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 #58

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


...FRIDAY JULY 10 2020 1:58 PM EDT...

See Tropical Storm Fay section below for more details on the only active tropical cyclone in the Atlantic basin. See area of interest sections below for additional area I am monitoring for tropical development in the coming days.


TROPICAL STORM FAY...While moving northward toward the southern New Jersey coast and over cooler waters...the intensity of thunderstorms on the north and east sides of Tropical Storm Fay's circulation have weakened. The thunderstorms have also dissipated over the center...leaving the center exposed as a cloud swirl while the remaining thunderstorms are in bands to the north and east. And yet Fay has strengthened a little more than expected to 60 mph maximum sustained winds...an indication of assistance from the eastern divergence zone of upper vorticity that has been trapped over the eastern United States. This makes Fay a less tropical system...and perhaps it could be argued that Fay is now a subtropical storm...supported tropically by the outflow of upper ridging that extends from the Caribbean to northwest Atlantic...and simulatenously supported non-tropically by the upper vorticity. I have adjusted the track westward as the current positon of Fay is a bit west of my previous track...an indication that the eastern United States upper vorticity is phasing with a large upper trough now moving across central North America to become a more amplified upper trough that keeps Fay tugged further west. In 24 hours while moving northward well inland...Fay will have finished losing its tropical status for sure...and as most of the models now agree transition into a re-strengthening non-tropical low pressure over southeastern Canada while located along the front after 24 hours. Surface observations indicate that Fay has brought tropical storm conditions along much of the New Jersey coast through the morning and this early afternoon...with gusty winds reaching the New York City metropolitan area...Long Island New York...and Connecticut coast and likely to increase as Fay nears. See bulletins on the home page of this site for expected impacts of Fay.

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

0 Hr Position (1200Z Jul 10)...60 mph maximum sustained wind tropical storm centered just offshore of New Jersey at 38.4N-74.5W

IOH 24 Hr Forecast (1200Z Jul 11)...Remnant low pressure merging with incoming front to the west...centered over the New York/Canada border at 45N-74W


AREA OF INTEREST #1...Warm southerly flow on the east side of newly-formed Tropical storm Fay is amplifying upper ridging from the Caribbean sea as far north as the northwest Atlantic...which is beginning to cause the shortwave upper trough that has recently exited eastern North America and entered the northwest Atlantic to amplify...triggering the foramtion of a new frontal surface low pressure offshore of Atlantic Canada in the increasing eastern divergence zone of the amplifying shortwave upper trough. The shortwave upper trough is expected to amplify further into a cut-off upper vortex as it moves into the open central Atlantic over the next few days. Therefore will be watching if the frontal low acqures tropical characteristics while it settles over central Atlantic waters of 23 deg C and a cold enough cut-off upper vortex to de-stabilize the atmosphere at these water temperatuers (forecasat to measure in the low 1200s of dekameters in height at 200 mb). Given the models overall show a stronger surface circulation with the frontal low...I have increased my peak odds of subtropical cyclone formation to 50%. Will watch for additional model runs in the coming days or evaluate the intensity of thunderstorm activity before considering an increase in odds beyond this point. I have lowered odds for the July 14th timeframe to 10% as the models now agree that the surface frontal low will lift north-northwest into a surface ridge weakness created by the remnants of Fay...which will pull the surface low into the northwest quadrant of the upper vortex where upper convergence and shear make conditions for tropical development hostile. By 120 hours...these hostile conditions and a track toward cooler waters will dominate...so odds of subtropical development are 0% for that timeframe. On a final note...forecast points in the outlook below are based on the location of the eastern divergence zone of the amplifying shortwave upper trough in the 0600Z GFS...followed by the position of the center of the upper vortex for the middle part of the forecast as this system will whirl toward the center of the upper vortex as a classical post-mature frontal low pressure does.

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

IOH 24 Hr Outlook (1200Z Jul 11)...0% chance of subtropical cyclone formation(northwestern Atlantic near 41.5N-44.5W)

IOH 48 Hr Outlook (1200Z Jul 12)...40% chance of subtropical cyclone formation (central Atlatnic near 40N-41W)

IOH 72 Hr Outlook (1200Z Jul 13)...50% chance of subtropical cyclone formation (central Atlantic near 39N-42W)

IOH 96 Hr Outlook (1200Z Jul 14)...10% chance of subtropical cyclone formation (northwestern Atlantic near 40N-44W)

IOH 120 Hr Outlook (1200Z Jul 15)...0% chance of subtropical cyclone formation (northwestern Atlantic near 43N-42W)


AREA OF INTEREST #2...A tropical wave of low pressure moving through the western Caribbean Sea has overnight lost thunderstorm activity over Nicaragua...Honduras...and the Caribbean Sea...all while redeveloping thunderstorm activity to the southwest of Guatemala in the eastern Pacific Ocean. The tropical wave is now a concern for development in the eastern Pacific basin and outside the scope of the Atlantic basin coverage provided on this website. Therefore this is my final statement on this tropical wave on this blog...the 0% in the outlook below reflects development chances in the Atlantic...visit www.nhc.noaa.gov for the latest on development chances in the eastern Pacific.

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

IOH 24 Hr Outlook (1200Z Jul 11)...0% chance of tropical cyclone formation (northwestern Guatemala near 17N-90.5W)


...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 Tropical Storm Fay...transitions into frontal low over eastern Canada by 66 hours as front currently approaching from the north-central and northeastern United States overruns the circulation. For area of interest #1...frontal low becomes cut-off from the mid-latitude westerlies in 54 hours while located near 40N-41W...evolves into possible subtropical cyclone while generally stalled in this area between 54 to 78 hours...lifts north-northwest into ridge weakness created by the non-tropical remnant of Fay...dissipating near 42N-42W in 108 hours. For area of interest #2...no tropical cyclone formation shown


0000Z ECMWF Model Run...For Tropical Storm Fay...transitions into frontal low over eastern Canada by 66 hours as front currently approaching from the north-central and northeastern United States overruns the circulation. For area of interest #1...frontal low becomes cut-off from the mid-latitude westerlies in 48 hours while located near 40.5N-42W...lifts north-northwest into ridge weakness created by the non-tropical remnant of Fay...dissipating near 43N-42W just after 96 hours. For area of interest #2...no tropical cyclone formation shown


0600Z GFS Model Run...For Tropical Storm Fay...gradually loses its identity over eastern Canada within the currently approaching front from the north-central and northeastern United States by 60 hours. For area of interest #1...frontal low becomes cut-off from the mid-latitude westerlies in 48 hours while located near 40N-41W...evolves into possible subtropical cyclone in this general area between 48 to 78 hours... lifts west-northwest into ridge weakness created by the non-tropical remnant of Fay...dissipating near 41.5N-45W in 108 hours. For area of interest #2...no tropical cyclone formation shown.


0600Z NAVGEM Model Run...For Tropical Storm Fay...transitions into frontal low over eastern Canada by 60 hours as front currently approaching from the north-central and northeastern United States overruns the circulation. For area of interest #1...frontal low becomes cut-off from the mid-latitude westerlies in 48 hours while located near 40N-41W...lifts north-northwest into ridge weakness creaetd by the non-tropical remnant of Fay...dissipating near 44N-42W in 126 hours. For area of interest #2...no tropical cyclone formation shown.

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