MY 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #161
*******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 OCTOBER 26 2020 10:42 PM EDT...
See remnants of Epsilon for a final statement on the former tropical cyclone. See Hurricane Zeta section below for the only currently active tropical cyclone in the Atlantic basin. See area of interest section below for the surface low pressure offshore of the eastern United States.
Elsewhere...upper vorticity lingering over the Lesser Antilles has not produced appreciable thunderstorm activity in its eastern divergence zone for a tropical disturbance to form...and unfavorable westerly shear in the region is likely to increase once the shortwave upper trough mentioned in area of interest #1 merges with this upper vorticity...with the merged string of upper vorticity taking an east-west shape more conducive to producing upper westerly winds. The upper vorticity is expected to elongate east-west under the strength of the upper ridge currently over Zeta once that ridge moves into the west Atlantic. The CMC and NAVGEM models suggest the current central Atlantic tropical wave may first get enhanced thunderstorms from the divergence of the upper vorticity as it moves toward the Caribbean Sea over the next few days...and potentially develop thereafter once the cold core upper vorticity breaks up as it remains cut-off from high latitude cold air...with the wave potentially finding more favorable upper winds for development in a gap between fractures of the vorticity. Therefore this tropical wave may be added as an area of interest for tropical development in the coming days.
REMNANTS OF EPSILON...While accelerating northeastward into the open far North Atlantic cold waters...Epsilon finally lost its central thunderstorms and warm core and has been declared a remnant frontal cyclone within the last 24 hours. Epsilon has been accelerated northeastward by the current North Atlantic upper trough and surface frontal cyclone...and it is the eastern divergence zone of this upper trough that has kept the strength of Epsilon’s remnant frontal cyclone elevated. Recently...the two frontal cyclones (Epsilon and the other North Atlantic one mentioned prior) have merge southeast of Greenland and southwest of Iceland...with the merged and intense storm now bringing very rough seas reaching the coasts of Iceland and Greenland. This is the final statement on Epsilon on this blog as it is no longer tropical and no longer has a distinct identity within the merged storm.
HURRICANE ZETA...As expected...once the shortwave upper trough passing north of Zeta and associated with area of interest #1 moved away...Zeta has strengthened into a hurricane this afternoon under an improved upper air pattern consisting of low shear and upper outflow beneath the expanding upper ridge over the western Caribbean...Gulf of Mexico...and eastern United States supported by warm air advection ahead of the frontal system approaching from the central and western US. Zeta has finally accelerated northwest toward the surface low pressure field of this frontal system...but has tracked slightly less north and more west such that hurricane conditions will hit Quintana Roo province in the northeast Yucatan peninsula over the next hours. The eastern parts of the Yucatan province will likely now have to hunker down for hurricane force conditions sometime tonight..with tropical storm force conditions elsewhere in the province...given the west adjustment in the forecast track. I have lowered my intensity forecast for Zeta as the updates track increases land interaction with the Yucatan...but I still suggest some strengthening by 24 hours as the brisk track of Zeta should bring the hurricane soon back over water. Weakening is then shown after 24 hours as the upper trough of the incoming frontal system will be likely imparting increasing wind shear.. The northward track is also expected to bend sharply eastward by 48 and 72 hours as the incoming front and upper trough push into Zeta...and I have once again sped up the northeast track in accordance with many of the latest model runs. As Zeta system merges with the front and becomes supported by the eastern divergence zone of the upper trough...it will transition into a non-tropical remand frontal cyclone as it makes landfall along the eastern US Gulf coast or just after landfall. Even as it becomes less tropical...Zeta will still bring high winds and coastal storm surge as it will only slowly weaken due to the support of the upper trough.
With these forecast updates...western Cuba is now in the clear for seeing winds...but will still sea coastal sea swells. Interests in Quintana Roo and the Yucatan province will have to shelter from wind and coastal storm surge tonight. Interests along the US Gulf coast along the Florida panhandle...Alabama and Mississippi coasts...and southeast Louisiana coast should also keep an eye on Zeta as it will bring high wind and coastal storm surge impact to parts of this region by late Wednesday and early Thursday. Gusty winds could spread inland across southern Mississippi...eastern Alabama...and much of Georgia. Heavy rainfall with some flash flooding potential from Zeta and its remnants is possible in the above mentioned land areas as well as the Carolinas and Virginia. I recommend gathering storm preparation supplies early to avoid a last minute rush in crowded stores amid the COVID 19 virus outbreak...and when venturing out in public during preparation wearing a mask and frequent hand sanitizing will reduce your exposure to the virus. In case you may have to relocate from impacts such as coastal storm surge...think of a hotel or family/friend residence as a public shelter may not be as ideal for controlling your exposure to the COVID 19 virus.
0 Hr Position (0000Z Oct 27)...80 mph maximum sustained wind hurricane centered in the northwestern Caribbean Sea at 19.9N-86.6W
IOH 24 Hr Forecast (0000Z Oct 28)...90 mph maximum sustained wind hurricane centered in the southern Gulf of Mexico at 23N-91W
IOH 48 Hr Forecast (0000Z Oct 29)...70 mph maximum sustained wind tropical storm centered just offshore of southeastern Louisiana at 28N-91W
IOH 72 Hr Forecast (0000Z Oct 30)...Remnant frontal low centered over the western North Carolina/South Carolina border at 35N-82.5W
AREA OF INTEREST #1...A shortwave upper trough moving rapidly eastward across the western Atlantic has produced a broad surface low pressure now near 35N-67W along with a large band of showers and thunderstorms. This location is further north and over waters below 26 deg C making tropical development unlikely at this point as upper air temps are also not cold enough to support tropical activity at these water temps (ignoring the 1200Z GFS model run which suggested otherwise). Instead this surface low will likely become absorbed into the cold front of a new frontal low to form to the north over southeast Canada in the next 24 hours (this other frontal low will be supported by the north fracture of the current North America upper trough). This is my final statement on this disturbance on this blog.
IOH 24 Hr Outlook (0000Z Oct 28)...0% chance of tropical cyclone formation (northwestern Atlantic near 40N-55W)
...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 Hurricane Zeta...makes landfall over the northeastern Yucatan peninsula at 18 hours...makes landfall over south-central Louisiana at 54 hours...remnant low elongates and loses a defined center by 84 hours over the Appalachian Mountains. For area of interest #1...surface low loses identity on south side of another frontal low to form over SE Canada by 30 hours. Elsewhere...current central Atlantic tropical wave strengthens to a surface low in the central Caribbean Sea by 120 hours...tropical cyclone formation suggested in long range.
0000Z ECMWF Model Run... For Hurricane Zeta...crosses the Yucatan peninsula and emerges from the northwest coast of the peninsula by 24 hours...makes landfall in southeast Louisiana between 48 and 72 hours while moving rapidly northeast...becomes absorbed into developing frontal low to the northwest shortly thereafter. For area of interest #1...surface low loses identity on south side of another frontal low to form over SE Canada just after 24 hours.
1200Z GFS Model Run...For Hurricane Zeta...makes landfall over the northeastern Yucatan peninsula at 18 hours...makes landfall over southeast Louisiana at 60 hours...remnant frontal low enters Atlantic from Virginia by 90 hours...remnant low finally loses identity along frontal zone while in open northwest Atlantic by 108 hours. For area of interest #1...possible tropical cyclone formation near 37.5N-64W at 18 hours...loses identity on south side of another frontal low to form over SE Canada by 36 hours.
1200Z NAVGEM Model Run...For Hurricane Zeta...makes landfall over the northeastern Yucatan peninsula at 12 hours...makes landfall over southeast Louisiana at 78 hours... remnant low elongates and loses a defined center by 108 hours while moving across North Carolina. For area of interest #1...surface low loses identity on south side of another frontal low to form over SE Canada by 36 hours. Elsewhere...north end of current central Atlantic tropical wave strengthens to a surface low at a location just north of Puerto Rico in 102 hours...in longer range moves northwest ahead of same front forecast to absorb remnants of Zeta.