*******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.**********
...SATURDAY JULY 4 2020 6:44 PM EDT...
See tropical depression five section below for the only active tropical cyclone in the Atlantic basin. See area of interest section below for other areas being monitored for tropical cyclone development.
TROPICAL DEPRESSION FIVE...The surface tropical low pressure locted just ahead of the cold front tied the northwestern Atlantic upper vortex has managed to strengthen into the fifth tropical depression of the 2020 Atlantic Hurricane Season while heading east-northeastward toward Bermuda. The depression has been assisted by a southern outflow channel streaming into upper vorticity to the south that has become cut-off from a much larger central Atlantic upper vortex to the east...but negative factors including westerly wind shear being generated by a shortwave upper trough about to eject from the eastern United States (which is pivoting around the longwave trough over southeastern Canada) and cooler waters just below 26 deg C have prevented the tropical depression from having strong thunderstorms over the center. Therefore like the computer models show...I forecast the depression to not strengthen and lose its identity in the southeastern side of the broad frontal low pressure to the north being generated by the shortwave upper trough. However the depression may bring gusty winds and heavy rains as it passes over Bermuda in the next 24 hours. Forecast track has been adjusted northward from my previous outlooks due to the current position and heading of the tropical depression.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1800Z Jul 4)...35 mph maximum sustained wind tropical depression centered at 31.1N-68.7W
IOH 24 Hr Forecast (1800Z Jul 5)...Absorbed by broad frontal low pressure while located just northeast of Bermuda near 34N-62W
AREA OF INTEREST #1...The cut-off upper vortex in the northwestern Atlantic with its eastern divergence zone has produced a surface frontal low pressure yesterday that has now arrived to the vicnity of 40N-60W...but has become overrun by the cold front being pushed southward by the southeastern Canadian upper trough. Therefore the surface low should remain a non-tropical frontal feature going forward...especially as the upper vortex becomes absorbed by the upper trough. This is my final statement on this featur on this blog as it has no potential to acquire tropical characteristics.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Jul 5)...0% chance of subtropical cyclone formation (north Atlantic near 44N-45W)
AREA OF INTEREST #2...Various long range computer models over the last few days have been suggesting tropical cyclone formation along or just offshore of the southeastern United States coast. Based on a general east-west band of thunderstorm activity over parts of the southeastern United States and northeastern United States Gulf coast which has featured some signs of rotation...it appears the surface feature that the models are picking up on developing is the tail end of the lengthy cold front tied to the northwestern Atlantic upper vortex. The upper air support for tropical development appears to be the eastern divergence zone of upper vorticity in the Gulf of Mexico and possibly the upper vorticity that has remained over the central United States. It is also possible the central United States upper vorticity gets caught in the mid-latitude westerlies and enhances the eastern upper outflow in the region. The eastern outflow may also get enhanced by shortwave upper troughs to eject from the western Canada upper vortex. Wind shear unfavorable to tropical development is expected to be on the low side as the cell of Caribbean upper ridging to the south expands northward over the region in the wake of the departing northwestern Atlantic upper vortex. Because the CMC...NAVGEM...and ECMWF models all show potential development and because of the current spin already seen along the tail end of the front in question...I have declared a new area of interest for tropical development today...with peak odds already at 30% due to three of the four models already being onboard for development (the fourth model...the GFS...is the only holdout while keeping the disturbance over land). A slow northeastward track from the northeastern Gulf of Mexico...eventually arriving to the southeastern United States coast and waters just offshore...is anticipated as the disturbance gets steered by the far western extent of the Atlantic surface subtropical ridge. The track maybe slowed as a lobe of blocking surface ridging may develop over the northeastern United States in the eastern convergence zone of the central North America upper ridge that is expected to persist during the forecast period.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Jul 5)...0% chance of tropical cyclone formation (Florida panhandle coast near 30.5N-86.5W)
IOH 48 Hr Outlook (1800Z Jul 6)...0% chance of tropical cyclone formation (Florida panhandle coast near 30.5N-86.5W)
IOH 72 Hr Outlook (1800Z Jul 7)...0% chance of tropical cyclone formation (southern Georgia near 31.5N-82.5W)
IOH 96 Hr Outlook (1800Z Jul 8)...10% chance of tropical cyclone formation (southern tip of South Carolina near 32N-81W)
IOH 120 Hr Outlook (1800Z Jul 9)...30% chance of tropical cyclone formation (just offshore of the Carolina coast near 33.5N-78.8W)
...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 five...shows circulation pass just north of Bermuda in 24 hours and losing its identity in the southeatern side of the broad frontal low pressure area to the north just after that time. For area of interest #1...frontal low located south-southeast of Newfoundland in 24 hours. For area of interest #2...consolidated low pressure center forms just offshore of Cape Fear North Carolina in 96 hours...in long range drifts slowly north-northeast across the North Carolina and mid-Atlatnic coast of the United States while possibly becoming a tropical cyclone.
1200Z ECMWF Model Run...For tropical depression five...shows circulation lose its identity in the southeatern side of the broad frontal low pressure area to the north in 24 hours while passing just north of Bermuda. For area of interest #1...frontal low located south-southeast of Newfoundland in 24 hours.
For area of interest #2...consolidated low pressure center forms just offshore of the South Carolina coast in 96 hours...in long range drifts slowly northeastward and arrives to a position just east of Cape Hatteras North Carolina in 144 hours as a possibly strong tropical cyclone.
1200Z GFS Model Run...For tropical depression five...shows circulation lose its identity in the southeatern side of the broad frontal low pressure area to the north in 24 hours while passing just north of Bermuda. For area of interest #1...frontal low located south-southeast of Newfoundland in 24 hours. For area of interest #2...shows surface low pressure consolidate inland over the Georgia/South Carolina border in 132 hours...drifts slowly north-northeastward inland across the mid-Atlantic States of the United States in the long range.
1200Z NAVGEM Model Run...For tropical depression five...shows circulation lose its identity in the southern side of the broad frontal low pressure area to the north in 12 hours while located west of Bermuda. For area of interest #1...frontal low located southeast of Newfoundland in 24 hours. For area of interest #2...shows surface low pressure consolidate inland over the Georgia/South Carolina border in 90 hours...drifts eastward to the South Carolina coast by 114 hours...in long range drifts slowly norhteastward toward North Carolina coast while intensifying as a tropical cyclone.
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