*******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.**********
...WEDNESDAY AUGUST 12 2020 11:31 AM EDT...
See tropical depression eleven section below for the only active tropical cyclone in the Atlantic basin.
Elsewhere...the cold front currently over the eastern United States will become stretched southwest-to-northeast across the northwestern Atlantic in about 3 days while its supporting upper trough likewise becomes stretched by a warm upper ridge to build over Canada. Models have trended with the stretched upper trough coalescing into an upper vortex over the northwestern Atlantic to the south of Newfoundland as the upper ridge over Canada builds over the eastern part of the nation...triggering a strong surface frontal cyclone now forecast to be north of the warm Gulf stream waters and reducing the chances that the forecast cyclone would acquire tropical characteristics. Therefore not declaring the frontal zone an area of interest for tropical development at this time.
TROPICAL DEPRESSION ELEVEN...The tropical wave of low pressure in the central tropical Atlantic became tropical depression eleven shortly after yesterday's birdseye view post. Since that time the depression has become better organized as the bursts of thunderstorms northwest of the center have become better organized into bands...and the thunderstorms appear to better cover the center as it appears the easterly shear driven by the broad tropical upper ridge in the region has lessened. The short-term intensity forecast is challenging as the depression has escaped an unfavorable upper vortex to the northeast...thus remaining tucked beneath a cell of supporting tropical upper ridging...and yet none of the models strengthen the depression much. Perhaps this is an indication that dry saharan air may inhibit strengthening...so for now I forecast this system to become and then remain a steady-state weak tropical storm. The current western Atlantic upper trough is expected to have lingering remnants that will shear this system as it nears the northeastern Caribbean islands and western Atlantic...therefore I forecast this system to weaken and then dissipate by the end of the 120-hour forecast period. This idea is also shown in the ECMWF and GFS models.
Regarding the track forecast...I have shifted the track points northwestward due to the current position and heading of this system. A curve to the north in the track is shown by 96 to 120 hours as the current frontal zone over the eastern United States will erode the west side of the steering Atlantic surface subtropical ridge.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1200Z Aug 12)...35 mph maximum sustained wind tropical depression centered at 12.4N-44.2W
IOH 24 Hr Forecasat (1200Z Aug 13)...40 mph maximum sustained wind tropical storm centered at 13.5N-49W
IOH 48 Hr Forecast (1200Z Aug 14)...40 mph maximum sustained wind tropical storm centered at 14.5N-54W
IOH 72 Hr Forecast (1200Z Aug 15)...40 mph maximum sustained wind tropical storm centered just east of the northern Lesser Antilles at 16N-58.5W
IOH 96 Hr Forecast (1200Z Aug 16)...35 mph maximum sustained wind tropical depression centered just northeast of the Virgin Islands at 19N-64W
IOH 120 Hr Forecast (1200Z Aug 17)...Remnant surface low pressure centred in the western Atlantic at 24N-66W
...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 tropical depression eleven...located north of Puerto Rico at 21N-66W in 120 hours...no strengthening shown. Elsewhere...rapidly intensifying frontal cyclone forms southeast of Nova Scotia and over cooler waters in 90 hours...lower chance of subtropical cyclone development from this feature.
0000Z ECMWF Model Run...For tropical depression eleven...degenerates into a tropical wave just north of the Lesser Antilles in 96 hours. Elsewhere...rapidly intensifying frontal cyclone forms just south of Newfoundland and over cooler waters in 96 hours...lower chance of subtropical cyclone development from this feature.
0600Z GFS Model Run...For tropical depression eleven...degenerates into a tropical wave just north of the Virgin Islands in 102 hours. Elsewhere...rapidly intensifying frontal cyclone forms just southeast of Newfoundland and over cooler waters in 126 hours...lower chance of subtropical cyclone development from this feature.
0600Z NAVGEM Model Run...For tropical depression eleven...gradually develops this system into a strong tropical cyclone that curves northwestward into the open western Atlantic...reaching 23N-60.5W in 120 hours. Elsewhere...rapidly intensifying frontal cyclone forms just southeast of Nova Scotia and over cooler waters in 114 hours...lower chance of subtropical cyclone development from this feature.