*******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.**********
...MONDAY JUNE 22 2020 10:53 PM EDT...
See subtropical depression four section below for the only active cyclone with tropical characteristics in the Atlantic basin. Elsewhere...the configuration of the Madden Julian Oscillation (MJO) favorble for tropical cyclone activity has shifted eastward toward the eastern Pacific and western Atlantic regions (https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml). However computer models agree that development will occur in the eastern Pacific instead of the western Atlatnic basin over the next few days.
SUBTROPICAL DEPRESSION FOUR...The cut-off upper vortex in the northwestern Atlantic and offshore of the northeastern United States continues shifting eastward as the upper vortex over Central Canada has finally had enough strength to push the blocking upper ridge that has been west of the upper vortex eastward. The surface low pressure that was generated by the eastern divergence zone of the vortex has become vertically stacked with the upper vortex while acquiring spiral bands of showers and thunderstorms supported by the instability provided by the warm Gulf stream waters and cool temperatures of the upper vortex. As a result...the surface low pressure is now subtropical depression four. Computer models have largely suggested the depression would eject northeastawrd away from the upper vortex while caught by the southwesterly flow of the surface Atlantic subtropical ridge...while the NAVGEM previosuly suggested the depression would stay entangled with the upper vortex and track more eastward and less northward. Now the NAVGEM suggests a northeastward ejection while the ECMWF has begun to show a solution more entagled with the upper vortex. Based on current satellite animation which shows a pure eastward track of the subtropical depression...I vote that the depression is in fact entangled with the upper vortex. Thus my forecast track lies south of the majority CMC-GFS-NAVGEM consensus...albeit I have a slight northward angle in my track given the majority. Regarding strength...since the depression is stacked beneath the center of the upper vortex where theere is a lack of divergence...and since there is no burst of thunderstorms developing near the center...I forecast no strengthening of the depression. I forecast dissipation to a remnant low by 48 hours when the depression reaches cooler waters outside of the warm Gulf stream.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Jun 22)...35 mph maximum sustained wind subtropical depression centered at 38.2N-65.7W
IOH 24 Hr Forecast (1800Z Jun 23)...35 mph maximum sustained wind subtropical depression centered at 39N-61.5W
IOH 48 Hr Forecast (1800Z Jun 24)...Remnant low centered at 40.5N-59W
...COMPUTER MODEL SUMMARY...
Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)
1200Z CMC Model Run...For subtropical depression four...located at 40N-62.5W by 24 hours...dissipated southeast of Nova Scotia by 48 hours
1200Z ECMWF Model Run...For subtropical depression four...located at 40N-62W by 24 hours...41N-58W by 48 hours...disspated by 72 hours.
1800Z GFS Model Run...For subtropical depression four...possibly stronger near 40N-61W at 24 hours...disspating east-southeast of Nova Scotia by 48 hours.
1800Z NAVGEM Model Run...For subtropical depression four...at 40N-62W by 24 hours...dissipating east-southeast of Nova Scotia by 48 hours.