*******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 MAY 28 2022 9:17 PM EDT...
Eastern Pacific Tropical Storm Agatha is expected to move northward into the Oaxaca region of southeastern Mexico over the next 48 hours while bringing tropical storm to hurricane force winds... coastal storm surge... and heavy rainfall... see the NHC website at hurricanes.gov (hurricanes dot gov) for more information on Agatha as coverage on this site is focused on Atlantic basin tropical activity.
For the Atlantic basin... the remnants of Agatha to be located over southeastern Mexico... the divergence zones of upper vorticity to be left behind over Florida and upper vorticity to slowly approach from Baja California... and upper anticyclonic ridging to be located ahead of (east of) the upper vorticity will create a large region of disturbed weather with increasing rainfall spanning southeastern Mexico... the Bay of Campeche... Belize... western Central America... the western Caribbean... western Cuba... the Cayman Islands... and the western Bahamas in the days ahead. Up to two areas within this disturbed weather pattern may consolidate into areas of interest for tropical cyclone formation... see area of interest #4 and #5 sections below for more information.
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... Computer models over the last several days have been steady in predicting the formation of what is now eastern Pacific Tropical Storm Agatha. The models have also been and continue to be steady in their prediction of Agatha shifting northward into southeastern Mexico... with a corresponding northward shift in tropical development potential toward the Bay of Campeche or western Caribbean waters of the Atlantic basin. The northward shift in tropical weather away from the eastern Pacific and toward the Atlantic basin is anticipated as (1) the upper anticyclonic ridge in the region with its supportive outflow expands northward in the wake of the major upper trough currently over eastern North America as it exits stage right... (2) as eastern Pacific tropical storm Agatha tracks north due to the western North America surface ridge weakness induced by the next major upper trough sliding into the west coast of North America... with surface convergence of Agatha and its eventual remnants helping to kick off thunderstorm activity toward the Atlantic basin’s Bay of Campeche and western Caribbean waters.
Whatever broad tropical low pressure emerges in the Atlantic basin... whether it be Agatha’s remnants directly or driven by the sprawling upper anticyclonic ridge’s outflow... is expected to generally shift northeast while following the surface ridge weakness associated with the major upper trough to slide from its current position on the west coast of North America. There is a large east-west spread in the models regarding the eventual final position of the broad tropical low by the end of the five day forecast period. This is not helped as the respected GFS and ECMWF comprise the extreme ends of the spread. The eastern outlier is the GFS as it forecasts the upper vorticity approaching from Baja California and upper vorticity to be left over Florida to merge... which would increase shear and suppress upper outflow in the Bay of Campeche... and the favorable upper anticyclonic ridge in the region as a result shifts east into the western Caribbean. The western outlier is the ECMWF where enough anticyclonic outflow persists between the two lobes of upper vorticity... allowing for development in the Bay of Campeche. I will note the most recent 12Z ECMWF run has shifted east... remains to be seen if this holds in future ECMWF runs.
In the outlook below... the forecast track is down the middle of the model spread. I assign 10% peak odds of tropical cyclone formation over the next five days... lower than the NHC’s 20% (as of this writing)... as my forecast track has increased land interaction with the Yucatan peninsula. Higher odds may be possible in future updates once this system moves beyond the Yucatan peninsula and either into the southeastern Gulf of Mexico or western Caribbean... assuming wind shear from the aforementioned upper vorticity does not become too high. Regardless of tropical cyclone development or not... will be watching for the formation of prolonged rainfall across southeastern Mexico... Belize... and western Central America in the days ahead.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z May 29)... 0% chance of tropical cyclone formation (southwestern Oaxaca near 16.5N-96.5W)
IOH 48 Hr Outlook (1800Z May 30)... 0% chance of tropical cyclone formation (southwestern Oaxaca near 16.5N-96.5W)
IOH 72 Hr Outlook (1800Z May 31)… 0% chance of tropical cyclone formation (Oaxaca/Veracruz border near 17.5N-94.5W)
IOH 96 Hr Outlook (1800Z Jun 1)... 10% chance of tropical cyclone formation (southeastern Bay of Campeche near 19.5N-92W)
IOH 120 Hr Outlook (1800Z Jun 2)... 10% chance of tropical cyclone formation (western Yucatan peninsula near 20N-90.2W)
AREA OF INTEREST 5... Warm core upper ridging across the central United States is currently amplifying due to warm surface southerly flow ahead of a western United States frontal system (with the frontal system supported by upper divergence ahead of a major upper trough swinging into the west coast of North America). This upper ridging is forecast to cut-off the south part of the current eastern North America... with the cut-off upper vorticity remaining generally stationary over and near the Florida peninsula in the days ahead. The eastern divergence zone of the upper vorticity may support the formation of a subtropical or tropical disturbance... with the GFS over the last several days consistently forecasting possible tropical cyclone formation out of this setup. Over the next five days... the best window for tropical development appears to be on days 4 and 5 once the cold core upper vorticity and associated shear weakens while remaining cut-off from high-latitude cold air. I have low 10% odds of tropical cyclone formation during this timeframe as the GFS remains the only model that shows development... and wind shear may remain elevated after day 5 as upper westerly flow increases with the eventual approach of the major upper trough currently at the west coast of North America.
Regarding impact to land areas... increased rainfall may develop over the western Bahamas over the next 72 hours (3 days) regardless of tropical cyclone formation or not.
******Infohurricanes.com outlook. Visit hurricanes.gov (hurricanes dot gov) for official outlook***********
IOH 24 Hr Outlook (1800Z May 29)...0% chance of tropical cyclone formation (east coast of Florida near 27N-80.5W)
IOH 48 Hr Outlook (1800Z May 30)...0% chance of tropical cyclone formation (east coast of Florida near 27N-80.5W)
IOH 72 Hr Outlook (1800Z May 31)...0% chance of tropical cyclone formation (offshore of the Florida east coast near 28N-79W)
IOH 96 Hr Outlook (1800Z Jun 1)...5% chance of tropical cyclone formation (western Atlantic near 28N-76W)
IOH 120 Hr Outlook (1800Z Jun 2)...10% chance of tropical cyclone formation (western Atlantic near 29N-75W)
...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 area of interest #4... eastern Pacific tropical storm Agatha makes landfall on the Oaxaca province coast of Mexico at 60 hours... at 108 hours a broad low pressure center containing the remnants of Agatha becomes defined on the Bay of Campeche Mexican coast near the Veracruz/Tabasco border... from 120 to 150 hours the broad low pressure shifts east-northeast toward Guatemala and the Yucatan peninsula while lacking a tightly-defined center
**For area of interest #5... no development shown
0000Z ECMWF Model Run...
**For area of interest #4...eastern Pacific tropical storm Agatha makes landfall in Mexico over southwestern Oaxaca province at 72 hours... broad low pressure area containing the remnants of Agatha lifts north into Bay of Campeche by 120 hours... tropical cyclone formation suggested at 19.5N-94W at 144 hours
**For area of interest #5... no development shown
0600Z GFS Model Run...
**For area of interest #4... the center of eastern Pacific Tropical Storm Agatha reaches the western Oaxaca coast of Mexico at 63 hours... center drifts slowly east along the Oaxaca coast and dissipates through 84 hours while a larger low pressure (supported by outflow of upper anticyclonic ridge in the region) develops around the remnants of Agatha and consumes it... upper vorticity over Florida splits upper anticyclonic ridge into two centers by 102 hours which causes the broad low pressure to split into two areas (western Caribbean and Bay of Campeche)... shear and outflow suppression from shortwave upper trough slowly arriving from Baja California suppresses Bay of Campeche tropical development while the western Caribbean center becomes a tropical depression south of western Cuba near 20N-84.5W at 129 hours.
**For area of interest #5... southern part of current upper trough over eastern North America becomes cut-off upper vorticity parked over the Florida peninsula from 27 to 84 hours... surface trough over western Bahamas supported by the divergence zone of the upper vorticity becomes established by 99 hours... surface trough evolves into surface low near 27.5N-74.5W by 120 hours... possible tropical depression suggested near 29N-74.5W at 129 hours
0600Z NAVGEM Model Run...
** For area of interest #4... eastern Pacific tropical storm Agatha makes landfall near the Oaxaca/Guerrero border at 72 hours... through 156 hours a broad low pressure area containing the remnants of Agatha shifts east-northeast toward Guatemala and the Yucatan peninsula while lacking a tightly-defined center
**For area of interest #5...no development shown