MY 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #59
*******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.**********
...SATURDAY JULY 11 2020 3:02 PM EDT...
See remnants of Fay section below for final statement on Fay as it is no longer a tropical system. See area of interest section below for an additional area I am monitoring for tropical development in the coming days.
REMNANTS OF FAY...After the center moved across northeastern New Jersey and far eastern New York state...and into the Canadian province of Quebec in the last 24 hours...Tropical Storm Fay has weakened to a tropical depression and then a remnant low pressure cloud swirl. The remnant low is becoming overrun by a large upper trough and surface cold front moving in from the west...therefore Fay is expected to re-strengthen over southeastern Quebec as a non-tropical frontal low supported by the upper trough over the next 24 hours. Warm surface southerly flow ahead of Fay and the frontal zone has amplified upper ridging into the western Atlantic. The resistance of the upper ridge is expected to cause the upper trough to split into two lobes of vorticity...one faster moving over northeastern Canada that moves into the far north Atlantic toward Greenland and Iceland after 24 hours...and one slower moving (due to the blockage of the upper ridge) to the south that exits the northeastern United States and Atlantic Canada into the northwest Atlantic. The result is that after 24 hours the remnant of Fay will weaken and lose its identity along the frontal zone while shifting east into coastal Quebec while located away from the supportive upper divergence zones of both lobes of vorticity. Given that Fay is no longer a tropical system...this is my final statement on Fay on this blog.
AREA OF INTEREST #1...Warm southerly flow on the east side of Fay's remnant low pressure and cold front overunning Fay is amplifying upper ridging across the western Atlantic...which has caused a shortwave upper trough to amplify as it moves across the northwest Atlantic and toward the open central Atlantic. The increasing eastern divergence zone of the amplifying upper trough has strengthened a surface frontal low pressure in the region into a well-defined cyclone. The upper trough is expected to amplify further into a cut-off upper vortex in the next 24 hours...therefore will be watching if the frontal cyclone acqures tropical characteristics while it settles over central Atlantic waters of 23 deg C and a cold enough cut-off upper vortex to potentially de-stabilize the atmosphere at these water temperatuers (forecasat to measure in the low 1200s of dekameters in height at 200 mb). So far thunderstorm activity has been weak with the surface cyclone...so I have dropped my peak odds of subtropical cyclone formation to 25%. I have lowered odds for the July 14th timeframe to 0% as the models agree that the surface cyclone low will lift northwest into a surface ridge weakness created by the remnants of Fay...which will pull the surface cyclone into the northwest quadrant of the upper vortex where upper convergence will quickly weaken the cyclone to a dissipating surface low. On a final note...forecast points in the outlook below are in the short-term based on the position of the center of the forecast upper vortex in the 1200Z GFS as the surface cyclone will whirl toward the center of the upper vortex as a classical post-mature frontal system does.
IOH 24 Hr Outlook (1200Z Jul 12)...10% chance of subtropical cyclone formation (central Atlatnic near 40.5N-40.5W)
IOH 48 Hr Outlook (1200Z Jul 13)...25% chance of subtropical cyclone formation (central Atlantic near 40.5N-42.5W)
IOH 72 Hr Outlook (1200Z Jul 14)...0% chance of subtropical cyclone formation (northwestern Atlantic near 42.5N-44W)
...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 area of interest #1...frontal low becomes cut-off from the mid-latitude westerlies in 24 hours while located near 40N-40W...lifts north-northwest into ridge weakness created by the non-tropical remnant of Fay...dissipating near 45N-43W in 66 hours.
0000Z ECMWF Model Run...For area of interest #1...frontal low becomes cut-off from the mid-latitude westerlies in 48 hours while located near 41N-40W...lifts north-northwest into ridge weakness created by the non-tropical remnant of Fay...dissipating near 44N-43W just after 72 hours.
1200Z GFS Model Run...For area of interest #1...frontal low becomes cut-off from the mid-latitude westerlies in 24 hours while located near 40.5N-40.5W...lifts northwest into ridge weakness created by the non-tropical remnant of Fay...dissipating near 43N-44W in 66 hours.
0600Z NAVGEM Model Run...For area of interest #1...frontal low becomes cut-off from the mid-latitude westerlies in 30 hours while located near 41N-40.5W...lifts northwest into ridge weakness creaetd by the non-tropical remnant of Fay...dissipating near 42N-44W in 78 hours.