BIRDSEYE VIEW POSTS

Since 2012 on the now retired Weather Underground blogs, I have been posting annotated "birdseye view" charts of the Atlantic basin, with a detailed explanation and forecasting that references the chart. From there you may know me as "NCHurricane2009." While I now do these "birdseye view" posts here, I will continue to do comments at Yale Climate Connections via Disqus where the former Weather Underground community has moved to. Feel free to reply to me there, at my Disqus feed at this link, or via e-mail at IOHurricanes@outlook.com 

 
 
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MY 2021 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #19

*******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 13 2021 10:32 PM EDT...

Satellite image from earlier this afternoon (1540Z). Areas of interest circled in yellow are not mentioned in the NHC tropical weather outlook. Areas circled in a green dashed line are in the NHC 5-day tropical weather outlook. Areas circled in a solid green line are in the NHC 2-day tropical weather outlook:

NHC TAFB Surface Analysis 1200Z:

GFS Model Upper-Level Winds 1800Z:

Note that even though today is Sunday...I have not classified this update as a “weekend edition” as I have had time to compose and include the computer model summary section at the end of the update.


See area of interest sections below for areas currently being monitored for tropical development in the Atlantic basin. Elsewhere...atmospheric conditions in the eastern tropical Atlantic have become more conducive for development in recent days with a reduction in shear and increase in upper outflow while low-latitude upper vorticity in the region has weakened. Dry Saharan Air from Western Africa has so far precluded tropical development...however the tropical waves of low pressure that have recently emerged from Western Africa have also been impressive for June while producing strong and distinct thunderstorm fields. Tonight’s 1800Z GFS model run has suggested that the currently vigorous tropical wave emerging from western Africa could develop over the eastern tropical Atlantic...therefore will be monitoring the region for any signs of tropical development in the coming days.


AREA OF INTEREST #1...The eastern Pacific tropical low pressure offshore of Oaxaca...tagged as Invest 93E...and tropical low pressure in the Bay of Campeche...tagged as Invest 92L...are in the process of merging over southeastern Mexico. Both features continue to produce widespread scattered thunderstorms while supported by the outflow of upper ridging in the region.


Computer models remain in strong agreement on the following:


(1) The current upper trough over the central Canada will merge with upper vorticity that has been lingering over the eastern US...resulting in a large upper trough dominating the eastern US. The western convergence zone of the large upper trough will continue to support surface ridging over the central US.


(2) Instead of having the central US surface ridge push the 92L/93E merger westward...models have the large eastern US upper trough amplify southward into the western edge of the Gulf of Mexico due to amplification of adjacent western US warm upper ridging (in association with a forecast western North America vigorous frontal system's warm sector). This results in the 92L/93E merger’s reformation northward in the Gulf of Mexico while transitioning into a subtropical or tropical cyclone boosted by the eastern divergence zone of the amplifying upper trough.


Due to the lack of short-term development of 92L...I have dropped short-term odds of development in the updated outlook below to 0%. Forecast track in the outlook is an east and north track as this system transitions into a subtropical or tropical system supported by the aforementioned upper trough. I have raised long term odds of development to 60% due to the ongoing model consensus of an upper trough that becomes highly amplified which will keep shear low and upper divergence high in the Gulf of Mexico.


Confidence is increasing in a coastal storm surge and wind event for the US Gulf coast anywhere from southeast Texas to Louisiana & Mississippi just after 5 days (Saturday). If the circulation of the forecast tropical or subtropical storm becomes large enough...it could drive coastal sea swells in the northeast Gulf (coastal Alabama and Florida panhandle). I will soon be updating the home page bulletins of this site to reflect this.

******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********

IOH 24 Hr Outlook (1800Z Jun 14)...0% chance of tropical cyclone formation (eastern Veracruz near 17.5N-95.5W)

IOH 48 Hr Outlook (1800Z Jun 15)...0% chance of tropical cyclone formation (eastern Tabasco/Chiapas border near 17.5N-92.5W)

IOH 72 Hr Outlook (1800Z Jun 16)...5% chance of tropical cyclone formation (west coast of Yucatan peninsula near 19N-90.5W)

IOH 96 Hr Outlook (1800Z Jun 17)...30% chance of tropical cyclone formation (Gulf of Mexico near 22.5N-90.5W)

IOH 120 Hr Outlook (1800Z Jun 18)...60% chance of tropical cyclone formation (Gulf of Mexico near 25N-90.5W)


AREA OF INTEREST #2...The eastern divergence zone of upper vorticity over the southeast US has triggered the formation of a frontal surface low offshore of the Carolinas...currently located at 32.5N-77W. The upper vorticity is amplified enough such that wind shear over the surface low is low...and with the surface low over warm Gulf Stream waters the NHC is monitoring it for tropical development. The upper trough currently over central Canada will soon arrive over New England and Atlantic Canada...and support a broad frontal cyclonic system that will soon steer this system northeast toward cooler waters and absorb it....thus keeping the window of time for tropical development short. And given the current lack of thunderstorms with the surface low...I have assigned 0% odds of tropical cyclone formation.

******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********

IOH 24 Hr Outlook (1800Z Jun 14)...0% chance of tropical cyclone formation (east-southeast of Cape Hatteras North Carolina at 34.5N-74W)


...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 area of interest #1...broad surface low coalesces over the eastern Bay of Campeche and western Yucatan peninsula at 90 hours...shifts north across the western Gulf of Mexico thru 120 hours while evolving into a tropical cyclone. For area of interest #2...surface low keeps its definition while moving northeast...while located offshore of Nova Scotia at 72 hours.


1200Z ECMWF Model Run...For area of interest #1...possible weak tropical cyclone formation shown in the western Gulf of Mexico near 24N-95W at 120 hours. For area of interest #2...surface low keeps its definition while moving northeast...while located offhshore SW Newfoundland is absorbed by larger frontal low over Atlantic Canada at 72 hours.


1800Z GFS Model Run...For area of interest #1...tropical cyclone formation shown in the western Gulf of Mexico near 24N-94W at 117 hours. For area of interest #2...surface low loses its closed circulation while located offshore of the North Carolina Outer Banks at 27 hours due to development of larger frontal low over SE Canada. Elsewhere...for tropical wave currently emerging from the west African coast...possible tropical cyclone formation shown at 9.8N-27.5W at 63 hours...weakens to surface trough near 14N-39W at 108 hours


1200Z NAVGEM Model Run...For area of interest #1...tropical cyclone formation in Bay of Campeche near 20.5N-94W at 102 hours...located in the western Gulf of Mexico near 22.5N-94W at 120 hours. For area of interest #2...tropical cyclone formation shown ESE of Cape Hatteras North Carolina at 30 hours...loses tropical character at 60 hours while located over cooler water at 41.5N-57.8W while circulation becomes elongated along warm front of large frontal low over eastern Canada.

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