*******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.**********
...THURSDAY JUNE 11 2020 10:45 AM EDT...
See area of interest section below for tropical wave approaching the southern Lesser Antilles that has been recently introduced into the National Hurricane Center tropical weather outlook. Elsewhere...the northern portion of the lengthy upper trough currently in the western Atlantic is forecast to dive south and amplify into a cold core upper vortex over or just east of the Azores in 72 hours while cut-off by the robust longwave upper ridge emerging from eastern North America. Computer models agree this will result in an associated surface frontal low pressure that potentially strengthens into a surface frontal cyclone as the CMC and ECMWF suggest...followed by an eastward drift away from the Azores in the long-range as the surface feature weakens below the upper vortex in its post-mature phase...all as the upper vortex gets pulled into the persistent and much larger upper vortex over western Europe. Even though water temperatures in this region are in the 18 to 20 deg C range...the upper vortex is forecast to be rather cold which could potentially aid in thunderstorm development and acquisition of tropical characteristics. However not introducing this weather system as an area of interest at this time as not all models agree that the surface feature will develop a consoldiated enough spin which would be neccessary for subtropical cyclone status.
AREA OF INTEREST #1...A typical surface tropical wave of low pressure originating from Africa has been introduced into the National Hurricane Center tropical weather outlook since last evening as it approaches Barbados and the southern Lesser Antilles. This is due to the development of a small but somewhat organized area of showers and thunderstorms with rotation. Looking back at my archived satellite imagery on these birdseye view posts...the tropical wave has been well-defined on satellite since it was in the central tropical Atlantic on June 7 while featuirng a cloud swirl...but thunderstorm activity was limited until last night when the tropical wave appeared to escape the strongest of the dry saharan air surge from Africa and took advantage of low shear and upper outflow on the west edge of a tropical upper ridge. This morning the thunderstorms have dwindled perhaps as the dry air surge has caught up to the tropical wave from the east...and combined with wind shear being generated over the eastern Caribbean Sea by an upper vortex tied to the lengthy western Atlantic upper trough...conditions appear hostile for development as this tropical wave advances into the eastern Caribbean Sea over the next 48 hours. Therefore I am not mentioning any impacts to Barbados and the southern Lesser Antilles from this tropical wave at the bulletins on the home page. I am also keeping odds of tropical cyclone development at 0% in the short-term despite the National Hurriacne Center's 10% odds for the 48 hour timeframe (probably the National Hurricane Center will drop those odds later today).
For the longer-term...warm and cold air advection on both sides of the remnant frontal cyclone of Cristobal noted in the above birdseye view chart are modifying the atmospheric setup which will ultimately control the fate of this tropical wave..specifically by amplification of the upper trough now over the Central United States and amplification of the upper ridge over eastern North America that will soon slide into the western Atlantic. The upper ridge will push the shearing Caribbean upper vortex westward and away...eventually merging with the south side of the amplified central United States upper trough by 60+ hours such that wind shear is likely to drop over the central Caribbean and adjacent Bahamas region. Meanwhile the surface cold front trailing from Cristobal's remnants and driven by the central United States upper trough will congeal with the remnants of the broad frontal low currently in the central Atlatnic...creating enough of a ridge weakness to draw any surface low pressure generated by the tropical wave on a west-northwest to northwest track. Therefore I keeps odds of development at 0% despite the drop in shear by 72 and 96 hours as such a track increases chances for land interaction with the northern Caribbean islands. I finally show a 5% chance of development at 120 hours in the waters between Cuba and the Bahamas...with such low odds due to my uncertainty as to whether or not this tropical wave will ever produce a surface low pressure area at this location in the long range.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Jun 12)...0% chance of tropical cyclone formation (eastern Caribbean Sea just west of the Lesser Antilles near 14N-62W)
IOH 48 Hr Outlook (1200Z Jun 13)...0% chance of tropical cyclone formation (eastern Caribbean Sea south of Puerto Rico near 16.5N-66.5W)
IOH 72 Hr Outlook (1200Z Jun 14)...0% chance of tropical cyclone formation (over the Dominican Repubic near 18.5N-72W)
IOH 96 Hr Outlook (1200Z Jun 15)...0% chance of tropical cyclone formation (over northeast coast of Cuba near 20.5N-76W)
IOH 120 Hr Outlook (1200Z Jun 16)...5% chance of tropical cyclone formation (between Cuba and the Bahamas near 23N-78W)
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
0000Z CMC Model Run...For area of interest #1...no tropical cyclone formation shown. Elsewhere...develops new frontal low pressure in northeastern Atlantic in 24 hours...dives south to a position just east-northeast of the Azores by 72 hours...consolidates and strengthens just northeast of the eastern Azores by 96 hours while cyclonically looping beneath its supporting cut-off upper vortex...begins drifting eastward away from the Azores at 120+ hours while weakening in the long range.
0000Z ECMWF Model Run...For area of interest #1...no tropical cyclone formation shown. Elsewhere...develops new frontal low pressure in northeastern Atlantic in 24 hours...dives south to a position just east of the Azores by 72 hours...consolidates and strengthens while cylonically looping beneath its supporting cut-off upper vortex and arrives into the Azores on this path by 96 hours...begins drifting eastward away from the Azores at 120+ hours while weakening in the long range.
0600Z GFS Model Run...For area of interest #1...no tropical cyclone formation shown. Elsewhere...develops new frontal low pressure in northeastern Atlantic in 24 hours...dives south to a position just east of the Azores by 72 hours...cylonically loops beneath its supporting cut-off upper vortex and arrives into the Azores on this path by 84 hours but does not show as consolidated of a circulation as the CMC and ECMWF...begins drifting eastward away from the Azores at 120+ hours while weakening in the long range.
0600Z NAVGEM Model Run...For area of interest #1...no tropical cyclone formation shown. Elsewhere...develops new frontal low pressure in northeastern Atlantic in 24 hours...dives south to a position just east of the Azores by 72 hours...cyclonically loops beneath its supporting cut-off upper vortex while crossing the Azores and arriving to a position just southwest of the Azores by 96 hours but does not show as consolidated of a circulation as the CMC and ECMWF...begins drifting eastward at 120+ hours while weakening in the long range.
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