MY 2020 ATLANTIC HURRICANE SEASON BIRDSEYE VIEW POST #143
*******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 OCTOBER 8 2020 12:07 PM EDT...
See Hurricane Delta section below for the only currently active tropical cyclone in the Atlantic basin. See area of interest sections below concerning the current area of disturbed weather in the central Caribbean Sea...and for an eastern tropical Atlantic wave of low pressure offshore of Africa showing some signs of organization which I have also added as an area of interest as of today.
HURRICANE DELTA...After departing the Yucatan peninsula yesterday afternoon and evening...Delta apparently has been struggling to re-organize its inner core as the hurricane weakened further to a category 1 hurricane. This could be from a one-two punch of undergoing an eye wall replacement cycle before crossing the Yucatan...followed by the landfall across the Yucatan. However overnight Delta has regained category 2 hurricane strength...and the most recent colorized infrared satellite pictures are finally suggesting a new eye is trying to pop open at the center of circulation. Therefore it is conceivable Delta strengthens as high as a minimal category 3 this afternoon...before the upper trough fragment from Mexico approaches and begins to negatively affect the hurricane with some wind shear. However my 24 hour forecast point has Delta at category 2 with the assumption the shear by then will weaken Delta from its peak Gulf of Mexico intensity. My intensity forecast is nudged downward a bit as Delta thus far has not strengthened as much as I anticipated in the previous forecast. My previous forecast track has verified this morning...therefore I am making no changes to the track forecast in this update which will take the center of circulation into south-central Louisiana by tomorrow night while the hurricane recurves northeastward under the steering influence of the incoming upper trough from Mexico. Despite seeing wind shear along with lower water temperatures in the northern Gulf of Mexico...Delta will likely be a gradually weakening storm hanging on to category 2 strength at landfall time due to supportive divergence on the east side of the incoming upper trough...and therefore will likely hang on to tropical storm force for some time as it moves inland...spreading gusty winds with damage potential inland from southern Louisiana into southern and central Mississippi by early Saturday. I expect by 72 hours Delta will transition into a remnant frontal low pressure supported by the upper trough while moving well inland over the eastern United States. See home page bulletins for expected impacts from Hurricane Delta.
11 AM EDT update...aircraft reconaissance indicates Delta has strengthened further to 105 mph maximum sustained winds with 968 mb central pressure. No changes to my forecast intensity shown below at this time as the forecast takes into account that Delta could peak as a category 3 hurricane later this afternoon as stated in the previous paragraph.
******Infohurricanes.com forecast. Visit hurricanes.gov (hurricanes dot gov) for official forecast***********
0 Hr Position (1200Z Oct 8)...100 mph maximum sustained wind hurricane centered over the western Gulf of Mexico at 23.7N-92.3W
IOH 24 Hr Forecast (1200Z Oct 9)...100 mph maximum sustained wind hurricane centered over the northwestern Gulf of Mexico at 27N-93.5W
IOH 48 Hr Forecacst (1200Z Oct 10)...45 mph maximum sustained wind tropical storm transitioning to a remnant frontal cyclone centered over central Mississippi at 32.5N-89.5W
IOH 72 Hr Forecast (1200Z Oct 11)...Remnant frontal low pressure centered over southeastern Kentucky at 37.5N-83.5W
AREA OF INTEREST #1...Thunderstorm activity in the north-central Caribbean Sea persists under the divergence zone of an upper vortex retrograding westward around the sprawling western Atlantic upper ridge. With this cold core upper vortex expected to disspiate by 72 hours while remaining cut-off from higher latitude cold air...the upper wind pattern will increasingly become more conducive to tropical development for any surface low pressure that does develop in the thunderstorm activity...as the western Atlantic upper ridge with its low shear and upper outflow overspreads the area in the wake of the upper vortex. However I have lowered peak 5-day odds of tropical cyclone formation to a very low 5% as the thunderstorm activity remains disorganized and a surface low pressure has not been seeded thus far. Forecast track in the outlook below is initially based on following the eastern diveregnce zone of the cut-off upper vortex in the 0600Z run of the GFS model...followed by a northward and northeastward bend in track toward the surface ridge weakness to be created by what will be the remnant frontal low pressure of Delta over the eastern United States. I am maintaining the outlook through 5 days (120 hours) as today's 0600Z GFS run shows the upper trough that will be tied to Delta's remnant being weaker...in response to a western US frontal system which is forecast to be stronger in the latest model projections (as the current upper trough incoming into the western US is stronger and more amplified than previously projected) such that the stronger warm southerly flow ahead of that frontal system will wash out the cold core upper trough tied to Delta's remnant. This will keep the western Atlantic upper ridge more intact such that wind shear for this potential disturbance could stay low in the long range.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Oct 9)...0% chance of tropical cyclone formation (just southeast of Jamaica near 17.5N-76W)
IOH 48 Hr Outlook (1200Z Oct 10)...0% chance of tropical cyclone formation (just south of Grand Cayman Island near 19N-81W)
IOH 72 Hr Outlook (1200Z Oct 11)...5% chance of tropical cyclone formation (western Cuba near 22.5N-84W)
IOH 96 Hr Outlook (1200Z Oct 12)...5% chance of tropical cyclone formation (south Florida near 25.5N-81W)
IOH 120 Hr Outlook (1200Z Oct 13)...5% chance of tropical cyclone formation (just north of the western Bahamas near 27N-78W)
AREA OF INTEREST #2...Over the last 24 hours...the National Hurricane Center has analyzed a tropical wave in the far eastern tropical Atlantic to be associated with a thunderstorm complex that was offshore of western Africa yesterday afternoon...and therefore currently has the wave axis at 24W longitude. However a much larger and stronger thunderstorm complex over western Africa from last night has moved offshore with some subtle signs of organization...and based on the curvature of the thunderstorm activity I estimate the lowest pressure of the wave to be further east near 11N-21W. Yesterday the NAVGEM model and today the CMC and GFS models suggest some development from this wave in a few days when it reaches the central tropical Atlantic...but based on the current organization and favoroable low shear and upper outflow environment of the eastern tropical Atlantic upper ridge...I forecast odds of tropical cyclone formation above 0% sooner than that. My peak odds of development of 35% over the next five days is a on the lower side as the models that do develop this wave only show a slight development signal (organization into a surface low) rather than explicitly showing a tropical cyclone forming. Over the next 96 hours this wave will generally continue westward under the influence of surface ridging in the eastern Atlantic...with a northward bend in track shown by 120 hours as the tropical wave potentially experiences a surface ridge weakness induced by a frontal zone to be left behind in the central Atlantic by the current eastern Canada frontal cyclone. A northward bend in track is also possible by that time should this system indeed develop and become tall enough to be steered by upper southwesterly flow associated with an upper trough fragment from eastern North America that will also be left behind with the frontal zone. I drop the odds of development below the 35% peak by that time as the southwesterly upper flow may induce some shear.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1200Z Oct 9)...0% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-26W)
IOH 48 Hr Outlook (1200Z Oct 10)...15% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-31W)
IOH 72 Hr Outlook (1200Z Oct 11)...25% chance of tropical cyclone formation (eastern tropical Atlantic near 11N-36W)
IOH 96 Hr Outlook (1200Z Oct 12)...35% chance of tropical cyclone formation (central tropical Atlantic near 11.5N-41W)
IOH 120 Hr Outlook (1200Z Oct 13)...20% chance of tropical cyclone formation (central tropical Atlantic near 13N-45W)
...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 Hurricane Delta...makes landfall just east of the Texas/Louisiana border at 54 hours...remnant low pressure loses identity over southeastern Missouri and ahead of incoming western US cold front by 102 hours. For area of interest #1...no tropical cyclone formation shown. For area of interest #2...tropical wave organizes into a tropical low pressure at 11N-54W at 126 hours.
0000Z ECMWF Model Run.....For Hurricane Delta...makes landfall just east of the Texas/Louisiana border at 48 hours...remnant low pressure loses identity over western Tennessee and ahead of incoming western US cold front by 96 hours. For areas of interest #1 and #2...no tropical cyclone formation shown.
0600Z GFS Model Run...For Hurricane Delta...makes landfall just east of the Texas/Louisiana border at 42 hours...remnant low pressure loses identity over western Tennessee and ahead of incoming western US cold front by 84 hours. For area of interest #1...no tropical cyclone formation shown. For area of interest #2...tropical wave organizes into a tropical low pressure at 10N-44W at 72 hours...tropical low weakens to a tropical wave near 53.5W at 114 hours. Elsewhere...tropical wave with organized low pressure spin emerges from western Africa at 126 hours...possible development as tropical wave moves across eastern tropical Atlantic suggested in the long range.
0600Z NAVGEM Model Run...For Hurricane Delta...makes landfall just east of the Texas/Louisiana border at 42 hours...remnant low pressure loses identity over Ohio and ahead of incoming western US cold front by 114 hours. For areas of interest #1 and #2...no tropical cyclone formation shown. Elsewhere...tropical wave with organized low pressure spin emerges from western Africa at 144 hours.