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 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #162

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


...TUESDAY OCTOBER 27 2020 10:24 PM EDT...

Satellite image as of 0150Z (Red marking active tropical cyclones or remnants of tropical cyclones...with Z marking Zeta. Green marks an are of interest in the NHC tropical weather outlook. Yellow marks an area of interest not in the NHC tropical weather outlook):


See Tropical Storm Zeta section below for the only currently active tropical cyclone in the Atlantic basin. See area of interest section below for the tropical wave of low pressure approaching the Caribbean Sea now being monitored for development.


TROPICAL STORM ZETA...With Zeta taking a more west track and cutting across a longer path over the land of the northern Yucatan peninsula in the last 24 hours...the hurricane has weakened to a tropical storm and its core

had been struggling to reorganize despite being back over water since the afternoon. However as we march into the nighttime hours...the core is establishing a well-defined eye type feature...and it is probable that Zeta will become a hurricane again soon. However by 24 hours I forecast Zeta to be just below hurricane force as I anticipate some weakening back to tropical storm force before tomorrow night’s US Gulf coast landfall... due to the upper trough of the incoming south-central US frontal system imparting increasing wind shear. This is the same as my intensity forecast from yesterday despite Zeta being weaker than that forecast...as today’s 1800Z GFS delays the arrival of the shear by showing anticyclonic flow over Zeta still present through 0600Z tomorrow (Oct 28)...whereas yesterday’s 1200Z GFS model fields which I used for my forecast yesterday had more linear shearing upper flow beginning by 0600Z Oct 28. The current northwest track of Zeta is also expected to bend sharply eastward by 24 hours as the incoming front and upper trough push into Zeta...and I have yet again sped up the northeast track to keep up with many of the latest model runs which keep on trending with a faster track. As Zeta system merges with the front and becomes supported by the eastern divergence zone of the upper trough...it will transition into a non-tropical remand frontal cyclone as it makes landfall along the eastern US Gulf coast or just after landfall. Even as it becomes less tropical...Zeta will still bring high winds and coastal storm surge as it will only slowly weaken due to the support of the upper trough.


Interests along the US Gulf coast along the western Florida panhandle...Alabama and Mississippi coasts...and southeast Louisiana coast should finish preparations for high winds and coastal storm surge by tomorrow morning as conditions will deteriorate by late tomorrow and into early Thursday. Gusty winds could spread inland across southern Mississippi...eastern Alabama...and much of Georgia. Heavy rainfall with some flash flooding potential from Zeta and its remnants is possible in the above mentioned land areas as well as the Carolinas and Virginia. When venturing out in public during preparation wearing a mask and frequent hand sanitizing will reduce your exposure to the COVID 19 virus. In case you may have to relocate from impacts such as coastal storm surge...think of a hotel or family/friend residence as a public shelter may not be as ideal for controlling your exposure to COVID 19.

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

0 Hr Position (0000Z Oct 28)...65 mph maximum sustained wind tropical storm centered in the southern Gulf of Mexico at 23.2N-90.8W

IOH 24 Hr Forecast (0000Z Oct 29)...70 mph maximum sustained wind tropical storm centered just offshore of southeastern Louisiana at 28.5N-90.5W

IOH 48 Hr Forecast (0000Z Oct 30)...Remnant frontal low centered over the eastern North Carolina/Virginia border at 36.3N-76.2W


AREA OF INTEREST #1...The current western Atlantic upper vorticity is forecast to elongate into an east-west string due to the strength of the upper ridge currently over Zeta once this ridge moves into the west Atlantic. The CMC and NAVGEM models suggest the current central Atlantic tropical wave approaching the Lesser Antilles may first get enhanced thunderstorms from the divergence of the upper vorticity...and potentially develop in the coming days once the cold core upper vorticity breaks up as it remains cut-off from high latitude cold air...with the wave potentially finding more favorable upper winds beneath an anticyclone to expand in between the fracturing vorticity. Given that the tropical wave is already seeing increased thunderstorms from the divergence zone of the upper vorticity and a surface spin appears to be present along the wave axis near 10N-54W around sunset...I have added this tropical wave as an area of interest for tropical development. Forecast positions below split the difference between the more southern CMC and more northern NAVGEM solutions...with odds of development kept low as neither the GFS or ECMWF develop this wave.

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

IOH 24 Hr Outlook (0000Z Oct 29)...0% chance of tropical cyclone formation (just west of the southern Lesser Antilles near 11N-61W)

IOH 48 Hr Outlook (0000Z Oct 30)...5% chance of tropical cyclone formation (eastern Caribbean Sea near 13N-65W)

IOH 72 Hr Outlook (0000Z Oct 31)...5% chance of tropical cyclone formation (central Caribbean Sea near 15N-70W)

IOH 96 Hr Outlook (0000Z Nov 1)...10% chance of tropical cyclone formation (just southeast of Jamaica near 17N-76W)

IOH 120 Hr Outlook (0000Z Nov 2)...15% chance of tropical cyclone formation (just south of Grand Cayman Island near 19N-81W)


...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 Tropical Storm Zeta...makes landfall over southeastern Louisiana between 30 and 36 hours...remnant low elongates and loses a defined center by 54 hours over the Appalachian Mountains. For area of interest #1...current central Atlantic tropical wave strengthens to a surface low in the central Caribbean Sea by 120 hours...tropical cyclone formation suggested in the western Caribbean Sea in long range.


1200Z ECMWF Model Run... For Tropical Storm Zeta...makes landfall in southeast Louisiana between 24 and 48 hours while moving rapidly northeast...as a remnant frontal low moves rapidly northeast into the open northwest Atlantic by 72 hours...gradually loses identity along front while moving into the open North Atlantic between 96 and 120 hours. For area of interest #1...no tropical cyclone formation shown.


1800Z GFS Model Run...For Tropical Storm Zeta...makes landfall over southeast Louisiana between 24 and 30 hours...remnant frontal low enters Atlantic from Virginia by 54 hours...remnant low loses identity along frontal zone while in open northwest Atlantic by 66 hours. For area of interest #1...no tropical cyclone formation shown.


1200Z NAVGEM Model Run...For Tropical Storm Zeta...makes landfall over southeast Louisiana at 36 hours...remnant frontal low enters Atlantic from Virginia by 66 hours... remnant low loses identity along frontal zone while in open northwest Atlantic by 78 hours. For area of interest #1...north end of current central Atlantic tropical wave strengthens to a surface low at a location just east of the eastern Bahamas in 102 hours...tropical cyclone formation suggested just northeast of the eastern Bahamas at 120 hours.

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