*******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.**********
...TUESDAY JUNE 16 2020 10:27 AM EDT...
See area of interest sections below for a complex disturbance that has emerged from Cuba to the waters offshore of the Carolinas under the support of an emerging cut-off upper vortex over the southeastern United States.
AREA OF INTEREST #1...The southeastern divergence zone of a developing cut-off upper vortex over the southeastern United States is supporting a surface trough with cloudiness...showers...and thunderstorms extending from Cuba...spanning northward through the western Bahamas...and into the surface frontal low pressure located offshore of Georgia and the Carolinas (area of interest #2). It maybe possible that this feature is the north fracture of the tropical wave that has been recently moving through the western Caribbean Sea...which is now exiting the region. I forecast a general northward drift of this disturbance in the short term while predicting that it may supersede area of interest #2 as the dominant feature supported by the divergence zone of the upper vortex. My longer range forecast points in the updated outlook below are shifted more offshore and now show a northeastward track into the open northwestern Atlantic. This has to do with the lastest presentation of the upper vortex in the GFS model run...which shows a southwest-northeast elongation lasting now thru June 19 (previously it showed the elongation taking a more north-south orientation by that date which would have allowed this disturbance to stay closer to the US east coast). The northeastward acceleration out to sea is due to the scheduled eastward shift of the upper vortex in the long range...with the upper vortex becoming more circular such that its eastern divergence zone would increase and wind shear unfavorable to tropical development would decrease. And with the forecast positions being over the warm Gulf stream waters extending into the northwest Atlantic...this is when I finally show odds of tropical cyclone development above 0%...but only have odds at 5% due to the overall lackluster computer model support...with only the GFS and NAVGEM showing a surface low pressure eventually forming in the northwestern Atlantic. The NAVGEM albeit is an eastern outlier...showing a surface low forming over Bermuda in 48 hours and then heading north-northeast into the open northwest Atlantic to 60W longitude. This could be the model developing the other surface trough off to the east underneath lower shear and upper outflow of upper ridging that is forecast to persist out ahead of the upper vortex...and this feature is the remnants of an old central Atlantic frontal low that reached maturity on June 10th through 12th. Discarding the NAVGEM solution while assuming that the primary area of activity will be tied to the eastern divergence zone of the uper vortex.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Jun 17)...0% chance of tropical cyclone formation (western Bahamas near 26N-78W)
IOH 48 Hr Outlook (1200Z Jun 18)...0% chance of tropical cyclone formation (east of the Florida/Georgia border near 30N-77.5W)
IOH 72 Hr Outlook (1200Z Jun 19)...0% chance of tropical cyclone formation (offshore of the southeastern United States near 32.5N-75W)
IOH 96 Hr Outlook (1200Z Jun 20)...5% chance of tropical cyclone formation (western Atlnatic near 35N-74W)
IOH 120 Hr Outlook (1200Z Jun 21)...5% chance of tropical cyclone formation(northwestern Atlantic near 37.5N-68W)
AREA OF INTEREST #2...A frontal zone has been slowly driven into the western Atlantic by a slow-moving longwave upper trough over eastern North America. The south part of the upper trough is getting cut off by a building central United States upper ridge into an upper vortex over the southeastern United States...with the eastern upper divergence maximum of the emerging vortex producing a low pressure center at the south end of the front offshore of the southeastern United States. This feature has been introduced into the National Hurricane Center tropical weather outlook since yesterday for possible subtropical cyclone formation in the event it builds thunderstorms closer to the center like a tropical feature and yet is supported non-tropically by the upper vortex. However the surface low has become less defined than it was yesterday in satellite pictures...and the showers and thunderstorms remain sheared well north of the center by the upper vortex and are located over North Carolina and Virginia. Therefore I have 0% odds that this system will become a subtropical cyclone. Models are in unanimous agreement that this surface low pressure will whirl northwestward into the mid-Atlantic United States around the northeast side of the upper vortex. Based on the southwest-northeast elongation of the upper vortex shown in the GFS thru 24 hours...I agree with a more north-northeast track and a further east landfall toward Cape Lookout during this timeframe. And with the upper vortex in the GFS shown to drift north by 48 hours...I prefer the more north CMC model solution that then shifts the surface low well inland into Virginia by that timeframe. Even though this system is unlikely to become a subtropical cyclone...heavy rainfall is possible over North Carolina and Virginia over the next day or so...with gusty winds possible on coastal areas of North Carolina should this surface low strengthen under the support of the upper vortex in the next 24 hours.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Jun 17)...0% chance of subtropical cyclone formation (Cape Lookout North Carolina near 34.8N-75.2W)
IOH 48 Hr Outlook (1200Z Jun 18)...0% chance of subtropical cyclone formation (Virginia near 37.5N-77.5W)
...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. For area of interest #2...moves surface low into outer banks of North Carolina by 36 hours...swings surface low northwestward inland and has it dissipate over Virginia by 66 hours.
0000Z ECMWF Model Run...For area of interest #1...no tropical cyclone formation shown. For area of interest #2...shows surface low make landfall over Cape Fear North Carolina by 24 hours...dissipates into surface trough over southeastern North Carolina by 48 hours.
0600Z GFS Model Run...For area of interest #1...no tropical cyclone formation shown...but a surface low pressure area shown north of Bermuda by 120 hours. For area of interest #2...shows surface low make landfall between Cape Fear and Cape Lookout by 30 hours...then swings surface low westward inland and has it dissipate over the North Carolina/Tennessee border by 60 hours.
0600Z NAVGEM Model Run...For area of interest #1...no tropical cyclone formation shown...but a surface low shown to form over Bermuda by 48 hours...positioned well northeast of Bermuda by 90 hours...then opening into a surface trough along 60W in the open northwest Atlantic by 102 hours. For area of interest #2...shows surface low make landfall over Cape Fear North Carolina by 24 hours...then swings surface low westward inland and has it dissipate over central North Carolina by 60 hours.
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