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 #11 (Weekend Edition)

*******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 JUNE 5 2021 2:20 PM EDT...

Satellite image as of 1600Z. 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 1200Z:

Welcome to what I call my “weekend edition” posts...where I put together the entire post on using only mobile phone tools instead of a laptop computer. This will allow me to execute these posts while on the go during weekend activities.


The Atlantic tropics are currently calm due to the presence of dry Saharan air in the eastern tropical Atlantic and widespread westerly wind shear. However two areas of interest for tropical development may develop in 5 to 7 days as follows:


(1) Warm upper ridging is expected to amplify across the United States due to surface southerly flow forecast on the west side of the Atlantic surface ridge and east side of one frontal system to develop across central Canada and another to become parked over the western US. This upper ridging will cut-off a part of the current upper trough entering the NW Atlantic into a vortex that dives southeast toward the waters north of the Caribbean Islands and south of Bermuda. The GFS since 0000Z has trended with an increasingly stronger surface subtropical or tropical system triggered by the divergence zone of the forecast vortex...and the NAVGEM has begun to pick up on this trend as well. If these model trends continue...will consider declaring a new area of interest in a special update tonight or in my next full update tomorrow as a surface feature could develop in as soon as five days.


(2) The latest computer model runs continue suggest that the current western Atlantic to Caribbean cold core upper vorticity will remain cut-off from mid-latitude cold air...resulting in its dissipation and replacement by warm core upper ridging with less shear and upper outflow more conducive for the lowering of surface pressures and tropical development across Central America and the Caribbean. For example the CMC model suggests eventual eastern Pacific development adjacent to Central America and SE Mexico...and the GFS suggests a broad lowering of surface pressures across the Caribbean and Central America. The NAVGEM suggests the eventual formation of a tropical surface low pressure in the western Caribbean Sea offshore of Central America. Due to the general inaccuracy of model runs in the long range...I have not highlighted the Caribbean Sea as an area of interest at this time.

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