*******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 20 2021 9:50 AM EDT...
Satellite image as of 1340Z. 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 0000Z:
GFS Model Upper-Level Winds 0000Z:
A warm deep-layered ridge has developed in the western Atlantic with the aid of the warm sector of the current eastern Canada frontal cyclone. The ridge has to cut-off a large portion of the upper trough currently in the North Atlantic into an upper vortex located just west of the Azores…with the divergence zone of the vortex in turn generating a frontal low which is expected to strengthen into a surface cyclone. The upper vortex is likely to become elongated while entangled with an adjacent upper vortex that has coalesced to the east and upper vorticity to be deposited by the current eastern Canada upper trough as that trough later nears the region. The surface cyclone is therefore likely to become elongated with possible multiple centers instead of a singular circular center needed for subtropical development. As a result I have not declared an area of interest in regards to this cyclone. Regardless of subtropical development or not… the Azores will experience a period of gusty winds and coastal surf within the next few days.
After this weekend and into mid-week… an additional surface cyclone is expected to form in the western Atlantic as yet another upper trough amplifies in response to the amplification of upstream warm core upper ridging. The incipient upper trough is currently located over western Canada. Some models hint that the south part of the upper trough could amplify enough to become a southern-located and very cold cut-off upper vortex located over mild water temps… resulting in enough instability for subtropical development of the forecast surface cyclone. Other models do not forecast a cut-off upper vortex… resulting in a less tropical surface cyclone located further north and closer to the US northeast and Atlantic Canada coasts. Regardless of which scenario plays out… coastal surf is likely for the US east coast… Atlantic Canada coast… and Bermuda by the middle of this upcoming week. Gusty winds are also possible for Bermuda if a more southern track takes place with the surface cyclone… and are possible for the Atlantic Canada and northeast US coast if a more northern track takes place.
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
0000Z CMC Model Run...
**Frontal low just west of the Azores intensifies into an elongated frontal cyclone through 78 hours while cyclonically whirling beneath the current upper vortex in the region… through 120 hours the surface cyclone whirls west toward upper vorticity to be left behind by the current upper trough over eastern Canada (once that trough later moves into the Atlantic) while becoming more elongated and splits into two frontal lows (one that continues west and another that coalesces south of the Azores)
0000Z ECMWF Model Run...
** Frontal low just west of the Azores intensifies into an elongated frontal cyclone through 96 hours while cyclonically whirling beneath the current upper vortex in the region… through 120+ hours begins to accelerate east and passes south of the Azores while moving with upper vorticity to be deposited by the current upper trough over eastern Canada (once that trough later moves into the Atlantic)
0600Z GFS Model Run...
**Frontal low just west of the Azores intensifies into an elongated frontal cyclone through 54 hours while cyclonically whirling beneath the current upper vortex in the region…through 120 hours the surface cyclone becomes more elongated and splits into two frontal lows (one that continues west and another that coalesces south of the Azores) while influenced by elongated upper vorticity that is deposited by the current upper trough over eastern Canada (once that trough later moves into the Atlantic)
**Current frontal system over western Canada forecast to enter west Atlantic by 60 hours… by 120 hours a rapidly intensifying frontal cyclone forecast along the front near 38N-59W with the aid of an upper vortex to become cut-off from the frontal system’s upper trough… frontal cyclone becomes an intense and possible subtropical storm located just northeast of Bermuda by 138 hours
0600Z NAVGEM Model Run...
**Frontal low just west of the Azores intensifies into an elongated frontal cyclone through 54 hours while cyclonically whirling beneath the current upper vortex in the region… the cyclonic whirl takes the center of the surface cyclone into the Azores by 78 hours… through 126 hours the surface cyclone becomes more elongated and splits into two frontal lows (one that continues west and another that coalesces south of the Azores) while influenced by elongated upper vorticity that is deposited by the current upper trough over eastern Canada (once that trough later moves into the Atlantic)