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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 

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*******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 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 dot gov) for the latest watches/warnings and official forecasts on active tropical cyclones.**********

...TUESDAY JULY 27 2021 2:41 PM EDT...

Regarding current activity in the Atlantic basin:

(a) Showers and thunderstorms persist south of Bermuda beneath supporting upper outflow and divergence at the east end of an upper ridge in the region. However no surface trough of low pressure has developed at this location.

(b) After producing showers and thunderstorms north of the Caribbean Islands this past weekend...a vigorous tropical wave of low pressure venturing westward through the Caribbean Sea is producing another concentrated cluster of thunderstorms northeast Nicaragua and Honduras...this time with the aid of split flow upper divergence between an upper vortex over Cuba and upper ridge cell over southeastern Mexico. Computer models do not forecast this tropical wave to develop as it continues across the western Caribbean Sea and toward Belize and southeastern the upper vortex is forecast to shift westward over the tropical wave while pushed by the southern US upper ridge. With the vortex moving over the wave...this will tend to suppress upper divergence over the wave by 48+ hours.

Regarding future activity in the Atlantic basin:

(a) The cold front currently over western Canada will reach the waters offshore of the southeastern United States in the coming days...with tropical development possible in the 4 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 as the GFS and ECMWF models have backed off of showing this solution for now.

(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 to the Atlantic basin ( All global computer models agree on showing lowering surface pressures in the eastern tropical Atlantic in about one 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 of the eastern tropical Atlantic upper ridge axis forecast to perist over the next several days. Therefore another area of interest may emerge in the eastern tropical Atlantic in about one week's time.


Source...Florida State University Experimental Forecast Tropical Cyclone Genesis Potential Fields (

1200Z CMC Model tropical cyclone formation shown in the Atlantic basin for the next seven days (168 hours)

0000Z ECMWF Model tropical cyclone formation shown in the Atlantic basin for the next seven days (168 hours)

1200Z GFS Model tropical cyclone formation shown in the Atlantic basin for the next seven days (168 hours)

0600Z NAVGEM Model tropical cyclone formation shown in the Atlantic basin for the next seven days (168 hours)

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