BIRDSEYE VIEW POSTS

Since 2012 on the now retired Weather Underground 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 at Yale Climate Connections via Disqus where the former Weather Underground community has moved to. Feel free to reply to me there, at my Disqus feed at this link, or via e-mail at IOHurricanes@outlook.com 

 
 
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MY 2021 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #77

*******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 AUGUST 12 2021 1:20

AM EDT...

Satellite image as of 2350Z. 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 1200Z:

GFS Model Upper-Level Winds 1800Z:

Potential Tropical Cyclone Six has become tropical cyclone Fred in the last 24 hours… but has become disrupted due to landfall across Haiti and the Dominican Republic. However will watch for potential redevelopment of this system as it moves back over water in the coming days… see Fred section below for details. Due to interruptions from severe weather where I live in Michigan… I have not been able to update areas of Interest #1 and #2 marked in the above charts. I will consider a special update tomorrow morning to update these areas of interest.


Elsewhere...satellite imagery shows another strong tropical wave with widespread thunderstorms in progress over Western Africa which will likely enter the eastern tropical Atlantic over the next 24 hours. In addition… yet another strong wave could emerge from western Africa in 3 days. Due to the widespread tropical upper ridging forecast to persist over the eastern tropical Atlantic... a haven of low shear and upper outflow will be present for these waves to also potentially become areas of interest for tropical development in the coming days as long as they stay south of the dry saharan air layer in the region.


TROPICAL DEPRESSION FRED... Shortly after my update yesterday… potential tropical cyclone six finally got around to developing a well-defined surface center and becoming Tropical Storm Fred… and managed to strengthen to 45 mph maximum sustained winds before landfall across the Dominican Republic this past afternoon. Fred is now a weaker tropical depression centered over northern Haiti due to the landfall. Based on the latest position of Fred...I have nudged my forecast track north and west. The forecast track is expected to curve increasingly north over the next five days as the as a large frontal cyclone currently over Canada is weakening the west extent of the steering Atlantic surface ridge. As the frontal cyclone departs and a surface ridge builds over the eastern US...the tail end of the front driven by the frontal cyclone is forecast to linger as a surface ridge weakness over the interior southeast US and to the south of that surface ridge with the support of the divergence zones of lingering upper vorticity over the eastern Gulf of Mexico and upper vorticity to be cut-off from the frontal cyclone’s upper trough in the vicinity of Iowa. For reasons explained in the next paragraph… in the longer range I am trending with a weaker/shallower Fred that moves a little more west in track toward the Florida panhandle while aiming for the interior southeast US surface ridge weakness instead of a stronger/taller Fred that turns more sharply north under the guidance of the lingering east Gulf upper vorticity. And for the short-term… I agree with the NHC forecast track which keeps Fred’s center along the north coast of Cuba rather than further north over offshore water as Fred’s thunderstorms are displaced south of center at the moment due to the current axis of upper vorticity over the west Atlantic… and the center itself may be becoming weak and diffuse from the land interaction with Haiti such that it has potential to regenerate south into the thunderstorms.


Regarding intensity...as I alluded to in the previous paragraph I am trending with a weaker Fred due to potential for negative influences such as land interaction with Cuba.. and lingering upper vorticity in the west Atlantic which the GFS has trended further east with over time by now keeping the lingering vorticity right into Fred’s forecast track and near the west coast of Florida instead of the eastern Gulf of Mexico. This upper vorticity could keep Fred’s thunderstorms displaced from the center. If Fred however fires enough thunderstorm latent heat release to weaken the lingering cool core upper vorticity… Fred could create a more favored upper environment for strengthening than I forecasted below… that remains to be seen.


The following land areas will have to watch for arrival of tropical storm conditions (gusty winds... heavy rain with flash flood potential... and coastal sea swells) in the coming days:

**Dominican Republic and Haiti... although Fred is a tropical depression with weak wind… the storm is still producing risk with heavy rains that could cause flash floods and mountainside mudslides

**Based on the latest forecast track... the potential for tropical storm conditions is no longer possible for Jamaica and the Cayman Islands.

** Cuban interests should have finished preparing for possible tropical storm conditions to arrive by tomorrow.

**Interests in the southeast Bahamas currently have a low risk of direct impacts due to Fred weakening to a tropical depression and upper winds keeping the strongest thunderstorms displaced to the south

**I recommend interests across south Florida and the Florida Keys gather storm prep supplies early for possible tropical storm conditions that could arrive early this weekend.

**Interests across the northwest Florida peninsula and Florida panhandle should be aware of Fred as it could bring tropical storm conditions in the region late this weekend.

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

0 Hr Position (0000Z Aug 12)…35 mph maximum sustained wind tropical depression centered over the Haiti/ Dominican Republic border at 19.2N-71.6W

IOH 24 Hr Forecast (0000Z Aug 13)…35 mph maximum sustained wind tropical depression centered over the north coast of Cuba at 21.5N-77.2W

IOH 48 Hr Forecast (0000Z Aug 14)… 40 mph maximum sustained wind tropical storm centered between Cuba and south Florida at 23.8N-80.2W

IOH 72 Hr Forecast (0000Z Aug 15)… 40 mph maximum sustained wind tropical storm centered between the Florida Keys and southwest Florida at 25.2N-81.5W

IOH 96 Hr Forecast (0000Z Aug 16)… 40 mph maximum sustained wind tropical storm centered offshore of western Florida at 27.5N-83W

IOH 120 Hr Forecast (0000Z Aug 17)… 40 mph maximum sustained wind tropical storm centered offshore of the Florida panhandle near 29N-85.5W


AREA OF INTEREST #1…Due to interruptions from severe weather where I live in Michigan… I have not been able to update this area of Interest (ongoing low pressure spin associated with the tropical wave in the eastern Atlantic). I will consider a special update tomorrow morning to update this area if interest.


AREA OF INTEREST #2… The large tropical wave that is traversing the central Atlantic appeared this past afternoon to spawn a new area of rotating thunderstorms on its south side… and so I have declared it another area of Interest. However as of this evening the thunderstorm activity has dwindled. Due to interruptions from severe weather where I live in Michigan… I have not been able to provide an full analysis on this area of Interest. I will consider a special update tomorrow morning to update this area if interest.


...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 depression Fred...emerges from NW Haiti at 18 hours as a remnant low… passes between Cuba and the Bahamas thru 54 hours… remnant low not forecast to regenerate into a tropical cyclone as it turns north across the Florida peninsula west coast thru 108 hours

**For area of interest #1… no tropical cyclone formation shown as system passes just north of the Caribbean Islands by 120 hours.

**For area of interest #2… no tropical cyclone formation shown

**Strong tropical wave forecast to emerge from Western Africa at 78 hours... develops a broad low pressure spin passing just south of the Republic of Cabo Verde Islands by 120 hours.

1200Z ECMWF Model Run...

** For tropical depression Fred... emerges from NW Haiti in next 24 hours as a remnant low… passes between Cuba and the Bahamas thru 48 hours… regains tropical depression status for short time at 96 hours while turning north along Florida peninsula west coast

**For area of interest #1… forecast to become a tropical depression while moving over the Virgin Islands at 96 hours… becomes a compact tropical storm while moving into the north coast of the Dominican Republic at 120 hours.

**For area of interest #2… no tropical cyclone formation shown


1800Z GFS Model Run...

**For tropical depression Fred...emerges from west coast of Haiti at 9 hours as a remnant low… moves across north coast of Cuba through 60 hours… quickly regains compact tropical storm status while lifting north into the Florida Keys at 75 hours… slides north along Florida west coast thru 102 hours… turns more northwest in track and reaches waters just offshore of Florida panhandle big bend coast at 120 hours.

**For area of interest #1… no tropical cyclone formation shown

**For area of interest #2… no tropical cyclone formation shown


1800Z NAVGEM Model Run...

** For tropical depression Fred... emerges from NW Haiti in next 18 hours as a remnant low… while crossing north Cuba coast regains tropical storm status at 54 hours… strengthening tropical storm passes over western Florida Keys at 72 hours… makes landfall over northwest Florida peninsula at 114 hours as an intense hurricane… located over SW Georgia as a weakening inland hurricane at 120 hours.

**For area of interest #1… no tropical cyclone formation shown

**For area of interest #2… no tropical cyclone formation shown

**Strong tropical wave forecast to emerge from Western Africa at 138 hours...quick tropical cyclone formation suggested just offshore of west Africa near 18N-18.5W at 150 hours.

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