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Coastal Watches/Warnings and Forecast Cone for Storm Center

* If the storm is forecast to dissipate within 3 days, the “Full Forecast” and “3 day” graphic will be identical

Click Here for a 5-day Cone Printer Friendly Graphic

How to use the cone graphic (video):

About this product:

NHC tropical cyclone forecast tracks can be in error. This forecast uncertainty is conveyed by the track forecast “cone”, the solid white and stippled white areas in the graphic. The solid white area depicts the track forecast uncertainty for days 1-3 of the forecast, while the stippled area depicts the uncertainty on days 4-5. Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70% of the time. To form the cone, a set of imaginary circles are placed along the forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions, where the size of each circle is set so that it encloses 67% of the previous five years official forecast errors. The cone is then formed by smoothly connecting the area swept out by the set of circles.

It is also important to realize that a tropical cyclone is not a point. Their effects can span many hundreds of miles from the center. The area experiencing hurricane force (one-minute average wind speeds of at least 74 mph) and tropical storm force (one-minute average wind speeds of 39-73 mph) winds can extend well beyond the white areas shown enclosing the most likely track area of the center. The distribution of hurricane and tropical storm force winds in this tropical cyclone can be seen in the Wind History graphic linked above.

Considering the combined forecast uncertainties in track, intensity, and size, the chances that any particular location will experience winds of 34 kt (tropical storm force), 50 kt, or 64 kt (hurricane force) from this tropical cyclone are presented in tabular form for selected locations and forecast positions. This information is also presented in graphical form for the 34 kt, 50 kt, and 64 kt thresholds.

Note:  A detailed definition of the NHC track forecast cone is also available.

  000 WTNT41 KNHC 042042 TCDAT1  Tropical Storm Wanda Discussion Number  20 NWS National Hurricane Center Miami FL       AL212021 900 PM GMT Thu Nov 04 2021  Wanda continues to maintain bands of moderately deep convection near the center, mainly over the northwestern semicircle.  The  cyclone also continues to show anticyclonic outflow.   However,  cold air clouds continue to wrap around the southern side of the  circulation, and in the big picture Wanda still gives the appearance  of being embedded in a larger-scale baroclinic low.  There has been  little change in the satellite intensity estimates since the  previous advisory, so the initial intensity is held at 40 kt.  Wanda is starting its anticipated turn and the initial motion is now  045/5.  During the next day or two,  a narrow mid-latitude ridge is  forecast to build to the northwest of the cyclone, and this should  cause Wanda to turn southeastward and southward by the 48 h point.   By 60-72 h, another mid-latitude trough approaching Wanda should  cause a northeastward turn with acceleration, with this motion  persisting through the end of the forecast period.  The new guidance  again shows a little more southward motion by 48 h than the previous  guidance, and the new forecast track is adjusted a little southward  near that time.  Little change in strength is likely during the next 24 h as Wanda remains over sea surface temperatures of near 20C.  By 48 h, the southward motion brings the center over slightly warmer water, and  at that time the cyclone should interact with an upper-level low  that develops nearby.  This combination could allow some  strengthening, and the intensity forecast show modest strengthening  from 24-48 h.  Many of the guidance models continue to show more  strengthening and a higher intensity than the official forecast  between 48-72 h, and some adjustment may be needed to that part of  the forecast in later advisories if this trend persists.  Between  72-96 h, Wanda is expected to merge with a frontal system and  become extratropical over the northeastern Atlantic.   FORECAST POSITIONS AND MAX WINDS  INIT  04/2100Z 42.4N  39.2W   40 KT  45 MPH  12H  05/0600Z 41.9N  38.7W   40 KT  45 MPH  24H  05/1800Z 40.1N  38.2W   40 KT  45 MPH  36H  06/0600Z 38.5N  38.1W   45 KT  50 MPH  48H  06/1800Z 38.0N  37.7W   50 KT  60 MPH  60H  07/0600Z 39.2N  35.9W   50 KT  60 MPH  72H  07/1800Z 42.6N  32.2W   50 KT  60 MPH  96H  08/1800Z 49.0N  23.0W   45 KT  50 MPH...POST-TROP/EXTRATROP 120H  09/1800Z 53.0N  12.5W   35 KT  40 MPH...POST-TROP/EXTRATROP  $$ Forecaster Beven  

Coastal Watches/Warnings and Forecast Cone for Storm Center

* If the storm is forecast to dissipate within 3 days, the “Full Forecast” and “3 day” graphic will be identical

Click Here for a 5-day Cone Printer Friendly Graphic

How to use the cone graphic (video):

About this product:

NHC tropical cyclone forecast tracks can be in error. This forecast uncertainty is conveyed by the track forecast “cone”, the solid white and stippled white areas in the graphic. The solid white area depicts the track forecast uncertainty for days 1-3 of the forecast, while the stippled area depicts the uncertainty on days 4-5. Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70% of the time. To form the cone, a set of imaginary circles are placed along the forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions, where the size of each circle is set so that it encloses 67% of the previous five years official forecast errors. The cone is then formed by smoothly connecting the area swept out by the set of circles.

It is also important to realize that a tropical cyclone is not a point. Their effects can span many hundreds of miles from the center. The area experiencing hurricane force (one-minute average wind speeds of at least 74 mph) and tropical storm force (one-minute average wind speeds of 39-73 mph) winds can extend well beyond the white areas shown enclosing the most likely track area of the center. The distribution of hurricane and tropical storm force winds in this tropical cyclone can be seen in the Wind History graphic linked above.

Considering the combined forecast uncertainties in track, intensity, and size, the chances that any particular location will experience winds of 34 kt (tropical storm force), 50 kt, or 64 kt (hurricane force) from this tropical cyclone are presented in tabular form for selected locations and forecast positions. This information is also presented in graphical form for the 34 kt, 50 kt, and 64 kt thresholds.

Note:  A detailed definition of the NHC track forecast cone is also available.

  000 WTNT41 KNHC 041449 TCDAT1  Tropical Storm Wanda Discussion Number  19 NWS National Hurricane Center Miami FL       AL212021 300 PM GMT Thu Nov 04 2021  Wanda continues to maintain bands of moderately deep convection  near the center, and the cyclone continues to display anticyclonic  outflow.  However, cold air clouds are wrapping around the southern  side of the circulation, and in the big picture Wanda appears to be  embedded in a larger-scale baroclinic low.  A recent ASCAT-A  overpass suggests that the maximum winds are now near 40 kt, which  is between the satellite intensity estimates from TAFB and SAB.  The initial motion is northward or 000/5 kt.  During the next  couple of days, a narrow mid-latitude ridge is forecast to build to  the northwest of the cyclone, which should cause Wanda to turn  southeastward and southward by the 48 h point.  By 60-72 h, another  mid-latitude trough approaching Wanda should finally cause the  system to begin to accelerate northeastward, with this motion  persisting through the end of the forecast period.  The new  guidance shows a little more southward motion by 48 h than the  previous guidance, and the new forecast track is adjusted a little  southward near that time.  Little change in strength is likely during the next 24 h as Wanda  remains over sea surface temperatures of near 20C.  By 48 h, the  southward motion brings the center over slightly warmer water, and  some modest strengthening is possible by that time.  Many of the  guidance models show more strengthening and a higher intensity than  the official forecast between 48-72 h, and some adjustment may be  needed to that part of the forecast in later advisories if this  trend persists.  By 96 h, Wanda is expected to merge with a frontal  system and become extratropical over the northeastern Atlantic.   FORECAST POSITIONS AND MAX WINDS  INIT  04/1500Z 41.9N  39.6W   40 KT  45 MPH  12H  05/0000Z 42.1N  38.9W   40 KT  45 MPH  24H  05/1200Z 41.0N  38.0W   40 KT  45 MPH  36H  06/0000Z 39.1N  37.7W   45 KT  50 MPH  48H  06/1200Z 38.1N  37.7W   50 KT  60 MPH  60H  07/0000Z 38.7N  36.6W   50 KT  60 MPH  72H  07/1200Z 41.0N  33.7W   50 KT  60 MPH  96H  08/1200Z 48.5N  23.0W   45 KT  50 MPH...POST-TROP/EXTRATROP 120H  09/1200Z 51.5N  13.5W   40 KT  45 MPH...POST-TROP/EXTRATROP  $$ Forecaster Beven  

Coastal Watches/Warnings and Forecast Cone for Storm Center

* If the storm is forecast to dissipate within 3 days, the “Full Forecast” and “3 day” graphic will be identical

Click Here for a 5-day Cone Printer Friendly Graphic

How to use the cone graphic (video):

About this product:

NHC tropical cyclone forecast tracks can be in error. This forecast uncertainty is conveyed by the track forecast “cone”, the solid white and stippled white areas in the graphic. The solid white area depicts the track forecast uncertainty for days 1-3 of the forecast, while the stippled area depicts the uncertainty on days 4-5. Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70% of the time. To form the cone, a set of imaginary circles are placed along the forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions, where the size of each circle is set so that it encloses 67% of the previous five years official forecast errors. The cone is then formed by smoothly connecting the area swept out by the set of circles.

It is also important to realize that a tropical cyclone is not a point. Their effects can span many hundreds of miles from the center. The area experiencing hurricane force (one-minute average wind speeds of at least 74 mph) and tropical storm force (one-minute average wind speeds of 39-73 mph) winds can extend well beyond the white areas shown enclosing the most likely track area of the center. The distribution of hurricane and tropical storm force winds in this tropical cyclone can be seen in the Wind History graphic linked above.

Considering the combined forecast uncertainties in track, intensity, and size, the chances that any particular location will experience winds of 34 kt (tropical storm force), 50 kt, or 64 kt (hurricane force) from this tropical cyclone are presented in tabular form for selected locations and forecast positions. This information is also presented in graphical form for the 34 kt, 50 kt, and 64 kt thresholds.

Note:  A detailed definition of the NHC track forecast cone is also available.

  000 WTNT41 KNHC 040847 TCDAT1  Tropical Storm Wanda Discussion Number  18 NWS National Hurricane Center Miami FL       AL212021 900 AM GMT Thu Nov 04 2021  Wanda continues to exhibit bands of moderately deep convection, and  these bands are strongest most numerous over the western portion of  the circulation.  The upper-level outflow has become better  defined, also over the western semicircle.  Overall, however, the  intensity of the convection has diminished slightly over the past  several hours.  The advisory intensity is held at 45 kt, which is  in agreement with Dvorak Current Intensity numbers from both SAB  and TAFB.  This is also in good agreement with earlier  scatterometer measurements.  The initial motion continues to be just east of north, or 010/8 kt  along the eastern side of a mid-latitude shortwave trough.  This  trough is expected to weaken very soon and Wanda should slow its  forward speed later this morning.  During the next 48 hours, a  narrow ridge is forecast to build to the northwest of the cyclone  and force it to turn eastward tonight and then southward on Friday.  By 72 hours, another mid-latitude trough approaching Wanda should  finally cause the system to begin to accelerate northeastward.  The  dynamical model guidance is in reasonably good agreement on the  evolution of the steering pattern over the next several days.   There has been little change to the official track forecast, which  remains close to the model consensus, and near the middle of the  guidance envelope.  Although Wanda is located over cool 20-21 deg C sea surface  temperatures, it has been able to maintain some deep convection and  winds of 45 kt.  On its projected path during the next day or two,  water temperatures beneath Wanda are not likely to get much cooler  and the upper-tropospheric temperatures are forecast to decrease  somewhat.  This could allow for some slight strengthening, as  indicated by the official intensity forecast.  In 4 to 5 days, the  global models show the system becoming embedded in a frontal zone  over the north Atlantic, so the NHC forecast calls for Wanda to  revert back to extratropical status by that time.   FORECAST POSITIONS AND MAX WINDS  INIT  04/0900Z 41.5N  39.5W   45 KT  50 MPH  12H  04/1800Z 42.1N  39.3W   50 KT  60 MPH  24H  05/0600Z 41.7N  38.2W   50 KT  60 MPH  36H  05/1800Z 40.1N  37.5W   50 KT  60 MPH  48H  06/0600Z 38.4N  37.5W   50 KT  60 MPH  60H  06/1800Z 38.2N  37.0W   45 KT  50 MPH  72H  07/0600Z 39.8N  35.0W   45 KT  50 MPH  96H  08/0600Z 47.0N  26.0W   45 KT  50 MPH...POST-TROP/EXTRATROP 120H  09/0600Z 52.0N  16.0W   40 KT  45 MPH...POST-TROP/EXTRATROP  $$ Forecaster Pasch  

Coastal Watches/Warnings and Forecast Cone for Storm Center

* If the storm is forecast to dissipate within 3 days, the “Full Forecast” and “3 day” graphic will be identical

Click Here for a 5-day Cone Printer Friendly Graphic

How to use the cone graphic (video):

About this product:

NHC tropical cyclone forecast tracks can be in error. This forecast uncertainty is conveyed by the track forecast “cone”, the solid white and stippled white areas in the graphic. The solid white area depicts the track forecast uncertainty for days 1-3 of the forecast, while the stippled area depicts the uncertainty on days 4-5. Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70% of the time. To form the cone, a set of imaginary circles are placed along the forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions, where the size of each circle is set so that it encloses 67% of the previous five years official forecast errors. The cone is then formed by smoothly connecting the area swept out by the set of circles.

It is also important to realize that a tropical cyclone is not a point. Their effects can span many hundreds of miles from the center. The area experiencing hurricane force (one-minute average wind speeds of at least 74 mph) and tropical storm force (one-minute average wind speeds of 39-73 mph) winds can extend well beyond the white areas shown enclosing the most likely track area of the center. The distribution of hurricane and tropical storm force winds in this tropical cyclone can be seen in the Wind History graphic linked above.

Considering the combined forecast uncertainties in track, intensity, and size, the chances that any particular location will experience winds of 34 kt (tropical storm force), 50 kt, or 64 kt (hurricane force) from this tropical cyclone are presented in tabular form for selected locations and forecast positions. This information is also presented in graphical form for the 34 kt, 50 kt, and 64 kt thresholds.

Note:  A detailed definition of the NHC track forecast cone is also available.

Coastal Watches/Warnings and Forecast Cone for Storm Center

* If the storm is forecast to dissipate within 3 days, the “Full Forecast” and “3 day” graphic will be identical

Click Here for a 5-day Cone Printer Friendly Graphic

How to use the cone graphic (video):

About this product:

NHC tropical cyclone forecast tracks can be in error. This forecast uncertainty is conveyed by the track forecast “cone”, the solid white and stippled white areas in the graphic. The solid white area depicts the track forecast uncertainty for days 1-3 of the forecast, while the stippled area depicts the uncertainty on days 4-5. Historical data indicate that the entire 5-day path of the center of the tropical cyclone will remain within the cone about 60-70% of the time. To form the cone, a set of imaginary circles are placed along the forecast track at the 12, 24, 36, 48, 72, 96, and 120 h positions, where the size of each circle is set so that it encloses 67% of the previous five years official forecast errors. The cone is then formed by smoothly connecting the area swept out by the set of circles.

It is also important to realize that a tropical cyclone is not a point. Their effects can span many hundreds of miles from the center. The area experiencing hurricane force (one-minute average wind speeds of at least 74 mph) and tropical storm force (one-minute average wind speeds of 39-73 mph) winds can extend well beyond the white areas shown enclosing the most likely track area of the center. The distribution of hurricane and tropical storm force winds in this tropical cyclone can be seen in the Wind History graphic linked above.

Considering the combined forecast uncertainties in track, intensity, and size, the chances that any particular location will experience winds of 34 kt (tropical storm force), 50 kt, or 64 kt (hurricane force) from this tropical cyclone are presented in tabular form for selected locations and forecast positions. This information is also presented in graphical form for the 34 kt, 50 kt, and 64 kt thresholds.

Note:  A detailed definition of the NHC track forecast cone is also available.

  000 WTNT41 KNHC 032050 TCDAT1  Tropical Storm Wanda Discussion Number  16 NWS National Hurricane Center Miami FL       AL212021 900 PM GMT Wed Nov 03 2021  Wanda's overall convective pattern has continued to improve since  the previous advisory with a curved convective band now wrapping  almost completely around the center, resulting in a 50-60-nmi wide  banded eye feature. However, the horizontal thickness of the  convective band has been waxing and waning, and cloud tops are only  around -50C to -55C. Satellite intensity estimates from TAFB and SAB  are a consensus T3.0/45 kt, while UW-CIMSS SATCON intensity  estimates range from 34 kt to 44 kt, respectively. Based on these  data, Wanda's intensity is being maintained at 45 kt. Although a  distinct eye feature is now evident, which would suggest a stronger  storm, a lower intensity is warranted since the cooler water beneath  the cyclone is likely creating a more stable boundary layer, which  is likely inhibiting the normal downward mixing of higher winds  aloft. This physical assumption is supported by weaker wind speeds  noted in earlier scatterometer surface wind data.  The initial motion estimate is a little east of due north, or 010/09  kt. There is no significant change to the previous forecast track  and rationale. An approaching mid-/upper-level trough from the west  should continue to lift Wanda northward for the next day or so,  followed by slowing and a sharp turn to the east by Thursday night  as the aforementioned trough weakens and lifts out to the north of  the cyclone. Subsequent ridging behind the trough will then force  Wanda southeastward to southward on Friday, followed by another  abrupt turn and acceleration to the northeast on Saturday as a  second and stronger deep-layer trough captures the cyclone. Despite  this complexity in the evolving steering pattern, the latest NHC  model guidance is in very agreement throughout the 120-h forecast  period on this track scenario. The new NHC forecast track is very  similar to the previous advisory track, and lies near or slightly  to the right of the tightly packed simple- and corrected-consensus  track models.  The improved inner-core convective structure argues for at least  some slight strengthening during the next couple of days despite  the expected 20-21-deg-C sea-surface temperatures (SST) beneath the  cyclone. Some cooling aloft associated with the aforementioned  second upper-level trough may help to offset the negative effects of  the relatively cool SSTs on day 3. In the 96-120-h period, Wanda is  expected to interact, and eventually merge, with a cold front  and become an extratropical low pressure system with gale-force  winds. The new official intensity forecast is very similar to the  previous advisory, and closely follows a blend of the intensity  consensus models IVCN, NOAA-HCCA, and Florida State FSSE.   FORECAST POSITIONS AND MAX WINDS  INIT  03/2100Z 39.8N  39.5W   45 KT  50 MPH  12H  04/0600Z 41.0N  39.4W   50 KT  60 MPH  24H  04/1800Z 41.9N  39.1W   50 KT  60 MPH  36H  05/0600Z 41.8N  38.0W   50 KT  60 MPH  48H  05/1800Z 40.3N  37.0W   50 KT  60 MPH  60H  06/0600Z 38.8N  36.9W   45 KT  50 MPH  72H  06/1800Z 38.1N  36.6W   45 KT  50 MPH  96H  07/1800Z 42.4N  31.5W   45 KT  50 MPH...POST-TROP/EXTRATROP 120H  08/1800Z 51.5N  19.2W   45 KT  50 MPH...POST-TROP/EXTRATROP  $$ Forecaster Stewart  

  000 WTNT41 KNHC 031458 TCDAT1  Tropical Storm Wanda Discussion Number  15 NWS National Hurricane Center Miami FL       AL212021 300 PM GMT Wed Nov 03 2021  Wanda appears well organized this morning, with visible satellite  imagery indicating cyclonically curved convective bands wrapping  practically all the way around the circulation center. However, the  cloud top temperatures associated with this activity are not very  cold, peaking between minus 50 to 55 C in the deepest convection. An  ASCAT-A scatterometer pass at 1021 UTC also did not show much change  in the peak derived winds (39-kt), although the 34-kt radii have  expanded a bit. Subjective Dvorak satellite estimates this morning  also remain unchanged at CI 2.5/35 kt from TAFB and CI 3.0/45 kt  from SAB. The current intensity is held at 45 kt for this advisory,  assuming some undersampling in the scatterometer data.  The storm is moving a little faster to the north-northeast at 015/9  kt. The short-term track philosophy is fairly straightforward, as  Wanda continues to be steered generally northward by a narrow  mid-level ridge centered to the east of the cyclone. The track  guidance remains in good agreement on this evolution over the next  24 hours. Thereafter, the spread in track solutions increases quite  dramatically, owing to uncertainty related to the degree of  influence an approaching shortwave trough to the north has on Wanda.  For now, both the deterministic ECMWF and GFS solutions show this  shortwave trough bypassing the cyclone to the north, and in its wake  a narrow but sharp mid-level ridge develops west of Wanda, resulting  in the cyclone being steered back southward between 48-72 hours.  However, the spread in track solutions from both the GFS and ECMWF  ensemble members is very large at this time frame. In fact, the 06z  GFS ensemble track spread at 60 h is more than 500 n mi, far greater  than the average forecast track errors for that period. Finally, a  stronger shortwave trough is expected to pick up Wanda in the latter  portion of the forecast period, resulting in an abrupt acceleration  to the northeast. The official track forecast is similar to the  previous one for the first 24 hours, but has been nudged a little  south between 48-72 h following the consensus aids. Given the high  spread of ensemble solutions beyond 36 h, the track forecast beyond  that time is of low confidence.  While Wanda's winds have not increased over the past 24 hours, its  structure on satellite imagery has improved, with convective banding  wrapping around the low-level center, aided by low vertical wind  shear over the system. Even though Wanda is over marginally warm  sea-surface temperatures (SSTs) that decrease further along the  track over the next 36 hours, this negative factor will be offset by  cooling upper-level temperatures overhead. The trough forecast to  bypass Wanda to the north could also provide a bit of baroclinic  enhancement aiding ascent over the cyclone. Most of the intensity  guidance responds to this environment by showing some slight  strengthening and the latest NHC forecast now shows a peak intensity  of 50 kt in the 36-48 h time-frame. Afterwards, some increase in  shear and decreasing mid-level moisture may lead to weakening,  though this could be offset by Wanda moving back over warmer SSTs as  it tracks back south. The official intensity forecast is a bit  higher than the previous one, but ultimately still shows Wanda  losing tropical characteristics by the end of the forecast period as  it merges with an approaching mid-latitude trough.   FORECAST POSITIONS AND MAX WINDS  INIT  03/1500Z 38.8N  39.8W   45 KT  50 MPH  12H  04/0000Z 40.1N  39.7W   45 KT  50 MPH  24H  04/1200Z 41.4N  39.6W   45 KT  50 MPH  36H  05/0000Z 41.9N  38.9W   50 KT  60 MPH  48H  05/1200Z 40.9N  37.5W   50 KT  60 MPH  60H  06/0000Z 39.2N  36.6W   45 KT  50 MPH  72H  06/1200Z 38.1N  36.6W   45 KT  50 MPH  96H  07/1200Z 40.1N  33.2W   45 KT  50 MPH...POST-TROP/EXTRATROP 120H  08/1200Z 47.1N  27.1W   45 KT  50 MPH...POST-TROP/EXTRATROP  $$ Forecaster Papin