MY 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #44
*******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.**********
...FRIDAY JUNE 26 2020 2:22 PM EDT...
See area of interest section below for a tropical wave south of the Republic of Cabo Verde Islands I have begun to monitor for tropical cyclone formation. Elsewhere...a shortwave upper trough ejecting from the eastern Canada upper vortex is driving a new frontal low pressure in the northwestern Atlantic that will be crossing the northwestern Atlantic warm Gulf stream waters on a path similar to what Tropical Storm Dolly took. Because the shortwave upper trough is not expected to stall as a cut-off upper vortex...this system is not expected to acquire tropical characteristics like Dolly did.
Another shortwave upper trough moving across the northwestern United States is driving a surface cold front currently moving through the central United States...with the shortwave expected to soon merge with the eastern Canda upper vortex while the front eventually arrives into the western Atlantic. Computer models no longer show a possible tropical cyclone forming along this front and beneath the upper ridging currently out ahead of the front over central North America...which will also be in the western Atlantic within the next few days. Instead models have shifted westward closer to the United States east coast with possible low pressure formation along the front...with the CMC and ECMWF suggesting only a a weak and non-tropical low pressure along the front perhaps driven by a shortwave upper trough ejecting from the eastern Canada upper vortex. The GFS has a more intersting solution where the upper vortex drifts southeastward into the northeastern United States while maintaining a circular shape...which would promote low enough wind shear over the warm Gulf stream waters for such a frontal low to acquire tropical characteritics while perhaps whirling northward into the upper vortex and toward the northeastern United States coast. Given the inconsistency in the latest suite of model runs...I have not declared this frontal zone an area of interest for tropical development at this time.
AREA OF INTEREST #1...A tropical wave of low pressure that emerged from the west coast of Africa yesterday appears to be showing some signs of organization in its thunderstorm activity this early afternoon while located well south of the Republic of Cabo Verde islands in the vicnity of 8N-25W. Due to these observations and notable computer model support in the model summary below that suggests the tropical wave will at least develop a low pressure spin within the next few days...I have begun to highlight it as an area of interest for tropical cyclone formation. The Atlantic surface subtropical ridge is forecast to be strong...which should keep the tropical wave moving briskly westward with little northward angle in its track...perhaps giving the tropical wave a chance to develop just south of the dry saharan air outbreak the lies to the north. But given that the dry saharan air outbreak has been very impressive...my odds of tropical cyclone formation are on the low side...only at 10% maximum...despite the tropical wave being below a cell of tropical upper ridging during the forecast period which would promote low wind shear and upper outflow that are otherwise favorable for tropical development. This expansive cell of upper ridging will be between upper vorticity that cuts-off from the current northeastern Atlantic upper trough and the upper vorticity currently in the western Atlantic. I drop odds of development to 0% by 120 hours as this is when computer models show the tropical wave weakening...perhaps from the dry saharan air and more likely from westerly wind shear to be generated in the vincity of the Lesser Antilles by the western Atlantic upper vorticity.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Jun 27)...5% chance of tropical cyclone formation (tropical Atlantic near 9N-31W)
IOH 48 Hr Outlook (1200Z Jun 28)...10% chance of tropical cyclone formation (tropical Atlantic near 10N-37.5W)
IOH 72 Hr Outlook (1200Z Jun 29)...10% chance of tropical cyclone formation (tropical Atlantic near 11N-45W)
IOH 96 Hr Outlook (1200Z Jun 30)...10% chance of tropical cyclone formation (tropical Atlantic near 12N-52W)
IOH 120 Hr Outlook (1200Z Jul 1)...0% chance of tropical cyclone formation(east of the Lesser Antilles near 13N-57.5W)
...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...tropical wave better defined near 11N-46W in 72 hours...surface low pressure center defined near 11N-51W by 90 hours...tropical wave nears to Lesser Antilles at 60W by 120 hours while losing low pressure center. Elsewhere...central US front swings into west Atlantic by 54 hours...weak low pressure along front offshore of North Carolina by 120 hours that tracks northeastward to 39N-65.5W by 144 hours.
0000Z ECMWF Model Run...For area of interest #1...tropical wave develops low pressure center near 9N-29W by 24 hours...possible small tropical cyclone near 11.5N-34W by 48 hours which reaches peak strength near 16N-47.5W by 96 hours...dissipates back into a tropical wave that crosses the northern Lesser Antilles by 144 hours. Elsewhere...central US front swings into west Atlantic by 72 hours...weak and broad low pressure along front offshore of North Carolina by 96 hours that tracks northeastward to 37N-70W by 120 hours.
0600Z GFS Model Run...For area of interest #1...tropical wave develops low pressure center near 9N-31W by 18 hours...low pressure reaches 10.5N-40W by 54 hours...opens back to a tropical wave near 43W longitude by 66 hours...tropical wave reaches Lesser Antilles by 120 hours. Elsewhere...central US front swings into west Atlantic by 72 hours...large broad low pressure along front offshore of the Carolinas by 102 hours which becomes possible tropical or subtropical cyclone near 35N-71W by 120 hours...possile cyclone swings north and makes landfall in Maine by 144 hours while weakening.
0600Z NAVGEM Model Run...Data error