BIRDSEYE VIEW POSTS

Since 2012 on the Weather Underground (www.wunderground.com) 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 via Disqus on Weather Underground at www.wunderground.com/cat6. You can see my Disqus feed at this link for my latest comments. Feel free to reply to me with your disqus account or e-mail at IOHurricanes@outlook.com 

 
 
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MY 2021 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #16

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


...THURSDAY JUNE 10 2021 10:35 PM EDT...

Satellite image as of 2050Z. 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:

See area of interest #1 section below regarding the potential for tropical development in the southern Gulf of Mexico and Caribbean waters adjacent to Central America and southeastern Mexico over the next week.


Elsewhere...the cold front trailing from the current northwest Atlantic frontal low will stall offshore of the northeast and mid-Atlantic US coasts. A weak surface low is forecast to form along the front...and offshore of the Carolinas...in about 3 days while atmospheric lift is enhanced by the eastern divergence zone of a fragment of the current upper vorticity over the central US as that fragment settles over the Carolinas. However in about 4 days...the upper trough currently over the northwestern US is forecast to arrive in New England and Atlantic Canada...and support a broad frontal cyclonic system that would quickly absorb anything that develops offshore of the Carolinas. Therefore I have not added a new area of interest for tropical development in regards to this situation.


AREA OF INTEREST #1...As of this evening (1800Z to 2100Z)...the outflow of upper ridging over the NW Caribbean Sea supports a cluster of thunderstorms over eastern Nicaragua and Honduras...with another cluster of activity over western Honduras...Guatemala...and SE Mexico supported by upper outflow and surface convergence of a tropical wave of low pressure passing 91W longitude. The current activity in the Gulf of Mexico is supported by the divergence zone of upper vorticity extending from the central US. In the above charts...the tropical wave passing 77.5W longitude is marked as an ongoing area of interest as the wave could become enhanced by the favorable upper outflow over the NW Caribbean...Central America...and SE Mexico that lies ahead in its path...likely evolving into a broad tropical low pressure.


Any broad low pressure that develops will move only slowly west-northwest from Central American and towards southeast Mexico and the southern Gulf of Mexico over the next few days as the west extent of the steering Atlantic surface ridge weakens from the current surface cold front trailing from the current NW Atlantic frontal low. At this time...it is hard to say if and when a tropical cyclone would ultimately consolidate within the broad circulation and over the adjacent eastern Pacific waters...or over the adjacent western Caribbean and southern Gulf of Mexico waters...or perhaps over both basins (i.e. an eastern Pacific tropical cyclone that develops in the long range...which then crosses over to the southern Gulf of Mexico...or alternatively a pair of twin tropical cyclones...one over the eastern Pacific...and another over the western Caribbean or southern Gulf of Mexico). Today’s 1200Z and 1800Z computer model guidance seemed to converge on the eventual formation of a tropical cyclone in the southwestern Gulf of Mexico (Bay of Campeche) in about a week from now...will have to see if this trend continues as so far the models have been inconsistent each day in forecasting the evolution of the forecast broad tropical low pressure. For now...I hold 0% odds of tropical cyclone formation thru 96 hours...with a slight increase to 10% odds by 120 hours as this system reaches the Bay of Campeche given the 1200Z and 1800Z model agreement on possible development here in the long range.


One key takeaway...an increase in heavy rainfall will be possible over parts of Central America and SE Mexico this weekend and into next week per the bulletins on the home page of this site....regardless of tropical cyclone development or not.

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

IOH 24 Hr Outlook (1800Z Jun 11)...0% chance of tropical cyclone formation (offshore of Nicaragua near 12.5N-82.5W)

IOH 48 Hr Outlook (1800Z Jun 12)...0% chance of tropical cyclone formation (Nicaragua/Honduras border near 13.8N-86W)

IOH 72 Hr Outlook (1800Z Jun 13)...0% chance of tropical cyclone formation (Honduras/Guatemala border near 15N-89.2W)

IOH 96 Hr Outlook (1800Z Jun 14)...0% chance of tropical cyclone formation (southeastern Mexico near 16.5N-92W)

IOH 120 Hr Outlook (1800Z Jun 15)...10% chance of tropical cyclone formation (Bay of Campeche coast of Mexico near 18.5N-94W)


...COMPUTER MODEL SUMMARY...

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


1200Z CMC Model Run...For area of interest #1...tropical cyclone formation in Bay of Campeche shown at 168 hours...near 21.5N-95.5W


1200Z ECMWF Model Run...For area of interest #1...weak surface low in Bay of Campeche forms at 96 hours near 20.5N-95.5W...the surface low undergoes a slow cyclonic loop on track through 144 hours...tropical cyclone formation shown in western Gulf of Mexico near 24.5N-95.5W at 168 hours.


1800Z GFS Model Run...For area of interest #1...surface low consolidates in western Bay of Campeche near 20N-96W at 144 hours.


1200Z NAVGEM Model Run...For area of interest #1...no tropical cyclone formation shown.

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