,Cape Verde)
 12H  30/0000Z  8.8N  25.8W   35 KT  40 MPH - Tropical Storm (WSW Praia,Cape Verde)
 24H  30/1200Z  9.5N  27.6W   45 KT  50 MPH - Tropical Storm (WSW Praia,Cape Verde)
 36H  01/0000Z 10.3N  29.9W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
 48H  01/1200Z 11.2N  31.9W   65 KT  75 MPH - Category 1 (WSW Praia,Cape Verde)
 60H  02/0000Z 12.4N  33.7W   70 KT  80 MPH - Category 1 (WSW Praia,Cape Verde)
 72H  02/1200Z 14.0N  35.4W   70 KT  80 MPH - Category 1 (WSW Praia,Cape Verde)
 96H  03/1200Z 18.4N  38.8W   55 KT  65 MPH - Tropical Storm (WSW Praia,Cape Verde)
120H  04/1200Z 24.3N  40.9W   45 KT  50 MPH - Tropical Storm (ENE San Juan,Puerto Rico)

NWS National Hurricane Center Miami FL 200 PM EDT Tue Sep 28, 2021

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

The National Hurricane Center is issuing advisories on Hurricane Sam, located several hundred miles east of the northern Leeward Islands.

  • 1. Showers and thunderstorms remain disorganized in association with a a broad area of low pressure located several hundred miles southwest of the Cabo Verde Islands. Environmental conditions are conducive for gradual development, and a tropical depression is likely to form during the next couple of days while the system moves slowly westward to west-northwestward over the central tropical Atlantic. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…80 percent.
  • 2. A broad area of low pressure located over the far eastern Atlantic several hundred miles south-southeast of the Cabo Verde Islands is producing a large area of showers and thunderstorms. This shower activity is gradually becoming better organized, and a tropical depression is expected to form in a day or so while the disturbance moves west-northwestward at 10 to 15 mph over the eastern tropical Atlantic. * Formation chance through 48 hours…high…90 percent. * Formation chance through 5 days…high...90 percent.
  • 3. A well-defined low pressure area associated with the remnants of Peter located about 400 miles east-northeast of Bermuda is producing gale-force winds. The associated showers and thunderstorms have become less organized during the past few hours, and the chances of this system becoming a short lived tropical depression or storm appear to be decreasing. This system is expected to move northeastward at about 10 mph into a region of very strong upper-level winds on Wednesday. Additional information on this system can be found in High Seas Forecasts issued by the National Weather Service. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…medium…40 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Tue Sep 28, 2021

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

The National Hurricane Center is issuing advisories on Hurricane Sam, located several hundred miles east of the northern Leeward Islands.

  • 1. A broad area of low pressure located several hundred miles southwest of the Cabo Verde Islands continues to produce an area of disorganized showers and thunderstorms. Environmental conditions are conducive for gradual development, and a tropical depression is likely to form during the next couple of days while the system moves westward to west-northwestward at 5 to 10 mph over the central tropical Atlantic. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…80 percent.
  • 2. Showers and thunderstorms are showing signs of organization in association with a tropical wave and broad area of low pressure located over the far eastern tropical Atlantic. Environmental conditions are conducive for development, and a tropical depression is likely to form in a day or two while the disturbance moves west-northwestward at 10 to 15 mph over the eastern tropical Atlantic. * Formation chance through 48 hours…high…80 percent. * Formation chance through 5 days…high...90 percent.
  • 3. A well-defined low pressure area associated with the remnants of Peter is located about 350 miles east-northeast of Bermuda. The associated showers and thunderstorms have increased a little this morning, but are still not well organized. This system could become a short-lived tropical depression while moving northeastward at about 10 mph before upper-level winds increase on Wednesday. * Formation chance through 48 hours…medium…50 percent. * Formation chance through 5 days…medium...50 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Mon Sep 27, 2021

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

The National Hurricane Center is issuing advisories on Hurricane Sam, located several hundred miles east of the northern Leeward Islands.

  • 1. A well-defined low pressure system associated with the remnants of Peter is located a few hundred miles east of Bermuda. Although shower and thunderstorm activity is currently disorganized, environmental conditions are expected to remain marginally conducive for a short-lived tropical depression to form tonight or Tuesday while the system moves northeastward at about 10 mph. By Wednesday, however, conditions are expected to become unfavorable for further development. * Formation chance through 48 hours…medium…60 percent. * Formation chance through 5 days…medium…60 percent.
  • 2. A broad area of low pressure located several hundred miles southwest of the Cabo Verde Islands is producing a large area of disorganized showers and thunderstorms. Environmental conditions are conducive for further development, and a tropical depression is likely to form during the next day or two while the system moves westward to west-northwestward at 5 to 10 mph over the central tropical Atlantic. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.
  • 3. A tropical wave located just offshore the west coast of Africa continues to produce a large area of disorganized showers and thunderstorms. Upper-level winds are conducive for gradual development, and a tropical depression is likely to form in a couple of days while the disturbance moves westward to west-northwestward at 10 to 15 mph over the far eastern tropical Atlantic. * Formation chance through 48 hours…high…70 percent. * Formation chance through 5 days…high…90 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Mon Sep 27, 2021

Corrected formation chances to medium in last two paragraphs

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

The National Hurricane Center is issuing advisories on Hurricane Sam, located several hundred miles east of the Lesser Antilles.

  • 1. An elongated area of low pressure associated with the remnants of Peter is located a few hundred miles east-southeast of Bermuda. Showers and thunderstorms associated with this system have changed little in organization since yesterday. However, environmental conditions are marginally conducive for some further development, and Peter could briefly become a tropical depression again during the next day or two while it moves northeastward near 10 mph. By midweek, environmental conditions are expected to become unfavorable for further development. * Formation chance through 48 hours…medium…50 percent. * Formation chance through 5 days…medium…50 percent.
  • 2. Disorganized showers and thunderstorms are associated with a broad area of low pressure located several hundred miles southwest of the Cabo Verde Islands. Environmental conditions are forecast to be conducive for further development of this disturbance, and a tropical depression is likely to form in a few days while it moves westward to west-northwestward at 5 to 10 mph over the central tropical Atlantic. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high...80 percent.
  • 3. A tropical wave is moving offshore the west coast of Africa and into the far eastern tropical Atlantic. Upper-level winds are forecast to be conducive for gradual development, and a tropical depression is likely to form in a few days while the system moves westward to west-northwestward at 10 to 15 mph over the far eastern tropical Atlantic. * Formation chance through 48 hours…medium…40 percent. * Formation chance through 5 days…high…80 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Sun Sep 26, 2021

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

The National Hurricane Center is issuing advisories on Hurricane Sam, located several hundred miles east of Lesser Antilles.

  • 1. Showers and thunderstorms have become a little better organized today in association with a surface trough (the remnants of Peter) located several hundred miles southeast of Bermuda. Upper-level winds are marginally conducive for further development, and Peter could become a tropical depression again during the next couple of days while it moves northeastward at about 10 mph. By midweek, environmental conditions are expected to become unfavorable for further development. * Formation chance through 48 hours…medium…50 percent. * Formation chance through 5 days…medium…50 percent.
  • 2. A tropical wave is expected to move off the west coast of Africa on Monday. Upper-level winds are forecast to be conducive for gradual development thereafter, and a tropical depression is likely to form in a few days while the system moves westward to west- northwestward at 10 to 15 mph over the far eastern tropical Atlantic. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…high…70 percent.
  • 3. A broad area of low pressure appears to be be forming several hundred miles southwest of the Cabo Verde Islands. Environmental conditions are forecast to support further development of this disturbance, and a tropical depression is likely to form around midweek while it moves westward at 5 to 10 mph. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…high...70 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Sun Sep 26, 2021

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

The National Hurricane Center is issuing advisories on Hurricane Sam, located about 900 miles east-southeast of the northern Leeward Islands.

  • 1. An elongated area of disorganized showers and thunderstorms associated with the remnants of Peter is located a few hundred miles southeast of Bermuda. Upper-level winds only appear marginally conducive for some slow development of this disturbance over the next couple of days as it moves northeastward at about 10 mph. * Formation chance through 48 hours…low…20 percent. * Formation chance through 5 days…low…20 percent.
  • 2. A tropical wave is expected to move off the west coast of Africa on Monday. Environmental conditions are forecast to be conducive for gradual development thereafter, and a tropical depression could form by midweek while the system moves westward to west-northwestward at 10 to 15 mph over the far eastern tropical Atlantic. * Formation chance through 48 hours…low…near 10 percent. * Formation chance through 5 days…medium...60 percent.
  • 3. A broad area of low pressure could form over the eastern or central tropical Atlantic early this week, to the west of the tropical wave that will be moving off the coast of Africa. Thereafter, environmental conditions could support some development of this disturbance while it moves westward at 5 to 10 mph through the middle of the week. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…30 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Sat Sep 25, 2021

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

The National Hurricane Center is issuing advisories on Hurricane Sam, located about 1000 miles east-southeast of the northern Leeward Islands, and has issued the last advisory on Post-Tropical Cyclone Teresa, located about 150 miles north of Bermuda.

  • 1. An area of disorganized showers and thunderstorms associated with the remnants of Peter is located several hundred miles south-southeast of Bermuda. Environmental conditions appear marginally conducive for slow development of this disturbance over the next few days as it moves northeastward at about 10 mph. * Formation chance through 48 hours…low…10 percent. * Formation chance through 5 days…low…20 percent.
  • 2. A tropical wave is expected to move off the west coast of Africa by early Monday. Thereafter, environmental conditions are forecast to be conducive for gradual development, and a tropical depression could form by the middle of next week while the system moves westward at 10 to 15 mph over the far eastern tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium...60 percent.
  • 3. A broad area of low pressure could form over the eastern or central tropical Atlantic early next week, to the west of the tropical wave that will be moving off the coast of Africa. Environmental conditions appear favorable for some development of this disturbance while it moves slowly westward through the middle of next week. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…low…20 percent.

NWS National Hurricane Center Miami FL 800 AM EDT Sat Sep 25, 2021

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

The National Hurricane Center is issuing advisories on Hurricane Sam, located about 1150 miles east-southeast of the northern Leeward Islands, and on Subtropical Storm Teresa, located about 150 miles north-northwest of Bermuda.

  • 1. An area of disorganized showers and thunderstorms associated with the remnants of Peter is located several hundred miles south of Bermuda. Environmental conditions appear marginally conducive for slow development of this disturbance over the next few days as it moves northeastward at 5 to 10 mph. *Formation chance through 48 hours…low…10 percent. *Formation chance through 5 days…low...20 percent.
  • 2. A tropical wave is expected to move off the west coast of Africa by early Monday. Thereafter, environmental conditions are forecast to be conducive for gradual development, and a tropical depression could form by the middle of next week while the system moves westward at 10 to 15 mph over the far eastern tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…50 percent.

NWS National Hurricane Center Miami FL 800 PM EDT Fri Sep 24, 2021

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

The National Hurricane Center is issuing advisories on Hurricane Sam, located about 1200 miles east-southeast of the northern Leeward Islands, and on newly formed Subtropical Storm Teresa, located about 150 miles north of Bermuda.

  • 1. A tropical wave is expected to move off the west coast of Africa early next week. Thereafter, environmental conditions are forecast to be conducive for gradual development, and a tropical depression could form by the middle of next week while the system moves westward at 10 to 15 mph over the far eastern tropical Atlantic. * Formation chance through 48 hours…low…near 0 percent. * Formation chance through 5 days…medium…50 percent.

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Video: Tropical Weather Update: Hurricane Sam is finally weakening