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 #60 (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.**********


…SUNDAY JULY 25 2021 11:59 PM EDT...

Satellite image as of 1900Z. 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:


A low-latitude cold core upper vorticity string that has been persisting across the Atlantic has begun to weaken and break up into separate vortices while remaining cut-off from high-latitude cold air. One of the more prominent upper vortices associated with the string has been meandering near Haiti and the Dominican Republic…producing enhanced showers and thunderstorms north of the Caribbean Islands with its eastern divergence zone yesterday…especially when then north end of a surface tropical wave of low pressure passed through the divergence zone. Another round of activity has developed north of the Caribbean Islands in the last 24 hours in a zone of upper divergence between the east side of the Haiti/D.R. upper vortex and west side of a small west Atlantic upper ridge cell that is developing in the wake of the collapsing upper vorticity string…and the more recent activity appears to have generated a weak surface trough of low pressure. Although the activity associated with surface trough has died down tonight…another resurgence of activity could result in the declaration of an area of interest for tropical development as the surface trough takes advantage of outflow and low shear beneath the expanding west Atlantic upper ridge cell. The surface trough…if it persists… is likely to track northwest between the Bahamas and Bermuda and toward the surface ridge weakness associated with the cold front driven by the current frontal low over eastern Canada.


Meanwhile…see the area of interest sections below for an update on the following:

(1) Area of interest #1...surface low pressure area offshore of Florida and Georgia

(2) Area of interest #2...frontal surface low pressure area that has quickly moved northeast to the waters far northeast of Bermuda.


AREA OF INTEREST #1...While steered by the surface ridge currently over the eastern US and western Atlantic…the surface low pressure swirl offshore of northeast Florida has been inching westward toward the coast and is centered near 30N-80W as of this writing. After earlier producing showers and thunderstorm near its center and for a time southwest of the center and on the northeast Florida coast…tonight the surface low is essentially void of activity while suppressed by the southeastern upper convergence zone of the upper ridge currently over the southeast US. Forecast track in the updated outlook below is shifted east due to the current position of the surface low…and is also shifted north as models have trended a little further south with the large frontal low over Canada which will allow it to weaken the steering surface ridge a little further. As the 24 hour forecast position is over land…and due to the suppressive upper convergence regime and current lack of activity in the circulation….I have dropped development odds to 0% and plan this to be my final statement on this system on this blog unless it continues to be mentioned in the NHC tropical weather outlook by my next update.


Regarding impacts…should the surface low manage to fire thunderstorms just before or as it makes landfall…some heavy rains may occur over northeast Florida or southeast Georgia in the next 24 hours. The potential for the other impacts outlined in previous posts and on the home page of this site have dropped.

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

IOH 24 Hr Outlook (0000Z Jul 27)…0% chance of tropical cyclone formation (southeast Georgia near 31.2N-82W)


AREA OF INTEREST #2...The surface frontal low pressure in the northwest Atlantic supported by the eastern divergence zone of the upper vorticity string in the region had developed some showers and thunderstorms near its center earlier today while at the northeast edge of warm Gulf Stream waters near 40N-55W. As the frontal low moves northeast into cooler waters while moving past 41N-54W tonight…the activity associated with the frontal low has become less organized while the organized cloud swirl to the southwest (near 37.5N-57W) is associated with the upper-level vorticity string. Due to northeast travel into cooler waters…tropical development is no longer possible with the surface frontal low…and this is my final statement on this feature on this blog.

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

IOH 24 Hr Outlook (0000Z Jul 27)…0% chance of tropical cyclone formation (northwest Atlantic near 51N-45W)

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