MY 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #32
*******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.**********
...SUNDAY JUNE 14 2020 10:50 AM EDT...
See area of interest section below for tropical wave currently entering the central Caribbean Sea from the eastern Caribbean. Elsewhere...the surface frontal low and upper vortex that has been pushed southward into the Azores by the deep-layered north Atlantic ridge lacks thunderstorm activity to acquire tropical characteristics. Therefore...subtropical cyclone formation is not expected as the surface circulation gradually weakens in its post-mature phase beneath the core of its parent upper vortex where there is a lack of upper divergence...as the surface circulation and upper vortex drift eastward toward the much larger western Europe upper vortex or gets kicked eastward by a high-latitude upper trough that eventually erodes the north Atlantic ridge.
AREA OF INTEREST #1...The once vigorous tropical wave that was east of the southern Lesser Antilles a few days ago is crossing the central Caribbean Sea and is headed for an elongated area of showers and thunderstorms that stretches from the waters offshore of Nicaragua and Honduras northeastward to the central and eastern Bahamas. This cloud pattern suggests...along with the latest suite of computer model runs...that the tropical wave may combine with a decaying former frontal low in the western Atlantic and surface front along the eastern United States coast into a lengthy north-south surface trough of low pressure spanning from the northwestern Caribbean to the waters offshore of the southeastern United States...to be supported by the eastern divergence zone of the eastern North America longwave upper trough. Of immediate interest is a rotation that has formed within the cloudiness offshore of the Nicargua/Honduras border...but the latest ASCAT passes do not show a closed surface spin...so one assumes this is a mid-level rotation. Satellite animation suggests this spin is drifting north. So while giving some weight to this feature...I have adjusted my updated outlook forecast points southward toward this feature...assuming that a pertubation of low pressure to originate from this feature and/or the incoming central Caribbean tropical wave will trek northward through the potential lengthy north-south surface trough to extend to the waters offshore of the southeastern United States. Whether or not a tropical cyclone forms from this activity will be heavily influenced by the evolution of the longwave upper trough over eastern North America...which the models show the south half of evolving into an upper vortex cut-off from the rest of the trough by a pattern of longwave upper ridging building over the central United States. The precise shape and evolution of the cut-off upper vortex will be influenced by the warm air advection zones of frontal systems that will sweep across the western and north-central United States...which will influence of the precise evolution of the adjacent central United States upper ridge. The latest GFS model run suggests an elongated southwest-northeast upper vortex through 96 hours which would produce southwesterly wind shear unfavorable to tropical cyclone development across the region. The shear may relax a bit and supportive upper divergence on the east side of the upper vortex may increase a bit by 120 hours when the GFS shows the upper vortex taking a more north-south shape...so this is when I finally show odds of development offshore of the southeastern United States above 0%...but I only have a very low 5% odds due to the overall lackluster computer model support.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Jun 15)...0% chance of tropical cyclone formation (west-southwest of Jamaica near 17.5N-81W)
IOH 48 Hr Outlook (1200Z Jun 16)...0% chance of tropical cyclone formation (between the Cayman Islands and Cuba near 20N-79.5W)
IOH 72 Hr Outlook (1200Z Jun 17)...0% chance of tropical cyclone formation (western Bahamas near 24N-78W)
IOH 96 Hr Outlook (1200Z Jun 18)...0% chance of tropical cyclone formation (north of the western Bahamas near 28N-77.5W)
IOH 120 Hr Outlook (1200Z Jun 19)...5% chance of tropical cyclone formation (offshore of the southeastern United States near 32.5N-75W)
...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...but a defined surface trough is shown offshore of the southeastern United States by 72 hours...with a surface low pressure center on the coast of North Carolina by 84 hours. Surface low drifts northeastward to waters offshore of Virginia and Delmarva peninsula by 120 hours.
0000Z ECMWF Model Run...For area of interest #1...no tropical cyclone formation shown...but a defined surface trough of low pressure shown just north of the western Bahamas by 72 hours...reaching the coastal Carolinas by 96 hours...then dissipating on east coast of Delmarva peninsula by 120 hours.
0600Z GFS Model Run...For area of interest #1...no tropical cyclone formation shown...but a surface trough of low pressure defined offshore of the southeastern United States by 78 hours...weak surface low defined just offshore of the Carolinas by 96 hours...moves inland into northeastern North Carolina and southeastern Virginia by 120 hours.
1200Z NAVGEM Model Run...For area of interest #1...no tropical cyclone formation shown.