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 #163

*******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 OCTOBER 28 2020 11:20 AM EDT...

See Hurricane 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 being monitored for development.


Satellite image of Hurricane Zeta strengthening earlier this morning:

HURRICANE ZETA...Zeta has done suprisingly well this morning while briskly re-strengthening from a tropical storm and into a huricane...reaching 90 mph maximum sustained winds...or top end category 1 status. This is as the hurricane remains in a low shear and upper outflow environemnt beneath an expansive upper ridge...but the strenghtening appears to be flattening with the maximum sustained winds staying at 90 mph between 8 AM and 11 AM EDT...and the central pressure only falling by 2 mb during that timespan. The eye has also recently lost its sharp definition on satellite pictures. This could be signs that wind shear induced by the upper trough of the incoming south-central US frontal system may be starting to shear the hurricane...which hopefully will make Zeta a weaker category 1 hurricane as it moves into southeast Louisiana tonight. As expected...Zeta's track is bending northeastward as the incoming front and upper trough are pushing into Zeta...but given Zeta is slightly west of my previous forecast track I have nudged my updated track westward. 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 remnant frontal cyclone as it makes landfall 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 be rushing preparations to completion for high winds and coastal storm surge...as conditions will deteriorate by tonight 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...and also Maryland and Delaware. 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 (1200Z Oct 28)...90 mph maximum sustained wind hurricane centered in the northern Gulf of Mexico at 26N-91.7W

IOH 24 Hr Forecast (1200Z Oct 29)...Remnant frontal low centered over northwestern North Carolina at 35.8N-80.5W


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. Various models continue to suggest the current central Atlantic tropical wave approaching the Lesser Antilles will continue to 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. As of this morning the maximum spin of the wave was seen in satellite animation near 11N-59W...and the outlook below is initialized based on that position. Forecast track below is adjusted southward over the previous as the ECMWF and GFS are now joining the CMC in showing development further south...with the NAVGEM by far remaining the northern outlier. My odds of development by day 5 have been increased to 30% as the GFS and ECMWF which were previously void of showing development are now showing development as of this morning. With these updates...it appears the potential for possible tropical cylone impacts from this tropical wave is higher for Central America (Nicaragua and Honduras) than the northern Caribbean Islands.

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

IOH 24 Hr Outlook (1200Z Oct 29)...0% chance of tropical cyclone formation (west of the southern Lesser Antilles near 11.5N-63W)

IOH 48 Hr Outlook (1200Z Oct 30)...5% chance of tropical cyclone formation (southeastern Caribbean Sea near 12N-72W)

IOH 72 Hr Outlook (1200Z Oct 31)...5% chance of tropical cyclone formation (south-central Caribbean Sea near 12.5N-72W)

IOH 96 Hr Outlook (1200Z Nov 1)...15% chance of tropical cyclone formation (south-central Caribbean Sea 13N-77W)

IOH 120 Hr Outlook (1200Z Nov 2)...30% chance of tropical cyclone formation (east of Nicaragua and Honduras near 13.5N-81W)


...COMPUTER MODEL SUMMARY...

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


0000Z CMC Model Run...For Hurricane Zeta...makes landfall over southeastern Louisiana at 24 hours...remnant low enters Atlantic from Maryland and Delaware by 48 hours and loses identity along front while in the open northwest Atlantic by 60 hours. For area of interest #1...tropical wave strengthens to a surface low in the central Caribbean Sea near 14N-76.5W by 84 hours...located east of Nicaragua by 120 hours...tropical cyclone formation suggested in long range while surface low moves toward coast of Honduras.


0000Z ECMWF Model Run... For Hurricane Zeta...makes landfall in southeast Louisiana at 24 hours while moving rapidly northeast...as a remnant frontal low moves rapidly northeast into the open northwest Atlantic from Maryland and Delaware by 48 hours...gradually loses identity along front while moving into the open North Atlantic by 96 hours. For area of interest #1...tropical wave organizes into a tropical low pressure east of Nicaragua by 120 hours.


0600Z GFS Model Run...For Hurricane Zeta...makes landfall over southeast Louisiana between 12 and 18 hours...remnant frontal low enters Atlantic from Maryland and Delaware by 42 hours...remnant low loses identity along frontal zone while in open north Atlantic by 66 hours. For area of interest #1...tropical wave strengthens to a surface low in the central Caribbean Sea near 14N-76.5W by 102 hours...tropical cyclone formation suggested in long range while surface low moves into east coast of Nicaragua.


0600Z NAVGEM Model Run...For Hurricane Zeta...makes landfall over southeast Louisiana at 18 hours...remnant frontal low enters Atlantic from Virginia by 42 hours... remnant low loses identity along frontal zone while in open northwest Atlantic by 54 hours. For area of interest #1...north end of tropical wave strengthens to a surface low at a location between Puerto Rico and the Dominican Republic at 66 hours...tropical cyclone formation suggested as surface low moves into the eastern Bahamas in 90 hours...by 120 hours tropical cyclone strengthens while moving into the central Bahamas.

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