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 #75

*******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 JULY 29 2020 1:15 PM EDT...

See area of interest section below for an update on the large and organizing tropical wave of low pressure now located in the eastern Caribbean Sea. Elsewhere...the eastern Atlantic tropical wave currently passing 30W longitude has seen a reduction in thunderstorm activity while ingesting dry Saharan air...and another tropical wave entering the eastern tropical Atlantic from western Africa is producing thunderstorm activity but without signs of organization. None of the computer models forecast development from either tropical wave at this time.


AREA OF INTEREST #1 (POTENTIAL TROPICAL CYCLONE NINE)...The rather large tropical wave of low pressure from the central tropical Atlantic has moved across the Lesser Antilles this morning and into the eastern Caribbean Sea...and its north side will be bringing coastal sea swells...gusty winds reaching tropical storm force...and heavy rains to the Virgin Islands and Puerto Rico later today. The 11 AM EDT advisory from the National Hurricane Center indicates that the surface circulation is gradually becoming more tightly defined toward the large and organized thunderstorm squalls that have been toward the west side of the tropical wave...and I am in agreement with the advisory central position based on the latest satellite animation. This position places this system further west...so my forecast track points are adjusted south and west accordingly. An axis of upper vorticity spanning the central and western Atlantic is likely to pull this system on a northward angle as this system strengthens/gets taller...thus a northward angle in track is shown throughout the forecast period. The northward angle in likely to increase just after 72 hours as the frontal system across the eastern United States creates a break in the Atlantic surface subtropical ridge. A sharp curve to the northeast may occur by 120 hours as this system potentially stays tall enough to get dragged by the upper westerly flow ahead of the upper trough currently over the northwestern United States...forecast to be over the eastern United States and quiet amplified by that timeframe. Putting this together with the initial southwest adjusted forecat track...I currently forecast the center of circulation to make landfall on the Dominican Republic southwest coast just after 24 hours...then moves across Haiti and along the south coast of Cuba through Saturday...then curve north across central Cuba and curve toward the west coast of the Florida peninsula from the eastern Gulf of Mexico by Sunday and Monday.


Regarding intensity...other than the internal broad structure taking time to consolidate this system is otherwise healthy with sprawling upper outflow supplied by tropical upper ridging that extends northward into the axis of upper vorticity mentioned in the previous paragraph. My intensity forecast is lowered as this system has still yet to consolidate into a tropical storm...but I still forecast a strong tropical storm for the southwest Dominican Republic/southeast Haiti landfall as it appears this system is now almost a tropcial storm and will have ongoing favorable conditions for a possible short-term brisk strengthening. For the later part of the forecast...I keep the intensity lowered but steady at 50 mph maximum sustained winds...a balance between unfavorable land interaction with the Dominican Republic...Haiti...and Cuba and possibly still favorable upper winds as the widespread hunderstorm latent heat release of this large system may break apart the axis of upper vorticity that lies to the north...which may reduce the negative shearing effects of the upper vorticity as this system moves closer to the vorticity axis. The 0600Z GFS model run in fact does show the upper vorticity continouously weakening during the forecast period. This may also provide an opportunity for strengthening when this system reaches the southeastern Gulf of Mexico in 96 hours...but I chose to not show strengthening durnig that timeframe as this system may still be recovering from a long stretch of land interaction. I do not show strengthening at 120 hours as this system may get sheared by upper westerly flow pushing this system toward the west coast of the Florida peninsula.


See bulletins at the home page of this site for impacts regarding the northern Caribbean Sea islands...I have added Jamaica to the bulletins as the more southwest track positions place this system closer toward Jamaica. Due to the COVID-19 virus emergency ongoing in the state of Florida...I suggest today is a good day in the Florida Keys and peninsula to start preparing for impacts such as coastal storm surge and power outages to avoid a last minute crowded rush that increases the potential of the virus spraed (for the panhandle I suggest a wait and see approach as it is still too early to know if the forecast could shift closer or away from this area). If this system keeps its large size on approach to Florida...storm surge may still be an issue in some areas even as a moderate tropical storm as the large wind field could still push a lot of water toward the coast. Also I would suggest thinking about the use of a family/friend residence or hotel location further inland if you live in an area prone to coastal storm surge in case you may have to relocate as the storm approaches and details of exact impacts become clearer...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 Jul 29)...45 mph maximum sustained wind potential tropical cyclone centered just west of the northern Lesser Antilles in the northeastern Caribbean Sea at 15.8N-63.7W

IOH 24 Hr Forecast (1200Z Jul 30)...60 mph maximum sustained wind tropical storm centered just south of the Dominican Republic southwest coast at 17.5N-70.5W

IOH 48 Hr Forecast (1200Z Jul 31)...50 mph maximum sustained wind tropical storm centered between Haiti...Cuba...and Jamica at 19N-75.5W

IOH 72 Hr Forecast (1200Z Aug 1)...50 mph maximum sustained wind tropical storm centered on the south coast of Cuba at 22N-79.8W

IOH 96 Hr Forecast (1200Z Aug 2)...50 mph maximum sustained wind tropical storm centered in the southeastern Gulf of Mexico just west of the Florida Keys at 24.5N-83.5W

IOH 120 Hr Forecast (1200Z Aug 3)...50 mph maximum sustained wind tropical storm making landfall on the west Florida coast just north of Tampa Bay at 28N-82.5W


...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 area of interest #1 (potential tropical cyclone nine)...tropical cyclone formation shown in 12 hours in the northeastern Caribbean Sea near 16.5N-62.5W...reaches the south coast of the Dominican Republic as a weak tropical storm in 36 hours...crosses Haiti through 48 hours...reaches the northeast coast of Cuba in 60 hours...reaches the Florida straits between Cuba and south Florida in 84 hours...crosses the Florida Keys in 96 hours...curves northward across the eastern Gulf of Mexico and just west of the Florida peninsula by 120 hours.


0000Z ECMWF Model Run...For area of interest #1 (potential tropical cyclone nine)...tropical cyclone formation shown just south of Puerto Rico near 17N-66W in 24 hours...reaches the waters between Jamaica and Haiti in 48 hours while degenerating into an elongated low pressure area...north side of low pressure area re-organizes in 72 hours at a location between Cuba and the Bahamas...low pressure area weakens in the southeastern Gulf of Mexico just northwest of Cuba at 120 hours.


0600Z GFS Model Run...For area of interest #1 (potential tropical cyclone nine)...tropical cyclone formation shown in the northeastern Caribbean near 16.5N-65W in 12 hours...moves across the Dominican Republic in 36 hours...moves between Haiti and the eastern Bahamas in 48 hours...located between Cuba and the Bahamas in 72 hours...reaches the south tip of the Florida peninsula in 96 hours...located in the eastern Gulf of Mexico just offshore of Fort Myers Florida in 120 hours.


0600Z NAVGEM Model Run...For area of interest #1 (potential tropical cyclone nine)...initialized at 0 hours as a large tropical storm instead of a tropical wave...shown to be a strengthening tropical storm in the northeast Caribbean near 16N-65.5W in 12 hours...makes landfall as a moderate or strong tropical storm on the south coast of the Dominican Republic in 30 hours...reaches the north coast of the Dominican Republic at the Haiti/Dominican Republic border in 42 hours...passes between Cuba and the Bahamas in 66 hours while strengthening...reaches the south tip of the Florida peninsula as a strong tropical cyclone in 96 hours...while curving north and northeast across the west coast of the Florida peninsula makes landfall between 96 and 120 hours...located over northeastern Florida just south of the Florida/Georgia border in 120 hours still as a strong tropical cyclone.

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