*******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.**********
…TUESDAY MAY 31 2022 10:48 PM EDT...
A broad tropical low pressure system containing the remnants of what was eastern Pacific Hurricane Agatha is expected to lift northeast and bring possible tropical storm conditions to western Cuba… south Florida… and the western Bahamas late this week and into the weekend. See area of Interest #4 section below for more details. Elsewhere… the surface trough currently in the vicinity of the Florida east coast and western Bahamas will only have a narrow window of time to develop in a pocket of low wind shear in about 48 hours as it moves eastward into open waters… see area of Interest #5 section below for details.
New to this site this year… I will be sequentially numbering up areas of interest for possible Atlantic tropical development. In this scheme… will reset back to #1 at the start of next year (January 2023). The current two areas of interest in this blog post are designated #4 and #5 as I designated the first three of this year earlier this month (in previous birdseye view posts on the home page). This scheme is to reduce confusion as Atlantic tropical activity increases during the peak of the hurricane season… when multiple simultaneous areas of interest begin and end which previously required shuffling around the area of interest numbers from update to update.
AREA OF INTEREST 4… The rugged southeastern Mexican terrain in Oaxaca and southern Veracruz provinces have in the last 24 hours rapidly torn apart the surface spin of what was eastern Pacific Hurricane Agatha. However satellite animation reveals a broad mid-level remnant low pressure spin currently over the Bay of Campeche coast of Mexico. The outflow of the upper anticyclonic ridge in the region has supported additional thunderstorm activity and a second mid-level low pressure spin seen in the western edge of the Caribbean. Dual regions of mid-level vorticity are confirmed on the CIMSS 850 mb vorticity product (http://tropic.ssec.wisc.edu/real-time/windmain.php?basin=atlantic&sat=wg8&prod=vor&zoom=&time=). At the surface the NHC TAFB analysis notes a surface trough in the Bay of Campeche as annotated in the above birdseye view chart. We still have a long way to go before this complex broad low pressure area can become a tropical cyclone as one of the mid-level spins will have to become the dominant… and the surface trough will have to be stacked with the dominant mid-level spin and strengthen into a closed circular surface low pressure spin.
The broad low pressure system is expected to track northeast while following the surface ridge weakness associated with the current central North America frontal system… as the frontal system and its supporting upper trough shift east with time. In the upper levels… vorticity from central Mexico has linked with upper vorticity over Florida… resulting in a southwest-to-northeast upper vorticity axis that will also help steer this system northeast. The longer term model consensus through day 5 continues to shift north… with the CMC… NAVGEM… and ECMWF showing this system cross the Florida peninsula. The GFS is the southern outlier with a long-term track just south of the Florida peninsula… followed by a western Bahamas crossover. My update long-range forecast track in the outlook below is between the southern GFS and the CMC-NAVGEM-ECMWF northern cluster. I have not selected the northern cluster forecast track at this time as it will be harder for development further north due to higher levels of shear in association with the aforementioned upper vorticity axis.
Regarding the probability of tropical cyclone formation over the next five days… the outlook below initially starts with 0% odds and then gradually ramps up to 40% by day 5 to give this system time to move away from the Yucatan peninsula and into warm southeastern Gulf of Mexico water… and to give time for the multiple mid-level spins to coalesce and spawn a singular surface center beneath. These are higher odds than the previous outlook as the models insist on eventual tropical cyclone formation. However my odds of development remain below the NHC’s 70% by day 5 (as of this writing) as I remain skeptical of the shear levels to be induced by the axis of upper vorticity. As this system begins to accelerate northeast while chasing the surface ridge weakness mentioned in the previous paragraph… that might help reduce the shear as the direction of travel would be aligned with the direction of the shearing upper winds. Even if this is the case… this system may still suffer from an elongated structure that would technically not count it as a tropical cyclone as cyclones by scientific definition require a circular structure with a well-defined center. The elongation is possible as the supportive upper divergence region of the upper vorticity axis will also be elongated.
Whether or not this system becomes elongated or circular… it has potential to strengthen due to the aforementioned upper divergence of the upper vorticity axis and anticyclonic outflow of the upper ridge to be located ahead of the upper vorticity. In an elongated state… note that this system may bring tropical storm conditions and be classified by the NHC as a potential tropical cyclone (PTC) in order to issue tropical storm warnings. Whether we have PTC or tropical storm status… the following is the expected timing for possible gusty winds… heavy rain… and coastal sea swells in the days ahead:
(1) For Friday and Saturday: Western Cuba… south Florida and the Florida Keys.
(2) For Sunday: the western Bahamas
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Jun 1)… 0% chance of tropical cyclone formation (southeastern Bay of Campeche near 19.5N-92W)
IOH 48 Hr Outlook (1800Z Jun 2)… 0% chance of tropical cyclone formation (western Yucatan peninsula near 20N-90.2W)
IOH 72 Hr Outlook (1800Z Jun 3)… 15% chance of tropical cyclone formation (northeast corner of the Yucatan peninsula near 21N-87W)
IOH 96 Hr Outlook (1800Z Jun 4)… 25% chance of tropical cyclone formation (offshore of northwest Cuba and southwest of the Florida Keys near 23.5N-82.8W)
IOH 120 Hr Outlook (1800Z Jun 5)… 40% chance of tropical cyclone formation (western Bahamas near 26N-78W)
AREA OF INTEREST 5… The eastern divergence zone of upper vorticity over Florida continues to sustain a surface trough of low pressure offshore. Upper westerly shearing winds also induced by the upper vorticity are keeping the thickest of the clouds east of the surface trough. Over the next few days… the best window for tropical cyclone development in association with this system appears to be on day 2 once the cold core upper vorticity and associated shear weakens while remaining cut-off from high-latitude cold air. However because this system’s cloud mass is less organized than 24 hours ago and because the computer model support remains weak…
I have lowered peak odds of tropical cyclone formation to 10%. Low odds are also sensible
as wind shear will ramp back up just after day 2 as upper westerly flow increases with the eventual approach of the major upper trough currently over central North America.
By day 3 the westerly flow ahead of the upper trough will have carried this system east-northeast into water temps below 26 deg C… and so I drop development odds to 0%
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z Jun 1)…0% chance of tropical cyclone formation (western Atlantic near 29N-75.5W)
IOH 48 Hr Outlook (1800Z Jun 2)…10% chance of tropical cyclone formation (western Atlantic near 29N-74.5W)
IOH 72 Hr Outlook (1800Z Jun 3)…0% chance of tropical cyclone formation (west-southwest of Bermuda near 30N-68.5W)
...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 #4... At 42 hours a broad low pressure area containing the remnants of Agatha becomes defined inland over the northern Guatemala/Mexico border... broad low pressure lifts northeast to the west edge of the Caribbean through 60 hours and passes just northwest of Cuba’s west tip through 72 hours... through 90 hours the circulation becomes elongated SW-NE spanning from the western Caribbean through south Florida... northeast end of the elongated circulation continues northeast into the western Atlantic where it becomes a tropical cyclone near 30.5N-75W at 120 hours.
1200Z ECMWF Model Run...
**For area of interest #4... At 48 hours a broad low pressure area containing the remnants of Agatha becomes defined inland over the Yucatan peninsula... continues northeast across much of the Florida peninsula as a stregthening but elongated circulation through 96 hours... intensifies into a large tropical cyclone offshore of the southeastern US near 30.2N-77.5W by 120 hours...
1200Z GFS Model Run...
**For area of interest #4… through 21 hours a broad low pressure area containing the remnants of Agatha becomes elongated NW-SE spanning from the Bay of Campeche to the western Caribbean… through 69 hours the broad low pressure lifts northeast into the western Caribbean while featuring multiple centers… through 102 hours the broad low pressure becomes elongated SW-NE spanning from the western Caribbean to the Florida Straits (between Cuba and Florida)… northeast end of the elongated circulation passes through the western Bahamas and becomes a tropical cyclone just northeast of the western Bahamas by 129 hours.
**For area of interest #5… Current surface trough just offshore of the east Florida coast and supporting upper vorticity move east-northeast…surface trough evolves to a surface low near 29.8N-70W at 57 hours… surface low passes just south of Bermuda at 81 hours… surface low weakens to a trough at 120 hours while located near 33.5N-55W
1200Z NAVGEM Model Run...
** For area of interest #4… at 30 hours a broad low pressure area containing the remnants of Agatha becomes defined inland over the Guatemala/Belize border… shifts northeast and becomes a tropical cyclone while reaching the northeast corner of the Yucatan peninsula at 72 hours… makes landfall over the southwestern Florida peninsula coast at 102 hours… enters the Atlantic from east-central Florida at 114 hours and strengthens further at 120 hours while located offshore of the southeast US near 30.5N-77.5W