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 #53 (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 JULY 17 2021 11:35 PM EDT...

Satellite image as of 2120Z. 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 1800Z:

GFS Model Upper-Level Winds 1800Z:

A pair of surface tropical waves of low pressure…one in the western Caribbean and another over the Yucatan peninsula and southern Gulf of Mexico…have seen an increase in thunderstorms while encountering zones of supportive upper divergence induced by upper vorticity in the region as illustrated in the above charts. However…these waves will soon move directly below the axes of upper vorticity where there is a lack of divergence…therefore tropical development is not expected in this region.


Tropical development in the Atlantic basin has been suppressed by low-latitude (southern located) upper vorticity toward the west side of the basin (mentioned in the previous paragraph) and dry Saharan air toward the east side of the basin. However some recent model runs suggest in about three days a strong tropical wave of low pressure from Western Africa will emerge into the eastern tropical Atlantic. The current configuration of the Madden Julian Oscillation (MJO) has favored suppressed thunderstorm activity in the Atlantic tropics since July started (https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml). While the recent upheaval of activity in the eastern Pacific suggests the favorable phase of the MJO might finally be shifting back east toward the Atlantic…the favorable MJO pulse may not make it east all the way to the forecast tropical wave…and none of today’s model runs develop the wave after it enters the Atlantic…perhaps as the wave is also forecast to exit Africa a little further to the north where it may ingest dry Saharan air. Therefore for now… I have not declared a new area of interest for the forecast tropical wave.

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