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 #94

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


...MONDAY AUGUST 17 2020 11:00 AM EDT...

See area of interest #3 section below for an update on the remnants of Tropical Storm Josephine as I am watching it for potential redevelopment as it curves northward toward Bermuda over the next couple of days. Also see area of interest #1...#2...and #4 sections below for central and eastern Atlantic tropical waves of low pressure being monitored for development. Elsewhere...the southern portion of the large upper trough over eastern North America is expected to become cut-off in the Gulf of Mexico due to an amplifying upper ridge over western North America. This cut-off upper trough may trigger a subtropical or tropical disturbance in the Gulf of Mexico with its eastern divergence zone in the next few days...with the tail end of the current front over the eastern United States possibly providing a surface low pressure field for this disturbance.


AREA OF INTEREST #1...The central Atlantic tropical wave of low pressure currently en route to the Lesser Antilles has seen its thunderstorm activity become increasingly organized this morning. This tropical wave will remain tucked beneath a cell of upper ridging thru the forecast period which will provide favorable low shear and upper outflow for potential tropical development...and the GFS...NAVGEM...and CMC models continue to show development of this tropical wave as it moves across the Caribbean Sea. Therefore I have notably raised my odds of tropical cyclone formation to a peak of 80% over the next five days...and if current organization trends continue I will begin a tropical cyclone formation forecast in my next birdseye view post. Regarding the forecast track...the upper trough over eastern North America and its associated surface cold front over the eastern United States are currenty forecast to pass too far north to weaken the steering Atlantic subtropical ridge. Therefore a steady west-northwest track across the Lesser Antilles and into the Caribbean Sea...perhaps approaching Jamaica and the Cayman Islands by days 4 and 5...appears likely. After 5 days...it appears a south fracture of the eastern North America upper trough will linger in the Gulf of Mexico for quiet some time while cut-off by an amplified upper ridge over western North America...with this cut-off trough's eastern divergence zone keeping low surface pressures in the Gulf of Mexico. Therefore it appears this low pressure field is likely to draw this system northwestward toward the Gulf of Mexico in the long range after 5 days.


Expect gusty winds and heavy rains starting late tonight in the southern and central Lesser Antilles. Interests in Jamaica...Cayman Islands...western Cuba...and the Yucatan peninsula of Mexico should also carefully monitor the progress of this tropical wave as conditions will be quiet favorable for tropical cyclone development.

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

IOH 24 Hr Outlook (1200Z Aug 18)...25% chance of tropical cyclone formation (Lesser Antilles near 13.5N-61W)

IOH 48 Hr Outlook (1200Z Aug 19)...45% chance of tropical cyclone formation (eastern Caribbean Sea near 14N-66.5W)

IOH 72 Hr Outlook (1200Z Aug 20)...60% chance of tropical cyclone formation (central Caribbean Sea south of Haiti near 15N-71.5W)

IOH 96 Hr Outlook (1200Z Aug 21)...70% chance of tropical cyclone formation (central Caribbean Sea just south of Jamaica near 16N-77W)

IOH 120 Hr Outlook (1200Z Aug 22)...80% chance of tropical cyclone formation (western Caribbean Sea just southwest of the Cayman Islands near 18N-82.5W)


AREA OF INTEREST #2...The tropical wave of low pressure in the far eastern Atalntic offshore of western Africa and south of the Republic of Cabo Verde continues to lack thunderstorms in its north half due to dry saharan air...but its southern half has become better organized while featuring increasing banding features and circular thunderstorm bursts. Therefore I have raised my short term odds of tropical cyclone formation. Other than the dry saharan air...conditions are favorable for this tropical wave to develop as the tropical wave will be embedded beneath tropical upper ridging providing low shear and upper outflow thru the forecast period. However I keep longer range odds of development at a low 25% due to the rapidly organizing tropical wave just to the west dominating the tropical waters in the vicinity of 30 and 35W longitude. In fact the CMC...ECMWF...and GFS have latched onto the wave to the west developing while no longer showing this wave developing. Thus I have introduced the wave to the west as a new area of interest for tropical development (see area of interest #4)...while keeping odds of development for this tropical wave low with the assumption that the wave to the west will likely stifle this wave's development while developing dominant surface inflow that steals the inflow of this wave's heat and moisture.

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

IOH 24 Hr Outlook (1200Z Aug 18)...25% chance of tropical cyclone formation (tropical atlantic near 11N-31W

IOH 48 Hr Outlook (1200Z Aug 19)...25% chance of tropical cyclone formation (tropical atlantic near 11.5N-36W)

IOH 72 Hr Outlook (1200Z Aug 20)...25% chance of tropical cyclone formation (tropical atlantic near 12N-42W)

IOH 96 Hr Outlook (1200Z Aug 21)...25% chance of tropical cyclone formation (tropical atlantic near 12.5N-49W)

IOH 120 Hr Outlook (1200Z Aug 22)...25% chance of tropical cyclone formation (tropical atlantic near 13N-55W)


AREA OF INTEREST #3 (REMNANTS OF JOSEPHINE)...The remnants of Tropical Storm Josephine continue as a surface trough of low pressure in the open western Atlantic in the vicnity of 25N-68W. If this remnant trough persists...it will curve northeastward toward Bermuda while steered in the flow ahead of the frontal zone approaching from the eastern United States and around the west side of the Atlantic surface subtropical ridge. Upper winds could become more conducive for redevelopment of Josephine starting in 24 hours as the cold core western Atlantic uppper trough that sheared apart Josephine is now weakening and breaking apart due to warm southerly flow ahead of the approaching fronal zone. By 48 hours shear may start to re-increase as the longwave upper trough over eastern North America approaches...but I keep some non-zero odds of development during that time as the shear may still be light enough as to not completely shut off development potential. But by 72 hours the shear will likey increase further...thus I drop the odds of development to 0%. I keep my peak odds of development at a low 10% due to the current lack of thunderstorms with this system on infrared satellite...and also due to no computer model support showing the remnant trough of Josephine redeveloping.

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

IOH 24 Hr Outlook (1800Z Aug 18)...10% chance of tropical cyclone formation (southwest of Bermuda near 28.5N-68W)

IOH 48 Hr Outlook (1800Z Aug 19)...10% chance of tropical cyclone formation (just southwest Bermuda near 31.5N-65.5W)

IOH 72 Hr Outlook (1800Z Aug 20)...0% chance of tropical cyclone formation (northeast of Bermuda near 34N-61W)


AREA OF INTEREST #4...A tropical wave of low pressure in the eastern tropical Atlantic in the vicnity of 30 to 35W longitude has rapidly seen an increase in the coverage and organization of its thunderstorms this morning...and due to model support from the CMC...GFS...and ECMWF now showing that this wave will become the dominant in the region...I have introduced it as an area of interest for tropical development. This tropical wave will continue steadily west across the Atlantic tropics and toward the Lesser Antilles over the next five days while steered by the Atlantic subtropical surface ridge...and will remain in a favorable low shear and upper outflow environment beneath upper ridging. With this favorable outlook and current organization...and also with the computer model support...I have peak odds at a high 80% for tropical cyclone formation during the five day forecast period. Unfortunately this means in addition to area of interest #1...the Lesser Antilles islands should also be monitoring this tropical wave for tropical cyclone formation. If this tropical wave remains well organized...I will do a tropical cyclone formation forecast for it by my next birdseye view post.

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

IOH 24 Hr Outlook (1200Z Aug 18)...35% chance of tropical cyclone formation (tropical atlantic near 12.5N-36W

IOH 48 Hr Outlook (1200Z Aug 19)...50% chance of tropical cyclone formation (tropical atlantic near 13N-41W)

IOH 72 Hr Outlook (1200Z Aug 20)...60% chance of tropical cyclone formation (tropical atlantic near 13.5N-47W)

IOH 96 Hr Outlook (1200Z Aug 21)...70% chance of tropical cyclone formation (tropical atlantic near 14N-53W)

IOH 120 Hr Outlook (1200Z Aug 22)...80% chance of tropical cyclone formation (just east of the Lesser Antilles near 15N-59W)


...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...tropical cyclone formation suggested just east of the eastern Honduras coast in 102 hours...postioned in the Yucatan channel waters between western Cuba and northeastern Yucatan peninsula in 138 hours as a compact and intensifying tropical cyclone. For area of interest #2...no tropical cyclone formation shown. For area of interest #3 (remnants of Josephine)...no tropical cyclone formation shown. For area of interest #4...shown to become a tropical cyclone at 15N-59W in 84 hours...located just east of the northern Lesser Antilles as a compact strengthening tropical cyclone in 120 hours. Elsewhere...tail end of frontal zone currently over the eastern United States decays into broad low pressure in the central Gulf of Mexico in 60 hours...nearly stationary tropical disturbance suggested through 126 hours that drifts into western Gulf of Mexico...after 126 hours disturbance loses definition to area of interest #1 as it become the dominant tropical cyclone in the region.


0000Z ECMWF Model Run...For area of interest #1...no tropical cyclone formation shown. For area of interest #2...no tropical cyclone formation shown. For area of interest #3 (remnants of Josephine)...no tropical cyclone formation shown. For area of interest #4...tropical cyclone formation suggested at 12.5N-40W in 48 hours...located over the Virgin Islands in 120 hours (no strengthening shown from 48 to 120 hours).


0600Z GFS Model Run...For area of interest #1...tropical wave organizes into a tropical low pressure east of Nicaragua in 96 hours...tropical cyclone formation suggested in the western Caribbean Sea near 18.5N-85W in 126 hours. For area of interest #2...no tropical cyclone formation shown. For area of interest #3 (remnants of Josephine)...no tropical cyclone formation shown. For area of interest #4...tropical wave organizes into a tropical low pressure centered east of the Lesser Antilles at 14N-58W in 102 hours...tropical cyclone formation suggested in the northeastern Caribbean Sea near 16.5N-62W in 126 hours.


0600Z NAVGEM Model Run...For area of interest #1...tropical cyclone formation suggested just southwest of Jamaica in 96 hours...strengthens rapidly between the Cayman Islands and western Cuba in 120 hours. For area of interest #2...no tropical cyclone formation shown. For area of interest #3 (remnants of Josephine)...no tropical cyclone formation shown. For area of interest #4...no tropical cyclone formation shown.

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