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 #53

*******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 JULY 6 2020 12:42 AM EDT...

See Tropical Storm Edouard section below for the only active tropical cyclone in the Atlantic basin. See area of interest sections below for other areas being monitored for tropical cyclone development.


TROPICAL DEPRESSION FIVE (RECENTLY UPGRADED TO TROPICAL STORM EDOUARD)...Last night while approaching Bermuda...tropical depression five appeared it was on its last leg with minimal thunderstorm activity and a poorer definition of its cloud swirl in infrared satellite. Then this past afternoon and through tonight while accelerating rapidly east-northeastward away from Bermuda in tandem with a broad frontal low pressure to its north and its supporting shortwave upper trough...thunderstorm bursts blossomed over and east of the surface circulation center...and now tropical depression five has recently been upgraded to Tropical Storm Edouard. These developments may have been due to Edouard reaching the south edge of warm gulf stream waters barely supportive of tropical development...but I think much moreso due to the eastern divergence zone of the aforementioned shortwave upper trough. The rapid east-northeast motion of Edouard appears to be reducing...but not eliminating...the westerly shear being generated by the same upper trough such that the upper trough's eastern divergence zone has actually helped the tropical storm rather than destructively shearing it. This is now the earliest fifth named storm in the Atlantic basin...assuring that the 2020 Atlantic hurricane season is officially off to a hyperactive start. The aformentioned shortwave upper trough and another shortwave over eastern Canada shoud merge into a more amplified upper trough with increased upper divergence in the next 24 hours...therefore I agree with the National Hurricane Center's forecast for additional strengthening to 45 mph maximum sustained winds. Edouard is already moving faster to the east-northeast than the 1800Z GFS showed...so my 24-hour forecast point is a bit east of that model run. The fast east-northeast track should put Edouard over much cooler waters temps such that its thunderstorms dissipate...ensuring that Edouard loses its tropical characteristics as it overtakes the broad frontal low pressure just to its north as the dominant frontal low pressure in the region.

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

0 Hr Position (1800Z Jul 5)...40 mph maximum sustained wind tropical storm centered at 37.2N-56.9W

IOH 24 Hr Forecast (1800Z Jul 6)...45 mph maximum sustained wind non-tropical remnant frontal low centered at 42N-46W


AREA OF INTEREST #1...The tail end of a long western Atlantic frontal zone in the northeastern Gulf of Mexico has transitioned into an east-west elongated tropical low pressure being supported by outflow streaming into upper vorticity to the northwest over the central United States and Gulf of Mexico upper vorticity to the south. This disturbance is expected to track generally northeastward around the western periphery of the Atlantic surface subtropical ridge during its lifetime. A more consolidated spin has appeared further west toward the Louisiana coast over the last day or so...which maybe why the models have shifted further west with the northeast track of this disturbance...keeping it further inland over the southeastern United States and then emerging over the western Atlantic waters offshore of the mid-Atlantic and northeastern United States where water temperatures are cooler. If true...this would reduce the chances of tropical cyclone formation which is why I keep my odds of development on the lower side (at 30%) in my updated outlook below. I have also not yet adjusted the forecast track of this disturbance northward with the models at this time...as the 1800Z GFS shows the best upper air support for tropical development in between the aforementioned pieces of upper vorticity further south. Based on the same GFS run...the central United States upper vorticity will remain to the west of the disturbance instead of moving faster and passing east of the disturbance...so it is possible the disturbance ends up consolidating as a non-tropical feature further north while supported by the eastern divergence zone of the upper vorticity. In the longer range...after 120 hours...a large shortwave upper trough to eject from the northwestern Canada upper vortex will likely ensure that this disturbance transitions to non-tropical as it parallels the northeastern United States coast.

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

IOH 24 Hr Outlook (1800Z Jul 6)...0% chance of tropical cyclone formation (Alabama/Florida/Georgia border near 30.8N-85W)

IOH 48 Hr Outlook (1800Z Jul 7)...0% chance of tropical cyclone formation (southern Georgia near 31.5N-82.5W)

IOH 72 Hr Outlook (1800Z Jul 8)...10% chance of tropical cyclone formation (southern tip of South Carolina near 32N-81W)

IOH 96 Hr Outlook (1800Z Jul 9)...30% chance of tropical cyclone formation (just offshore of the Carolina coast near 33.5N-78.8W)

IOH 120 Hr Outlook (1800Z Jul 10)...20% chance of tropical cyclone formation (just offshore of the northern Outer Banks of North Carolina near 36.5N-75W)


AREA OF INTEREST #2...A tropical wave of low pressure in the central tropical Atlantic over the last 24 hours has impressively built up showers and thunderstorms to the south of the dry saharan air layer...gaining mention in the National Hurricane Center tropical weather outlook tonight. More recently...a circular burst of thunderstorms near 11N-51W has continued to grow with a general curved band of thunderstorms north of the burst...therefore I have gone ahead and placed a decent 40% odds of tropical cyclone formation in my outlook below for the next 24 hours...higher than the National Hurricane Center's tropical weather outlook which had 10% odds. I start tapering the odds of development down to 30% at 48 hours as the computer model support from the NAVGEM model...the only model to show some development...drops by that point even though the wave remains under favorable upper ridging with low shear and upper outflow...perhaps from the dry saharan air? I forecast an increasing north angle in track as the tropical wave moves into the Caribbean Sea while the wave begins reaching the western extent of the Atlantic subtropical surface ridge. I begin dropping odds of development toward 0% by 96 and 120 hours as the upper vortex over the eastern Bahamas is forecast to shift southward over the tropical wave which would suppress its upper outflow.

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

IOH 24 Hr Outlook (1800Z Jul 6)...40% chance of tropical cyclone formation (east of the southern Lesser Antilles near 12N-56W)

IOH 48 Hr Outlook (1800Z Jul 7)...30% chance of tropical cyclone formation (just west of the southern Lesser Antilles near 13N-61W)

IOH 72 Hr Outlook (1800Z Jul 8)...30% chance of tropical cyclone formation (eastern Caribbean Sea near 15N-66W)

IOH 96 Hr Outlook (1800Z Jul 9)...10% chance of tropical cyclone formation (south of the Dominican Republic near 17N-71W)

IOH 120 Hr Outlook (1800Z Jul 10)...0% chance of tropical cyclone formation (just northeast of Jamaica near 18N-76W)


...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 five...shows circulation transition to the dominant non-tropical feature in the region...reaching the northeast Atlantic in 54 hours. For area of interest #1...consolidated low pressure center forms over the Alabama/Georgia border in 48 hours...reaches outer Banks of North Carolina in 84 hours...reaches New Jersey coast in 126 hours. For area of interest #2...no tropical cyclone formation shown.


1200Z ECMWF Model Run...For tropical depression five...shows circulation transition to the dominant non-tropical feature in the region...reaching the northeast Atlantic in 48 hours. For area of interest #1...broad low pressure center becomes defined on South Carolina coast in 72 hours...moves just offshore of Carolinas in 96 hours...shifts northward into Outer Banks of North Carolina in 120 hours. For area of interest #2...no tropical cyclone formation shown.


1800Z GFS Model Run...For tropical depression five...shows circulation transition to the dominant non-tropical feature in the region...reaching the northeast Atlantic in 48 hours. For area of interest #1...broad low pressure center becomes defined on North Carolina coast in 90 hours...reaches New Jersey coast in 120 hours. For area of interest #2...no tropical cyclone formation shown.


1200Z NAVGEM Model Run...For tropical depression five...shows circulation transition to the dominant non-tropical feature in the region...reaching the northeast Atlantic in 48 hours. For area of interest #1...surface low pressure becomes defined at the northern Georgia/South Carolina border in 84 hours...reaches Cape Hatteras North Carolina in 120 hours...shown strengthening while moving north-northeastward parallel to northeastern United States coast in long range (possibly as a non-tropical cyclone supported by the eatern divergence zone of an approaching shortwave upper trough). For area of interest #2...low pressure center shown forming near 12N-52.5W in 30 hours...weakens back to a tropical wave while nearing Barbados and the southern Lesser Antilles in 48 hours.

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