MY 2021 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #155
*******Note that forecasts and outlooks in this post are NOT the official forecast from the National Hurricane Center (NHC). They are my own detailed views on the Atlantic tropics based on current observations and latest computer model runs. As such do not make decisions based on my posts...consult news media...watches and warnings from your local weather office...and any evacuation orders issued by local governments to make the most informed and best decisions. Visit the NHC website hurricanes.gov (hurricanes dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********
...SATURDAY NOVEMBER 6 2021 12:15 AM EDT...
Satellite image as of 0240Z. Areas of interest circled in yellow are not mentioned in the NHC tropical weather outlook. Areas circled in a green dashed line are in the NHC 5-day tropical weather outlook. Areas circled in a solid green are in the NHC 2-day tropical weather outlook:
NHC TAFB Surface Analysis 1800Z (Nov 5):
GFS Model Upper-Level Winds 1800Z (Nov 5):
See Wanda section below for an update on the tropical storm located in the open north-central Atlantic. Elsewhere… in approximately two days...the currently amplified eastern US upper trough and eastern Gulf of Mexico surface frontal low pressure it is generating is forecast to be located just offshore of the eastern US. The frontal low is forecast to become a rapidly intensifying frontal cyclone beneath the strong upper divergence zone of the amplified upper trough. If the upper trough amplifies into a sufficiently cold upper vortex that keeps the surface cyclone on a more south track over mild/warmer waters… their may be enough instability to allow the surface cyclone to acquire tropical characteristics in approximately five days from today. However the model guidance has not trended toward forecasting an amplified upper trough/vortex… and the potential for a tropical event from the surface cyclone is decreasing. Regardless… expect the surface cyclone to generate coastal sea swells for the east coast of North America by late this weekend and/or early next week.
TROPICAL STORM WANDA…Wanda has continued south under the steering influence of the western Atlantic surface ridge that has been approaching from the west. Due to this direction of travel… the tropical storm has become more separated from the nearby cold front to the north while showing a distinct circular swirl with scattered showers and weak thunderstorms now separate from the front’s cloud band. Wanda’s tropical character is ongoing despite being over water temps in the low 20s of deg C and under upper-level air that is not very cold (200 mb heights above 1200 dekameters). The shower and weak thunderstorm activity and Wanda’s long stretch of having 50 mph maximum sustained winds is likely attributed to the supportive eastern divergence zone of the central Atlantic upper trough in the region.
By 24+ hours… the current longwave upper trough currently approaching from eastern Canada and it’s associated northwest Atlantic surface frontal cyclone will erode steering surface ridge… which will finally sling Wanda northeast into the high latitudes after spending the last several days in a twisting meandering path. Over the next 24 hours Wanda will remain in the same conditions that have kept it going as a 50 mph wind tropical storm (see prior paragraph for details on these conditions) … and so my intensity forecast is kept steady-state through that time. Between 24 and 48 hours… the approaching longwave upper trough from eastern Canada will retain cold upper air temps and it’s amplified structure… which will increase the instability and upper divergence over Wanda while it remains over low-20 deg C waters. I project Wanda to strengthen in this environment. Once Wanda crosses the 20 deg C isotherm and reaches cooler waters in the teens of deg C by 48 hours… I anticipate Wanda will finally begin losing its tropical characteristics.
The short-term south turn that Wanda has been undergoing is bringing Wanda closer to the Azores. This could result in coastal sea swells for the Azores this weekend and/or early next week.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (0000Z Nov 6)… 50 mph maximum sustained wind tropical storm centered at 38N-38.1W
IOH 24 Hr Forecast (0000Z Nov 7)… 50 mph maximum sustained wind tropical storm centered at 37.5N-37.5W
IOH 48 Hr Forecast (0000Z Nov 8)… 60 mph maximum sustained wind tropical storm transitioning into a non-tropical frontal cyclone… centered at 43N-31W
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z (Nov 5) CMC Model Run...
**For Tropical Storm Wanda...continues south and reaches 37.5N-38.2W at 24 hours… afterwards accelerates northeast and by 66 hours loses identity along cold front of the currently approaching northwest Atlantic frontal cyclone.
1200Z (Nov 5) ECMWF Model Run...
**For Tropical Storm Wanda... continues south and reaches 37.5N-38.2W at 24 hours… afterwards accelerates northeast and between 48 and 72 hours loses identity along cold front of the currently approaching northwest Atlantic frontal cyclone.
1800Z (Nov 5) GFS Model Run...
**For Tropical Storm Wanda... continues south and reaches 38N-38W at 24 hours… afterwards accelerates northeast and by 57 hours loses identity along cold front of the currently approaching northwest Atlantic frontal cyclone.
1800Z (Nov 5) NAVGEM Model Run...
**For Tropical Storm Wanda... continues south and reaches 37.2N-38.5W at 24 hours… afterwards accelerates northeast and by 66 hours loses identity along cold front of the currently approaching northwest Atlantic frontal cyclone.