*******Note that forecast 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 18 2023 3:27 AM EDT...
The central Caribbean surface low pressure area has become disorganized under hostile upper-level winds while moving into Jamaica and eastern Cuba... and tropical cyclone formation of this feature is no longer possible going forward... see area of interest #53 section below for more information.
In the northeastern Atlantic... monitoring a new frontal low moving toward the Azores for signs of acquiring tropical characteristics as it has developed a comma-shaped region of showers and thunderstorms near its center... see area of interest #55 section below for more information.
Elsewhere... noting the remnants of the tropical low over Jamaica and eastern Cuba will soon be merging with the complex frontal low offshore of the southeastern United States to make a classical non-tropical frontal system. The lowest pressures of the merged system will be shifting north-northeast across Atlantic Canada... the far north Atlantic... and into Greenland while its lengthy surface cold front stretches southward across the open central Atlantic and Caribbean Sea. Two area of the front may evolve into tropical areas of interest in the days ahead as follows:
(1) Some global model runs suggest the open central Atlantic part of the front and regional upper troughing will evolve into a cut-off deep-layer low pressure system with possible tropical characteristics within the next seven days as enough upstream upper ridging develops to the west. As such may need to declare yet another tropical area of interest for the open central Atlantic in future updates... particularly if global models converge on this scenario.
(2) The tail end of the front in the Caribbean may evolve into a new tropical low pressure disturbance to the south of Jamaica within the next three days. The upper air support for the tropical low and associated thunderstorms would be provided by the outflow of the upper ridge cell currently over Mexico... as that ridge cell later shifts east across the Caribbean in the mid-latitude westerly flow.
AREA OF INTEREST #53 (POTENTIAL TROPICAL CYCLONE TWENTY-TWO)... The broad central Caribbean tropical low has lifted northeastward across Jamaica and eastern Cuba while steered in deep-layer flow ahead of the complex frontal low offshore of the southeastern United States and associated upper trough. The elongated divergence zone of the upper trough has caused this system to transition into a disorganized elongated surface low... while southwesterly shear imparted by the upper trough has displaced the thunderstorm activity to the east of the axis of lowest surface pressures. Therefore tropical cyclone formation of this feature is no longer possible going forward. The primary impact from this system remains pockets of heavy rainfall with flash flooding potential that has overspread Jamaica... eastern Cuba... Haiti... the Dominican Republic... and the southeastern Bahamas. The heavy rainfall has also already been transported as far northeast as Bermuda by the regional deep-layer southwesterly flow. This is my final statement on this area of interest on this blog.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0600Z Nov 19)... 0% chance of tropical cyclone (western Atlantic near 25N-70W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 1 AM EDT***************************
Formation chance through 48 hours... 0%
Formation chance through 7 days... 0%
AREA OF INTEREST #55... The eastern divergence zone of the current north Atlantic upper trough has produced a new and intensifying surface frontal low heading east toward the Azores. A warm core deep-layer ridge will be materializing west of this system and subsequenlty pass north of this system in the warm sector of the frontal system that will be moving rapidly into the north Atlantic from its current position offshore of the southeastern US. The deep-layer ridge will initially cut-off a portion of this system's upper trough into an upper vortex that will become stacked with the surface frontal low as this system moves across the Azores... with the surface low and upper vortex then accelerating southwestward and away from the Azores by 48+ hours under the steering influence of the deep-layer ridge. Despite this system being currently located over 19 deg C waters... upper air temps associated with the regional upper trough are rather cold (200 mb heights well below 1200 dekameters) which has produced enough instability to generate a comma shaped area of showers and thunderstorms near the center of the surface frontal low... therefore I have upgraded the frontal low to a tropical area of interest while now monitoring it for signs of acquiring tropical characteristics. The frontal low reaches peak strength at 24 hours... after which time it decays under a lack of supporting divergence underneath the cut-off upper vortex. Global model agree on dissipating the surface low by 96 hours and this is when I drop odds of subtropical cylcone formation to 0%.
Regardless of whether or not this system acquires tropical characteristics... gusty winds and coastal surf are expected across the Azores within the next 48 hours.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (0600Z Nov 19)... 20% chance of subtropical cyclone formation (western Azores near 39N-30W)
IOH 48 Hr Outlook (0600Z Nov 20)... 20% chance of subtropical cyclone formation (south of the eastern Azores near 36N-27.5W)
IOH 72 Hr Outlook (0600Z Nov 21)... 10% chance of subtropical cyclone formation (eastern Atlantic near 33N-30W)
IOH 96 Hr Outlook (0600Z Nov 22)... 0% chance of subtropical cyclone formation (eastern Atlantic near 33N-30W)
*****National Hurricane Center (hurricanes.gov) official outlook as of 1 AM EDT***************************
Not in the offical outlook
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields(http://moe.met.fsu.edu/tcgengifs/).
1200Z (Nov 17) CMC Model Run...
**For area of interest #53... elongated tropical low just southwest of Jamaica loses identity along cold front driven by western Atlantic frontal low while located across Jamaica and eastern Cuba by 24 hours
**For area of interest #55... compact frontal cyclone currently heading toward the Azores moves into the western Azores by 42 hours... frontal cyclone then drifts southeast into the waters just south of the eastern Azores through 60 hours under influence of upstream deep-layer ridge... frontal cyclone then accelerates west-southwest as the steering deep-layer ridge passes to the north while weakening and dissipates near 35N-37W at 96 hours
**Tail end of cold front that absorbs AOI #53 evolves into a tropical low just southeast of Jamaica at 66 hours... tropical low drifts west under influence of surface ridge that builds behind the front and weakens to a trough just south of Jamaica at 108 hours... while located just south of the Cayman Islands the surface trough dissipates at 156+ hours under increasing hostile westerly shear
1200Z (Nov 17) ECMWF Model Run...
**For area of interest #53... elongated tropical low just southwest of Jamaica loses identity along cold front driven by western Atlantic frontal low while located across eastern Cuba and southeastern Bahamas by 18 hours
**For area of interest #55... compact frontal cyclone currently heading toward the Azores moves across the Azores thorugh 48 hours... frontal cyclone then accelerates southwest under influnce of deep-layer ridge passing to the north while weakening and dissipates near 34N-30W at 114 hours
**Tail end of cold front that absorbs AOI #53 evolves into a tropical low just southeast of Jamaica at 66 hours... tropical low drifts west under influence of surface ridge that builds behind the front and weakens to a trough just south of Jamaica at 108 hours... while located just south of the Cayman Islands the surface trough dissipates at 144+ hours under increasing hostile westerly shear
**Central part of cold front that absorbs AOI #53 arrives into the open central Atlantic through 102 hours... this part of the front and regional upper troughing evolves into a cut-off deep-layer subtropical low near 31.5N-36W by 168 hours
0000Z (Nov 18) GFS Model Run...
**For area of interest #53... elongated tropical low just southwest of Jamaica loses identity along cold front driven by western Atlantic frontal low while located across Jamaica and eastern Cuba by 9 hours
**For area of interest #55... compact frontal cyclone currently heading toward the Azores moves across the Azores thorugh 39 hours... frontal cyclone then accelerates southwest under influnce of deep-layer ridge passing to the north while weakening and dissipates near 32.5N-35W at 81 hours
0000Z (Nov 18) NAVGEM Model Run...
**For area of interest #53... elongated tropical low just west of Jamaica loses identity alogn cold front driven by western Atlantic frontal low over the next 12 hours
**For area of interest #55... compact frontal cyclone currently heading toward the Azores moves across the Azores through 42 hours... frontal cyclone then accelerates southwest under influnce of deep-layer ridge passing to the north while weakening and dissipates near 31.2N-32.5W at 90 hours
**Central part of cold front that absorbs AOI #53 arrives into the open central Atlantic through 84 hours... this part of the front and regional upper troughing evolves into a cut-off deep-layer subtropical low near 30N-41W by 120 hours... while drifting south the subtropical low evolves into a subtropical cyclone near 28.8N-41W at 138 hours... subtropical cyclone then drifts west and reaches 29N-43W at 168 hours