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 #63

*******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.**********


...WEDNESDAY JULY 28 2021 10:34 PM EDT...

Satellite image as of 2310Z. 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:


Regarding current activity in the Atlantic basin:

(a) The vigorous tropical wave of low pressure that was moving through the Caribbean Sea is now over land while passing over southeastern Mexico and western Central America. The tropical wave is producing scattered thunderstorms over land while aided by the outflow of the upper ridge currently over southeast Mexico…however tropical development is not expected as the upper vortex currently over western Cuba will continue to shift west under the influence of the southern US upper ridge and suppress thunderstorm activity over adjacent western Caribbean and southwestern Gulf of Mexico waters.

(b) A surface low pressure area over the coastal Carolinas has formed with the support of divergence on the east side of a shortwave upper trough…however tropical development is not expected as the shortwave upper trough shifts offshore and produces hostile shear over the region.


Regarding future activity in the Atlantic basin:

(a) The cold front currently over the central United States will reach the waters offshore of the southeastern United States in the coming days...with tropical development possible in the 3 to 5 day window as the tail end of the front decays beneath an offshore extension of the current southern United States sprawling upper ridge creating an environment of low shear and upper outflow. However I have not declared an area of interest for this frontal zone at this time as the models have not been consistent in showing tropical development.

(b) Conditions in the low-latitudes of the tropical Atlantic will soon return to a more favorable state as the upward-motion phase of the Madden Julian Oscillation (MJO) is shifting east into the Atlantic basin (https://www.cpc.ncep.noaa.gov/products/precip/CWlink/MJO/mjo.shtml). All global computer models agree on showing lowering surface pressures in the eastern tropical Atlantic over the next week...perhaps a signature of vigorous tropical waves of low pressure emerging from Africa and being aided by the MJO's arrival and also the outflow and divergence of the eastern tropical Atlantic upper ridge axis forecast to perist over the next several days. In fact the outflow and divergence of this upper ridge axis is already contributing to widespread thunderstorm activity over Western Africa and the far eastern Atlantic. Therefore another area of interest may emerge in the eastern tropical Atlantic over the course of the next week.


...COMPUTER MODEL SUMMARY...

Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (http://moe.met.fsu.edu/tcgengifs/)

1200Z CMC Model Run...no tropical cyclone formation shown in the Atlantic basin for the next seven days (168 hours)


1200Z ECMWF Model Run...

**Cold front currently over the central US reaches the west Atlantic by 72 hours…possible tropical development near 39N-70W at 120 hours.


1800Z GFS Model Run...no tropical cyclone formation shown in the Atlantic basin for the next seven days (168 hours)


1200Z NAVGEM Model Run...no tropical cyclone formation shown in the Atlantic basin for the next seven days (168 hours)

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