*******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.**********
...SUNDAY JUNE 4 2023 2:26 PM EDT...
Arlene has weakened to a remnant low pressure area while moving southeastward and then eastward across the southeastern Gulf of Mexico and Florida Straits... and toward the northwestern Bahamas. Also noting that the upper trough that Arlene is embedded within is no longer producing thunderstorms over Cuba and Hispaniola (Haiti and the Dominican Republic). See Remnants of Arlene section below for a final statement on this system.
For the northeastern Atlantic Ocean... an upper vortex is sliding eastward into the region. By Tuesday... the southeastern divergence zone of the vortex is forecast to producing a rapidly strengthening surface frontal cyclone between the Azores and Canary Islands. As of this writing only the GFS and NAVGEM models suggest the surface cyclone would have a well-defined center potentially supporting subtropical development... with the GFS suggesting a well-defined center on Tuesday before later becoming entangled with another center to develop to the northeast... while the NAVGEM suggests a well-defined center lasting for longer. Although sea-suface temperatures in the region have recently warmed to 20 deg C (nhc.noaa.gov/sst)... the 200 mb height of the upper vortex core is forecast to be just above 1190 dekameters. Would prefer to see more forecast instability thru colder upper air temps (lower 200 mb heights) for these water temps before issuing outlooks on possible subtropical development... therefore I have not done so at this time. Regardless of its eventual structure (non-tropical... subtropical etc)... the forecast cyclone will likely be large enough to bring periods of coastal surf...heavy rainfall... and gusty winds to the Azores and Canary Islands starting tomorrow and lasting through Wednesday.
REMNANTS OF ARLENE... Within the last 36 hours... Arlene weakened to a tropical depression and then remnant low pressure swirl while continuing southeastward across the southeastern Gulf of Mexico thanks to ongoing northwesterly shear and upper convergence on the back side of the quasi-stationary upper trough in the region which suppressed thunderstorm activity in the circulation. As of Saturday evening and through today... Arlene has reached the westerly flow on the other side of the upper trough axis which allowed the track of the remnant low to curve eastward through the Florida Straits and toward the northwestern Bahamas. While taking advantage of divergence on the other side of the upper trough axis... the remnant low was able to produce pockets of showers and thunderstorms across the Florida Keys and southern Florida peninsula... and as of this writing some of this activity is now over the northwestern Bahamas. However the remnant low of Arlene is not expected to re-develop as the upper trough is tilted southwest-to-northeast which is resulting in excessive westerly shear levels... instead the remnants of Arlene is expected to continue across the northwestern Bahamas later today and lose its identity with an elongated surface trough to materialize between Bermuda and the Bahamas (the surface trough will be generated by the elongated southeastern divergence zone of the upper trough). This is my final statement on Arlene on this blog as it is no longer a tropical cyclone.
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
0000Z (Jun 4) CMC Model Run...
**No tropical cyclone formation forecast for the Atlantic basin for the next 168 hours (7 days)
0000Z (Jun 4) ECMWF Model Run...
**No tropical cyclone formation forecast for the Atlantic basin for the next 168 hours (7 days)
1200Z (Jun 4) GFS Model Run...
**No tropical cyclone formation forecast for the Atlantic basin for the next 168 hours (7 days)
0600Z (Jun 4) NAVGEM Model Run...
**No tropical cyclone formation forecast for the Atlantic basin for the next 168 hours (7 days)